// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Spreadtrum Communications Inc.

#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dma/sprd-dma.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_dma.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/spi/spi.h>

#define SPRD_SPI_TXD                    0x0
#define SPRD_SPI_CLKD                   0x4
#define SPRD_SPI_CTL0                   0x8
#define SPRD_SPI_CTL1                   0xc
#define SPRD_SPI_CTL2                   0x10
#define SPRD_SPI_CTL3                   0x14
#define SPRD_SPI_CTL4                   0x18
#define SPRD_SPI_CTL5                   0x1c
#define SPRD_SPI_INT_EN                 0x20
#define SPRD_SPI_INT_CLR                0x24
#define SPRD_SPI_INT_RAW_STS            0x28
#define SPRD_SPI_INT_MASK_STS           0x2c
#define SPRD_SPI_STS1                   0x30
#define SPRD_SPI_STS2                   0x34
#define SPRD_SPI_DSP_WAIT               0x38
#define SPRD_SPI_STS3                   0x3c
#define SPRD_SPI_CTL6                   0x40
#define SPRD_SPI_STS4                   0x44
#define SPRD_SPI_FIFO_RST               0x48
#define SPRD_SPI_CTL7                   0x4c
#define SPRD_SPI_STS5                   0x50
#define SPRD_SPI_CTL8                   0x54
#define SPRD_SPI_CTL9                   0x58
#define SPRD_SPI_CTL10                  0x5c
#define SPRD_SPI_CTL11                  0x60
#define SPRD_SPI_CTL12                  0x64
#define SPRD_SPI_STS6                   0x68
#define SPRD_SPI_STS7                   0x6c
#define SPRD_SPI_STS8                   0x70
#define SPRD_SPI_STS9                   0x74

/* Bits & mask definition for register CTL0 */
#define SPRD_SPI_SCK_REV                BIT(13)
#define SPRD_SPI_NG_TX                  BIT(1)
#define SPRD_SPI_NG_RX                  BIT(0)
#define SPRD_SPI_CHNL_LEN_MASK          GENMASK(4, 0)
#define SPRD_SPI_CSN_MASK               GENMASK(11, 8)
#define SPRD_SPI_CS0_VALID              BIT(8)

/* Bits & mask definition for register SPI_INT_EN */
#define SPRD_SPI_TX_END_INT_EN          BIT(8)
#define SPRD_SPI_RX_END_INT_EN          BIT(9)

/* Bits & mask definition for register SPI_INT_RAW_STS */
#define SPRD_SPI_TX_END_RAW             BIT(8)
#define SPRD_SPI_RX_END_RAW             BIT(9)

/* Bits & mask definition for register SPI_INT_CLR */
#define SPRD_SPI_TX_END_CLR             BIT(8)
#define SPRD_SPI_RX_END_CLR             BIT(9)

/* Bits & mask definition for register INT_MASK_STS */
#define SPRD_SPI_MASK_RX_END            BIT(9)
#define SPRD_SPI_MASK_TX_END            BIT(8)

/* Bits & mask definition for register STS2 */
#define SPRD_SPI_TX_BUSY                BIT(8)

/* Bits & mask definition for register CTL1 */
#define SPRD_SPI_RX_MODE                BIT(12)
#define SPRD_SPI_TX_MODE                BIT(13)
#define SPRD_SPI_RTX_MD_MASK            GENMASK(13, 12)

/* Bits & mask definition for register CTL2 */
#define SPRD_SPI_DMA_EN                 BIT(6)

/* Bits & mask definition for register CTL4 */
#define SPRD_SPI_START_RX               BIT(9)
#define SPRD_SPI_ONLY_RECV_MASK         GENMASK(8, 0)

/* Bits & mask definition for register SPI_INT_CLR */
#define SPRD_SPI_RX_END_INT_CLR         BIT(9)
#define SPRD_SPI_TX_END_INT_CLR         BIT(8)

/* Bits & mask definition for register SPI_INT_RAW */
#define SPRD_SPI_RX_END_IRQ             BIT(9)
#define SPRD_SPI_TX_END_IRQ             BIT(8)

/* Bits & mask definition for register CTL12 */
#define SPRD_SPI_SW_RX_REQ              BIT(0)
#define SPRD_SPI_SW_TX_REQ              BIT(1)

/* Bits & mask definition for register CTL7 */
#define SPRD_SPI_DATA_LINE2_EN          BIT(15)
#define SPRD_SPI_MODE_MASK              GENMASK(5, 3)
#define SPRD_SPI_MODE_OFFSET            3
#define SPRD_SPI_3WIRE_MODE             4
#define SPRD_SPI_4WIRE_MODE             0

/* Bits & mask definition for register CTL8 */
#define SPRD_SPI_TX_MAX_LEN_MASK        GENMASK(19, 0)
#define SPRD_SPI_TX_LEN_H_MASK          GENMASK(3, 0)
#define SPRD_SPI_TX_LEN_H_OFFSET        16

/* Bits & mask definition for register CTL9 */
#define SPRD_SPI_TX_LEN_L_MASK          GENMASK(15, 0)

/* Bits & mask definition for register CTL10 */
#define SPRD_SPI_RX_MAX_LEN_MASK        GENMASK(19, 0)
#define SPRD_SPI_RX_LEN_H_MASK          GENMASK(3, 0)
#define SPRD_SPI_RX_LEN_H_OFFSET        16

/* Bits & mask definition for register CTL11 */
#define SPRD_SPI_RX_LEN_L_MASK          GENMASK(15, 0)

/* Default & maximum word delay cycles */
#define SPRD_SPI_MIN_DELAY_CYCLE        14
#define SPRD_SPI_MAX_DELAY_CYCLE        130

#define SPRD_SPI_FIFO_SIZE              32
#define SPRD_SPI_CHIP_CS_NUM            0x4
#define SPRD_SPI_CHNL_LEN               2
#define SPRD_SPI_DEFAULT_SOURCE         26000000
#define SPRD_SPI_MAX_SPEED_HZ           48000000
#define SPRD_SPI_AUTOSUSPEND_DELAY      100
#define SPRD_SPI_DMA_STEP               8

enum sprd_spi_dma_channel {
        SPRD_SPI_RX,
        SPRD_SPI_TX,
        SPRD_SPI_MAX,
};

struct sprd_spi_dma {
        bool enable;
        struct dma_chan *dma_chan[SPRD_SPI_MAX];
        enum dma_slave_buswidth width;
        u32 fragmens_len;
        u32 rx_len;
};

struct sprd_spi {
        void __iomem *base;
        phys_addr_t phy_base;
        struct device *dev;
        struct clk *clk;
        int irq;
        u32 src_clk;
        u32 hw_mode;
        u32 trans_len;
        u32 trans_mode;
        u32 word_delay;
        u32 hw_speed_hz;
        u32 len;
        int status;
        struct sprd_spi_dma dma;
        struct completion xfer_completion;
        const void *tx_buf;
        void *rx_buf;
        int (*read_bufs)(struct sprd_spi *ss, u32 len);
        int (*write_bufs)(struct sprd_spi *ss, u32 len);
};

static u32 sprd_spi_transfer_max_timeout(struct sprd_spi *ss,
                                         struct spi_transfer *t)
{
        /*
         * The time spent on transmission of the full FIFO data is the maximum
         * SPI transmission time.
         */
        u32 size = t->bits_per_word * SPRD_SPI_FIFO_SIZE;
        u32 bit_time_us = DIV_ROUND_UP(USEC_PER_SEC, ss->hw_speed_hz);
        u32 total_time_us = size * bit_time_us;
        /*
         * There is an interval between data and the data in our SPI hardware,
         * so the total transmission time need add the interval time.
         */
        u32 interval_cycle = SPRD_SPI_FIFO_SIZE * ss->word_delay;
        u32 interval_time_us = DIV_ROUND_UP(interval_cycle * USEC_PER_SEC,
                                            ss->src_clk);

        return total_time_us + interval_time_us;
}

static int sprd_spi_wait_for_tx_end(struct sprd_spi *ss, struct spi_transfer *t)
{
        u32 val, us;
        int ret;

        us = sprd_spi_transfer_max_timeout(ss, t);
        ret = readl_relaxed_poll_timeout(ss->base + SPRD_SPI_INT_RAW_STS, val,
                                         val & SPRD_SPI_TX_END_IRQ, 0, us);
        if (ret) {
                dev_err(ss->dev, "SPI error, spi send timeout!\n");
                return ret;
        }

        ret = readl_relaxed_poll_timeout(ss->base + SPRD_SPI_STS2, val,
                                         !(val & SPRD_SPI_TX_BUSY), 0, us);
        if (ret) {
                dev_err(ss->dev, "SPI error, spi busy timeout!\n");
                return ret;
        }

        writel_relaxed(SPRD_SPI_TX_END_INT_CLR, ss->base + SPRD_SPI_INT_CLR);

        return 0;
}

static int sprd_spi_wait_for_rx_end(struct sprd_spi *ss, struct spi_transfer *t)
{
        u32 val, us;
        int ret;

        us = sprd_spi_transfer_max_timeout(ss, t);
        ret = readl_relaxed_poll_timeout(ss->base + SPRD_SPI_INT_RAW_STS, val,
                                         val & SPRD_SPI_RX_END_IRQ, 0, us);
        if (ret) {
                dev_err(ss->dev, "SPI error, spi rx timeout!\n");
                return ret;
        }

        writel_relaxed(SPRD_SPI_RX_END_INT_CLR, ss->base + SPRD_SPI_INT_CLR);

        return 0;
}

static void sprd_spi_tx_req(struct sprd_spi *ss)
{
        writel_relaxed(SPRD_SPI_SW_TX_REQ, ss->base + SPRD_SPI_CTL12);
}

static void sprd_spi_rx_req(struct sprd_spi *ss)
{
        writel_relaxed(SPRD_SPI_SW_RX_REQ, ss->base + SPRD_SPI_CTL12);
}

static void sprd_spi_enter_idle(struct sprd_spi *ss)
{
        u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL1);

        val &= ~SPRD_SPI_RTX_MD_MASK;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL1);
}

static void sprd_spi_set_transfer_bits(struct sprd_spi *ss, u32 bits)
{
        u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL0);

        /* Set the valid bits for every transaction */
        val &= ~(SPRD_SPI_CHNL_LEN_MASK << SPRD_SPI_CHNL_LEN);
        val |= bits << SPRD_SPI_CHNL_LEN;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
}

static void sprd_spi_set_tx_length(struct sprd_spi *ss, u32 length)
{
        u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL8);

        length &= SPRD_SPI_TX_MAX_LEN_MASK;
        val &= ~SPRD_SPI_TX_LEN_H_MASK;
        val |= length >> SPRD_SPI_TX_LEN_H_OFFSET;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL8);

        val = length & SPRD_SPI_TX_LEN_L_MASK;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL9);
}

static void sprd_spi_set_rx_length(struct sprd_spi *ss, u32 length)
{
        u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL10);

        length &= SPRD_SPI_RX_MAX_LEN_MASK;
        val &= ~SPRD_SPI_RX_LEN_H_MASK;
        val |= length >> SPRD_SPI_RX_LEN_H_OFFSET;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL10);

        val = length & SPRD_SPI_RX_LEN_L_MASK;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL11);
}

static void sprd_spi_chipselect(struct spi_device *sdev, bool cs)
{
        struct spi_controller *sctlr = sdev->controller;
        struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
        u32 val;

        val = readl_relaxed(ss->base + SPRD_SPI_CTL0);
        /*  The SPI controller will pull down CS pin if cs is 0 */
        if (!cs) {
                val &= ~SPRD_SPI_CS0_VALID;
                writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
        } else {
                val |= SPRD_SPI_CSN_MASK;
                writel_relaxed(val, ss->base + SPRD_SPI_CTL0);
        }
}

static int sprd_spi_write_only_receive(struct sprd_spi *ss, u32 len)
{
        u32 val;

        /* Clear the start receive bit and reset receive data number */
        val = readl_relaxed(ss->base + SPRD_SPI_CTL4);
        val &= ~(SPRD_SPI_START_RX | SPRD_SPI_ONLY_RECV_MASK);
        writel_relaxed(val, ss->base + SPRD_SPI_CTL4);

        /* Set the receive data length */
        val = readl_relaxed(ss->base + SPRD_SPI_CTL4);
        val |= len & SPRD_SPI_ONLY_RECV_MASK;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL4);

        /* Trigger to receive data */
        val = readl_relaxed(ss->base + SPRD_SPI_CTL4);
        val |= SPRD_SPI_START_RX;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL4);

        return len;
}

static int sprd_spi_write_bufs_u8(struct sprd_spi *ss, u32 len)
{
        u8 *tx_p = (u8 *)ss->tx_buf;
        int i;

        for (i = 0; i < len; i++)
                writeb_relaxed(tx_p[i], ss->base + SPRD_SPI_TXD);

        ss->tx_buf += i;
        return i;
}

static int sprd_spi_write_bufs_u16(struct sprd_spi *ss, u32 len)
{
        u16 *tx_p = (u16 *)ss->tx_buf;
        int i;

        for (i = 0; i < len; i++)
                writew_relaxed(tx_p[i], ss->base + SPRD_SPI_TXD);

        ss->tx_buf += i << 1;
        return i << 1;
}

static int sprd_spi_write_bufs_u32(struct sprd_spi *ss, u32 len)
{
        u32 *tx_p = (u32 *)ss->tx_buf;
        int i;

        for (i = 0; i < len; i++)
                writel_relaxed(tx_p[i], ss->base + SPRD_SPI_TXD);

        ss->tx_buf += i << 2;
        return i << 2;
}

static int sprd_spi_read_bufs_u8(struct sprd_spi *ss, u32 len)
{
        u8 *rx_p = (u8 *)ss->rx_buf;
        int i;

        for (i = 0; i < len; i++)
                rx_p[i] = readb_relaxed(ss->base + SPRD_SPI_TXD);

        ss->rx_buf += i;
        return i;
}

static int sprd_spi_read_bufs_u16(struct sprd_spi *ss, u32 len)
{
        u16 *rx_p = (u16 *)ss->rx_buf;
        int i;

        for (i = 0; i < len; i++)
                rx_p[i] = readw_relaxed(ss->base + SPRD_SPI_TXD);

        ss->rx_buf += i << 1;
        return i << 1;
}

static int sprd_spi_read_bufs_u32(struct sprd_spi *ss, u32 len)
{
        u32 *rx_p = (u32 *)ss->rx_buf;
        int i;

        for (i = 0; i < len; i++)
                rx_p[i] = readl_relaxed(ss->base + SPRD_SPI_TXD);

        ss->rx_buf += i << 2;
        return i << 2;
}

static int sprd_spi_txrx_bufs(struct spi_device *sdev, struct spi_transfer *t)
{
        struct sprd_spi *ss = spi_controller_get_devdata(sdev->controller);
        u32 trans_len = ss->trans_len, len;
        int ret, write_size = 0, read_size = 0;

        while (trans_len) {
                len = trans_len > SPRD_SPI_FIFO_SIZE ? SPRD_SPI_FIFO_SIZE :
                        trans_len;
                if (ss->trans_mode & SPRD_SPI_TX_MODE) {
                        sprd_spi_set_tx_length(ss, len);
                        write_size += ss->write_bufs(ss, len);

                        /*
                         * For our 3 wires mode or dual TX line mode, we need
                         * to request the controller to transfer.
                         */
                        if (ss->hw_mode & SPI_3WIRE || ss->hw_mode & SPI_TX_DUAL)
                                sprd_spi_tx_req(ss);

                        ret = sprd_spi_wait_for_tx_end(ss, t);
                } else {
                        sprd_spi_set_rx_length(ss, len);

                        /*
                         * For our 3 wires mode or dual TX line mode, we need
                         * to request the controller to read.
                         */
                        if (ss->hw_mode & SPI_3WIRE || ss->hw_mode & SPI_TX_DUAL)
                                sprd_spi_rx_req(ss);
                        else
                                write_size += ss->write_bufs(ss, len);

                        ret = sprd_spi_wait_for_rx_end(ss, t);
                }

                if (ret)
                        goto complete;

                if (ss->trans_mode & SPRD_SPI_RX_MODE)
                        read_size += ss->read_bufs(ss, len);

                trans_len -= len;
        }

        if (ss->trans_mode & SPRD_SPI_TX_MODE)
                ret = write_size;
        else
                ret = read_size;
complete:
        sprd_spi_enter_idle(ss);

        return ret;
}

static void sprd_spi_irq_enable(struct sprd_spi *ss)
{
        u32 val;

        /* Clear interrupt status before enabling interrupt. */
        writel_relaxed(SPRD_SPI_TX_END_CLR | SPRD_SPI_RX_END_CLR,
                ss->base + SPRD_SPI_INT_CLR);
        /* Enable SPI interrupt only in DMA mode. */
        val = readl_relaxed(ss->base + SPRD_SPI_INT_EN);
        writel_relaxed(val | SPRD_SPI_TX_END_INT_EN |
                       SPRD_SPI_RX_END_INT_EN,
                       ss->base + SPRD_SPI_INT_EN);
}

static void sprd_spi_irq_disable(struct sprd_spi *ss)
{
        writel_relaxed(0, ss->base + SPRD_SPI_INT_EN);
}

static void sprd_spi_dma_enable(struct sprd_spi *ss, bool enable)
{
        u32 val = readl_relaxed(ss->base + SPRD_SPI_CTL2);

        if (enable)
                val |= SPRD_SPI_DMA_EN;
        else
                val &= ~SPRD_SPI_DMA_EN;

        writel_relaxed(val, ss->base + SPRD_SPI_CTL2);
}

static int sprd_spi_dma_submit(struct dma_chan *dma_chan,
                               struct dma_slave_config *c,
                               struct sg_table *sg,
                               enum dma_transfer_direction dir)
{
        struct dma_async_tx_descriptor *desc;
        dma_cookie_t cookie;
        unsigned long flags;
        int ret;

        ret = dmaengine_slave_config(dma_chan, c);
        if (ret < 0)
                return ret;

        flags = SPRD_DMA_FLAGS(SPRD_DMA_CHN_MODE_NONE, SPRD_DMA_NO_TRG,
                               SPRD_DMA_FRAG_REQ, SPRD_DMA_TRANS_INT);
        desc = dmaengine_prep_slave_sg(dma_chan, sg->sgl, sg->nents, dir, flags);
        if (!desc)
                return  -ENODEV;

        cookie = dmaengine_submit(desc);
        if (dma_submit_error(cookie))
                return dma_submit_error(cookie);

        dma_async_issue_pending(dma_chan);

        return 0;
}

static int sprd_spi_dma_rx_config(struct sprd_spi *ss, struct spi_transfer *t)
{
        struct dma_chan *dma_chan = ss->dma.dma_chan[SPRD_SPI_RX];
        struct dma_slave_config config = {
                .src_addr = ss->phy_base,
                .src_addr_width = ss->dma.width,
                .dst_addr_width = ss->dma.width,
                .dst_maxburst = ss->dma.fragmens_len,
        };
        int ret;

        ret = sprd_spi_dma_submit(dma_chan, &config, &t->rx_sg, DMA_DEV_TO_MEM);
        if (ret)
                return ret;

        return ss->dma.rx_len;
}

static int sprd_spi_dma_tx_config(struct sprd_spi *ss, struct spi_transfer *t)
{
        struct dma_chan *dma_chan = ss->dma.dma_chan[SPRD_SPI_TX];
        struct dma_slave_config config = {
                .dst_addr = ss->phy_base,
                .src_addr_width = ss->dma.width,
                .dst_addr_width = ss->dma.width,
                .src_maxburst = ss->dma.fragmens_len,
        };
        int ret;

        ret = sprd_spi_dma_submit(dma_chan, &config, &t->tx_sg, DMA_MEM_TO_DEV);
        if (ret)
                return ret;

        return t->len;
}

static int sprd_spi_dma_request(struct sprd_spi *ss)
{
        ss->dma.dma_chan[SPRD_SPI_RX] = dma_request_chan(ss->dev, "rx_chn");
        if (IS_ERR_OR_NULL(ss->dma.dma_chan[SPRD_SPI_RX]))
                return dev_err_probe(ss->dev, PTR_ERR(ss->dma.dma_chan[SPRD_SPI_RX]),
                                     "request RX DMA channel failed!\n");

        ss->dma.dma_chan[SPRD_SPI_TX]  = dma_request_chan(ss->dev, "tx_chn");
        if (IS_ERR_OR_NULL(ss->dma.dma_chan[SPRD_SPI_TX])) {
                dma_release_channel(ss->dma.dma_chan[SPRD_SPI_RX]);
                return dev_err_probe(ss->dev, PTR_ERR(ss->dma.dma_chan[SPRD_SPI_TX]),
                                     "request TX DMA channel failed!\n");
        }

        return 0;
}

static void sprd_spi_dma_release(struct sprd_spi *ss)
{
        if (ss->dma.dma_chan[SPRD_SPI_RX])
                dma_release_channel(ss->dma.dma_chan[SPRD_SPI_RX]);

        if (ss->dma.dma_chan[SPRD_SPI_TX])
                dma_release_channel(ss->dma.dma_chan[SPRD_SPI_TX]);
}

static int sprd_spi_dma_txrx_bufs(struct spi_device *sdev,
                                  struct spi_transfer *t)
{
        struct sprd_spi *ss = spi_master_get_devdata(sdev->master);
        u32 trans_len = ss->trans_len;
        int ret, write_size = 0;

        reinit_completion(&ss->xfer_completion);
        sprd_spi_irq_enable(ss);
        if (ss->trans_mode & SPRD_SPI_TX_MODE) {
                write_size = sprd_spi_dma_tx_config(ss, t);
                sprd_spi_set_tx_length(ss, trans_len);

                /*
                 * For our 3 wires mode or dual TX line mode, we need
                 * to request the controller to transfer.
                 */
                if (ss->hw_mode & SPI_3WIRE || ss->hw_mode & SPI_TX_DUAL)
                        sprd_spi_tx_req(ss);
        } else {
                sprd_spi_set_rx_length(ss, trans_len);

                /*
                 * For our 3 wires mode or dual TX line mode, we need
                 * to request the controller to read.
                 */
                if (ss->hw_mode & SPI_3WIRE || ss->hw_mode & SPI_TX_DUAL)
                        sprd_spi_rx_req(ss);
                else
                        write_size = ss->write_bufs(ss, trans_len);
        }

        if (write_size < 0) {
                ret = write_size;
                dev_err(ss->dev, "failed to write, ret = %d\n", ret);
                goto trans_complete;
        }

        if (ss->trans_mode & SPRD_SPI_RX_MODE) {
                /*
                 * Set up the DMA receive data length, which must be an
                 * integral multiple of fragment length. But when the length
                 * of received data is less than fragment length, DMA can be
                 * configured to receive data according to the actual length
                 * of received data.
                 */
                ss->dma.rx_len = t->len > ss->dma.fragmens_len ?
                        (t->len - t->len % ss->dma.fragmens_len) :
                         t->len;
                ret = sprd_spi_dma_rx_config(ss, t);
                if (ret < 0) {
                        dev_err(&sdev->dev,
                                "failed to configure rx DMA, ret = %d\n", ret);
                        goto trans_complete;
                }
        }

        sprd_spi_dma_enable(ss, true);
        wait_for_completion(&(ss->xfer_completion));

        if (ss->trans_mode & SPRD_SPI_TX_MODE)
                ret = write_size;
        else
                ret = ss->dma.rx_len;

trans_complete:
        sprd_spi_dma_enable(ss, false);
        sprd_spi_enter_idle(ss);
        sprd_spi_irq_disable(ss);

        return ret;
}

static void sprd_spi_set_speed(struct sprd_spi *ss, u32 speed_hz)
{
        /*
         * From SPI datasheet, the prescale calculation formula:
         * prescale = SPI source clock / (2 * SPI_freq) - 1;
         */
        u32 clk_div = DIV_ROUND_UP(ss->src_clk, speed_hz << 1) - 1;

        /* Save the real hardware speed */
        ss->hw_speed_hz = (ss->src_clk >> 1) / (clk_div + 1);
        writel_relaxed(clk_div, ss->base + SPRD_SPI_CLKD);
}

static int sprd_spi_init_hw(struct sprd_spi *ss, struct spi_transfer *t)
{
        struct spi_delay *d = &t->word_delay;
        u16 word_delay, interval;
        u32 val;

        if (d->unit != SPI_DELAY_UNIT_SCK)
                return -EINVAL;

        val = readl_relaxed(ss->base + SPRD_SPI_CTL0);
        val &= ~(SPRD_SPI_SCK_REV | SPRD_SPI_NG_TX | SPRD_SPI_NG_RX);
        /* Set default chip selection, clock phase and clock polarity */
        val |= ss->hw_mode & SPI_CPHA ? SPRD_SPI_NG_RX : SPRD_SPI_NG_TX;
        val |= ss->hw_mode & SPI_CPOL ? SPRD_SPI_SCK_REV : 0;
        writel_relaxed(val, ss->base + SPRD_SPI_CTL0);

        /*
         * Set the intervals of two SPI frames, and the inteval calculation
         * formula as below per datasheet:
         * interval time (source clock cycles) = interval * 4 + 10.
         */
        word_delay = clamp_t(u16, d->value, SPRD_SPI_MIN_DELAY_CYCLE,
                             SPRD_SPI_MAX_DELAY_CYCLE);
        interval = DIV_ROUND_UP(word_delay - 10, 4);
        ss->word_delay = interval * 4 + 10;
        writel_relaxed(interval, ss->base + SPRD_SPI_CTL5);

        /* Reset SPI fifo */
        writel_relaxed(1, ss->base + SPRD_SPI_FIFO_RST);
        writel_relaxed(0, ss->base + SPRD_SPI_FIFO_RST);

        /* Set SPI work mode */
        val = readl_relaxed(ss->base + SPRD_SPI_CTL7);
        val &= ~SPRD_SPI_MODE_MASK;

        if (ss->hw_mode & SPI_3WIRE)
                val |= SPRD_SPI_3WIRE_MODE << SPRD_SPI_MODE_OFFSET;
        else
                val |= SPRD_SPI_4WIRE_MODE << SPRD_SPI_MODE_OFFSET;

        if (ss->hw_mode & SPI_TX_DUAL)
                val |= SPRD_SPI_DATA_LINE2_EN;
        else
                val &= ~SPRD_SPI_DATA_LINE2_EN;

        writel_relaxed(val, ss->base + SPRD_SPI_CTL7);

        return 0;
}

static int sprd_spi_setup_transfer(struct spi_device *sdev,
                                   struct spi_transfer *t)
{
        struct sprd_spi *ss = spi_controller_get_devdata(sdev->controller);
        u8 bits_per_word = t->bits_per_word;
        u32 val, mode = 0;
        int ret;

        ss->len = t->len;
        ss->tx_buf = t->tx_buf;
        ss->rx_buf = t->rx_buf;

        ss->hw_mode = sdev->mode;
        ret = sprd_spi_init_hw(ss, t);
        if (ret)
                return ret;

        /* Set tansfer speed and valid bits */
        sprd_spi_set_speed(ss, t->speed_hz);
        sprd_spi_set_transfer_bits(ss, bits_per_word);

        if (bits_per_word > 16)
                bits_per_word = round_up(bits_per_word, 16);
        else
                bits_per_word = round_up(bits_per_word, 8);

        switch (bits_per_word) {
        case 8:
                ss->trans_len = t->len;
                ss->read_bufs = sprd_spi_read_bufs_u8;
                ss->write_bufs = sprd_spi_write_bufs_u8;
                ss->dma.width = DMA_SLAVE_BUSWIDTH_1_BYTE;
                ss->dma.fragmens_len = SPRD_SPI_DMA_STEP;
                break;
        case 16:
                ss->trans_len = t->len >> 1;
                ss->read_bufs = sprd_spi_read_bufs_u16;
                ss->write_bufs = sprd_spi_write_bufs_u16;
                ss->dma.width = DMA_SLAVE_BUSWIDTH_2_BYTES;
                ss->dma.fragmens_len = SPRD_SPI_DMA_STEP << 1;
                break;
        case 32:
                ss->trans_len = t->len >> 2;
                ss->read_bufs = sprd_spi_read_bufs_u32;
                ss->write_bufs = sprd_spi_write_bufs_u32;
                ss->dma.width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                ss->dma.fragmens_len = SPRD_SPI_DMA_STEP << 2;
                break;
        default:
                return -EINVAL;
        }

        /* Set transfer read or write mode */
        val = readl_relaxed(ss->base + SPRD_SPI_CTL1);
        val &= ~SPRD_SPI_RTX_MD_MASK;
        if (t->tx_buf)
                mode |= SPRD_SPI_TX_MODE;
        if (t->rx_buf)
                mode |= SPRD_SPI_RX_MODE;

        writel_relaxed(val | mode, ss->base + SPRD_SPI_CTL1);

        ss->trans_mode = mode;

        /*
         * If in only receive mode, we need to trigger the SPI controller to
         * receive data automatically.
         */
        if (ss->trans_mode == SPRD_SPI_RX_MODE)
                ss->write_bufs = sprd_spi_write_only_receive;

        return 0;
}

static int sprd_spi_transfer_one(struct spi_controller *sctlr,
                                 struct spi_device *sdev,
                                 struct spi_transfer *t)
{
        int ret;

        ret = sprd_spi_setup_transfer(sdev, t);
        if (ret)
                goto setup_err;

        if (sctlr->can_dma(sctlr, sdev, t))
                ret = sprd_spi_dma_txrx_bufs(sdev, t);
        else
                ret = sprd_spi_txrx_bufs(sdev, t);

        if (ret == t->len)
                ret = 0;
        else if (ret >= 0)
                ret = -EREMOTEIO;

setup_err:
        spi_finalize_current_transfer(sctlr);

        return ret;
}

static irqreturn_t sprd_spi_handle_irq(int irq, void *data)
{
        struct sprd_spi *ss = (struct sprd_spi *)data;
        u32 val = readl_relaxed(ss->base + SPRD_SPI_INT_MASK_STS);

        if (val & SPRD_SPI_MASK_TX_END) {
                writel_relaxed(SPRD_SPI_TX_END_CLR, ss->base + SPRD_SPI_INT_CLR);
                if (!(ss->trans_mode & SPRD_SPI_RX_MODE))
                        complete(&ss->xfer_completion);

                return IRQ_HANDLED;
        }

        if (val & SPRD_SPI_MASK_RX_END) {
                writel_relaxed(SPRD_SPI_RX_END_CLR, ss->base + SPRD_SPI_INT_CLR);
                if (ss->dma.rx_len < ss->len) {
                        ss->rx_buf += ss->dma.rx_len;
                        ss->dma.rx_len +=
                                ss->read_bufs(ss, ss->len - ss->dma.rx_len);
                }
                complete(&ss->xfer_completion);

                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static int sprd_spi_irq_init(struct platform_device *pdev, struct sprd_spi *ss)
{
        int ret;

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

        ret = devm_request_irq(&pdev->dev, ss->irq, sprd_spi_handle_irq,
                                0, pdev->name, ss);
        if (ret)
                dev_err(&pdev->dev, "failed to request spi irq %d, ret = %d\n",
                        ss->irq, ret);

        return ret;
}

static int sprd_spi_clk_init(struct platform_device *pdev, struct sprd_spi *ss)
{
        struct clk *clk_spi, *clk_parent;

        clk_spi = devm_clk_get(&pdev->dev, "spi");
        if (IS_ERR(clk_spi)) {
                dev_warn(&pdev->dev, "can't get the spi clock\n");
                clk_spi = NULL;
        }

        clk_parent = devm_clk_get(&pdev->dev, "source");
        if (IS_ERR(clk_parent)) {
                dev_warn(&pdev->dev, "can't get the source clock\n");
                clk_parent = NULL;
        }

        ss->clk = devm_clk_get(&pdev->dev, "enable");
        if (IS_ERR(ss->clk)) {
                dev_err(&pdev->dev, "can't get the enable clock\n");
                return PTR_ERR(ss->clk);
        }

        if (!clk_set_parent(clk_spi, clk_parent))
                ss->src_clk = clk_get_rate(clk_spi);
        else
                ss->src_clk = SPRD_SPI_DEFAULT_SOURCE;

        return 0;
}

static bool sprd_spi_can_dma(struct spi_controller *sctlr,
                             struct spi_device *spi, struct spi_transfer *t)
{
        struct sprd_spi *ss = spi_controller_get_devdata(sctlr);

        return ss->dma.enable && (t->len > SPRD_SPI_FIFO_SIZE);
}

static int sprd_spi_dma_init(struct platform_device *pdev, struct sprd_spi *ss)
{
        int ret;

        ret = sprd_spi_dma_request(ss);
        if (ret) {
                if (ret == -EPROBE_DEFER)
                        return ret;

                dev_warn(&pdev->dev,
                         "failed to request dma, enter no dma mode, ret = %d\n",
                         ret);

                return 0;
        }

        ss->dma.enable = true;

        return 0;
}

static int sprd_spi_probe(struct platform_device *pdev)
{
        struct spi_controller *sctlr;
        struct resource *res;
        struct sprd_spi *ss;
        int ret;

        pdev->id = of_alias_get_id(pdev->dev.of_node, "spi");
        sctlr = spi_alloc_master(&pdev->dev, sizeof(*ss));
        if (!sctlr)
                return -ENOMEM;

        ss = spi_controller_get_devdata(sctlr);
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        ss->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(ss->base)) {
                ret = PTR_ERR(ss->base);
                goto free_controller;
        }

        ss->phy_base = res->start;
        ss->dev = &pdev->dev;
        sctlr->dev.of_node = pdev->dev.of_node;
        sctlr->mode_bits = SPI_CPOL | SPI_CPHA | SPI_3WIRE | SPI_TX_DUAL;
        sctlr->bus_num = pdev->id;
        sctlr->set_cs = sprd_spi_chipselect;
        sctlr->transfer_one = sprd_spi_transfer_one;
        sctlr->can_dma = sprd_spi_can_dma;
        sctlr->auto_runtime_pm = true;
        sctlr->max_speed_hz = min_t(u32, ss->src_clk >> 1,
                                    SPRD_SPI_MAX_SPEED_HZ);

        init_completion(&ss->xfer_completion);
        platform_set_drvdata(pdev, sctlr);
        ret = sprd_spi_clk_init(pdev, ss);
        if (ret)
                goto free_controller;

        ret = sprd_spi_irq_init(pdev, ss);
        if (ret)
                goto free_controller;

        ret = sprd_spi_dma_init(pdev, ss);
        if (ret)
                goto free_controller;

        ret = clk_prepare_enable(ss->clk);
        if (ret)
                goto release_dma;

        ret = pm_runtime_set_active(&pdev->dev);
        if (ret < 0)
                goto disable_clk;

        pm_runtime_set_autosuspend_delay(&pdev->dev,
                                         SPRD_SPI_AUTOSUSPEND_DELAY);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_enable(&pdev->dev);
        ret = pm_runtime_get_sync(&pdev->dev);
        if (ret < 0) {
                dev_err(&pdev->dev, "failed to resume SPI controller\n");
                goto err_rpm_put;
        }

        ret = devm_spi_register_controller(&pdev->dev, sctlr);
        if (ret)
                goto err_rpm_put;

        pm_runtime_mark_last_busy(&pdev->dev);
        pm_runtime_put_autosuspend(&pdev->dev);

        return 0;

err_rpm_put:
        pm_runtime_put_noidle(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
disable_clk:
        clk_disable_unprepare(ss->clk);
release_dma:
        sprd_spi_dma_release(ss);
free_controller:
        spi_controller_put(sctlr);

        return ret;
}

static int sprd_spi_remove(struct platform_device *pdev)
{
        struct spi_controller *sctlr = platform_get_drvdata(pdev);
        struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
        int ret;

        ret = pm_runtime_get_sync(ss->dev);
        if (ret < 0) {
                dev_err(ss->dev, "failed to resume SPI controller\n");
                return ret;
        }

        spi_controller_suspend(sctlr);

        if (ss->dma.enable)
                sprd_spi_dma_release(ss);
        clk_disable_unprepare(ss->clk);
        pm_runtime_put_noidle(&pdev->dev);
        pm_runtime_disable(&pdev->dev);

        return 0;
}

static int __maybe_unused sprd_spi_runtime_suspend(struct device *dev)
{
        struct spi_controller *sctlr = dev_get_drvdata(dev);
        struct sprd_spi *ss = spi_controller_get_devdata(sctlr);

        if (ss->dma.enable)
                sprd_spi_dma_release(ss);

        clk_disable_unprepare(ss->clk);

        return 0;
}

static int __maybe_unused sprd_spi_runtime_resume(struct device *dev)
{
        struct spi_controller *sctlr = dev_get_drvdata(dev);
        struct sprd_spi *ss = spi_controller_get_devdata(sctlr);
        int ret;

        ret = clk_prepare_enable(ss->clk);
        if (ret)
                return ret;

        if (!ss->dma.enable)
                return 0;

        ret = sprd_spi_dma_request(ss);
        if (ret)
                clk_disable_unprepare(ss->clk);

        return ret;
}

static const struct dev_pm_ops sprd_spi_pm_ops = {
        SET_RUNTIME_PM_OPS(sprd_spi_runtime_suspend,
                           sprd_spi_runtime_resume, NULL)
};

static const struct of_device_id sprd_spi_of_match[] = {
        { .compatible = "sprd,sc9860-spi", },
        { /* sentinel */ }
};

static struct platform_driver sprd_spi_driver = {
        .driver = {
                .name = "sprd-spi",
                .of_match_table = sprd_spi_of_match,
                .pm = &sprd_spi_pm_ops,
        },
        .probe = sprd_spi_probe,
        .remove  = sprd_spi_remove,
};

module_platform_driver(sprd_spi_driver);

MODULE_DESCRIPTION("Spreadtrum SPI Controller driver");
MODULE_AUTHOR("Lanqing Liu <lanqing.liu@spreadtrum.com>");
MODULE_LICENSE("GPL v2");