// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2012 - 2014 Allwinner Tech
 * Pan Nan <pannan@allwinnertech.com>
 *
 * Copyright (C) 2014 Maxime Ripard
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>
#include <linux/dmaengine.h>

#include <linux/spi/spi.h>

#define SUN6I_AUTOSUSPEND_TIMEOUT       2000

#define SUN6I_FIFO_DEPTH                128
#define SUN8I_FIFO_DEPTH                64

#define SUN6I_GBL_CTL_REG               0x04
#define SUN6I_GBL_CTL_BUS_ENABLE                BIT(0)
#define SUN6I_GBL_CTL_MASTER                    BIT(1)
#define SUN6I_GBL_CTL_TP                        BIT(7)
#define SUN6I_GBL_CTL_RST                       BIT(31)

#define SUN6I_TFR_CTL_REG               0x08
#define SUN6I_TFR_CTL_CPHA                      BIT(0)
#define SUN6I_TFR_CTL_CPOL                      BIT(1)
#define SUN6I_TFR_CTL_SPOL                      BIT(2)
#define SUN6I_TFR_CTL_CS_MASK                   0x30
#define SUN6I_TFR_CTL_CS(cs)                    (((cs) << 4) & SUN6I_TFR_CTL_CS_MASK)
#define SUN6I_TFR_CTL_CS_MANUAL                 BIT(6)
#define SUN6I_TFR_CTL_CS_LEVEL                  BIT(7)
#define SUN6I_TFR_CTL_DHB                       BIT(8)
#define SUN6I_TFR_CTL_SDC                       BIT(11)
#define SUN6I_TFR_CTL_FBS                       BIT(12)
#define SUN6I_TFR_CTL_SDM                       BIT(13)
#define SUN6I_TFR_CTL_XCH                       BIT(31)

#define SUN6I_INT_CTL_REG               0x10
#define SUN6I_INT_CTL_RF_RDY                    BIT(0)
#define SUN6I_INT_CTL_TF_ERQ                    BIT(4)
#define SUN6I_INT_CTL_RF_OVF                    BIT(8)
#define SUN6I_INT_CTL_TC                        BIT(12)

#define SUN6I_INT_STA_REG               0x14

#define SUN6I_FIFO_CTL_REG              0x18
#define SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_MASK   0xff
#define SUN6I_FIFO_CTL_RF_DRQ_EN                BIT(8)
#define SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_BITS   0
#define SUN6I_FIFO_CTL_RF_RST                   BIT(15)
#define SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_MASK   0xff
#define SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_BITS   16
#define SUN6I_FIFO_CTL_TF_DRQ_EN                BIT(24)
#define SUN6I_FIFO_CTL_TF_RST                   BIT(31)

#define SUN6I_FIFO_STA_REG              0x1c
#define SUN6I_FIFO_STA_RF_CNT_MASK              GENMASK(7, 0)
#define SUN6I_FIFO_STA_TF_CNT_MASK              GENMASK(23, 16)

#define SUN6I_CLK_CTL_REG               0x24
#define SUN6I_CLK_CTL_CDR2_MASK                 0xff
#define SUN6I_CLK_CTL_CDR2(div)                 (((div) & SUN6I_CLK_CTL_CDR2_MASK) << 0)
#define SUN6I_CLK_CTL_CDR1_MASK                 0xf
#define SUN6I_CLK_CTL_CDR1(div)                 (((div) & SUN6I_CLK_CTL_CDR1_MASK) << 8)
#define SUN6I_CLK_CTL_DRS                       BIT(12)

#define SUN6I_MAX_XFER_SIZE             0xffffff

#define SUN6I_BURST_CNT_REG             0x30

#define SUN6I_XMIT_CNT_REG              0x34

#define SUN6I_BURST_CTL_CNT_REG         0x38
#define SUN6I_BURST_CTL_CNT_STC_MASK            GENMASK(23, 0)
#define SUN6I_BURST_CTL_CNT_DRM                 BIT(28)
#define SUN6I_BURST_CTL_CNT_QUAD_EN             BIT(29)

#define SUN6I_TXDATA_REG                0x200
#define SUN6I_RXDATA_REG                0x300

struct sun6i_spi_cfg {
        unsigned long           fifo_depth;
        bool                    has_clk_ctl;
        u32                     mode_bits;
};

struct sun6i_spi {
        struct spi_controller   *host;
        void __iomem            *base_addr;
        dma_addr_t              dma_addr_rx;
        dma_addr_t              dma_addr_tx;
        struct clk              *hclk;
        struct clk              *mclk;
        struct reset_control    *rstc;

        struct completion       done;
        struct completion       dma_rx_done;

        const u8                *tx_buf;
        u8                      *rx_buf;
        int                     len;
        const struct sun6i_spi_cfg *cfg;
};

static inline u32 sun6i_spi_read(struct sun6i_spi *sspi, u32 reg)
{
        return readl(sspi->base_addr + reg);
}

static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
{
        writel(value, sspi->base_addr + reg);
}

static inline u32 sun6i_spi_get_rx_fifo_count(struct sun6i_spi *sspi)
{
        u32 reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);

        return FIELD_GET(SUN6I_FIFO_STA_RF_CNT_MASK, reg);
}

static inline u32 sun6i_spi_get_tx_fifo_count(struct sun6i_spi *sspi)
{
        u32 reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);

        return FIELD_GET(SUN6I_FIFO_STA_TF_CNT_MASK, reg);
}

static inline void sun6i_spi_disable_interrupt(struct sun6i_spi *sspi, u32 mask)
{
        u32 reg = sun6i_spi_read(sspi, SUN6I_INT_CTL_REG);

        reg &= ~mask;
        sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, reg);
}

static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi)
{
        u32 len;
        u8 byte;

        /* See how much data is available */
        len = sun6i_spi_get_rx_fifo_count(sspi);

        while (len--) {
                byte = readb(sspi->base_addr + SUN6I_RXDATA_REG);
                if (sspi->rx_buf)
                        *sspi->rx_buf++ = byte;
        }
}

static inline void sun6i_spi_fill_fifo(struct sun6i_spi *sspi)
{
        u32 cnt;
        int len;
        u8 byte;

        /* See how much data we can fit */
        cnt = sspi->cfg->fifo_depth - sun6i_spi_get_tx_fifo_count(sspi);

        len = min((int)cnt, sspi->len);

        while (len--) {
                byte = sspi->tx_buf ? *sspi->tx_buf++ : 0;
                writeb(byte, sspi->base_addr + SUN6I_TXDATA_REG);
                sspi->len--;
        }
}

static void sun6i_spi_set_cs(struct spi_device *spi, bool enable)
{
        struct sun6i_spi *sspi = spi_controller_get_devdata(spi->controller);
        u32 reg;

        reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
        reg &= ~SUN6I_TFR_CTL_CS_MASK;
        reg |= SUN6I_TFR_CTL_CS(spi_get_chipselect(spi, 0));

        if (enable)
                reg |= SUN6I_TFR_CTL_CS_LEVEL;
        else
                reg &= ~SUN6I_TFR_CTL_CS_LEVEL;

        sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
}

static size_t sun6i_spi_max_transfer_size(struct spi_device *spi)
{
        return SUN6I_MAX_XFER_SIZE - 1;
}

static void sun6i_spi_dma_rx_cb(void *param)
{
        struct sun6i_spi *sspi = param;

        complete(&sspi->dma_rx_done);
}

static int sun6i_spi_prepare_dma(struct sun6i_spi *sspi,
                                 struct spi_transfer *tfr)
{
        struct dma_async_tx_descriptor *rxdesc, *txdesc;
        struct spi_controller *host = sspi->host;

        rxdesc = NULL;
        if (tfr->rx_buf) {
                struct dma_slave_config rxconf = {
                        .direction = DMA_DEV_TO_MEM,
                        .src_addr = sspi->dma_addr_rx,
                        .src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
                        .src_maxburst = 8,
                };

                dmaengine_slave_config(host->dma_rx, &rxconf);

                rxdesc = dmaengine_prep_slave_sg(host->dma_rx,
                                                 tfr->rx_sg.sgl,
                                                 tfr->rx_sg.nents,
                                                 DMA_DEV_TO_MEM,
                                                 DMA_PREP_INTERRUPT);
                if (!rxdesc)
                        return -EINVAL;
                rxdesc->callback_param = sspi;
                rxdesc->callback = sun6i_spi_dma_rx_cb;
        }

        txdesc = NULL;
        if (tfr->tx_buf) {
                struct dma_slave_config txconf = {
                        .direction = DMA_MEM_TO_DEV,
                        .dst_addr = sspi->dma_addr_tx,
                        .dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
                        .dst_maxburst = 8,
                };

                dmaengine_slave_config(host->dma_tx, &txconf);

                txdesc = dmaengine_prep_slave_sg(host->dma_tx,
                                                 tfr->tx_sg.sgl,
                                                 tfr->tx_sg.nents,
                                                 DMA_MEM_TO_DEV,
                                                 DMA_PREP_INTERRUPT);
                if (!txdesc) {
                        if (rxdesc)
                                dmaengine_terminate_sync(host->dma_rx);
                        return -EINVAL;
                }
        }

        if (tfr->rx_buf) {
                dmaengine_submit(rxdesc);
                dma_async_issue_pending(host->dma_rx);
        }

        if (tfr->tx_buf) {
                dmaengine_submit(txdesc);
                dma_async_issue_pending(host->dma_tx);
        }

        return 0;
}

static int sun6i_spi_transfer_one(struct spi_controller *host,
                                  struct spi_device *spi,
                                  struct spi_transfer *tfr)
{
        struct sun6i_spi *sspi = spi_controller_get_devdata(host);
        unsigned int div, div_cdr1, div_cdr2;
        unsigned long time_left;
        unsigned int start, end, tx_time;
        unsigned int trig_level;
        unsigned int tx_len = 0, rx_len = 0, nbits = 0;
        bool use_dma;
        int ret = 0;
        u32 reg;

        if (tfr->len > SUN6I_MAX_XFER_SIZE)
                return -EINVAL;

        reinit_completion(&sspi->done);
        reinit_completion(&sspi->dma_rx_done);
        sspi->tx_buf = tfr->tx_buf;
        sspi->rx_buf = tfr->rx_buf;
        sspi->len = tfr->len;
        use_dma = host->can_dma ? host->can_dma(host, spi, tfr) : false;

        /* Clear pending interrupts */
        sun6i_spi_write(sspi, SUN6I_INT_STA_REG, ~0);

        /* Reset FIFO */
        sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG,
                        SUN6I_FIFO_CTL_RF_RST | SUN6I_FIFO_CTL_TF_RST);

        reg = 0;

        if (!use_dma) {
                /*
                 * Setup FIFO interrupt trigger level
                 * Here we choose 3/4 of the full fifo depth, as it's
                 * the hardcoded value used in old generation of Allwinner
                 * SPI controller. (See spi-sun4i.c)
                 */
                trig_level = sspi->cfg->fifo_depth / 4 * 3;
        } else {
                /*
                 * Setup FIFO DMA request trigger level
                 * We choose 1/2 of the full fifo depth, that value will
                 * be used as DMA burst length.
                 */
                trig_level = sspi->cfg->fifo_depth / 2;

                if (tfr->tx_buf)
                        reg |= SUN6I_FIFO_CTL_TF_DRQ_EN;
                if (tfr->rx_buf)
                        reg |= SUN6I_FIFO_CTL_RF_DRQ_EN;
        }

        reg |= (trig_level << SUN6I_FIFO_CTL_RF_RDY_TRIG_LEVEL_BITS) |
               (trig_level << SUN6I_FIFO_CTL_TF_ERQ_TRIG_LEVEL_BITS);

        sun6i_spi_write(sspi, SUN6I_FIFO_CTL_REG, reg);

        /*
         * Setup the transfer control register: Chip Select,
         * polarities, etc.
         */
        reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);

        if (spi->mode & SPI_CPOL)
                reg |= SUN6I_TFR_CTL_CPOL;
        else
                reg &= ~SUN6I_TFR_CTL_CPOL;

        if (spi->mode & SPI_CPHA)
                reg |= SUN6I_TFR_CTL_CPHA;
        else
                reg &= ~SUN6I_TFR_CTL_CPHA;

        if (spi->mode & SPI_LSB_FIRST)
                reg |= SUN6I_TFR_CTL_FBS;
        else
                reg &= ~SUN6I_TFR_CTL_FBS;

        /*
         * If it's a TX only transfer, we don't want to fill the RX
         * FIFO with bogus data
         */
        if (sspi->rx_buf) {
                reg &= ~SUN6I_TFR_CTL_DHB;
                rx_len = tfr->len;
        } else {
                reg |= SUN6I_TFR_CTL_DHB;
        }

        /* We want to control the chip select manually */
        reg |= SUN6I_TFR_CTL_CS_MANUAL;

        sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);

        if (sspi->cfg->has_clk_ctl) {
                unsigned int mclk_rate = clk_get_rate(sspi->mclk);

                /* Ensure that we have a parent clock fast enough */
                if (mclk_rate < (2 * tfr->speed_hz)) {
                        clk_set_rate(sspi->mclk, 2 * tfr->speed_hz);
                        mclk_rate = clk_get_rate(sspi->mclk);
                }

                /*
                 * Setup clock divider.
                 *
                 * We have two choices there. Either we can use the clock
                 * divide rate 1, which is calculated thanks to this formula:
                 * SPI_CLK = MOD_CLK / (2 ^ cdr)
                 * Or we can use CDR2, which is calculated with the formula:
                 * SPI_CLK = MOD_CLK / (2 * (cdr + 1))
                 * Wether we use the former or the latter is set through the
                 * DRS bit.
                 *
                 * First try CDR2, and if we can't reach the expected
                 * frequency, fall back to CDR1.
                 */
                div_cdr1 = DIV_ROUND_UP(mclk_rate, tfr->speed_hz);
                div_cdr2 = DIV_ROUND_UP(div_cdr1, 2);
                if (div_cdr2 <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) {
                        reg = SUN6I_CLK_CTL_CDR2(div_cdr2 - 1) | SUN6I_CLK_CTL_DRS;
                        tfr->effective_speed_hz = mclk_rate / (2 * div_cdr2);
                } else {
                        div = min(SUN6I_CLK_CTL_CDR1_MASK, order_base_2(div_cdr1));
                        reg = SUN6I_CLK_CTL_CDR1(div);
                        tfr->effective_speed_hz = mclk_rate / (1 << div);
                }

                sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg);
        } else {
                clk_set_rate(sspi->mclk, tfr->speed_hz);
                tfr->effective_speed_hz = clk_get_rate(sspi->mclk);

                /*
                 * Configure work mode.
                 *
                 * There are three work modes depending on the controller clock
                 * frequency:
                 * - normal sample mode           : CLK <= 24MHz SDM=1 SDC=0
                 * - delay half-cycle sample mode : CLK <= 40MHz SDM=0 SDC=0
                 * - delay one-cycle sample mode  : CLK >= 80MHz SDM=0 SDC=1
                 */
                reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
                reg &= ~(SUN6I_TFR_CTL_SDM | SUN6I_TFR_CTL_SDC);

                if (tfr->effective_speed_hz <= 24000000)
                        reg |= SUN6I_TFR_CTL_SDM;
                else if (tfr->effective_speed_hz >= 80000000)
                        reg |= SUN6I_TFR_CTL_SDC;

                sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg);
        }

        /* Finally enable the bus - doing so before might raise SCK to HIGH */
        reg = sun6i_spi_read(sspi, SUN6I_GBL_CTL_REG);
        reg |= SUN6I_GBL_CTL_BUS_ENABLE;
        sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, reg);

        /* Setup the transfer now... */
        if (sspi->tx_buf) {
                tx_len = tfr->len;
                nbits = tfr->tx_nbits;
        } else if (tfr->rx_buf) {
                nbits = tfr->rx_nbits;
        }

        switch (nbits) {
        case SPI_NBITS_DUAL:
                reg = SUN6I_BURST_CTL_CNT_DRM;
                break;
        case SPI_NBITS_QUAD:
                reg = SUN6I_BURST_CTL_CNT_QUAD_EN;
                break;
        case SPI_NBITS_SINGLE:
        default:
                reg = FIELD_PREP(SUN6I_BURST_CTL_CNT_STC_MASK, tx_len);
        }

        /* Setup the counters */
        sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG, reg);
        sun6i_spi_write(sspi, SUN6I_BURST_CNT_REG, tfr->len);
        sun6i_spi_write(sspi, SUN6I_XMIT_CNT_REG, tx_len);

        if (!use_dma) {
                /* Fill the TX FIFO */
                sun6i_spi_fill_fifo(sspi);
        } else {
                ret = sun6i_spi_prepare_dma(sspi, tfr);
                if (ret) {
                        dev_warn(&host->dev,
                                 "%s: prepare DMA failed, ret=%d",
                                 dev_name(&spi->dev), ret);
                        return ret;
                }
        }

        /* Enable the interrupts */
        reg = SUN6I_INT_CTL_TC;

        if (!use_dma) {
                if (rx_len > sspi->cfg->fifo_depth)
                        reg |= SUN6I_INT_CTL_RF_RDY;
                if (tx_len > sspi->cfg->fifo_depth)
                        reg |= SUN6I_INT_CTL_TF_ERQ;
        }

        sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, reg);

        /* Start the transfer */
        reg = sun6i_spi_read(sspi, SUN6I_TFR_CTL_REG);
        sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg | SUN6I_TFR_CTL_XCH);

        tx_time = spi_controller_xfer_timeout(host, tfr);
        start = jiffies;
        time_left = wait_for_completion_timeout(&sspi->done,
                                                msecs_to_jiffies(tx_time));

        if (!use_dma) {
                sun6i_spi_drain_fifo(sspi);
        } else {
                if (time_left && rx_len) {
                        /*
                         * Even though RX on the peripheral side has finished
                         * RX DMA might still be in flight
                         */
                        time_left = wait_for_completion_timeout(&sspi->dma_rx_done,
                                                                time_left);
                        if (!time_left)
                                dev_warn(&host->dev, "RX DMA timeout\n");
                }
        }

        end = jiffies;
        if (!time_left) {
                dev_warn(&host->dev,
                         "%s: timeout transferring %u bytes@%iHz for %i(%i)ms",
                         dev_name(&spi->dev), tfr->len, tfr->speed_hz,
                         jiffies_to_msecs(end - start), tx_time);
                ret = -ETIMEDOUT;
        }

        sun6i_spi_write(sspi, SUN6I_INT_CTL_REG, 0);

        if (ret && use_dma) {
                dmaengine_terminate_sync(host->dma_rx);
                dmaengine_terminate_sync(host->dma_tx);
        }

        return ret;
}

static irqreturn_t sun6i_spi_handler(int irq, void *dev_id)
{
        struct sun6i_spi *sspi = dev_id;
        u32 status = sun6i_spi_read(sspi, SUN6I_INT_STA_REG);

        /* Transfer complete */
        if (status & SUN6I_INT_CTL_TC) {
                sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TC);
                complete(&sspi->done);
                return IRQ_HANDLED;
        }

        /* Receive FIFO 3/4 full */
        if (status & SUN6I_INT_CTL_RF_RDY) {
                sun6i_spi_drain_fifo(sspi);
                /* Only clear the interrupt _after_ draining the FIFO */
                sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_RF_RDY);
                return IRQ_HANDLED;
        }

        /* Transmit FIFO 3/4 empty */
        if (status & SUN6I_INT_CTL_TF_ERQ) {
                sun6i_spi_fill_fifo(sspi);

                if (!sspi->len)
                        /* nothing left to transmit */
                        sun6i_spi_disable_interrupt(sspi, SUN6I_INT_CTL_TF_ERQ);

                /* Only clear the interrupt _after_ re-seeding the FIFO */
                sun6i_spi_write(sspi, SUN6I_INT_STA_REG, SUN6I_INT_CTL_TF_ERQ);

                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

static int sun6i_spi_runtime_resume(struct device *dev)
{
        struct spi_controller *host = dev_get_drvdata(dev);
        struct sun6i_spi *sspi = spi_controller_get_devdata(host);
        int ret;

        ret = clk_prepare_enable(sspi->hclk);
        if (ret) {
                dev_err(dev, "Couldn't enable AHB clock\n");
                goto out;
        }

        ret = clk_prepare_enable(sspi->mclk);
        if (ret) {
                dev_err(dev, "Couldn't enable module clock\n");
                goto err;
        }

        ret = reset_control_deassert(sspi->rstc);
        if (ret) {
                dev_err(dev, "Couldn't deassert the device from reset\n");
                goto err2;
        }

        sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG,
                        SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP);

        return 0;

err2:
        clk_disable_unprepare(sspi->mclk);
err:
        clk_disable_unprepare(sspi->hclk);
out:
        return ret;
}

static int sun6i_spi_runtime_suspend(struct device *dev)
{
        struct spi_controller *host = dev_get_drvdata(dev);
        struct sun6i_spi *sspi = spi_controller_get_devdata(host);

        reset_control_assert(sspi->rstc);
        clk_disable_unprepare(sspi->mclk);
        clk_disable_unprepare(sspi->hclk);

        return 0;
}

static bool sun6i_spi_can_dma(struct spi_controller *host,
                              struct spi_device *spi,
                              struct spi_transfer *xfer)
{
        struct sun6i_spi *sspi = spi_controller_get_devdata(host);

        /*
         * If the number of spi words to transfer is less or equal than
         * the fifo length we can just fill the fifo and wait for a single
         * irq, so don't bother setting up dma
         */
        return xfer->len > sspi->cfg->fifo_depth;
}

static int sun6i_spi_probe(struct platform_device *pdev)
{
        struct spi_controller *host;
        struct sun6i_spi *sspi;
        struct resource *mem;
        int ret = 0, irq;

        host = spi_alloc_host(&pdev->dev, sizeof(struct sun6i_spi));
        if (!host) {
                dev_err(&pdev->dev, "Unable to allocate SPI Host\n");
                return -ENOMEM;
        }

        platform_set_drvdata(pdev, host);
        sspi = spi_controller_get_devdata(host);

        sspi->base_addr = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
        if (IS_ERR(sspi->base_addr)) {
                ret = PTR_ERR(sspi->base_addr);
                goto err_free_host;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                ret = -ENXIO;
                goto err_free_host;
        }

        ret = devm_request_irq(&pdev->dev, irq, sun6i_spi_handler,
                               0, "sun6i-spi", sspi);
        if (ret) {
                dev_err(&pdev->dev, "Cannot request IRQ\n");
                goto err_free_host;
        }

        sspi->host = host;
        sspi->cfg = of_device_get_match_data(&pdev->dev);

        host->max_speed_hz = 100 * 1000 * 1000;
        host->min_speed_hz = 3 * 1000;
        host->use_gpio_descriptors = true;
        host->set_cs = sun6i_spi_set_cs;
        host->transfer_one = sun6i_spi_transfer_one;
        host->num_chipselect = 4;
        host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST |
                          sspi->cfg->mode_bits;
        host->bits_per_word_mask = SPI_BPW_MASK(8);
        host->auto_runtime_pm = true;
        host->max_transfer_size = sun6i_spi_max_transfer_size;

        sspi->hclk = devm_clk_get(&pdev->dev, "ahb");
        if (IS_ERR(sspi->hclk)) {
                dev_err(&pdev->dev, "Unable to acquire AHB clock\n");
                ret = PTR_ERR(sspi->hclk);
                goto err_free_host;
        }

        sspi->mclk = devm_clk_get(&pdev->dev, "mod");
        if (IS_ERR(sspi->mclk)) {
                dev_err(&pdev->dev, "Unable to acquire module clock\n");
                ret = PTR_ERR(sspi->mclk);
                goto err_free_host;
        }

        init_completion(&sspi->done);
        init_completion(&sspi->dma_rx_done);

        sspi->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
        if (IS_ERR(sspi->rstc)) {
                dev_err(&pdev->dev, "Couldn't get reset controller\n");
                ret = PTR_ERR(sspi->rstc);
                goto err_free_host;
        }

        host->dma_tx = dma_request_chan(&pdev->dev, "tx");
        if (IS_ERR(host->dma_tx)) {
                /* Check tx to see if we need defer probing driver */
                if (PTR_ERR(host->dma_tx) == -EPROBE_DEFER) {
                        ret = -EPROBE_DEFER;
                        goto err_free_host;
                }
                dev_warn(&pdev->dev, "Failed to request TX DMA channel\n");
                host->dma_tx = NULL;
        }

        host->dma_rx = dma_request_chan(&pdev->dev, "rx");
        if (IS_ERR(host->dma_rx)) {
                if (PTR_ERR(host->dma_rx) == -EPROBE_DEFER) {
                        ret = -EPROBE_DEFER;
                        goto err_free_dma_tx;
                }
                dev_warn(&pdev->dev, "Failed to request RX DMA channel\n");
                host->dma_rx = NULL;
        }

        if (host->dma_tx && host->dma_rx) {
                sspi->dma_addr_tx = mem->start + SUN6I_TXDATA_REG;
                sspi->dma_addr_rx = mem->start + SUN6I_RXDATA_REG;
                host->can_dma = sun6i_spi_can_dma;
        }

        /*
         * This wake-up/shutdown pattern is to be able to have the
         * device woken up, even if runtime_pm is disabled
         */
        ret = sun6i_spi_runtime_resume(&pdev->dev);
        if (ret) {
                dev_err(&pdev->dev, "Couldn't resume the device\n");
                goto err_free_dma_rx;
        }

        pm_runtime_set_autosuspend_delay(&pdev->dev, SUN6I_AUTOSUSPEND_TIMEOUT);
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);
        pm_runtime_enable(&pdev->dev);

        ret = devm_spi_register_controller(&pdev->dev, host);
        if (ret) {
                dev_err(&pdev->dev, "cannot register SPI host\n");
                goto err_pm_disable;
        }

        return 0;

err_pm_disable:
        pm_runtime_disable(&pdev->dev);
        sun6i_spi_runtime_suspend(&pdev->dev);
err_free_dma_rx:
        if (host->dma_rx)
                dma_release_channel(host->dma_rx);
err_free_dma_tx:
        if (host->dma_tx)
                dma_release_channel(host->dma_tx);
err_free_host:
        spi_controller_put(host);
        return ret;
}

static void sun6i_spi_remove(struct platform_device *pdev)
{
        struct spi_controller *host = platform_get_drvdata(pdev);

        pm_runtime_force_suspend(&pdev->dev);

        if (host->dma_tx)
                dma_release_channel(host->dma_tx);
        if (host->dma_rx)
                dma_release_channel(host->dma_rx);
}

static const struct sun6i_spi_cfg sun6i_a31_spi_cfg = {
        .fifo_depth     = SUN6I_FIFO_DEPTH,
        .has_clk_ctl    = true,
};

static const struct sun6i_spi_cfg sun8i_h3_spi_cfg = {
        .fifo_depth     = SUN8I_FIFO_DEPTH,
        .has_clk_ctl    = true,
};

static const struct sun6i_spi_cfg sun50i_r329_spi_cfg = {
        .fifo_depth     = SUN8I_FIFO_DEPTH,
        .mode_bits      = SPI_RX_DUAL | SPI_TX_DUAL | SPI_RX_QUAD | SPI_TX_QUAD,
};

static const struct of_device_id sun6i_spi_match[] = {
        { .compatible = "allwinner,sun6i-a31-spi", .data = &sun6i_a31_spi_cfg },
        { .compatible = "allwinner,sun8i-h3-spi",  .data = &sun8i_h3_spi_cfg },
        { .compatible = "allwinner,sun50i-r329-spi", .data = &sun50i_r329_spi_cfg },
        /*
         * A523's SPI controller has a combined RX buffer + FIFO counter
         * at offset 0x400, instead of split buffer count in FIFO status
         * register. But in practice we only care about the FIFO level.
         */
        { .compatible = "allwinner,sun55i-a523-spi", .data = &sun50i_r329_spi_cfg },
        {}
};
MODULE_DEVICE_TABLE(of, sun6i_spi_match);

static const struct dev_pm_ops sun6i_spi_pm_ops = {
        .runtime_resume         = sun6i_spi_runtime_resume,
        .runtime_suspend        = sun6i_spi_runtime_suspend,
};

static struct platform_driver sun6i_spi_driver = {
        .probe  = sun6i_spi_probe,
        .remove = sun6i_spi_remove,
        .driver = {
                .name           = "sun6i-spi",
                .of_match_table = sun6i_spi_match,
                .pm             = &sun6i_spi_pm_ops,
        },
};
module_platform_driver(sun6i_spi_driver);

MODULE_AUTHOR("Pan Nan <pannan@allwinnertech.com>");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_DESCRIPTION("Allwinner A31 SPI controller driver");
MODULE_LICENSE("GPL");