// SPDX-License-Identifier: GPL-2.0
/*
 * drivers/i2c/busses/i2c-tegra.c
 *
 * Copyright (C) 2010 Google, Inc.
 * Author: Colin Cross <ccross@android.com>
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>

#define BYTES_PER_FIFO_WORD 4

#define I2C_CNFG                                0x000
#define I2C_CNFG_DEBOUNCE_CNT_SHIFT             12
#define I2C_CNFG_PACKET_MODE_EN                 BIT(10)
#define I2C_CNFG_NEW_MASTER_FSM                 BIT(11)
#define I2C_CNFG_MULTI_MASTER_MODE              BIT(17)
#define I2C_STATUS                              0x01C
#define I2C_SL_CNFG                             0x020
#define I2C_SL_CNFG_NACK                        BIT(1)
#define I2C_SL_CNFG_NEWSL                       BIT(2)
#define I2C_SL_ADDR1                            0x02c
#define I2C_SL_ADDR2                            0x030
#define I2C_TX_FIFO                             0x050
#define I2C_RX_FIFO                             0x054
#define I2C_PACKET_TRANSFER_STATUS              0x058
#define I2C_FIFO_CONTROL                        0x05c
#define I2C_FIFO_CONTROL_TX_FLUSH               BIT(1)
#define I2C_FIFO_CONTROL_RX_FLUSH               BIT(0)
#define I2C_FIFO_CONTROL_TX_TRIG(x)             (((x) - 1) << 5)
#define I2C_FIFO_CONTROL_RX_TRIG(x)             (((x) - 1) << 2)
#define I2C_FIFO_STATUS                         0x060
#define I2C_FIFO_STATUS_TX_MASK                 0xF0
#define I2C_FIFO_STATUS_TX_SHIFT                4
#define I2C_FIFO_STATUS_RX_MASK                 0x0F
#define I2C_FIFO_STATUS_RX_SHIFT                0
#define I2C_INT_MASK                            0x064
#define I2C_INT_STATUS                          0x068
#define I2C_INT_BUS_CLR_DONE                    BIT(11)
#define I2C_INT_PACKET_XFER_COMPLETE            BIT(7)
#define I2C_INT_NO_ACK                          BIT(3)
#define I2C_INT_ARBITRATION_LOST                BIT(2)
#define I2C_INT_TX_FIFO_DATA_REQ                BIT(1)
#define I2C_INT_RX_FIFO_DATA_REQ                BIT(0)
#define I2C_CLK_DIVISOR                         0x06c
#define I2C_CLK_DIVISOR_STD_FAST_MODE_SHIFT     16

#define DVC_CTRL_REG1                           0x000
#define DVC_CTRL_REG1_INTR_EN                   BIT(10)
#define DVC_CTRL_REG3                           0x008
#define DVC_CTRL_REG3_SW_PROG                   BIT(26)
#define DVC_CTRL_REG3_I2C_DONE_INTR_EN          BIT(30)
#define DVC_STATUS                              0x00c
#define DVC_STATUS_I2C_DONE_INTR                BIT(30)

#define I2C_ERR_NONE                            0x00
#define I2C_ERR_NO_ACK                          BIT(0)
#define I2C_ERR_ARBITRATION_LOST                BIT(1)
#define I2C_ERR_UNKNOWN_INTERRUPT               BIT(2)
#define I2C_ERR_RX_BUFFER_OVERFLOW              BIT(3)

#define PACKET_HEADER0_HEADER_SIZE_SHIFT        28
#define PACKET_HEADER0_PACKET_ID_SHIFT          16
#define PACKET_HEADER0_CONT_ID_SHIFT            12
#define PACKET_HEADER0_PROTOCOL_I2C             BIT(4)

#define I2C_HEADER_CONT_ON_NAK                  BIT(21)
#define I2C_HEADER_READ                         BIT(19)
#define I2C_HEADER_10BIT_ADDR                   BIT(18)
#define I2C_HEADER_IE_ENABLE                    BIT(17)
#define I2C_HEADER_REPEAT_START                 BIT(16)
#define I2C_HEADER_CONTINUE_XFER                BIT(15)
#define I2C_HEADER_SLAVE_ADDR_SHIFT             1

#define I2C_BUS_CLEAR_CNFG                      0x084
#define I2C_BC_SCLK_THRESHOLD                   9
#define I2C_BC_SCLK_THRESHOLD_SHIFT             16
#define I2C_BC_STOP_COND                        BIT(2)
#define I2C_BC_TERMINATE                        BIT(1)
#define I2C_BC_ENABLE                           BIT(0)
#define I2C_BUS_CLEAR_STATUS                    0x088
#define I2C_BC_STATUS                           BIT(0)

#define I2C_CONFIG_LOAD                         0x08C
#define I2C_MSTR_CONFIG_LOAD                    BIT(0)

#define I2C_CLKEN_OVERRIDE                      0x090
#define I2C_MST_CORE_CLKEN_OVR                  BIT(0)

#define I2C_CONFIG_LOAD_TIMEOUT                 1000000

#define I2C_MST_FIFO_CONTROL                    0x0b4
#define I2C_MST_FIFO_CONTROL_RX_FLUSH           BIT(0)
#define I2C_MST_FIFO_CONTROL_TX_FLUSH           BIT(1)
#define I2C_MST_FIFO_CONTROL_RX_TRIG(x)         (((x) - 1) <<  4)
#define I2C_MST_FIFO_CONTROL_TX_TRIG(x)         (((x) - 1) << 16)

#define I2C_MST_FIFO_STATUS                     0x0b8
#define I2C_MST_FIFO_STATUS_RX_MASK             0xff
#define I2C_MST_FIFO_STATUS_RX_SHIFT            0
#define I2C_MST_FIFO_STATUS_TX_MASK             0xff0000
#define I2C_MST_FIFO_STATUS_TX_SHIFT            16

#define I2C_INTERFACE_TIMING_0                  0x94
#define I2C_THIGH_SHIFT                         8
#define I2C_INTERFACE_TIMING_1                  0x98

#define I2C_STANDARD_MODE                       100000
#define I2C_FAST_MODE                           400000
#define I2C_FAST_PLUS_MODE                      1000000

/* Packet header size in bytes */
#define I2C_PACKET_HEADER_SIZE                  12

/*
 * Upto I2C_PIO_MODE_MAX_LEN bytes, controller will use PIO mode,
 * above this, controller will use DMA to fill FIFO.
 * MAX PIO len is 20 bytes excluding packet header.
 */
#define I2C_PIO_MODE_MAX_LEN                    32

/*
 * msg_end_type: The bus control which need to be send at end of transfer.
 * @MSG_END_STOP: Send stop pulse at end of transfer.
 * @MSG_END_REPEAT_START: Send repeat start at end of transfer.
 * @MSG_END_CONTINUE: The following on message is coming and so do not send
 *              stop or repeat start.
 */
enum msg_end_type {
        MSG_END_STOP,
        MSG_END_REPEAT_START,
        MSG_END_CONTINUE,
};

/**
 * struct tegra_i2c_hw_feature : Different HW support on Tegra
 * @has_continue_xfer_support: Continue transfer supports.
 * @has_per_pkt_xfer_complete_irq: Has enable/disable capability for transfer
 *              complete interrupt per packet basis.
 * @has_single_clk_source: The I2C controller has single clock source. Tegra30
 *              and earlier SoCs have two clock sources i.e. div-clk and
 *              fast-clk.
 * @has_config_load_reg: Has the config load register to load the new
 *              configuration.
 * @clk_divisor_hs_mode: Clock divisor in HS mode.
 * @clk_divisor_std_mode: Clock divisor in standard mode. It is
 *              applicable if there is no fast clock source i.e. single clock
 *              source.
 * @clk_divisor_fast_mode: Clock divisor in fast mode. It is
 *              applicable if there is no fast clock source i.e. single clock
 *              source.
 * @clk_divisor_fast_plus_mode: Clock divisor in fast mode plus. It is
 *              applicable if there is no fast clock source (i.e. single
 *              clock source).
 * @has_multi_master_mode: The I2C controller supports running in single-master
 *              or multi-master mode.
 * @has_slcg_override_reg: The I2C controller supports a register that
 *              overrides the second level clock gating.
 * @has_mst_fifo: The I2C controller contains the new MST FIFO interface that
 *              provides additional features and allows for longer messages to
 *              be transferred in one go.
 * @quirks: i2c adapter quirks for limiting write/read transfer size and not
 *              allowing 0 length transfers.
 * @supports_bus_clear: Bus Clear support to recover from bus hang during
 *              SDA stuck low from device for some unknown reasons.
 * @has_apb_dma: Support of APBDMA on corresponding Tegra chip.
 * @tlow_std_mode: Low period of the clock in standard mode.
 * @thigh_std_mode: High period of the clock in standard mode.
 * @tlow_fast_fastplus_mode: Low period of the clock in fast/fast-plus modes.
 * @thigh_fast_fastplus_mode: High period of the clock in fast/fast-plus modes.
 * @setup_hold_time_std_mode: Setup and hold time for start and stop conditions
 *              in standard mode.
 * @setup_hold_time_fast_fast_plus_mode: Setup and hold time for start and stop
 *              conditions in fast/fast-plus modes.
 * @setup_hold_time_hs_mode: Setup and hold time for start and stop conditions
 *              in HS mode.
 * @has_interface_timing_reg: Has interface timing register to program the tuned
 *              timing settings.
 */
struct tegra_i2c_hw_feature {
        bool has_continue_xfer_support;
        bool has_per_pkt_xfer_complete_irq;
        bool has_single_clk_source;
        bool has_config_load_reg;
        int clk_divisor_hs_mode;
        int clk_divisor_std_mode;
        int clk_divisor_fast_mode;
        u16 clk_divisor_fast_plus_mode;
        bool has_multi_master_mode;
        bool has_slcg_override_reg;
        bool has_mst_fifo;
        const struct i2c_adapter_quirks *quirks;
        bool supports_bus_clear;
        bool has_apb_dma;
        u8 tlow_std_mode;
        u8 thigh_std_mode;
        u8 tlow_fast_fastplus_mode;
        u8 thigh_fast_fastplus_mode;
        u32 setup_hold_time_std_mode;
        u32 setup_hold_time_fast_fast_plus_mode;
        u32 setup_hold_time_hs_mode;
        bool has_interface_timing_reg;
};

/**
 * struct tegra_i2c_dev - per device I2C context
 * @dev: device reference for power management
 * @hw: Tegra I2C HW feature
 * @adapter: core I2C layer adapter information
 * @div_clk: clock reference for div clock of I2C controller
 * @fast_clk: clock reference for fast clock of I2C controller
 * @rst: reset control for the I2C controller
 * @base: ioremapped registers cookie
 * @base_phys: physical base address of the I2C controller
 * @cont_id: I2C controller ID, used for packet header
 * @irq: IRQ number of transfer complete interrupt
 * @irq_disabled: used to track whether or not the interrupt is enabled
 * @is_dvc: identifies the DVC I2C controller, has a different register layout
 * @msg_complete: transfer completion notifier
 * @msg_err: error code for completed message
 * @msg_buf: pointer to current message data
 * @msg_buf_remaining: size of unsent data in the message buffer
 * @msg_read: identifies read transfers
 * @bus_clk_rate: current I2C bus clock rate
 * @clk_divisor_non_hs_mode: clock divider for non-high-speed modes
 * @is_multimaster_mode: track if I2C controller is in multi-master mode
 * @xfer_lock: lock to serialize transfer submission and processing
 * @tx_dma_chan: DMA transmit channel
 * @rx_dma_chan: DMA receive channel
 * @dma_phys: handle to DMA resources
 * @dma_buf: pointer to allocated DMA buffer
 * @dma_buf_size: DMA buffer size
 * @is_curr_dma_xfer: indicates active DMA transfer
 * @dma_complete: DMA completion notifier
 */
struct tegra_i2c_dev {
        struct device *dev;
        const struct tegra_i2c_hw_feature *hw;
        struct i2c_adapter adapter;
        struct clk *div_clk;
        struct clk *fast_clk;
        struct reset_control *rst;
        void __iomem *base;
        phys_addr_t base_phys;
        int cont_id;
        int irq;
        bool irq_disabled;
        int is_dvc;
        struct completion msg_complete;
        int msg_err;
        u8 *msg_buf;
        size_t msg_buf_remaining;
        int msg_read;
        u32 bus_clk_rate;
        u16 clk_divisor_non_hs_mode;
        bool is_multimaster_mode;
        /* xfer_lock: lock to serialize transfer submission and processing */
        spinlock_t xfer_lock;
        struct dma_chan *tx_dma_chan;
        struct dma_chan *rx_dma_chan;
        dma_addr_t dma_phys;
        u32 *dma_buf;
        unsigned int dma_buf_size;
        bool is_curr_dma_xfer;
        struct completion dma_complete;
};

static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
                       unsigned long reg)
{
        writel(val, i2c_dev->base + reg);
}

static u32 dvc_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
{
        return readl(i2c_dev->base + reg);
}

/*
 * i2c_writel and i2c_readl will offset the register if necessary to talk
 * to the I2C block inside the DVC block
 */
static unsigned long tegra_i2c_reg_addr(struct tegra_i2c_dev *i2c_dev,
                                        unsigned long reg)
{
        if (i2c_dev->is_dvc)
                reg += (reg >= I2C_TX_FIFO) ? 0x10 : 0x40;
        return reg;
}

static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
                       unsigned long reg)
{
        writel(val, i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));

        /* Read back register to make sure that register writes completed */
        if (reg != I2C_TX_FIFO)
                readl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
}

static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
{
        return readl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
}

static void i2c_writesl(struct tegra_i2c_dev *i2c_dev, void *data,
                        unsigned long reg, int len)
{
        writesl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len);
}

static void i2c_readsl(struct tegra_i2c_dev *i2c_dev, void *data,
                       unsigned long reg, int len)
{
        readsl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len);
}

static void tegra_i2c_mask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
{
        u32 int_mask;

        int_mask = i2c_readl(i2c_dev, I2C_INT_MASK) & ~mask;
        i2c_writel(i2c_dev, int_mask, I2C_INT_MASK);
}

static void tegra_i2c_unmask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
{
        u32 int_mask;

        int_mask = i2c_readl(i2c_dev, I2C_INT_MASK) | mask;
        i2c_writel(i2c_dev, int_mask, I2C_INT_MASK);
}

static void tegra_i2c_dma_complete(void *args)
{
        struct tegra_i2c_dev *i2c_dev = args;

        complete(&i2c_dev->dma_complete);
}

static int tegra_i2c_dma_submit(struct tegra_i2c_dev *i2c_dev, size_t len)
{
        struct dma_async_tx_descriptor *dma_desc;
        enum dma_transfer_direction dir;
        struct dma_chan *chan;

        dev_dbg(i2c_dev->dev, "starting DMA for length: %zu\n", len);
        reinit_completion(&i2c_dev->dma_complete);
        dir = i2c_dev->msg_read ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV;
        chan = i2c_dev->msg_read ? i2c_dev->rx_dma_chan : i2c_dev->tx_dma_chan;
        dma_desc = dmaengine_prep_slave_single(chan, i2c_dev->dma_phys,
                                               len, dir, DMA_PREP_INTERRUPT |
                                               DMA_CTRL_ACK);
        if (!dma_desc) {
                dev_err(i2c_dev->dev, "failed to get DMA descriptor\n");
                return -EINVAL;
        }

        dma_desc->callback = tegra_i2c_dma_complete;
        dma_desc->callback_param = i2c_dev;
        dmaengine_submit(dma_desc);
        dma_async_issue_pending(chan);
        return 0;
}

static void tegra_i2c_release_dma(struct tegra_i2c_dev *i2c_dev)
{
        if (i2c_dev->dma_buf) {
                dma_free_coherent(i2c_dev->dev, i2c_dev->dma_buf_size,
                                  i2c_dev->dma_buf, i2c_dev->dma_phys);
                i2c_dev->dma_buf = NULL;
        }

        if (i2c_dev->tx_dma_chan) {
                dma_release_channel(i2c_dev->tx_dma_chan);
                i2c_dev->tx_dma_chan = NULL;
        }

        if (i2c_dev->rx_dma_chan) {
                dma_release_channel(i2c_dev->rx_dma_chan);
                i2c_dev->rx_dma_chan = NULL;
        }
}

static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
{
        struct dma_chan *chan;
        u32 *dma_buf;
        dma_addr_t dma_phys;
        int err;

        if (!i2c_dev->hw->has_apb_dma)
                return 0;

        if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA)) {
                dev_dbg(i2c_dev->dev, "Support for APB DMA not enabled!\n");
                return 0;
        }

        chan = dma_request_slave_channel_reason(i2c_dev->dev, "rx");
        if (IS_ERR(chan)) {
                err = PTR_ERR(chan);
                goto err_out;
        }

        i2c_dev->rx_dma_chan = chan;

        chan = dma_request_slave_channel_reason(i2c_dev->dev, "tx");
        if (IS_ERR(chan)) {
                err = PTR_ERR(chan);
                goto err_out;
        }

        i2c_dev->tx_dma_chan = chan;

        dma_buf = dma_alloc_coherent(i2c_dev->dev, i2c_dev->dma_buf_size,
                                     &dma_phys, GFP_KERNEL | __GFP_NOWARN);
        if (!dma_buf) {
                dev_err(i2c_dev->dev, "failed to allocate the DMA buffer\n");
                err = -ENOMEM;
                goto err_out;
        }

        i2c_dev->dma_buf = dma_buf;
        i2c_dev->dma_phys = dma_phys;
        return 0;

err_out:
        tegra_i2c_release_dma(i2c_dev);
        if (err != -EPROBE_DEFER) {
                dev_err(i2c_dev->dev, "cannot use DMA: %d\n", err);
                dev_err(i2c_dev->dev, "falling back to PIO\n");
                return 0;
        }

        return err;
}

static int tegra_i2c_flush_fifos(struct tegra_i2c_dev *i2c_dev)
{
        unsigned long timeout = jiffies + HZ;
        unsigned int offset;
        u32 mask, val;

        if (i2c_dev->hw->has_mst_fifo) {
                mask = I2C_MST_FIFO_CONTROL_TX_FLUSH |
                       I2C_MST_FIFO_CONTROL_RX_FLUSH;
                offset = I2C_MST_FIFO_CONTROL;
        } else {
                mask = I2C_FIFO_CONTROL_TX_FLUSH |
                       I2C_FIFO_CONTROL_RX_FLUSH;
                offset = I2C_FIFO_CONTROL;
        }

        val = i2c_readl(i2c_dev, offset);
        val |= mask;
        i2c_writel(i2c_dev, val, offset);

        while (i2c_readl(i2c_dev, offset) & mask) {
                if (time_after(jiffies, timeout)) {
                        dev_warn(i2c_dev->dev, "timeout waiting for fifo flush\n");
                        return -ETIMEDOUT;
                }
                usleep_range(1000, 2000);
        }
        return 0;
}

static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
{
        u32 val;
        int rx_fifo_avail;
        u8 *buf = i2c_dev->msg_buf;
        size_t buf_remaining = i2c_dev->msg_buf_remaining;
        int words_to_transfer;

        /*
         * Catch overflow due to message fully sent
         * before the check for RX FIFO availability.
         */
        if (WARN_ON_ONCE(!(i2c_dev->msg_buf_remaining)))
                return -EINVAL;

        if (i2c_dev->hw->has_mst_fifo) {
                val = i2c_readl(i2c_dev, I2C_MST_FIFO_STATUS);
                rx_fifo_avail = (val & I2C_MST_FIFO_STATUS_RX_MASK) >>
                        I2C_MST_FIFO_STATUS_RX_SHIFT;
        } else {
                val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
                rx_fifo_avail = (val & I2C_FIFO_STATUS_RX_MASK) >>
                        I2C_FIFO_STATUS_RX_SHIFT;
        }

        /* Rounds down to not include partial word at the end of buf */
        words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
        if (words_to_transfer > rx_fifo_avail)
                words_to_transfer = rx_fifo_avail;

        i2c_readsl(i2c_dev, buf, I2C_RX_FIFO, words_to_transfer);

        buf += words_to_transfer * BYTES_PER_FIFO_WORD;
        buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
        rx_fifo_avail -= words_to_transfer;

        /*
         * If there is a partial word at the end of buf, handle it manually to
         * prevent overwriting past the end of buf
         */
        if (rx_fifo_avail > 0 && buf_remaining > 0) {
                /*
                 * buf_remaining > 3 check not needed as rx_fifo_avail == 0
                 * when (words_to_transfer was > rx_fifo_avail) earlier
                 * in this function.
                 */
                val = i2c_readl(i2c_dev, I2C_RX_FIFO);
                val = cpu_to_le32(val);
                memcpy(buf, &val, buf_remaining);
                buf_remaining = 0;
                rx_fifo_avail--;
        }

        /* RX FIFO must be drained, otherwise it's an Overflow case. */
        if (WARN_ON_ONCE(rx_fifo_avail))
                return -EINVAL;

        i2c_dev->msg_buf_remaining = buf_remaining;
        i2c_dev->msg_buf = buf;

        return 0;
}

static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
{
        u32 val;
        int tx_fifo_avail;
        u8 *buf = i2c_dev->msg_buf;
        size_t buf_remaining = i2c_dev->msg_buf_remaining;
        int words_to_transfer;

        if (i2c_dev->hw->has_mst_fifo) {
                val = i2c_readl(i2c_dev, I2C_MST_FIFO_STATUS);
                tx_fifo_avail = (val & I2C_MST_FIFO_STATUS_TX_MASK) >>
                        I2C_MST_FIFO_STATUS_TX_SHIFT;
        } else {
                val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
                tx_fifo_avail = (val & I2C_FIFO_STATUS_TX_MASK) >>
                        I2C_FIFO_STATUS_TX_SHIFT;
        }

        /* Rounds down to not include partial word at the end of buf */
        words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;

        /* It's very common to have < 4 bytes, so optimize that case. */
        if (words_to_transfer) {
                if (words_to_transfer > tx_fifo_avail)
                        words_to_transfer = tx_fifo_avail;

                /*
                 * Update state before writing to FIFO.  If this casues us
                 * to finish writing all bytes (AKA buf_remaining goes to 0) we
                 * have a potential for an interrupt (PACKET_XFER_COMPLETE is
                 * not maskable).  We need to make sure that the isr sees
                 * buf_remaining as 0 and doesn't call us back re-entrantly.
                 */
                buf_remaining -= words_to_transfer * BYTES_PER_FIFO_WORD;
                tx_fifo_avail -= words_to_transfer;
                i2c_dev->msg_buf_remaining = buf_remaining;
                i2c_dev->msg_buf = buf +
                        words_to_transfer * BYTES_PER_FIFO_WORD;
                barrier();

                i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);

                buf += words_to_transfer * BYTES_PER_FIFO_WORD;
        }

        /*
         * If there is a partial word at the end of buf, handle it manually to
         * prevent reading past the end of buf, which could cross a page
         * boundary and fault.
         */
        if (tx_fifo_avail > 0 && buf_remaining > 0) {
                /*
                 * buf_remaining > 3 check not needed as tx_fifo_avail == 0
                 * when (words_to_transfer was > tx_fifo_avail) earlier
                 * in this function for non-zero words_to_transfer.
                 */
                memcpy(&val, buf, buf_remaining);
                val = le32_to_cpu(val);

                /* Again update before writing to FIFO to make sure isr sees. */
                i2c_dev->msg_buf_remaining = 0;
                i2c_dev->msg_buf = NULL;
                barrier();

                i2c_writel(i2c_dev, val, I2C_TX_FIFO);
        }

        return 0;
}

/*
 * One of the Tegra I2C blocks is inside the DVC (Digital Voltage Controller)
 * block.  This block is identical to the rest of the I2C blocks, except that
 * it only supports master mode, it has registers moved around, and it needs
 * some extra init to get it into I2C mode.  The register moves are handled
 * by i2c_readl and i2c_writel
 */
static void tegra_dvc_init(struct tegra_i2c_dev *i2c_dev)
{
        u32 val;

        val = dvc_readl(i2c_dev, DVC_CTRL_REG3);
        val |= DVC_CTRL_REG3_SW_PROG;
        val |= DVC_CTRL_REG3_I2C_DONE_INTR_EN;
        dvc_writel(i2c_dev, val, DVC_CTRL_REG3);

        val = dvc_readl(i2c_dev, DVC_CTRL_REG1);
        val |= DVC_CTRL_REG1_INTR_EN;
        dvc_writel(i2c_dev, val, DVC_CTRL_REG1);
}

static int tegra_i2c_runtime_resume(struct device *dev)
{
        struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);
        int ret;

        ret = pinctrl_pm_select_default_state(i2c_dev->dev);
        if (ret)
                return ret;

        if (!i2c_dev->hw->has_single_clk_source) {
                ret = clk_enable(i2c_dev->fast_clk);
                if (ret < 0) {
                        dev_err(i2c_dev->dev,
                                "Enabling fast clk failed, err %d\n", ret);
                        return ret;
                }
        }

        ret = clk_enable(i2c_dev->div_clk);
        if (ret < 0) {
                dev_err(i2c_dev->dev,
                        "Enabling div clk failed, err %d\n", ret);
                clk_disable(i2c_dev->fast_clk);
                return ret;
        }

        return 0;
}

static int tegra_i2c_runtime_suspend(struct device *dev)
{
        struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);

        clk_disable(i2c_dev->div_clk);
        if (!i2c_dev->hw->has_single_clk_source)
                clk_disable(i2c_dev->fast_clk);

        return pinctrl_pm_select_idle_state(i2c_dev->dev);
}

static int tegra_i2c_wait_for_config_load(struct tegra_i2c_dev *i2c_dev)
{
        unsigned long reg_offset;
        void __iomem *addr;
        u32 val;
        int err;

        if (i2c_dev->hw->has_config_load_reg) {
                reg_offset = tegra_i2c_reg_addr(i2c_dev, I2C_CONFIG_LOAD);
                addr = i2c_dev->base + reg_offset;
                i2c_writel(i2c_dev, I2C_MSTR_CONFIG_LOAD, I2C_CONFIG_LOAD);
                if (in_interrupt())
                        err = readl_poll_timeout_atomic(addr, val, val == 0,
                                                        1000,
                                                        I2C_CONFIG_LOAD_TIMEOUT);
                else
                        err = readl_poll_timeout(addr, val, val == 0, 1000,
                                                 I2C_CONFIG_LOAD_TIMEOUT);

                if (err) {
                        dev_warn(i2c_dev->dev,
                                 "timeout waiting for config load\n");
                        return err;
                }
        }

        return 0;
}

static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev, bool clk_reinit)
{
        u32 val;
        int err;
        u32 clk_divisor, clk_multiplier;
        u32 tsu_thd;
        u8 tlow, thigh;

        err = pm_runtime_get_sync(i2c_dev->dev);
        if (err < 0) {
                dev_err(i2c_dev->dev, "runtime resume failed %d\n", err);
                return err;
        }

        reset_control_assert(i2c_dev->rst);
        udelay(2);
        reset_control_deassert(i2c_dev->rst);

        if (i2c_dev->is_dvc)
                tegra_dvc_init(i2c_dev);

        val = I2C_CNFG_NEW_MASTER_FSM | I2C_CNFG_PACKET_MODE_EN |
                (0x2 << I2C_CNFG_DEBOUNCE_CNT_SHIFT);

        if (i2c_dev->hw->has_multi_master_mode)
                val |= I2C_CNFG_MULTI_MASTER_MODE;

        i2c_writel(i2c_dev, val, I2C_CNFG);
        i2c_writel(i2c_dev, 0, I2C_INT_MASK);

        /* Make sure clock divisor programmed correctly */
        clk_divisor = i2c_dev->hw->clk_divisor_hs_mode;
        clk_divisor |= i2c_dev->clk_divisor_non_hs_mode <<
                                        I2C_CLK_DIVISOR_STD_FAST_MODE_SHIFT;
        i2c_writel(i2c_dev, clk_divisor, I2C_CLK_DIVISOR);

        if (i2c_dev->bus_clk_rate > I2C_STANDARD_MODE &&
            i2c_dev->bus_clk_rate <= I2C_FAST_PLUS_MODE) {
                tlow = i2c_dev->hw->tlow_fast_fastplus_mode;
                thigh = i2c_dev->hw->thigh_fast_fastplus_mode;
                tsu_thd = i2c_dev->hw->setup_hold_time_fast_fast_plus_mode;
        } else {
                tlow = i2c_dev->hw->tlow_std_mode;
                thigh = i2c_dev->hw->thigh_std_mode;
                tsu_thd = i2c_dev->hw->setup_hold_time_std_mode;
        }

        if (i2c_dev->hw->has_interface_timing_reg) {
                val = (thigh << I2C_THIGH_SHIFT) | tlow;
                i2c_writel(i2c_dev, val, I2C_INTERFACE_TIMING_0);
        }

        /*
         * configure setup and hold times only when tsu_thd is non-zero.
         * otherwise, preserve the chip default values
         */
        if (i2c_dev->hw->has_interface_timing_reg && tsu_thd)
                i2c_writel(i2c_dev, tsu_thd, I2C_INTERFACE_TIMING_1);

        if (!clk_reinit) {
                clk_multiplier = (tlow + thigh + 2);
                clk_multiplier *= (i2c_dev->clk_divisor_non_hs_mode + 1);
                err = clk_set_rate(i2c_dev->div_clk,
                                   i2c_dev->bus_clk_rate * clk_multiplier);
                if (err) {
                        dev_err(i2c_dev->dev,
                                "failed changing clock rate: %d\n", err);
                        goto err;
                }
        }

        if (!i2c_dev->is_dvc) {
                u32 sl_cfg = i2c_readl(i2c_dev, I2C_SL_CNFG);

                sl_cfg |= I2C_SL_CNFG_NACK | I2C_SL_CNFG_NEWSL;
                i2c_writel(i2c_dev, sl_cfg, I2C_SL_CNFG);
                i2c_writel(i2c_dev, 0xfc, I2C_SL_ADDR1);
                i2c_writel(i2c_dev, 0x00, I2C_SL_ADDR2);
        }

        err = tegra_i2c_flush_fifos(i2c_dev);
        if (err)
                goto err;

        if (i2c_dev->is_multimaster_mode && i2c_dev->hw->has_slcg_override_reg)
                i2c_writel(i2c_dev, I2C_MST_CORE_CLKEN_OVR, I2C_CLKEN_OVERRIDE);

        err = tegra_i2c_wait_for_config_load(i2c_dev);
        if (err)
                goto err;

        if (i2c_dev->irq_disabled) {
                i2c_dev->irq_disabled = false;
                enable_irq(i2c_dev->irq);
        }

err:
        pm_runtime_put(i2c_dev->dev);
        return err;
}

static int tegra_i2c_disable_packet_mode(struct tegra_i2c_dev *i2c_dev)
{
        u32 cnfg;

        /*
         * NACK interrupt is generated before the I2C controller generates
         * the STOP condition on the bus. So wait for 2 clock periods
         * before disabling the controller so that the STOP condition has
         * been delivered properly.
         */
        udelay(DIV_ROUND_UP(2 * 1000000, i2c_dev->bus_clk_rate));

        cnfg = i2c_readl(i2c_dev, I2C_CNFG);
        if (cnfg & I2C_CNFG_PACKET_MODE_EN)
                i2c_writel(i2c_dev, cnfg & ~I2C_CNFG_PACKET_MODE_EN, I2C_CNFG);

        return tegra_i2c_wait_for_config_load(i2c_dev);
}

static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
{
        u32 status;
        const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
        struct tegra_i2c_dev *i2c_dev = dev_id;

        status = i2c_readl(i2c_dev, I2C_INT_STATUS);

        spin_lock(&i2c_dev->xfer_lock);
        if (status == 0) {
                dev_warn(i2c_dev->dev, "irq status 0 %08x %08x %08x\n",
                         i2c_readl(i2c_dev, I2C_PACKET_TRANSFER_STATUS),
                         i2c_readl(i2c_dev, I2C_STATUS),
                         i2c_readl(i2c_dev, I2C_CNFG));
                i2c_dev->msg_err |= I2C_ERR_UNKNOWN_INTERRUPT;

                if (!i2c_dev->irq_disabled) {
                        disable_irq_nosync(i2c_dev->irq);
                        i2c_dev->irq_disabled = true;
                }
                goto err;
        }

        if (unlikely(status & status_err)) {
                tegra_i2c_disable_packet_mode(i2c_dev);
                if (status & I2C_INT_NO_ACK)
                        i2c_dev->msg_err |= I2C_ERR_NO_ACK;
                if (status & I2C_INT_ARBITRATION_LOST)
                        i2c_dev->msg_err |= I2C_ERR_ARBITRATION_LOST;
                goto err;
        }

        /*
         * I2C transfer is terminated during the bus clear so skip
         * processing the other interrupts.
         */
        if (i2c_dev->hw->supports_bus_clear && (status & I2C_INT_BUS_CLR_DONE))
                goto err;

        if (!i2c_dev->is_curr_dma_xfer) {
                if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
                        if (tegra_i2c_empty_rx_fifo(i2c_dev)) {
                                /*
                                 * Overflow error condition: message fully sent,
                                 * with no XFER_COMPLETE interrupt but hardware
                                 * asks to transfer more.
                                 */
                                i2c_dev->msg_err |= I2C_ERR_RX_BUFFER_OVERFLOW;
                                goto err;
                        }
                }

                if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
                        if (i2c_dev->msg_buf_remaining)
                                tegra_i2c_fill_tx_fifo(i2c_dev);
                        else
                                tegra_i2c_mask_irq(i2c_dev,
                                                   I2C_INT_TX_FIFO_DATA_REQ);
                }
        }

        i2c_writel(i2c_dev, status, I2C_INT_STATUS);
        if (i2c_dev->is_dvc)
                dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);

        /*
         * During message read XFER_COMPLETE interrupt is triggered prior to
         * DMA completion and during message write XFER_COMPLETE interrupt is
         * triggered after DMA completion.
         * PACKETS_XFER_COMPLETE indicates completion of all bytes of transfer.
         * so forcing msg_buf_remaining to 0 in DMA mode.
         */
        if (status & I2C_INT_PACKET_XFER_COMPLETE) {
                if (i2c_dev->is_curr_dma_xfer)
                        i2c_dev->msg_buf_remaining = 0;
                /*
                 * Underflow error condition: XFER_COMPLETE before message
                 * fully sent.
                 */
                if (WARN_ON_ONCE(i2c_dev->msg_buf_remaining)) {
                        i2c_dev->msg_err |= I2C_ERR_UNKNOWN_INTERRUPT;
                        goto err;
                }
                complete(&i2c_dev->msg_complete);
        }
        goto done;
err:
        /* An error occurred, mask all interrupts */
        tegra_i2c_mask_irq(i2c_dev, I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST |
                I2C_INT_PACKET_XFER_COMPLETE | I2C_INT_TX_FIFO_DATA_REQ |
                I2C_INT_RX_FIFO_DATA_REQ);
        if (i2c_dev->hw->supports_bus_clear)
                tegra_i2c_mask_irq(i2c_dev, I2C_INT_BUS_CLR_DONE);
        i2c_writel(i2c_dev, status, I2C_INT_STATUS);
        if (i2c_dev->is_dvc)
                dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);

        if (i2c_dev->is_curr_dma_xfer) {
                if (i2c_dev->msg_read)
                        dmaengine_terminate_async(i2c_dev->rx_dma_chan);
                else
                        dmaengine_terminate_async(i2c_dev->tx_dma_chan);

                complete(&i2c_dev->dma_complete);
        }

        complete(&i2c_dev->msg_complete);
done:
        spin_unlock(&i2c_dev->xfer_lock);
        return IRQ_HANDLED;
}

static void tegra_i2c_config_fifo_trig(struct tegra_i2c_dev *i2c_dev,
                                       size_t len)
{
        u32 val, reg;
        u8 dma_burst;
        struct dma_slave_config slv_config = {0};
        struct dma_chan *chan;
        int ret;
        unsigned long reg_offset;

        if (i2c_dev->hw->has_mst_fifo)
                reg = I2C_MST_FIFO_CONTROL;
        else
                reg = I2C_FIFO_CONTROL;

        if (i2c_dev->is_curr_dma_xfer) {
                if (len & 0xF)
                        dma_burst = 1;
                else if (len & 0x10)
                        dma_burst = 4;
                else
                        dma_burst = 8;

                if (i2c_dev->msg_read) {
                        chan = i2c_dev->rx_dma_chan;
                        reg_offset = tegra_i2c_reg_addr(i2c_dev, I2C_RX_FIFO);
                        slv_config.src_addr = i2c_dev->base_phys + reg_offset;
                        slv_config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                        slv_config.src_maxburst = dma_burst;

                        if (i2c_dev->hw->has_mst_fifo)
                                val = I2C_MST_FIFO_CONTROL_RX_TRIG(dma_burst);
                        else
                                val = I2C_FIFO_CONTROL_RX_TRIG(dma_burst);
                } else {
                        chan = i2c_dev->tx_dma_chan;
                        reg_offset = tegra_i2c_reg_addr(i2c_dev, I2C_TX_FIFO);
                        slv_config.dst_addr = i2c_dev->base_phys + reg_offset;
                        slv_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                        slv_config.dst_maxburst = dma_burst;

                        if (i2c_dev->hw->has_mst_fifo)
                                val = I2C_MST_FIFO_CONTROL_TX_TRIG(dma_burst);
                        else
                                val = I2C_FIFO_CONTROL_TX_TRIG(dma_burst);
                }

                slv_config.device_fc = true;
                ret = dmaengine_slave_config(chan, &slv_config);
                if (ret < 0) {
                        dev_err(i2c_dev->dev, "DMA slave config failed: %d\n",
                                ret);
                        dev_err(i2c_dev->dev, "falling back to PIO\n");
                        tegra_i2c_release_dma(i2c_dev);
                        i2c_dev->is_curr_dma_xfer = false;
                } else {
                        goto out;
                }
        }

        if (i2c_dev->hw->has_mst_fifo)

                val = I2C_MST_FIFO_CONTROL_TX_TRIG(8) |
                      I2C_MST_FIFO_CONTROL_RX_TRIG(1);
        else
                val = I2C_FIFO_CONTROL_TX_TRIG(8) |
                      I2C_FIFO_CONTROL_RX_TRIG(1);
out:
        i2c_writel(i2c_dev, val, reg);
}

static int tegra_i2c_issue_bus_clear(struct i2c_adapter *adap)
{
        struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
        int err;
        unsigned long time_left;
        u32 reg;

        reinit_completion(&i2c_dev->msg_complete);
        reg = (I2C_BC_SCLK_THRESHOLD << I2C_BC_SCLK_THRESHOLD_SHIFT) |
              I2C_BC_STOP_COND | I2C_BC_TERMINATE;
        i2c_writel(i2c_dev, reg, I2C_BUS_CLEAR_CNFG);
        if (i2c_dev->hw->has_config_load_reg) {
                err = tegra_i2c_wait_for_config_load(i2c_dev);
                if (err)
                        return err;
        }

        reg |= I2C_BC_ENABLE;
        i2c_writel(i2c_dev, reg, I2C_BUS_CLEAR_CNFG);
        tegra_i2c_unmask_irq(i2c_dev, I2C_INT_BUS_CLR_DONE);

        time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
                                                msecs_to_jiffies(50));
        if (time_left == 0) {
                dev_err(i2c_dev->dev, "timed out for bus clear\n");
                return -ETIMEDOUT;
        }

        reg = i2c_readl(i2c_dev, I2C_BUS_CLEAR_STATUS);
        if (!(reg & I2C_BC_STATUS)) {
                dev_err(i2c_dev->dev,
                        "un-recovered arbitration lost\n");
                return -EIO;
        }

        return -EAGAIN;
}

static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
                              struct i2c_msg *msg,
                              enum msg_end_type end_state)
{
        u32 packet_header;
        u32 int_mask;
        unsigned long time_left;
        unsigned long flags;
        size_t xfer_size;
        u32 *buffer = NULL;
        int err = 0;
        bool dma;
        u16 xfer_time = 100;

        tegra_i2c_flush_fifos(i2c_dev);

        i2c_dev->msg_buf = msg->buf;
        i2c_dev->msg_buf_remaining = msg->len;
        i2c_dev->msg_err = I2C_ERR_NONE;
        i2c_dev->msg_read = (msg->flags & I2C_M_RD);
        reinit_completion(&i2c_dev->msg_complete);

        if (i2c_dev->msg_read)
                xfer_size = msg->len;
        else
                xfer_size = msg->len + I2C_PACKET_HEADER_SIZE;

        xfer_size = ALIGN(xfer_size, BYTES_PER_FIFO_WORD);
        i2c_dev->is_curr_dma_xfer = (xfer_size > I2C_PIO_MODE_MAX_LEN) &&
                                    i2c_dev->dma_buf;
        tegra_i2c_config_fifo_trig(i2c_dev, xfer_size);
        dma = i2c_dev->is_curr_dma_xfer;
        /*
         * Transfer time in mSec = Total bits / transfer rate
         * Total bits = 9 bits per byte (including ACK bit) + Start & stop bits
         */
        xfer_time += DIV_ROUND_CLOSEST(((xfer_size * 9) + 2) * MSEC_PER_SEC,
                                        i2c_dev->bus_clk_rate);
        spin_lock_irqsave(&i2c_dev->xfer_lock, flags);

        int_mask = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
        tegra_i2c_unmask_irq(i2c_dev, int_mask);
        if (dma) {
                if (i2c_dev->msg_read) {
                        dma_sync_single_for_device(i2c_dev->dev,
                                                   i2c_dev->dma_phys,
                                                   xfer_size,
                                                   DMA_FROM_DEVICE);
                        err = tegra_i2c_dma_submit(i2c_dev, xfer_size);
                        if (err < 0) {
                                dev_err(i2c_dev->dev,
                                        "starting RX DMA failed, err %d\n",
                                        err);
                                goto unlock;
                        }

                } else {
                        dma_sync_single_for_cpu(i2c_dev->dev,
                                                i2c_dev->dma_phys,
                                                xfer_size,
                                                DMA_TO_DEVICE);
                        buffer = i2c_dev->dma_buf;
                }
        }

        packet_header = (0 << PACKET_HEADER0_HEADER_SIZE_SHIFT) |
                        PACKET_HEADER0_PROTOCOL_I2C |
                        (i2c_dev->cont_id << PACKET_HEADER0_CONT_ID_SHIFT) |
                        (1 << PACKET_HEADER0_PACKET_ID_SHIFT);
        if (dma && !i2c_dev->msg_read)
                *buffer++ = packet_header;
        else
                i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);

        packet_header = msg->len - 1;
        if (dma && !i2c_dev->msg_read)
                *buffer++ = packet_header;
        else
                i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);

        packet_header = I2C_HEADER_IE_ENABLE;
        if (end_state == MSG_END_CONTINUE)
                packet_header |= I2C_HEADER_CONTINUE_XFER;
        else if (end_state == MSG_END_REPEAT_START)
                packet_header |= I2C_HEADER_REPEAT_START;
        if (msg->flags & I2C_M_TEN) {
                packet_header |= msg->addr;
                packet_header |= I2C_HEADER_10BIT_ADDR;
        } else {
                packet_header |= msg->addr << I2C_HEADER_SLAVE_ADDR_SHIFT;
        }
        if (msg->flags & I2C_M_IGNORE_NAK)
                packet_header |= I2C_HEADER_CONT_ON_NAK;
        if (msg->flags & I2C_M_RD)
                packet_header |= I2C_HEADER_READ;
        if (dma && !i2c_dev->msg_read)
                *buffer++ = packet_header;
        else
                i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);

        if (!i2c_dev->msg_read) {
                if (dma) {
                        memcpy(buffer, msg->buf, msg->len);
                        dma_sync_single_for_device(i2c_dev->dev,
                                                   i2c_dev->dma_phys,
                                                   xfer_size,
                                                   DMA_TO_DEVICE);
                        err = tegra_i2c_dma_submit(i2c_dev, xfer_size);
                        if (err < 0) {
                                dev_err(i2c_dev->dev,
                                        "starting TX DMA failed, err %d\n",
                                        err);
                                goto unlock;
                        }
                } else {
                        tegra_i2c_fill_tx_fifo(i2c_dev);
                }
        }

        if (i2c_dev->hw->has_per_pkt_xfer_complete_irq)
                int_mask |= I2C_INT_PACKET_XFER_COMPLETE;
        if (!dma) {
                if (msg->flags & I2C_M_RD)
                        int_mask |= I2C_INT_RX_FIFO_DATA_REQ;
                else if (i2c_dev->msg_buf_remaining)
                        int_mask |= I2C_INT_TX_FIFO_DATA_REQ;
        }

        tegra_i2c_unmask_irq(i2c_dev, int_mask);
        dev_dbg(i2c_dev->dev, "unmasked irq: %02x\n",
                i2c_readl(i2c_dev, I2C_INT_MASK));

unlock:
        spin_unlock_irqrestore(&i2c_dev->xfer_lock, flags);

        if (dma) {
                if (err)
                        return err;

                time_left = wait_for_completion_timeout(&i2c_dev->dma_complete,
                                                        msecs_to_jiffies(xfer_time));
                if (time_left == 0) {
                        dev_err(i2c_dev->dev, "DMA transfer timeout\n");
                        dmaengine_terminate_sync(i2c_dev->msg_read ?
                                                 i2c_dev->rx_dma_chan :
                                                 i2c_dev->tx_dma_chan);
                        tegra_i2c_init(i2c_dev, true);
                        return -ETIMEDOUT;
                }

                if (i2c_dev->msg_read && i2c_dev->msg_err == I2C_ERR_NONE) {
                        dma_sync_single_for_cpu(i2c_dev->dev,
                                                i2c_dev->dma_phys,
                                                xfer_size,
                                                DMA_FROM_DEVICE);
                        memcpy(i2c_dev->msg_buf, i2c_dev->dma_buf,
                               msg->len);
                }

                if (i2c_dev->msg_err != I2C_ERR_NONE)
                        dmaengine_synchronize(i2c_dev->msg_read ?
                                              i2c_dev->rx_dma_chan :
                                              i2c_dev->tx_dma_chan);
        }

        time_left = wait_for_completion_timeout(&i2c_dev->msg_complete,
                                                msecs_to_jiffies(xfer_time));
        tegra_i2c_mask_irq(i2c_dev, int_mask);

        if (time_left == 0) {
                dev_err(i2c_dev->dev, "i2c transfer timed out\n");

                tegra_i2c_init(i2c_dev, true);
                return -ETIMEDOUT;
        }

        dev_dbg(i2c_dev->dev, "transfer complete: %lu %d %d\n",
                time_left, completion_done(&i2c_dev->msg_complete),
                i2c_dev->msg_err);

        i2c_dev->is_curr_dma_xfer = false;
        if (likely(i2c_dev->msg_err == I2C_ERR_NONE))
                return 0;

        tegra_i2c_init(i2c_dev, true);
        /* start recovery upon arbitration loss in single master mode */
        if (i2c_dev->msg_err == I2C_ERR_ARBITRATION_LOST) {
                if (!i2c_dev->is_multimaster_mode)
                        return i2c_recover_bus(&i2c_dev->adapter);
                return -EAGAIN;
        }

        if (i2c_dev->msg_err == I2C_ERR_NO_ACK) {
                if (msg->flags & I2C_M_IGNORE_NAK)
                        return 0;
                return -EREMOTEIO;
        }

        return -EIO;
}

static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
                          int num)
{
        struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
        int i;
        int ret;

        ret = pm_runtime_get_sync(i2c_dev->dev);
        if (ret < 0) {
                dev_err(i2c_dev->dev, "runtime resume failed %d\n", ret);
                return ret;
        }

        for (i = 0; i < num; i++) {
                enum msg_end_type end_type = MSG_END_STOP;

                if (i < (num - 1)) {
                        if (msgs[i + 1].flags & I2C_M_NOSTART)
                                end_type = MSG_END_CONTINUE;
                        else
                                end_type = MSG_END_REPEAT_START;
                }
                ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], end_type);
                if (ret)
                        break;
        }

        pm_runtime_put(i2c_dev->dev);

        return ret ?: i;
}

static u32 tegra_i2c_func(struct i2c_adapter *adap)
{
        struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
        u32 ret = I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
                  I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;

        if (i2c_dev->hw->has_continue_xfer_support)
                ret |= I2C_FUNC_NOSTART;
        return ret;
}

static void tegra_i2c_parse_dt(struct tegra_i2c_dev *i2c_dev)
{
        struct device_node *np = i2c_dev->dev->of_node;
        int ret;
        bool multi_mode;

        ret = of_property_read_u32(np, "clock-frequency",
                                   &i2c_dev->bus_clk_rate);
        if (ret)
                i2c_dev->bus_clk_rate = 100000; /* default clock rate */

        multi_mode = of_property_read_bool(np, "multi-master");
        i2c_dev->is_multimaster_mode = multi_mode;
}

static const struct i2c_algorithm tegra_i2c_algo = {
        .master_xfer    = tegra_i2c_xfer,
        .functionality  = tegra_i2c_func,
};

/* payload size is only 12 bit */
static const struct i2c_adapter_quirks tegra_i2c_quirks = {
        .flags = I2C_AQ_NO_ZERO_LEN,
        .max_read_len = SZ_4K,
        .max_write_len = SZ_4K - I2C_PACKET_HEADER_SIZE,
};

static const struct i2c_adapter_quirks tegra194_i2c_quirks = {
        .flags = I2C_AQ_NO_ZERO_LEN,
        .max_write_len = SZ_64K - I2C_PACKET_HEADER_SIZE,
};

static struct i2c_bus_recovery_info tegra_i2c_recovery_info = {
        .recover_bus = tegra_i2c_issue_bus_clear,
};

static const struct tegra_i2c_hw_feature tegra20_i2c_hw = {
        .has_continue_xfer_support = false,
        .has_per_pkt_xfer_complete_irq = false,
        .has_single_clk_source = false,
        .clk_divisor_hs_mode = 3,
        .clk_divisor_std_mode = 0,
        .clk_divisor_fast_mode = 0,
        .clk_divisor_fast_plus_mode = 0,
        .has_config_load_reg = false,
        .has_multi_master_mode = false,
        .has_slcg_override_reg = false,
        .has_mst_fifo = false,
        .quirks = &tegra_i2c_quirks,
        .supports_bus_clear = false,
        .has_apb_dma = true,
        .tlow_std_mode = 0x4,
        .thigh_std_mode = 0x2,
        .tlow_fast_fastplus_mode = 0x4,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0x0,
        .setup_hold_time_fast_fast_plus_mode = 0x0,
        .setup_hold_time_hs_mode = 0x0,
        .has_interface_timing_reg = false,
};

static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
        .has_continue_xfer_support = true,
        .has_per_pkt_xfer_complete_irq = false,
        .has_single_clk_source = false,
        .clk_divisor_hs_mode = 3,
        .clk_divisor_std_mode = 0,
        .clk_divisor_fast_mode = 0,
        .clk_divisor_fast_plus_mode = 0,
        .has_config_load_reg = false,
        .has_multi_master_mode = false,
        .has_slcg_override_reg = false,
        .has_mst_fifo = false,
        .quirks = &tegra_i2c_quirks,
        .supports_bus_clear = false,
        .has_apb_dma = true,
        .tlow_std_mode = 0x4,
        .thigh_std_mode = 0x2,
        .tlow_fast_fastplus_mode = 0x4,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0x0,
        .setup_hold_time_fast_fast_plus_mode = 0x0,
        .setup_hold_time_hs_mode = 0x0,
        .has_interface_timing_reg = false,
};

static const struct tegra_i2c_hw_feature tegra114_i2c_hw = {
        .has_continue_xfer_support = true,
        .has_per_pkt_xfer_complete_irq = true,
        .has_single_clk_source = true,
        .clk_divisor_hs_mode = 1,
        .clk_divisor_std_mode = 0x19,
        .clk_divisor_fast_mode = 0x19,
        .clk_divisor_fast_plus_mode = 0x10,
        .has_config_load_reg = false,
        .has_multi_master_mode = false,
        .has_slcg_override_reg = false,
        .has_mst_fifo = false,
        .quirks = &tegra_i2c_quirks,
        .supports_bus_clear = true,
        .has_apb_dma = true,
        .tlow_std_mode = 0x4,
        .thigh_std_mode = 0x2,
        .tlow_fast_fastplus_mode = 0x4,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0x0,
        .setup_hold_time_fast_fast_plus_mode = 0x0,
        .setup_hold_time_hs_mode = 0x0,
        .has_interface_timing_reg = false,
};

static const struct tegra_i2c_hw_feature tegra124_i2c_hw = {
        .has_continue_xfer_support = true,
        .has_per_pkt_xfer_complete_irq = true,
        .has_single_clk_source = true,
        .clk_divisor_hs_mode = 1,
        .clk_divisor_std_mode = 0x19,
        .clk_divisor_fast_mode = 0x19,
        .clk_divisor_fast_plus_mode = 0x10,
        .has_config_load_reg = true,
        .has_multi_master_mode = false,
        .has_slcg_override_reg = true,
        .has_mst_fifo = false,
        .quirks = &tegra_i2c_quirks,
        .supports_bus_clear = true,
        .has_apb_dma = true,
        .tlow_std_mode = 0x4,
        .thigh_std_mode = 0x2,
        .tlow_fast_fastplus_mode = 0x4,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0x0,
        .setup_hold_time_fast_fast_plus_mode = 0x0,
        .setup_hold_time_hs_mode = 0x0,
        .has_interface_timing_reg = true,
};

static const struct tegra_i2c_hw_feature tegra210_i2c_hw = {
        .has_continue_xfer_support = true,
        .has_per_pkt_xfer_complete_irq = true,
        .has_single_clk_source = true,
        .clk_divisor_hs_mode = 1,
        .clk_divisor_std_mode = 0x19,
        .clk_divisor_fast_mode = 0x19,
        .clk_divisor_fast_plus_mode = 0x10,
        .has_config_load_reg = true,
        .has_multi_master_mode = false,
        .has_slcg_override_reg = true,
        .has_mst_fifo = false,
        .quirks = &tegra_i2c_quirks,
        .supports_bus_clear = true,
        .has_apb_dma = true,
        .tlow_std_mode = 0x4,
        .thigh_std_mode = 0x2,
        .tlow_fast_fastplus_mode = 0x4,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0,
        .setup_hold_time_fast_fast_plus_mode = 0,
        .setup_hold_time_hs_mode = 0,
        .has_interface_timing_reg = true,
};

static const struct tegra_i2c_hw_feature tegra186_i2c_hw = {
        .has_continue_xfer_support = true,
        .has_per_pkt_xfer_complete_irq = true,
        .has_single_clk_source = true,
        .clk_divisor_hs_mode = 1,
        .clk_divisor_std_mode = 0x16,
        .clk_divisor_fast_mode = 0x19,
        .clk_divisor_fast_plus_mode = 0x10,
        .has_config_load_reg = true,
        .has_multi_master_mode = false,
        .has_slcg_override_reg = true,
        .has_mst_fifo = false,
        .quirks = &tegra_i2c_quirks,
        .supports_bus_clear = true,
        .has_apb_dma = false,
        .tlow_std_mode = 0x4,
        .thigh_std_mode = 0x3,
        .tlow_fast_fastplus_mode = 0x4,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0,
        .setup_hold_time_fast_fast_plus_mode = 0,
        .setup_hold_time_hs_mode = 0,
        .has_interface_timing_reg = true,
};

static const struct tegra_i2c_hw_feature tegra194_i2c_hw = {
        .has_continue_xfer_support = true,
        .has_per_pkt_xfer_complete_irq = true,
        .has_single_clk_source = true,
        .clk_divisor_hs_mode = 1,
        .clk_divisor_std_mode = 0x4f,
        .clk_divisor_fast_mode = 0x3c,
        .clk_divisor_fast_plus_mode = 0x16,
        .has_config_load_reg = true,
        .has_multi_master_mode = true,
        .has_slcg_override_reg = true,
        .has_mst_fifo = true,
        .quirks = &tegra194_i2c_quirks,
        .supports_bus_clear = true,
        .has_apb_dma = false,
        .tlow_std_mode = 0x8,
        .thigh_std_mode = 0x7,
        .tlow_fast_fastplus_mode = 0x2,
        .thigh_fast_fastplus_mode = 0x2,
        .setup_hold_time_std_mode = 0x08080808,
        .setup_hold_time_fast_fast_plus_mode = 0x02020202,
        .setup_hold_time_hs_mode = 0x090909,
        .has_interface_timing_reg = true,
};

/* Match table for of_platform binding */
static const struct of_device_id tegra_i2c_of_match[] = {
        { .compatible = "nvidia,tegra194-i2c", .data = &tegra194_i2c_hw, },
        { .compatible = "nvidia,tegra186-i2c", .data = &tegra186_i2c_hw, },
        { .compatible = "nvidia,tegra210-i2c", .data = &tegra210_i2c_hw, },
        { .compatible = "nvidia,tegra124-i2c", .data = &tegra124_i2c_hw, },
        { .compatible = "nvidia,tegra114-i2c", .data = &tegra114_i2c_hw, },
        { .compatible = "nvidia,tegra30-i2c", .data = &tegra30_i2c_hw, },
        { .compatible = "nvidia,tegra20-i2c", .data = &tegra20_i2c_hw, },
        { .compatible = "nvidia,tegra20-i2c-dvc", .data = &tegra20_i2c_hw, },
        {},
};
MODULE_DEVICE_TABLE(of, tegra_i2c_of_match);

static int tegra_i2c_probe(struct platform_device *pdev)
{
        struct tegra_i2c_dev *i2c_dev;
        struct resource *res;
        struct clk *div_clk;
        struct clk *fast_clk;
        void __iomem *base;
        phys_addr_t base_phys;
        int irq;
        int ret;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        base_phys = res->start;
        base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(base))
                return PTR_ERR(base);

        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!res) {
                dev_err(&pdev->dev, "no irq resource\n");
                return -EINVAL;
        }
        irq = res->start;

        div_clk = devm_clk_get(&pdev->dev, "div-clk");
        if (IS_ERR(div_clk)) {
                if (PTR_ERR(div_clk) != -EPROBE_DEFER)
                        dev_err(&pdev->dev, "missing controller clock\n");

                return PTR_ERR(div_clk);
        }

        i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
        if (!i2c_dev)
                return -ENOMEM;

        i2c_dev->base = base;
        i2c_dev->base_phys = base_phys;
        i2c_dev->div_clk = div_clk;
        i2c_dev->adapter.algo = &tegra_i2c_algo;
        i2c_dev->adapter.retries = 1;
        i2c_dev->adapter.timeout = 6 * HZ;
        i2c_dev->irq = irq;
        i2c_dev->cont_id = pdev->id;
        i2c_dev->dev = &pdev->dev;

        i2c_dev->rst = devm_reset_control_get_exclusive(&pdev->dev, "i2c");
        if (IS_ERR(i2c_dev->rst)) {
                dev_err(&pdev->dev, "missing controller reset\n");
                return PTR_ERR(i2c_dev->rst);
        }

        tegra_i2c_parse_dt(i2c_dev);

        i2c_dev->hw = of_device_get_match_data(&pdev->dev);
        i2c_dev->is_dvc = of_device_is_compatible(pdev->dev.of_node,
                                                  "nvidia,tegra20-i2c-dvc");
        i2c_dev->adapter.quirks = i2c_dev->hw->quirks;
        i2c_dev->dma_buf_size = i2c_dev->adapter.quirks->max_write_len +
                                I2C_PACKET_HEADER_SIZE;
        init_completion(&i2c_dev->msg_complete);
        init_completion(&i2c_dev->dma_complete);
        spin_lock_init(&i2c_dev->xfer_lock);

        if (!i2c_dev->hw->has_single_clk_source) {
                fast_clk = devm_clk_get(&pdev->dev, "fast-clk");
                if (IS_ERR(fast_clk)) {
                        dev_err(&pdev->dev, "missing fast clock\n");
                        return PTR_ERR(fast_clk);
                }
                i2c_dev->fast_clk = fast_clk;
        }

        platform_set_drvdata(pdev, i2c_dev);

        if (!i2c_dev->hw->has_single_clk_source) {
                ret = clk_prepare(i2c_dev->fast_clk);
                if (ret < 0) {
                        dev_err(i2c_dev->dev, "Clock prepare failed %d\n", ret);
                        return ret;
                }
        }

        if (i2c_dev->bus_clk_rate > I2C_FAST_MODE &&
            i2c_dev->bus_clk_rate <= I2C_FAST_PLUS_MODE)
                i2c_dev->clk_divisor_non_hs_mode =
                                i2c_dev->hw->clk_divisor_fast_plus_mode;
        else if (i2c_dev->bus_clk_rate > I2C_STANDARD_MODE &&
                 i2c_dev->bus_clk_rate <= I2C_FAST_MODE)
                i2c_dev->clk_divisor_non_hs_mode =
                                i2c_dev->hw->clk_divisor_fast_mode;
        else
                i2c_dev->clk_divisor_non_hs_mode =
                                i2c_dev->hw->clk_divisor_std_mode;

        ret = clk_prepare(i2c_dev->div_clk);
        if (ret < 0) {
                dev_err(i2c_dev->dev, "Clock prepare failed %d\n", ret);
                goto unprepare_fast_clk;
        }

        pm_runtime_enable(&pdev->dev);
        if (!pm_runtime_enabled(&pdev->dev)) {
                ret = tegra_i2c_runtime_resume(&pdev->dev);
                if (ret < 0) {
                        dev_err(&pdev->dev, "runtime resume failed\n");
                        goto unprepare_div_clk;
                }
        }

        if (i2c_dev->is_multimaster_mode) {
                ret = clk_enable(i2c_dev->div_clk);
                if (ret < 0) {
                        dev_err(i2c_dev->dev, "div_clk enable failed %d\n",
                                ret);
                        goto disable_rpm;
                }
        }

        if (i2c_dev->hw->supports_bus_clear)
                i2c_dev->adapter.bus_recovery_info = &tegra_i2c_recovery_info;

        ret = tegra_i2c_init_dma(i2c_dev);
        if (ret < 0)
                goto disable_div_clk;

        ret = tegra_i2c_init(i2c_dev, false);
        if (ret) {
                dev_err(&pdev->dev, "Failed to initialize i2c controller\n");
                goto release_dma;
        }

        ret = devm_request_irq(&pdev->dev, i2c_dev->irq,
                               tegra_i2c_isr, 0, dev_name(&pdev->dev), i2c_dev);
        if (ret) {
                dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
                goto release_dma;
        }

        i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
        i2c_dev->adapter.owner = THIS_MODULE;
        i2c_dev->adapter.class = I2C_CLASS_DEPRECATED;
        strlcpy(i2c_dev->adapter.name, dev_name(&pdev->dev),
                sizeof(i2c_dev->adapter.name));
        i2c_dev->adapter.dev.parent = &pdev->dev;
        i2c_dev->adapter.nr = pdev->id;
        i2c_dev->adapter.dev.of_node = pdev->dev.of_node;

        ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
        if (ret)
                goto release_dma;

        return 0;

release_dma:
        tegra_i2c_release_dma(i2c_dev);

disable_div_clk:
        if (i2c_dev->is_multimaster_mode)
                clk_disable(i2c_dev->div_clk);

disable_rpm:
        pm_runtime_disable(&pdev->dev);
        if (!pm_runtime_status_suspended(&pdev->dev))
                tegra_i2c_runtime_suspend(&pdev->dev);

unprepare_div_clk:
        clk_unprepare(i2c_dev->div_clk);

unprepare_fast_clk:
        if (!i2c_dev->hw->has_single_clk_source)
                clk_unprepare(i2c_dev->fast_clk);

        return ret;
}

static int tegra_i2c_remove(struct platform_device *pdev)
{
        struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);

        i2c_del_adapter(&i2c_dev->adapter);

        if (i2c_dev->is_multimaster_mode)
                clk_disable(i2c_dev->div_clk);

        pm_runtime_disable(&pdev->dev);
        if (!pm_runtime_status_suspended(&pdev->dev))
                tegra_i2c_runtime_suspend(&pdev->dev);

        clk_unprepare(i2c_dev->div_clk);
        if (!i2c_dev->hw->has_single_clk_source)
                clk_unprepare(i2c_dev->fast_clk);

        tegra_i2c_release_dma(i2c_dev);
        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tegra_i2c_suspend(struct device *dev)
{
        struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);

        i2c_mark_adapter_suspended(&i2c_dev->adapter);

        return 0;
}

static int tegra_i2c_resume(struct device *dev)
{
        struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);
        int err;

        err = tegra_i2c_init(i2c_dev, false);
        if (err)
                return err;

        i2c_mark_adapter_resumed(&i2c_dev->adapter);

        return 0;
}

static const struct dev_pm_ops tegra_i2c_pm = {
        SET_SYSTEM_SLEEP_PM_OPS(tegra_i2c_suspend, tegra_i2c_resume)
        SET_RUNTIME_PM_OPS(tegra_i2c_runtime_suspend, tegra_i2c_runtime_resume,
                           NULL)
};

#define TEGRA_I2C_PM    (&tegra_i2c_pm)
#else
#define TEGRA_I2C_PM    NULL
#endif

static struct platform_driver tegra_i2c_driver = {
        .probe   = tegra_i2c_probe,
        .remove  = tegra_i2c_remove,
        .driver  = {
                .name  = "tegra-i2c",
                .of_match_table = tegra_i2c_of_match,
                .pm    = TEGRA_I2C_PM,
        },
};

module_platform_driver(tegra_i2c_driver);

MODULE_DESCRIPTION("nVidia Tegra2 I2C Bus Controller driver");
MODULE_AUTHOR("Colin Cross");
MODULE_LICENSE("GPL v2");