// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017-2018, The Linux foundation. All rights reserved.

#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dma/qcom-gpi-dma.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/log2.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/pm_runtime.h>
#include <linux/qcom-geni-se.h>
#include <linux/spi/spi.h>
#include <linux/spinlock.h>

/* SPI SE specific registers and respective register fields */
#define SE_SPI_CPHA             0x224
#define CPHA                    BIT(0)

#define SE_SPI_LOOPBACK         0x22c
#define LOOPBACK_ENABLE         0x1
#define NORMAL_MODE             0x0
#define LOOPBACK_MSK            GENMASK(1, 0)

#define SE_SPI_CPOL             0x230
#define CPOL                    BIT(2)

#define SE_SPI_DEMUX_OUTPUT_INV 0x24c
#define CS_DEMUX_OUTPUT_INV_MSK GENMASK(3, 0)

#define SE_SPI_DEMUX_SEL        0x250
#define CS_DEMUX_OUTPUT_SEL     GENMASK(3, 0)

#define SE_SPI_TRANS_CFG        0x25c
#define CS_TOGGLE               BIT(0)

#define SE_SPI_WORD_LEN         0x268
#define WORD_LEN_MSK            GENMASK(9, 0)
#define MIN_WORD_LEN            4

#define SE_SPI_TX_TRANS_LEN     0x26c
#define SE_SPI_RX_TRANS_LEN     0x270
#define TRANS_LEN_MSK           GENMASK(23, 0)

#define SE_SPI_PRE_POST_CMD_DLY 0x274

#define SE_SPI_DELAY_COUNTERS   0x278
#define SPI_INTER_WORDS_DELAY_MSK       GENMASK(9, 0)
#define SPI_CS_CLK_DELAY_MSK            GENMASK(19, 10)
#define SPI_CS_CLK_DELAY_SHFT           10

/* M_CMD OP codes for SPI */
#define SPI_TX_ONLY             1
#define SPI_RX_ONLY             2
#define SPI_TX_RX               7
#define SPI_CS_ASSERT           8
#define SPI_CS_DEASSERT         9
#define SPI_SCK_ONLY            10
/* M_CMD params for SPI */
#define SPI_PRE_CMD_DELAY       BIT(0)
#define TIMESTAMP_BEFORE        BIT(1)
#define FRAGMENTATION           BIT(2)
#define TIMESTAMP_AFTER         BIT(3)
#define POST_CMD_DELAY          BIT(4)

#define GSI_LOOPBACK_EN         BIT(0)
#define GSI_CS_TOGGLE           BIT(3)
#define GSI_CPHA                BIT(4)
#define GSI_CPOL                BIT(5)

struct spi_geni_master {
        struct geni_se se;
        struct device *dev;
        u32 tx_fifo_depth;
        u32 fifo_width_bits;
        u32 tx_wm;
        u32 last_mode;
        unsigned long cur_speed_hz;
        unsigned long cur_sclk_hz;
        unsigned int cur_bits_per_word;
        unsigned int tx_rem_bytes;
        unsigned int rx_rem_bytes;
        const struct spi_transfer *cur_xfer;
        struct completion cs_done;
        struct completion cancel_done;
        struct completion abort_done;
        unsigned int oversampling;
        spinlock_t lock;
        int irq;
        bool cs_flag;
        bool abort_failed;
        struct dma_chan *tx;
        struct dma_chan *rx;
        int cur_xfer_mode;
};

static int get_spi_clk_cfg(unsigned int speed_hz,
                        struct spi_geni_master *mas,
                        unsigned int *clk_idx,
                        unsigned int *clk_div)
{
        unsigned long sclk_freq;
        unsigned int actual_hz;
        int ret;

        ret = geni_se_clk_freq_match(&mas->se,
                                speed_hz * mas->oversampling,
                                clk_idx, &sclk_freq, false);
        if (ret) {
                dev_err(mas->dev, "Failed(%d) to find src clk for %dHz\n",
                                                        ret, speed_hz);
                return ret;
        }

        *clk_div = DIV_ROUND_UP(sclk_freq, mas->oversampling * speed_hz);
        actual_hz = sclk_freq / (mas->oversampling * *clk_div);

        dev_dbg(mas->dev, "req %u=>%u sclk %lu, idx %d, div %d\n", speed_hz,
                                actual_hz, sclk_freq, *clk_idx, *clk_div);
        ret = dev_pm_opp_set_rate(mas->dev, sclk_freq);
        if (ret)
                dev_err(mas->dev, "dev_pm_opp_set_rate failed %d\n", ret);
        else
                mas->cur_sclk_hz = sclk_freq;

        return ret;
}

static void handle_fifo_timeout(struct spi_master *spi,
                                struct spi_message *msg)
{
        struct spi_geni_master *mas = spi_master_get_devdata(spi);
        unsigned long time_left;
        struct geni_se *se = &mas->se;

        spin_lock_irq(&mas->lock);
        reinit_completion(&mas->cancel_done);
        writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
        mas->cur_xfer = NULL;
        geni_se_cancel_m_cmd(se);
        spin_unlock_irq(&mas->lock);

        time_left = wait_for_completion_timeout(&mas->cancel_done, HZ);
        if (time_left)
                return;

        spin_lock_irq(&mas->lock);
        reinit_completion(&mas->abort_done);
        geni_se_abort_m_cmd(se);
        spin_unlock_irq(&mas->lock);

        time_left = wait_for_completion_timeout(&mas->abort_done, HZ);
        if (!time_left) {
                dev_err(mas->dev, "Failed to cancel/abort m_cmd\n");

                /*
                 * No need for a lock since SPI core has a lock and we never
                 * access this from an interrupt.
                 */
                mas->abort_failed = true;
        }
}

static void handle_gpi_timeout(struct spi_master *spi, struct spi_message *msg)
{
        struct spi_geni_master *mas = spi_master_get_devdata(spi);

        dmaengine_terminate_sync(mas->tx);
        dmaengine_terminate_sync(mas->rx);
}

static void spi_geni_handle_err(struct spi_master *spi, struct spi_message *msg)
{
        struct spi_geni_master *mas = spi_master_get_devdata(spi);

        switch (mas->cur_xfer_mode) {
        case GENI_SE_FIFO:
                handle_fifo_timeout(spi, msg);
                break;
        case GENI_GPI_DMA:
                handle_gpi_timeout(spi, msg);
                break;
        default:
                dev_err(mas->dev, "Abort on Mode:%d not supported", mas->cur_xfer_mode);
        }
}

static bool spi_geni_is_abort_still_pending(struct spi_geni_master *mas)
{
        struct geni_se *se = &mas->se;
        u32 m_irq, m_irq_en;

        if (!mas->abort_failed)
                return false;

        /*
         * The only known case where a transfer times out and then a cancel
         * times out then an abort times out is if something is blocking our
         * interrupt handler from running.  Avoid starting any new transfers
         * until that sorts itself out.
         */
        spin_lock_irq(&mas->lock);
        m_irq = readl(se->base + SE_GENI_M_IRQ_STATUS);
        m_irq_en = readl(se->base + SE_GENI_M_IRQ_EN);
        spin_unlock_irq(&mas->lock);

        if (m_irq & m_irq_en) {
                dev_err(mas->dev, "Interrupts pending after abort: %#010x\n",
                        m_irq & m_irq_en);
                return true;
        }

        /*
         * If we're here the problem resolved itself so no need to check more
         * on future transfers.
         */
        mas->abort_failed = false;

        return false;
}

static void spi_geni_set_cs(struct spi_device *slv, bool set_flag)
{
        struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
        struct spi_master *spi = dev_get_drvdata(mas->dev);
        struct geni_se *se = &mas->se;
        unsigned long time_left;

        if (!(slv->mode & SPI_CS_HIGH))
                set_flag = !set_flag;

        if (set_flag == mas->cs_flag)
                return;

        pm_runtime_get_sync(mas->dev);

        if (spi_geni_is_abort_still_pending(mas)) {
                dev_err(mas->dev, "Can't set chip select\n");
                goto exit;
        }

        spin_lock_irq(&mas->lock);
        if (mas->cur_xfer) {
                dev_err(mas->dev, "Can't set CS when prev xfer running\n");
                spin_unlock_irq(&mas->lock);
                goto exit;
        }

        mas->cs_flag = set_flag;
        reinit_completion(&mas->cs_done);
        if (set_flag)
                geni_se_setup_m_cmd(se, SPI_CS_ASSERT, 0);
        else
                geni_se_setup_m_cmd(se, SPI_CS_DEASSERT, 0);
        spin_unlock_irq(&mas->lock);

        time_left = wait_for_completion_timeout(&mas->cs_done, HZ);
        if (!time_left) {
                dev_warn(mas->dev, "Timeout setting chip select\n");
                handle_fifo_timeout(spi, NULL);
        }

exit:
        pm_runtime_put(mas->dev);
}

static void spi_setup_word_len(struct spi_geni_master *mas, u16 mode,
                                        unsigned int bits_per_word)
{
        unsigned int pack_words;
        bool msb_first = (mode & SPI_LSB_FIRST) ? false : true;
        struct geni_se *se = &mas->se;
        u32 word_len;

        /*
         * If bits_per_word isn't a byte aligned value, set the packing to be
         * 1 SPI word per FIFO word.
         */
        if (!(mas->fifo_width_bits % bits_per_word))
                pack_words = mas->fifo_width_bits / bits_per_word;
        else
                pack_words = 1;
        geni_se_config_packing(&mas->se, bits_per_word, pack_words, msb_first,
                                                                true, true);
        word_len = (bits_per_word - MIN_WORD_LEN) & WORD_LEN_MSK;
        writel(word_len, se->base + SE_SPI_WORD_LEN);
}

static int geni_spi_set_clock_and_bw(struct spi_geni_master *mas,
                                        unsigned long clk_hz)
{
        u32 clk_sel, m_clk_cfg, idx, div;
        struct geni_se *se = &mas->se;
        int ret;

        if (clk_hz == mas->cur_speed_hz)
                return 0;

        ret = get_spi_clk_cfg(clk_hz, mas, &idx, &div);
        if (ret) {
                dev_err(mas->dev, "Err setting clk to %lu: %d\n", clk_hz, ret);
                return ret;
        }

        /*
         * SPI core clock gets configured with the requested frequency
         * or the frequency closer to the requested frequency.
         * For that reason requested frequency is stored in the
         * cur_speed_hz and referred in the consecutive transfer instead
         * of calling clk_get_rate() API.
         */
        mas->cur_speed_hz = clk_hz;

        clk_sel = idx & CLK_SEL_MSK;
        m_clk_cfg = (div << CLK_DIV_SHFT) | SER_CLK_EN;
        writel(clk_sel, se->base + SE_GENI_CLK_SEL);
        writel(m_clk_cfg, se->base + GENI_SER_M_CLK_CFG);

        /* Set BW quota for CPU as driver supports FIFO mode only. */
        se->icc_paths[CPU_TO_GENI].avg_bw = Bps_to_icc(mas->cur_speed_hz);
        ret = geni_icc_set_bw(se);
        if (ret)
                return ret;

        return 0;
}

static int setup_fifo_params(struct spi_device *spi_slv,
                                        struct spi_master *spi)
{
        struct spi_geni_master *mas = spi_master_get_devdata(spi);
        struct geni_se *se = &mas->se;
        u32 loopback_cfg = 0, cpol = 0, cpha = 0, demux_output_inv = 0;
        u32 demux_sel;

        if (mas->last_mode != spi_slv->mode) {
                if (spi_slv->mode & SPI_LOOP)
                        loopback_cfg = LOOPBACK_ENABLE;

                if (spi_slv->mode & SPI_CPOL)
                        cpol = CPOL;

                if (spi_slv->mode & SPI_CPHA)
                        cpha = CPHA;

                if (spi_slv->mode & SPI_CS_HIGH)
                        demux_output_inv = BIT(spi_slv->chip_select);

                demux_sel = spi_slv->chip_select;
                mas->cur_bits_per_word = spi_slv->bits_per_word;

                spi_setup_word_len(mas, spi_slv->mode, spi_slv->bits_per_word);
                writel(loopback_cfg, se->base + SE_SPI_LOOPBACK);
                writel(demux_sel, se->base + SE_SPI_DEMUX_SEL);
                writel(cpha, se->base + SE_SPI_CPHA);
                writel(cpol, se->base + SE_SPI_CPOL);
                writel(demux_output_inv, se->base + SE_SPI_DEMUX_OUTPUT_INV);

                mas->last_mode = spi_slv->mode;
        }

        return geni_spi_set_clock_and_bw(mas, spi_slv->max_speed_hz);
}

static void
spi_gsi_callback_result(void *cb, const struct dmaengine_result *result)
{
        struct spi_master *spi = cb;

        spi->cur_msg->status = -EIO;
        if (result->result != DMA_TRANS_NOERROR) {
                dev_err(&spi->dev, "DMA txn failed: %d\n", result->result);
                spi_finalize_current_transfer(spi);
                return;
        }

        if (!result->residue) {
                spi->cur_msg->status = 0;
                dev_dbg(&spi->dev, "DMA txn completed\n");
        } else {
                dev_err(&spi->dev, "DMA xfer has pending: %d\n", result->residue);
        }

        spi_finalize_current_transfer(spi);
}

static int setup_gsi_xfer(struct spi_transfer *xfer, struct spi_geni_master *mas,
                          struct spi_device *spi_slv, struct spi_master *spi)
{
        unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
        struct dma_slave_config config = {};
        struct gpi_spi_config peripheral = {};
        struct dma_async_tx_descriptor *tx_desc, *rx_desc;
        int ret;

        config.peripheral_config = &peripheral;
        config.peripheral_size = sizeof(peripheral);
        peripheral.set_config = true;

        if (xfer->bits_per_word != mas->cur_bits_per_word ||
            xfer->speed_hz != mas->cur_speed_hz) {
                mas->cur_bits_per_word = xfer->bits_per_word;
                mas->cur_speed_hz = xfer->speed_hz;
        }

        if (xfer->tx_buf && xfer->rx_buf) {
                peripheral.cmd = SPI_DUPLEX;
        } else if (xfer->tx_buf) {
                peripheral.cmd = SPI_TX;
                peripheral.rx_len = 0;
        } else if (xfer->rx_buf) {
                peripheral.cmd = SPI_RX;
                if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) {
                        peripheral.rx_len = ((xfer->len << 3) / mas->cur_bits_per_word);
                } else {
                        int bytes_per_word = (mas->cur_bits_per_word / BITS_PER_BYTE) + 1;

                        peripheral.rx_len = (xfer->len / bytes_per_word);
                }
        }

        peripheral.loopback_en = !!(spi_slv->mode & SPI_LOOP);
        peripheral.clock_pol_high = !!(spi_slv->mode & SPI_CPOL);
        peripheral.data_pol_high = !!(spi_slv->mode & SPI_CPHA);
        peripheral.cs = spi_slv->chip_select;
        peripheral.pack_en = true;
        peripheral.word_len = xfer->bits_per_word - MIN_WORD_LEN;

        ret = get_spi_clk_cfg(mas->cur_speed_hz, mas,
                              &peripheral.clk_src, &peripheral.clk_div);
        if (ret) {
                dev_err(mas->dev, "Err in get_spi_clk_cfg() :%d\n", ret);
                return ret;
        }

        if (!xfer->cs_change) {
                if (!list_is_last(&xfer->transfer_list, &spi->cur_msg->transfers))
                        peripheral.fragmentation = FRAGMENTATION;
        }

        if (peripheral.cmd & SPI_RX) {
                dmaengine_slave_config(mas->rx, &config);
                rx_desc = dmaengine_prep_slave_sg(mas->rx, xfer->rx_sg.sgl, xfer->rx_sg.nents,
                                                  DMA_DEV_TO_MEM, flags);
                if (!rx_desc) {
                        dev_err(mas->dev, "Err setting up rx desc\n");
                        return -EIO;
                }
        }

        /*
         * Prepare the TX always, even for RX or tx_buf being null, we would
         * need TX to be prepared per GSI spec
         */
        dmaengine_slave_config(mas->tx, &config);
        tx_desc = dmaengine_prep_slave_sg(mas->tx, xfer->tx_sg.sgl, xfer->tx_sg.nents,
                                          DMA_MEM_TO_DEV, flags);
        if (!tx_desc) {
                dev_err(mas->dev, "Err setting up tx desc\n");
                return -EIO;
        }

        tx_desc->callback_result = spi_gsi_callback_result;
        tx_desc->callback_param = spi;

        if (peripheral.cmd & SPI_RX)
                dmaengine_submit(rx_desc);
        dmaengine_submit(tx_desc);

        if (peripheral.cmd & SPI_RX)
                dma_async_issue_pending(mas->rx);

        dma_async_issue_pending(mas->tx);
        return 1;
}

static bool geni_can_dma(struct spi_controller *ctlr,
                         struct spi_device *slv, struct spi_transfer *xfer)
{
        struct spi_geni_master *mas = spi_master_get_devdata(slv->master);

        /* check if dma is supported */
        return mas->cur_xfer_mode != GENI_SE_FIFO;
}

static int spi_geni_prepare_message(struct spi_master *spi,
                                        struct spi_message *spi_msg)
{
        struct spi_geni_master *mas = spi_master_get_devdata(spi);
        int ret;

        switch (mas->cur_xfer_mode) {
        case GENI_SE_FIFO:
                if (spi_geni_is_abort_still_pending(mas))
                        return -EBUSY;
                ret = setup_fifo_params(spi_msg->spi, spi);
                if (ret)
                        dev_err(mas->dev, "Couldn't select mode %d\n", ret);
                return ret;

        case GENI_GPI_DMA:
                /* nothing to do for GPI DMA */
                return 0;
        }

        dev_err(mas->dev, "Mode not supported %d", mas->cur_xfer_mode);
        return -EINVAL;
}

static int spi_geni_grab_gpi_chan(struct spi_geni_master *mas)
{
        int ret;

        mas->tx = dma_request_chan(mas->dev, "tx");
        if (IS_ERR(mas->tx)) {
                ret = dev_err_probe(mas->dev, PTR_ERR(mas->tx),
                                    "Failed to get tx DMA ch\n");
                goto err_tx;
        }

        mas->rx = dma_request_chan(mas->dev, "rx");
        if (IS_ERR(mas->rx)) {
                ret = dev_err_probe(mas->dev, PTR_ERR(mas->rx),
                                    "Failed to get rx DMA ch\n");
                goto err_rx;
        }

        return 0;

err_rx:
        mas->rx = NULL;
        dma_release_channel(mas->tx);
err_tx:
        mas->tx = NULL;
        return ret;
}

static void spi_geni_release_dma_chan(struct spi_geni_master *mas)
{
        if (mas->rx) {
                dma_release_channel(mas->rx);
                mas->rx = NULL;
        }

        if (mas->tx) {
                dma_release_channel(mas->tx);
                mas->tx = NULL;
        }
}

static int spi_geni_init(struct spi_geni_master *mas)
{
        struct geni_se *se = &mas->se;
        unsigned int proto, major, minor, ver;
        u32 spi_tx_cfg, fifo_disable;
        int ret = -ENXIO;

        pm_runtime_get_sync(mas->dev);

        proto = geni_se_read_proto(se);
        if (proto != GENI_SE_SPI) {
                dev_err(mas->dev, "Invalid proto %d\n", proto);
                goto out_pm;
        }
        mas->tx_fifo_depth = geni_se_get_tx_fifo_depth(se);

        /* Width of Tx and Rx FIFO is same */
        mas->fifo_width_bits = geni_se_get_tx_fifo_width(se);

        /*
         * Hardware programming guide suggests to configure
         * RX FIFO RFR level to fifo_depth-2.
         */
        geni_se_init(se, mas->tx_fifo_depth - 3, mas->tx_fifo_depth - 2);
        /* Transmit an entire FIFO worth of data per IRQ */
        mas->tx_wm = 1;
        ver = geni_se_get_qup_hw_version(se);
        major = GENI_SE_VERSION_MAJOR(ver);
        minor = GENI_SE_VERSION_MINOR(ver);

        if (major == 1 && minor == 0)
                mas->oversampling = 2;
        else
                mas->oversampling = 1;

        fifo_disable = readl(se->base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;
        switch (fifo_disable) {
        case 1:
                ret = spi_geni_grab_gpi_chan(mas);
                if (!ret) { /* success case */
                        mas->cur_xfer_mode = GENI_GPI_DMA;
                        geni_se_select_mode(se, GENI_GPI_DMA);
                        dev_dbg(mas->dev, "Using GPI DMA mode for SPI\n");
                        break;
                }
                /*
                 * in case of failure to get dma channel, we can still do the
                 * FIFO mode, so fallthrough
                 */
                dev_warn(mas->dev, "FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode\n");
                fallthrough;

        case 0:
                mas->cur_xfer_mode = GENI_SE_FIFO;
                geni_se_select_mode(se, GENI_SE_FIFO);
                ret = 0;
                break;
        }

        /* We always control CS manually */
        spi_tx_cfg = readl(se->base + SE_SPI_TRANS_CFG);
        spi_tx_cfg &= ~CS_TOGGLE;
        writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG);

out_pm:
        pm_runtime_put(mas->dev);
        return ret;
}

static unsigned int geni_byte_per_fifo_word(struct spi_geni_master *mas)
{
        /*
         * Calculate how many bytes we'll put in each FIFO word.  If the
         * transfer words don't pack cleanly into a FIFO word we'll just put
         * one transfer word in each FIFO word.  If they do pack we'll pack 'em.
         */
        if (mas->fifo_width_bits % mas->cur_bits_per_word)
                return roundup_pow_of_two(DIV_ROUND_UP(mas->cur_bits_per_word,
                                                       BITS_PER_BYTE));

        return mas->fifo_width_bits / BITS_PER_BYTE;
}

static bool geni_spi_handle_tx(struct spi_geni_master *mas)
{
        struct geni_se *se = &mas->se;
        unsigned int max_bytes;
        const u8 *tx_buf;
        unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
        unsigned int i = 0;

        /* Stop the watermark IRQ if nothing to send */
        if (!mas->cur_xfer) {
                writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
                return false;
        }

        max_bytes = (mas->tx_fifo_depth - mas->tx_wm) * bytes_per_fifo_word;
        if (mas->tx_rem_bytes < max_bytes)
                max_bytes = mas->tx_rem_bytes;

        tx_buf = mas->cur_xfer->tx_buf + mas->cur_xfer->len - mas->tx_rem_bytes;
        while (i < max_bytes) {
                unsigned int j;
                unsigned int bytes_to_write;
                u32 fifo_word = 0;
                u8 *fifo_byte = (u8 *)&fifo_word;

                bytes_to_write = min(bytes_per_fifo_word, max_bytes - i);
                for (j = 0; j < bytes_to_write; j++)
                        fifo_byte[j] = tx_buf[i++];
                iowrite32_rep(se->base + SE_GENI_TX_FIFOn, &fifo_word, 1);
        }
        mas->tx_rem_bytes -= max_bytes;
        if (!mas->tx_rem_bytes) {
                writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
                return false;
        }
        return true;
}

static void geni_spi_handle_rx(struct spi_geni_master *mas)
{
        struct geni_se *se = &mas->se;
        u32 rx_fifo_status;
        unsigned int rx_bytes;
        unsigned int rx_last_byte_valid;
        u8 *rx_buf;
        unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
        unsigned int i = 0;

        rx_fifo_status = readl(se->base + SE_GENI_RX_FIFO_STATUS);
        rx_bytes = (rx_fifo_status & RX_FIFO_WC_MSK) * bytes_per_fifo_word;
        if (rx_fifo_status & RX_LAST) {
                rx_last_byte_valid = rx_fifo_status & RX_LAST_BYTE_VALID_MSK;
                rx_last_byte_valid >>= RX_LAST_BYTE_VALID_SHFT;
                if (rx_last_byte_valid && rx_last_byte_valid < 4)
                        rx_bytes -= bytes_per_fifo_word - rx_last_byte_valid;
        }

        /* Clear out the FIFO and bail if nowhere to put it */
        if (!mas->cur_xfer) {
                for (i = 0; i < DIV_ROUND_UP(rx_bytes, bytes_per_fifo_word); i++)
                        readl(se->base + SE_GENI_RX_FIFOn);
                return;
        }

        if (mas->rx_rem_bytes < rx_bytes)
                rx_bytes = mas->rx_rem_bytes;

        rx_buf = mas->cur_xfer->rx_buf + mas->cur_xfer->len - mas->rx_rem_bytes;
        while (i < rx_bytes) {
                u32 fifo_word = 0;
                u8 *fifo_byte = (u8 *)&fifo_word;
                unsigned int bytes_to_read;
                unsigned int j;

                bytes_to_read = min(bytes_per_fifo_word, rx_bytes - i);
                ioread32_rep(se->base + SE_GENI_RX_FIFOn, &fifo_word, 1);
                for (j = 0; j < bytes_to_read; j++)
                        rx_buf[i++] = fifo_byte[j];
        }
        mas->rx_rem_bytes -= rx_bytes;
}

static void setup_fifo_xfer(struct spi_transfer *xfer,
                                struct spi_geni_master *mas,
                                u16 mode, struct spi_master *spi)
{
        u32 m_cmd = 0;
        u32 len;
        struct geni_se *se = &mas->se;
        int ret;

        /*
         * Ensure that our interrupt handler isn't still running from some
         * prior command before we start messing with the hardware behind
         * its back.  We don't need to _keep_ the lock here since we're only
         * worried about racing with out interrupt handler.  The SPI core
         * already handles making sure that we're not trying to do two
         * transfers at once or setting a chip select and doing a transfer
         * concurrently.
         *
         * NOTE: we actually _can't_ hold the lock here because possibly we
         * might call clk_set_rate() which needs to be able to sleep.
         */
        spin_lock_irq(&mas->lock);
        spin_unlock_irq(&mas->lock);

        if (xfer->bits_per_word != mas->cur_bits_per_word) {
                spi_setup_word_len(mas, mode, xfer->bits_per_word);
                mas->cur_bits_per_word = xfer->bits_per_word;
        }

        /* Speed and bits per word can be overridden per transfer */
        ret = geni_spi_set_clock_and_bw(mas, xfer->speed_hz);
        if (ret)
                return;

        mas->tx_rem_bytes = 0;
        mas->rx_rem_bytes = 0;

        if (!(mas->cur_bits_per_word % MIN_WORD_LEN))
                len = xfer->len * BITS_PER_BYTE / mas->cur_bits_per_word;
        else
                len = xfer->len / (mas->cur_bits_per_word / BITS_PER_BYTE + 1);
        len &= TRANS_LEN_MSK;

        mas->cur_xfer = xfer;
        if (xfer->tx_buf) {
                m_cmd |= SPI_TX_ONLY;
                mas->tx_rem_bytes = xfer->len;
                writel(len, se->base + SE_SPI_TX_TRANS_LEN);
        }

        if (xfer->rx_buf) {
                m_cmd |= SPI_RX_ONLY;
                writel(len, se->base + SE_SPI_RX_TRANS_LEN);
                mas->rx_rem_bytes = xfer->len;
        }

        /*
         * Lock around right before we start the transfer since our
         * interrupt could come in at any time now.
         */
        spin_lock_irq(&mas->lock);
        geni_se_setup_m_cmd(se, m_cmd, FRAGMENTATION);
        if (m_cmd & SPI_TX_ONLY) {
                if (geni_spi_handle_tx(mas))
                        writel(mas->tx_wm, se->base + SE_GENI_TX_WATERMARK_REG);
        }
        spin_unlock_irq(&mas->lock);
}

static int spi_geni_transfer_one(struct spi_master *spi,
                                struct spi_device *slv,
                                struct spi_transfer *xfer)
{
        struct spi_geni_master *mas = spi_master_get_devdata(spi);

        if (spi_geni_is_abort_still_pending(mas))
                return -EBUSY;

        /* Terminate and return success for 0 byte length transfer */
        if (!xfer->len)
                return 0;

        if (mas->cur_xfer_mode == GENI_SE_FIFO) {
                setup_fifo_xfer(xfer, mas, slv->mode, spi);
                return 1;
        }
        return setup_gsi_xfer(xfer, mas, slv, spi);
}

static irqreturn_t geni_spi_isr(int irq, void *data)
{
        struct spi_master *spi = data;
        struct spi_geni_master *mas = spi_master_get_devdata(spi);
        struct geni_se *se = &mas->se;
        u32 m_irq;

        m_irq = readl(se->base + SE_GENI_M_IRQ_STATUS);
        if (!m_irq)
                return IRQ_NONE;

        if (m_irq & (M_CMD_OVERRUN_EN | M_ILLEGAL_CMD_EN | M_CMD_FAILURE_EN |
                     M_RX_FIFO_RD_ERR_EN | M_RX_FIFO_WR_ERR_EN |
                     M_TX_FIFO_RD_ERR_EN | M_TX_FIFO_WR_ERR_EN))
                dev_warn(mas->dev, "Unexpected IRQ err status %#010x\n", m_irq);

        spin_lock(&mas->lock);

        if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
                geni_spi_handle_rx(mas);

        if (m_irq & M_TX_FIFO_WATERMARK_EN)
                geni_spi_handle_tx(mas);

        if (m_irq & M_CMD_DONE_EN) {
                if (mas->cur_xfer) {
                        spi_finalize_current_transfer(spi);
                        mas->cur_xfer = NULL;
                        /*
                         * If this happens, then a CMD_DONE came before all the
                         * Tx buffer bytes were sent out. This is unusual, log
                         * this condition and disable the WM interrupt to
                         * prevent the system from stalling due an interrupt
                         * storm.
                         *
                         * If this happens when all Rx bytes haven't been
                         * received, log the condition. The only known time
                         * this can happen is if bits_per_word != 8 and some
                         * registers that expect xfer lengths in num spi_words
                         * weren't written correctly.
                         */
                        if (mas->tx_rem_bytes) {
                                writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
                                dev_err(mas->dev, "Premature done. tx_rem = %d bpw%d\n",
                                        mas->tx_rem_bytes, mas->cur_bits_per_word);
                        }
                        if (mas->rx_rem_bytes)
                                dev_err(mas->dev, "Premature done. rx_rem = %d bpw%d\n",
                                        mas->rx_rem_bytes, mas->cur_bits_per_word);
                } else {
                        complete(&mas->cs_done);
                }
        }

        if (m_irq & M_CMD_CANCEL_EN)
                complete(&mas->cancel_done);
        if (m_irq & M_CMD_ABORT_EN)
                complete(&mas->abort_done);

        /*
         * It's safe or a good idea to Ack all of our interrupts at the end
         * of the function. Specifically:
         * - M_CMD_DONE_EN / M_RX_FIFO_LAST_EN: Edge triggered interrupts and
         *   clearing Acks. Clearing at the end relies on nobody else having
         *   started a new transfer yet or else we could be clearing _their_
         *   done bit, but everyone grabs the spinlock before starting a new
         *   transfer.
         * - M_RX_FIFO_WATERMARK_EN / M_TX_FIFO_WATERMARK_EN: These appear
         *   to be "latched level" interrupts so it's important to clear them
         *   _after_ you've handled the condition and always safe to do so
         *   since they'll re-assert if they're still happening.
         */
        writel(m_irq, se->base + SE_GENI_M_IRQ_CLEAR);

        spin_unlock(&mas->lock);

        return IRQ_HANDLED;
}

static int spi_geni_probe(struct platform_device *pdev)
{
        int ret, irq;
        struct spi_master *spi;
        struct spi_geni_master *mas;
        void __iomem *base;
        struct clk *clk;
        struct device *dev = &pdev->dev;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
        if (ret) {
                ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
                if (ret)
                        return dev_err_probe(dev, ret, "could not set DMA mask\n");
        }

        base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(base))
                return PTR_ERR(base);

        clk = devm_clk_get(dev, "se");
        if (IS_ERR(clk))
                return PTR_ERR(clk);

        spi = devm_spi_alloc_master(dev, sizeof(*mas));
        if (!spi)
                return -ENOMEM;

        platform_set_drvdata(pdev, spi);
        mas = spi_master_get_devdata(spi);
        mas->irq = irq;
        mas->dev = dev;
        mas->se.dev = dev;
        mas->se.wrapper = dev_get_drvdata(dev->parent);
        mas->se.base = base;
        mas->se.clk = clk;

        ret = devm_pm_opp_set_clkname(&pdev->dev, "se");
        if (ret)
                return ret;
        /* OPP table is optional */
        ret = devm_pm_opp_of_add_table(&pdev->dev);
        if (ret && ret != -ENODEV) {
                dev_err(&pdev->dev, "invalid OPP table in device tree\n");
                return ret;
        }

        spi->bus_num = -1;
        spi->dev.of_node = dev->of_node;
        spi->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH;
        spi->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
        spi->num_chipselect = 4;
        spi->max_speed_hz = 50000000;
        spi->prepare_message = spi_geni_prepare_message;
        spi->transfer_one = spi_geni_transfer_one;
        spi->can_dma = geni_can_dma;
        spi->dma_map_dev = dev->parent;
        spi->auto_runtime_pm = true;
        spi->handle_err = spi_geni_handle_err;
        spi->use_gpio_descriptors = true;

        init_completion(&mas->cs_done);
        init_completion(&mas->cancel_done);
        init_completion(&mas->abort_done);
        spin_lock_init(&mas->lock);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev, 250);
        pm_runtime_enable(dev);

        ret = geni_icc_get(&mas->se, NULL);
        if (ret)
                goto spi_geni_probe_runtime_disable;
        /* Set the bus quota to a reasonable value for register access */
        mas->se.icc_paths[GENI_TO_CORE].avg_bw = Bps_to_icc(CORE_2X_50_MHZ);
        mas->se.icc_paths[CPU_TO_GENI].avg_bw = GENI_DEFAULT_BW;

        ret = geni_icc_set_bw(&mas->se);
        if (ret)
                goto spi_geni_probe_runtime_disable;

        ret = spi_geni_init(mas);
        if (ret)
                goto spi_geni_probe_runtime_disable;

        /*
         * check the mode supported and set_cs for fifo mode only
         * for dma (gsi) mode, the gsi will set cs based on params passed in
         * TRE
         */
        if (mas->cur_xfer_mode == GENI_SE_FIFO)
                spi->set_cs = spi_geni_set_cs;

        ret = request_irq(mas->irq, geni_spi_isr, 0, dev_name(dev), spi);
        if (ret)
                goto spi_geni_release_dma;

        ret = spi_register_master(spi);
        if (ret)
                goto spi_geni_probe_free_irq;

        return 0;
spi_geni_probe_free_irq:
        free_irq(mas->irq, spi);
spi_geni_release_dma:
        spi_geni_release_dma_chan(mas);
spi_geni_probe_runtime_disable:
        pm_runtime_disable(dev);
        return ret;
}

static int spi_geni_remove(struct platform_device *pdev)
{
        struct spi_master *spi = platform_get_drvdata(pdev);
        struct spi_geni_master *mas = spi_master_get_devdata(spi);

        /* Unregister _before_ disabling pm_runtime() so we stop transfers */
        spi_unregister_master(spi);

        spi_geni_release_dma_chan(mas);

        free_irq(mas->irq, spi);
        pm_runtime_disable(&pdev->dev);
        return 0;
}

static int __maybe_unused spi_geni_runtime_suspend(struct device *dev)
{
        struct spi_master *spi = dev_get_drvdata(dev);
        struct spi_geni_master *mas = spi_master_get_devdata(spi);
        int ret;

        /* Drop the performance state vote */
        dev_pm_opp_set_rate(dev, 0);

        ret = geni_se_resources_off(&mas->se);
        if (ret)
                return ret;

        return geni_icc_disable(&mas->se);
}

static int __maybe_unused spi_geni_runtime_resume(struct device *dev)
{
        struct spi_master *spi = dev_get_drvdata(dev);
        struct spi_geni_master *mas = spi_master_get_devdata(spi);
        int ret;

        ret = geni_icc_enable(&mas->se);
        if (ret)
                return ret;

        ret = geni_se_resources_on(&mas->se);
        if (ret)
                return ret;

        return dev_pm_opp_set_rate(mas->dev, mas->cur_sclk_hz);
}

static int __maybe_unused spi_geni_suspend(struct device *dev)
{
        struct spi_master *spi = dev_get_drvdata(dev);
        int ret;

        ret = spi_master_suspend(spi);
        if (ret)
                return ret;

        ret = pm_runtime_force_suspend(dev);
        if (ret)
                spi_master_resume(spi);

        return ret;
}

static int __maybe_unused spi_geni_resume(struct device *dev)
{
        struct spi_master *spi = dev_get_drvdata(dev);
        int ret;

        ret = pm_runtime_force_resume(dev);
        if (ret)
                return ret;

        ret = spi_master_resume(spi);
        if (ret)
                pm_runtime_force_suspend(dev);

        return ret;
}

static const struct dev_pm_ops spi_geni_pm_ops = {
        SET_RUNTIME_PM_OPS(spi_geni_runtime_suspend,
                                        spi_geni_runtime_resume, NULL)
        SET_SYSTEM_SLEEP_PM_OPS(spi_geni_suspend, spi_geni_resume)
};

static const struct of_device_id spi_geni_dt_match[] = {
        { .compatible = "qcom,geni-spi" },
        {}
};
MODULE_DEVICE_TABLE(of, spi_geni_dt_match);

static struct platform_driver spi_geni_driver = {
        .probe  = spi_geni_probe,
        .remove = spi_geni_remove,
        .driver = {
                .name = "geni_spi",
                .pm = &spi_geni_pm_ops,
                .of_match_table = spi_geni_dt_match,
        },
};
module_platform_driver(spi_geni_driver);

MODULE_DESCRIPTION("SPI driver for GENI based QUP cores");
MODULE_LICENSE("GPL v2");