/*
 * Driver for Amlogic Meson SPI communication controller (SPICC)
 *
 * Copyright (C) BayLibre, SAS
 * Author: Neil Armstrong <narmstrong@baylibre.com>
 *
 * SPDX-License-Identifier: GPL-2.0+
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/reset.h>
#include <linux/pinctrl/consumer.h>
#include <linux/dma-mapping.h>

/*
 * There are two modes for data transmission: PIO and DMA.
 * When bits_per_word is 8, 16, 24, or 32, data is transferred using PIO mode.
 * When bits_per_word is 64, DMA mode is used by default.
 *
 * DMA achieves a transfer with one or more SPI bursts, each SPI burst is made
 * up of one or more DMA bursts. The DMA burst implementation mechanism is,
 * For TX, when the number of words in TXFIFO is less than the preset
 * reading threshold, SPICC starts a reading DMA burst, which reads the preset
 * number of words from TX buffer, then writes them into TXFIFO.
 * For RX, when the number of words in RXFIFO is greater than the preset
 * writing threshold, SPICC starts a writing request burst, which reads the
 * preset number of words from RXFIFO, then write them into RX buffer.
 * DMA works if the transfer meets the following conditions,
 * - 64 bits per word
 * - The transfer length in word must be multiples of the dma_burst_len, and
 *   the dma_burst_len should be one of 8,7...2, otherwise, it will be split
 *   into several SPI bursts by this driver
 */

#define SPICC_MAX_BURST 128

/* Register Map */
#define SPICC_RXDATA    0x00

#define SPICC_TXDATA    0x04

#define SPICC_CONREG    0x08
#define SPICC_ENABLE            BIT(0)
#define SPICC_MODE_MASTER       BIT(1)
#define SPICC_XCH               BIT(2)
#define SPICC_SMC               BIT(3)
#define SPICC_POL               BIT(4)
#define SPICC_PHA               BIT(5)
#define SPICC_SSCTL             BIT(6)
#define SPICC_SSPOL             BIT(7)
#define SPICC_DRCTL_MASK        GENMASK(9, 8)
#define SPICC_DRCTL_IGNORE      0
#define SPICC_DRCTL_FALLING     1
#define SPICC_DRCTL_LOWLEVEL    2
#define SPICC_CS_MASK           GENMASK(13, 12)
#define SPICC_DATARATE_MASK     GENMASK(18, 16)
#define SPICC_DATARATE_DIV4     0
#define SPICC_DATARATE_DIV8     1
#define SPICC_DATARATE_DIV16    2
#define SPICC_DATARATE_DIV32    3
#define SPICC_BITLENGTH_MASK    GENMASK(24, 19)
#define SPICC_BURSTLENGTH_MASK  GENMASK(31, 25)

#define SPICC_INTREG    0x0c
#define SPICC_TE_EN     BIT(0) /* TX FIFO Empty Interrupt */
#define SPICC_TH_EN     BIT(1) /* TX FIFO Half-Full Interrupt */
#define SPICC_TF_EN     BIT(2) /* TX FIFO Full Interrupt */
#define SPICC_RR_EN     BIT(3) /* RX FIFO Ready Interrupt */
#define SPICC_RH_EN     BIT(4) /* RX FIFO Half-Full Interrupt */
#define SPICC_RF_EN     BIT(5) /* RX FIFO Full Interrupt */
#define SPICC_RO_EN     BIT(6) /* RX FIFO Overflow Interrupt */
#define SPICC_TC_EN     BIT(7) /* Transfert Complete Interrupt */

#define SPICC_DMAREG    0x10
#define SPICC_DMA_ENABLE                BIT(0)
#define SPICC_TXFIFO_THRESHOLD_MASK     GENMASK(5, 1)
#define SPICC_RXFIFO_THRESHOLD_MASK     GENMASK(10, 6)
#define SPICC_READ_BURST_MASK           GENMASK(14, 11)
#define SPICC_WRITE_BURST_MASK          GENMASK(18, 15)
#define SPICC_DMA_URGENT                BIT(19)
#define SPICC_DMA_THREADID_MASK         GENMASK(25, 20)
#define SPICC_DMA_BURSTNUM_MASK         GENMASK(31, 26)

#define SPICC_STATREG   0x14
#define SPICC_TE        BIT(0) /* TX FIFO Empty Interrupt */
#define SPICC_TH        BIT(1) /* TX FIFO Half-Full Interrupt */
#define SPICC_TF        BIT(2) /* TX FIFO Full Interrupt */
#define SPICC_RR        BIT(3) /* RX FIFO Ready Interrupt */
#define SPICC_RH        BIT(4) /* RX FIFO Half-Full Interrupt */
#define SPICC_RF        BIT(5) /* RX FIFO Full Interrupt */
#define SPICC_RO        BIT(6) /* RX FIFO Overflow Interrupt */
#define SPICC_TC        BIT(7) /* Transfert Complete Interrupt */

#define SPICC_PERIODREG 0x18
#define SPICC_PERIOD    GENMASK(14, 0)  /* Wait cycles */

#define SPICC_TESTREG   0x1c
#define SPICC_TXCNT_MASK        GENMASK(4, 0)   /* TX FIFO Counter */
#define SPICC_RXCNT_MASK        GENMASK(9, 5)   /* RX FIFO Counter */
#define SPICC_SMSTATUS_MASK     GENMASK(12, 10) /* State Machine Status */
#define SPICC_LBC_RO            BIT(13) /* Loop Back Control Read-Only */
#define SPICC_LBC_W1            BIT(14) /* Loop Back Control Write-Only */
#define SPICC_SWAP_RO           BIT(14) /* RX FIFO Data Swap Read-Only */
#define SPICC_SWAP_W1           BIT(15) /* RX FIFO Data Swap Write-Only */
#define SPICC_DLYCTL_RO_MASK    GENMASK(20, 15) /* Delay Control Read-Only */
#define SPICC_MO_DELAY_MASK     GENMASK(17, 16) /* Master Output Delay */
#define SPICC_MO_NO_DELAY       0
#define SPICC_MO_DELAY_1_CYCLE  1
#define SPICC_MO_DELAY_2_CYCLE  2
#define SPICC_MO_DELAY_3_CYCLE  3
#define SPICC_MI_DELAY_MASK     GENMASK(19, 18) /* Master Input Delay */
#define SPICC_MI_NO_DELAY       0
#define SPICC_MI_DELAY_1_CYCLE  1
#define SPICC_MI_DELAY_2_CYCLE  2
#define SPICC_MI_DELAY_3_CYCLE  3
#define SPICC_MI_CAP_DELAY_MASK GENMASK(21, 20) /* Master Capture Delay */
#define SPICC_CAP_AHEAD_2_CYCLE 0
#define SPICC_CAP_AHEAD_1_CYCLE 1
#define SPICC_CAP_NO_DELAY      2
#define SPICC_CAP_DELAY_1_CYCLE 3
#define SPICC_FIFORST_RO_MASK   GENMASK(22, 21) /* FIFO Softreset Read-Only */
#define SPICC_FIFORST_W1_MASK   GENMASK(23, 22) /* FIFO Softreset Write-Only */

#define SPICC_DRADDR    0x20    /* Read Address of DMA */

#define SPICC_DWADDR    0x24    /* Write Address of DMA */

#define SPICC_LD_CNTL0  0x28
#define VSYNC_IRQ_SRC_SELECT            BIT(0)
#define DMA_EN_SET_BY_VSYNC             BIT(2)
#define XCH_EN_SET_BY_VSYNC             BIT(3)
#define DMA_READ_COUNTER_EN             BIT(4)
#define DMA_WRITE_COUNTER_EN            BIT(5)
#define DMA_RADDR_LOAD_BY_VSYNC         BIT(6)
#define DMA_WADDR_LOAD_BY_VSYNC         BIT(7)
#define DMA_ADDR_LOAD_FROM_LD_ADDR      BIT(8)

#define SPICC_LD_CNTL1  0x2c
#define DMA_READ_COUNTER                GENMASK(15, 0)
#define DMA_WRITE_COUNTER               GENMASK(31, 16)
#define DMA_BURST_LEN_DEFAULT           8
#define DMA_BURST_COUNT_MAX             0xffff
#define SPI_BURST_LEN_MAX       (DMA_BURST_LEN_DEFAULT * DMA_BURST_COUNT_MAX)

#define SPICC_ENH_CTL0  0x38    /* Enhanced Feature */
#define SPICC_ENH_CLK_CS_DELAY_MASK     GENMASK(15, 0)
#define SPICC_ENH_DATARATE_MASK         GENMASK(23, 16)
#define SPICC_ENH_DATARATE_EN           BIT(24)
#define SPICC_ENH_MOSI_OEN              BIT(25)
#define SPICC_ENH_CLK_OEN               BIT(26)
#define SPICC_ENH_CS_OEN                BIT(27)
#define SPICC_ENH_CLK_CS_DELAY_EN       BIT(28)
#define SPICC_ENH_MAIN_CLK_AO           BIT(29)

#define writel_bits_relaxed(mask, val, addr) \
        writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)

struct meson_spicc_data {
        unsigned int                    max_speed_hz;
        unsigned int                    min_speed_hz;
        unsigned int                    fifo_size;
        bool                            has_oen;
        bool                            has_enhance_clk_div;
        bool                            has_pclk;
};

struct meson_spicc_device {
        struct spi_controller           *host;
        struct platform_device          *pdev;
        void __iomem                    *base;
        struct clk                      *core;
        struct clk                      *pclk;
        struct clk_divider              pow2_div;
        struct clk                      *clk;
        struct spi_message              *message;
        struct spi_transfer             *xfer;
        struct completion               done;
        const struct meson_spicc_data   *data;
        u8                              *tx_buf;
        u8                              *rx_buf;
        unsigned int                    bytes_per_word;
        unsigned long                   tx_remain;
        unsigned long                   rx_remain;
        unsigned long                   xfer_remain;
        struct pinctrl                  *pinctrl;
        struct pinctrl_state            *pins_idle_high;
        struct pinctrl_state            *pins_idle_low;
        dma_addr_t                      tx_dma;
        dma_addr_t                      rx_dma;
        bool                            using_dma;
};

#define pow2_clk_to_spicc(_div) container_of(_div, struct meson_spicc_device, pow2_div)

static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
{
        u32 conf;

        if (!spicc->data->has_oen) {
                /* Try to get pinctrl states for idle high/low */
                spicc->pins_idle_high = pinctrl_lookup_state(spicc->pinctrl,
                                                             "idle-high");
                if (IS_ERR(spicc->pins_idle_high)) {
                        dev_warn(&spicc->pdev->dev, "can't get idle-high pinctrl\n");
                        spicc->pins_idle_high = NULL;
                }
                spicc->pins_idle_low = pinctrl_lookup_state(spicc->pinctrl,
                                                             "idle-low");
                if (IS_ERR(spicc->pins_idle_low)) {
                        dev_warn(&spicc->pdev->dev, "can't get idle-low pinctrl\n");
                        spicc->pins_idle_low = NULL;
                }
                return;
        }

        conf = readl_relaxed(spicc->base + SPICC_ENH_CTL0) |
                SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN;

        writel_relaxed(conf, spicc->base + SPICC_ENH_CTL0);
}

static int meson_spicc_dma_map(struct meson_spicc_device *spicc,
                               struct spi_transfer *t)
{
        struct device *dev = spicc->host->dev.parent;

        if (!(t->tx_buf && t->rx_buf))
                return -EINVAL;

        t->tx_dma = dma_map_single(dev, (void *)t->tx_buf, t->len, DMA_TO_DEVICE);
        if (dma_mapping_error(dev, t->tx_dma))
                return -ENOMEM;

        t->rx_dma = dma_map_single(dev, t->rx_buf, t->len, DMA_FROM_DEVICE);
        if (dma_mapping_error(dev, t->rx_dma))
                return -ENOMEM;

        spicc->tx_dma = t->tx_dma;
        spicc->rx_dma = t->rx_dma;

        return 0;
}

static void meson_spicc_dma_unmap(struct meson_spicc_device *spicc,
                                  struct spi_transfer *t)
{
        struct device *dev = spicc->host->dev.parent;

        if (t->tx_dma)
                dma_unmap_single(dev, t->tx_dma, t->len, DMA_TO_DEVICE);
        if (t->rx_dma)
                dma_unmap_single(dev, t->rx_dma, t->len, DMA_FROM_DEVICE);
}

/*
 * According to the remain words length, calculate a suitable spi burst length
 * and a dma burst length for current spi burst
 */
static u32 meson_spicc_calc_dma_len(struct meson_spicc_device *spicc,
                                    u32 len, u32 *dma_burst_len)
{
        u32 i;

        if (len <= spicc->data->fifo_size) {
                *dma_burst_len = len;
                return len;
        }

        *dma_burst_len = DMA_BURST_LEN_DEFAULT;

        if (len == (SPI_BURST_LEN_MAX + 1))
                return SPI_BURST_LEN_MAX - DMA_BURST_LEN_DEFAULT;

        if (len >= SPI_BURST_LEN_MAX)
                return SPI_BURST_LEN_MAX;

        for (i = DMA_BURST_LEN_DEFAULT; i > 1; i--)
                if ((len % i) == 0) {
                        *dma_burst_len = i;
                        return len;
                }

        i = len % DMA_BURST_LEN_DEFAULT;
        len -= i;

        if (i == 1)
                len -= DMA_BURST_LEN_DEFAULT;

        return len;
}

static void meson_spicc_setup_dma(struct meson_spicc_device *spicc)
{
        unsigned int len;
        unsigned int dma_burst_len, dma_burst_count;
        unsigned int count_en = 0;
        unsigned int txfifo_thres = 0;
        unsigned int read_req = 0;
        unsigned int rxfifo_thres = 31;
        unsigned int write_req = 0;
        unsigned int ld_ctr1 = 0;

        writel_relaxed(spicc->tx_dma, spicc->base + SPICC_DRADDR);
        writel_relaxed(spicc->rx_dma, spicc->base + SPICC_DWADDR);

        /* Set the max burst length to support a transmission with length of
         * no more than 1024 bytes(128 words), which must use the CS management
         * because of some strict timing requirements
         */
        writel_bits_relaxed(SPICC_BURSTLENGTH_MASK, SPICC_BURSTLENGTH_MASK,
                            spicc->base + SPICC_CONREG);

        len = meson_spicc_calc_dma_len(spicc, spicc->xfer_remain,
                                       &dma_burst_len);
        spicc->xfer_remain -= len;
        dma_burst_count = DIV_ROUND_UP(len, dma_burst_len);
        dma_burst_len--;

        if (spicc->tx_dma) {
                spicc->tx_dma += len;
                count_en |= DMA_READ_COUNTER_EN;
                txfifo_thres = spicc->data->fifo_size - dma_burst_len;
                read_req = dma_burst_len;
                ld_ctr1 |= FIELD_PREP(DMA_READ_COUNTER, dma_burst_count);
        }

        if (spicc->rx_dma) {
                spicc->rx_dma += len;
                count_en |= DMA_WRITE_COUNTER_EN;
                rxfifo_thres = dma_burst_len;
                write_req = dma_burst_len;
                ld_ctr1 |= FIELD_PREP(DMA_WRITE_COUNTER, dma_burst_count);
        }

        writel_relaxed(count_en, spicc->base + SPICC_LD_CNTL0);
        writel_relaxed(ld_ctr1, spicc->base + SPICC_LD_CNTL1);
        writel_relaxed(SPICC_DMA_ENABLE
                    | SPICC_DMA_URGENT
                    | FIELD_PREP(SPICC_TXFIFO_THRESHOLD_MASK, txfifo_thres)
                    | FIELD_PREP(SPICC_READ_BURST_MASK, read_req)
                    | FIELD_PREP(SPICC_RXFIFO_THRESHOLD_MASK, rxfifo_thres)
                    | FIELD_PREP(SPICC_WRITE_BURST_MASK, write_req),
                    spicc->base + SPICC_DMAREG);
}

static irqreturn_t meson_spicc_dma_irq(struct meson_spicc_device *spicc)
{
        if (readl_relaxed(spicc->base + SPICC_DMAREG) & SPICC_DMA_ENABLE)
                return IRQ_HANDLED;

        if (spicc->xfer_remain) {
                meson_spicc_setup_dma(spicc);
        } else {
                writel_bits_relaxed(SPICC_SMC, 0, spicc->base + SPICC_CONREG);
                writel_relaxed(0, spicc->base + SPICC_INTREG);
                writel_relaxed(0, spicc->base + SPICC_DMAREG);
                meson_spicc_dma_unmap(spicc, spicc->xfer);
                complete(&spicc->done);
        }

        return IRQ_HANDLED;
}

static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
{
        return !!FIELD_GET(SPICC_TF,
                           readl_relaxed(spicc->base + SPICC_STATREG));
}

static inline bool meson_spicc_rxready(struct meson_spicc_device *spicc)
{
        return FIELD_GET(SPICC_RH | SPICC_RR | SPICC_RF,
                         readl_relaxed(spicc->base + SPICC_STATREG));
}

static inline u32 meson_spicc_pull_data(struct meson_spicc_device *spicc)
{
        unsigned int bytes = spicc->bytes_per_word;
        unsigned int byte_shift = 0;
        u32 data = 0;
        u8 byte;

        while (bytes--) {
                byte = *spicc->tx_buf++;
                data |= (byte & 0xff) << byte_shift;
                byte_shift += 8;
        }

        spicc->tx_remain--;
        return data;
}

static inline void meson_spicc_push_data(struct meson_spicc_device *spicc,
                                         u32 data)
{
        unsigned int bytes = spicc->bytes_per_word;
        unsigned int byte_shift = 0;
        u8 byte;

        while (bytes--) {
                byte = (data >> byte_shift) & 0xff;
                *spicc->rx_buf++ = byte;
                byte_shift += 8;
        }

        spicc->rx_remain--;
}

static inline void meson_spicc_rx(struct meson_spicc_device *spicc)
{
        /* Empty RX FIFO */
        while (spicc->rx_remain &&
               meson_spicc_rxready(spicc))
                meson_spicc_push_data(spicc,
                                readl_relaxed(spicc->base + SPICC_RXDATA));
}

static inline void meson_spicc_tx(struct meson_spicc_device *spicc)
{
        /* Fill Up TX FIFO */
        while (spicc->tx_remain &&
               !meson_spicc_txfull(spicc))
                writel_relaxed(meson_spicc_pull_data(spicc),
                               spicc->base + SPICC_TXDATA);
}

static inline void meson_spicc_setup_burst(struct meson_spicc_device *spicc)
{

        unsigned int burst_len = min_t(unsigned int,
                                       spicc->xfer_remain /
                                       spicc->bytes_per_word,
                                       spicc->data->fifo_size);
        /* Setup Xfer variables */
        spicc->tx_remain = burst_len;
        spicc->rx_remain = burst_len;
        spicc->xfer_remain -= burst_len * spicc->bytes_per_word;

        /* Setup burst length */
        writel_bits_relaxed(SPICC_BURSTLENGTH_MASK,
                        FIELD_PREP(SPICC_BURSTLENGTH_MASK,
                                burst_len - 1),
                        spicc->base + SPICC_CONREG);

        /* Fill TX FIFO */
        meson_spicc_tx(spicc);
}

static irqreturn_t meson_spicc_irq(int irq, void *data)
{
        struct meson_spicc_device *spicc = (void *) data;

        writel_bits_relaxed(SPICC_TC, SPICC_TC, spicc->base + SPICC_STATREG);

        if (spicc->using_dma)
                return meson_spicc_dma_irq(spicc);

        /* Empty RX FIFO */
        meson_spicc_rx(spicc);

        if (!spicc->xfer_remain) {
                /* Disable all IRQs */
                writel(0, spicc->base + SPICC_INTREG);

                complete(&spicc->done);

                return IRQ_HANDLED;
        }

        /* Setup burst */
        meson_spicc_setup_burst(spicc);

        /* Start burst */
        writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);

        return IRQ_HANDLED;
}

static void meson_spicc_auto_io_delay(struct meson_spicc_device *spicc)
{
        u32 div, hz;
        u32 mi_delay, cap_delay;
        u32 conf;

        if (spicc->data->has_enhance_clk_div) {
                div = FIELD_GET(SPICC_ENH_DATARATE_MASK,
                                readl_relaxed(spicc->base + SPICC_ENH_CTL0));
                div++;
                div <<= 1;
        } else {
                div = FIELD_GET(SPICC_DATARATE_MASK,
                                readl_relaxed(spicc->base + SPICC_CONREG));
                div += 2;
                div = 1 << div;
        }

        mi_delay = SPICC_MI_NO_DELAY;
        cap_delay = SPICC_CAP_AHEAD_2_CYCLE;
        hz = clk_get_rate(spicc->clk);

        if (hz >= 100000000)
                cap_delay = SPICC_CAP_DELAY_1_CYCLE;
        else if (hz >= 80000000)
                cap_delay = SPICC_CAP_NO_DELAY;
        else if (hz >= 40000000)
                cap_delay = SPICC_CAP_AHEAD_1_CYCLE;
        else if (div >= 16)
                mi_delay = SPICC_MI_DELAY_3_CYCLE;
        else if (div >= 8)
                mi_delay = SPICC_MI_DELAY_2_CYCLE;
        else if (div >= 6)
                mi_delay = SPICC_MI_DELAY_1_CYCLE;

        conf = readl_relaxed(spicc->base + SPICC_TESTREG);
        conf &= ~(SPICC_MO_DELAY_MASK | SPICC_MI_DELAY_MASK
                  | SPICC_MI_CAP_DELAY_MASK);
        conf |= FIELD_PREP(SPICC_MI_DELAY_MASK, mi_delay);
        conf |= FIELD_PREP(SPICC_MI_CAP_DELAY_MASK, cap_delay);
        writel_relaxed(conf, spicc->base + SPICC_TESTREG);
}

static void meson_spicc_setup_xfer(struct meson_spicc_device *spicc,
                                   struct spi_transfer *xfer)
{
        u32 conf, conf_orig;

        /* Read original configuration */
        conf = conf_orig = readl_relaxed(spicc->base + SPICC_CONREG);

        /* Setup word width */
        FIELD_MODIFY(SPICC_BITLENGTH_MASK, &conf,
                     (spicc->bytes_per_word << 3) - 1);

        /* Ignore if unchanged */
        if (conf != conf_orig)
                writel_relaxed(conf, spicc->base + SPICC_CONREG);

        clk_set_rate(spicc->clk, xfer->speed_hz);

        meson_spicc_auto_io_delay(spicc);

        writel_relaxed(0, spicc->base + SPICC_DMAREG);
}

static void meson_spicc_reset_fifo(struct meson_spicc_device *spicc)
{
        if (spicc->data->has_oen)
                writel_bits_relaxed(SPICC_ENH_MAIN_CLK_AO,
                                    SPICC_ENH_MAIN_CLK_AO,
                                    spicc->base + SPICC_ENH_CTL0);

        writel_bits_relaxed(SPICC_FIFORST_W1_MASK, SPICC_FIFORST_W1_MASK,
                            spicc->base + SPICC_TESTREG);

        while (meson_spicc_rxready(spicc))
                readl_relaxed(spicc->base + SPICC_RXDATA);

        if (spicc->data->has_oen)
                writel_bits_relaxed(SPICC_ENH_MAIN_CLK_AO, 0,
                                    spicc->base + SPICC_ENH_CTL0);
}

static int meson_spicc_transfer_one(struct spi_controller *host,
                                    struct spi_device *spi,
                                    struct spi_transfer *xfer)
{
        struct meson_spicc_device *spicc = spi_controller_get_devdata(host);
        uint64_t timeout;

        /* Store current transfer */
        spicc->xfer = xfer;

        /* Setup transfer parameters */
        spicc->tx_buf = (u8 *)xfer->tx_buf;
        spicc->rx_buf = (u8 *)xfer->rx_buf;
        spicc->xfer_remain = xfer->len;

        /* Pre-calculate word size */
        spicc->bytes_per_word =
           DIV_ROUND_UP(spicc->xfer->bits_per_word, 8);

        if (xfer->len % spicc->bytes_per_word)
                return -EINVAL;

        /* Setup transfer parameters */
        meson_spicc_setup_xfer(spicc, xfer);

        meson_spicc_reset_fifo(spicc);

        /* Setup wait for completion */
        reinit_completion(&spicc->done);

        /* For each byte we wait for 8 cycles of the SPI clock */
        timeout = 8LL * MSEC_PER_SEC * xfer->len;
        do_div(timeout, xfer->speed_hz);

        /* Add 10us delay between each fifo bursts */
        timeout += ((xfer->len >> 4) * 10) / MSEC_PER_SEC;

        /* Increase it twice and add 200 ms tolerance */
        timeout += timeout + 200;

        if (xfer->bits_per_word == 64) {
                int ret;

                /* dma_burst_len 1 can't trigger a dma burst */
                if (xfer->len < 16)
                        return -EINVAL;

                ret = meson_spicc_dma_map(spicc, xfer);
                if (ret) {
                        meson_spicc_dma_unmap(spicc, xfer);
                        dev_err(host->dev.parent, "dma map failed\n");
                        return ret;
                }

                spicc->using_dma = true;
                spicc->xfer_remain = DIV_ROUND_UP(xfer->len, spicc->bytes_per_word);
                meson_spicc_setup_dma(spicc);
                writel_relaxed(SPICC_TE_EN, spicc->base + SPICC_INTREG);
                writel_bits_relaxed(SPICC_SMC, SPICC_SMC, spicc->base + SPICC_CONREG);
        } else {
                spicc->using_dma = false;
                /* Setup burst */
                meson_spicc_setup_burst(spicc);

                /* Start burst */
                writel_bits_relaxed(SPICC_XCH, SPICC_XCH, spicc->base + SPICC_CONREG);

                /* Enable interrupts */
                writel_relaxed(SPICC_TC_EN, spicc->base + SPICC_INTREG);
        }

        if (!wait_for_completion_timeout(&spicc->done, msecs_to_jiffies(timeout)))
                return -ETIMEDOUT;

        return 0;
}

static int meson_spicc_prepare_message(struct spi_controller *host,
                                       struct spi_message *message)
{
        struct meson_spicc_device *spicc = spi_controller_get_devdata(host);
        struct spi_device *spi = message->spi;
        u32 conf = readl_relaxed(spicc->base + SPICC_CONREG) & SPICC_DATARATE_MASK;

        /* Store current message */
        spicc->message = message;

        /* Enable Master */
        conf |= SPICC_ENABLE;
        conf |= SPICC_MODE_MASTER;

        /* SMC = 0 */

        /* Setup transfer mode */
        if (spi->mode & SPI_CPOL)
                conf |= SPICC_POL;
        else
                conf &= ~SPICC_POL;

        if (!spicc->data->has_oen) {
                if (spi->mode & SPI_CPOL) {
                        if (spicc->pins_idle_high)
                                pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_high);
                } else {
                        if (spicc->pins_idle_low)
                                pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_low);
                }
        }

        if (spi->mode & SPI_CPHA)
                conf |= SPICC_PHA;
        else
                conf &= ~SPICC_PHA;

        /* SSCTL = 0 */

        if (spi->mode & SPI_CS_HIGH)
                conf |= SPICC_SSPOL;
        else
                conf &= ~SPICC_SSPOL;

        if (spi->mode & SPI_READY)
                conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_LOWLEVEL);
        else
                conf |= FIELD_PREP(SPICC_DRCTL_MASK, SPICC_DRCTL_IGNORE);

        /* Select CS */
        conf |= FIELD_PREP(SPICC_CS_MASK, spi_get_chipselect(spi, 0));

        /* Default 8bit word */
        conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, 8 - 1);

        writel_relaxed(conf, spicc->base + SPICC_CONREG);

        /* Setup no wait cycles by default */
        writel_relaxed(0, spicc->base + SPICC_PERIODREG);

        writel_bits_relaxed(SPICC_LBC_W1,
                            spi->mode & SPI_LOOP ? SPICC_LBC_W1 : 0,
                            spicc->base + SPICC_TESTREG);

        return 0;
}

static int meson_spicc_unprepare_transfer(struct spi_controller *host)
{
        struct meson_spicc_device *spicc = spi_controller_get_devdata(host);
        u32 conf = readl_relaxed(spicc->base + SPICC_CONREG) & SPICC_DATARATE_MASK;

        /* Disable all IRQs */
        writel(0, spicc->base + SPICC_INTREG);

        device_reset_optional(&spicc->pdev->dev);

        /* Set default configuration, keeping datarate field */
        writel_relaxed(conf, spicc->base + SPICC_CONREG);

        if (!spicc->data->has_oen)
                pinctrl_select_default_state(&spicc->pdev->dev);

        return 0;
}

static int meson_spicc_setup(struct spi_device *spi)
{
        if (!spi->controller_state)
                spi->controller_state = spi_controller_get_devdata(spi->controller);

        /* DMA works at 64 bits, the rest works on PIO */
        if (spi->bits_per_word != 8 &&
            spi->bits_per_word != 16 &&
            spi->bits_per_word != 24 &&
            spi->bits_per_word != 32 &&
            spi->bits_per_word != 64)
                return -EINVAL;

        return 0;
}

static void meson_spicc_cleanup(struct spi_device *spi)
{
        spi->controller_state = NULL;
}

/*
 * The Clock Mux
 *            x-----------------x   x------------x    x------\
 *        |---| pow2 fixed div  |---| pow2 div   |----|      |
 *        |   x-----------------x   x------------x    |      |
 * src ---|                                           | mux  |-- out
 *        |   x-----------------x   x------------x    |      |
 *        |---| enh fixed div   |---| enh div    |0---|      |
 *            x-----------------x   x------------x    x------/
 *
 * Clk path for GX series:
 *    src -> pow2 fixed div -> pow2 div -> out
 *
 * Clk path for AXG series:
 *    src -> pow2 fixed div -> pow2 div -> mux -> out
 *    src -> enh fixed div -> enh div -> mux -> out
 *
 * Clk path for G12A series:
 *    pclk -> pow2 fixed div -> pow2 div -> mux -> out
 *    pclk -> enh fixed div -> enh div -> mux -> out
 *
 * The pow2 divider is tied to the controller HW state, and the
 * divider is only valid when the controller is initialized.
 *
 * A set of clock ops is added to make sure we don't read/set this
 * clock rate while the controller is in an unknown state.
 */

static unsigned long meson_spicc_pow2_recalc_rate(struct clk_hw *hw,
                                                  unsigned long parent_rate)
{
        struct clk_divider *divider = to_clk_divider(hw);
        struct meson_spicc_device *spicc = pow2_clk_to_spicc(divider);

        if (!spicc->host->cur_msg)
                return 0;

        return clk_divider_ops.recalc_rate(hw, parent_rate);
}

static int meson_spicc_pow2_determine_rate(struct clk_hw *hw,
                                           struct clk_rate_request *req)
{
        struct clk_divider *divider = to_clk_divider(hw);
        struct meson_spicc_device *spicc = pow2_clk_to_spicc(divider);

        if (!spicc->host->cur_msg)
                return -EINVAL;

        return clk_divider_ops.determine_rate(hw, req);
}

static int meson_spicc_pow2_set_rate(struct clk_hw *hw, unsigned long rate,
                                     unsigned long parent_rate)
{
        struct clk_divider *divider = to_clk_divider(hw);
        struct meson_spicc_device *spicc = pow2_clk_to_spicc(divider);

        if (!spicc->host->cur_msg)
                return -EINVAL;

        return clk_divider_ops.set_rate(hw, rate, parent_rate);
}

static const struct clk_ops meson_spicc_pow2_clk_ops = {
        .recalc_rate = meson_spicc_pow2_recalc_rate,
        .determine_rate = meson_spicc_pow2_determine_rate,
        .set_rate = meson_spicc_pow2_set_rate,
};

static int meson_spicc_pow2_clk_init(struct meson_spicc_device *spicc)
{
        struct device *dev = &spicc->pdev->dev;
        struct clk_fixed_factor *pow2_fixed_div;
        struct clk_init_data init;
        struct clk *clk;
        struct clk_parent_data parent_data[2];
        char name[64];

        memset(&init, 0, sizeof(init));
        memset(&parent_data, 0, sizeof(parent_data));

        init.parent_data = parent_data;

        /* algorithm for pow2 div: rate = freq / 4 / (2 ^ N) */

        pow2_fixed_div = devm_kzalloc(dev, sizeof(*pow2_fixed_div), GFP_KERNEL);
        if (!pow2_fixed_div)
                return -ENOMEM;

        snprintf(name, sizeof(name), "%s#pow2_fixed_div", dev_name(dev));
        init.name = name;
        init.ops = &clk_fixed_factor_ops;
        if (spicc->data->has_pclk) {
                init.flags = CLK_SET_RATE_PARENT;
                parent_data[0].hw = __clk_get_hw(spicc->pclk);
        } else {
                init.flags = 0;
                parent_data[0].hw = __clk_get_hw(spicc->core);
        }
        init.num_parents = 1;

        pow2_fixed_div->mult = 1;
        pow2_fixed_div->div = 4;
        pow2_fixed_div->hw.init = &init;

        clk = devm_clk_register(dev, &pow2_fixed_div->hw);
        if (WARN_ON(IS_ERR(clk)))
                return PTR_ERR(clk);

        snprintf(name, sizeof(name), "%s#pow2_div", dev_name(dev));
        init.name = name;
        init.ops = &meson_spicc_pow2_clk_ops;
        /*
         * Set NOCACHE here to make sure we read the actual HW value
         * since we reset the HW after each transfer.
         */
        init.flags = CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE;
        parent_data[0].hw = &pow2_fixed_div->hw;
        init.num_parents = 1;

        spicc->pow2_div.shift = 16;
        spicc->pow2_div.width = 3;
        spicc->pow2_div.flags = CLK_DIVIDER_POWER_OF_TWO;
        spicc->pow2_div.reg = spicc->base + SPICC_CONREG;
        spicc->pow2_div.hw.init = &init;

        spicc->clk = devm_clk_register(dev, &spicc->pow2_div.hw);
        if (WARN_ON(IS_ERR(spicc->clk)))
                return PTR_ERR(spicc->clk);

        return 0;
}

static int meson_spicc_enh_clk_init(struct meson_spicc_device *spicc)
{
        struct device *dev = &spicc->pdev->dev;
        struct clk_fixed_factor *enh_fixed_div;
        struct clk_divider *enh_div;
        struct clk_mux *mux;
        struct clk_init_data init;
        struct clk *clk;
        struct clk_parent_data parent_data[2];
        char name[64];

        memset(&init, 0, sizeof(init));
        memset(&parent_data, 0, sizeof(parent_data));

        init.parent_data = parent_data;

        /* algorithm for enh div: rate = freq / 2 / (N + 1) */

        enh_fixed_div = devm_kzalloc(dev, sizeof(*enh_fixed_div), GFP_KERNEL);
        if (!enh_fixed_div)
                return -ENOMEM;

        snprintf(name, sizeof(name), "%s#enh_fixed_div", dev_name(dev));
        init.name = name;
        init.ops = &clk_fixed_factor_ops;
        if (spicc->data->has_pclk) {
                init.flags = CLK_SET_RATE_PARENT;
                parent_data[0].hw = __clk_get_hw(spicc->pclk);
        } else {
                init.flags = 0;
                parent_data[0].hw = __clk_get_hw(spicc->core);
        }
        init.num_parents = 1;

        enh_fixed_div->mult = 1;
        enh_fixed_div->div = 2;
        enh_fixed_div->hw.init = &init;

        clk = devm_clk_register(dev, &enh_fixed_div->hw);
        if (WARN_ON(IS_ERR(clk)))
                return PTR_ERR(clk);

        enh_div = devm_kzalloc(dev, sizeof(*enh_div), GFP_KERNEL);
        if (!enh_div)
                return -ENOMEM;

        snprintf(name, sizeof(name), "%s#enh_div", dev_name(dev));
        init.name = name;
        init.ops = &clk_divider_ops;
        init.flags = CLK_SET_RATE_PARENT;
        parent_data[0].hw = &enh_fixed_div->hw;
        init.num_parents = 1;

        enh_div->shift  = 16;
        enh_div->width  = 8;
        enh_div->reg = spicc->base + SPICC_ENH_CTL0;
        enh_div->hw.init = &init;

        clk = devm_clk_register(dev, &enh_div->hw);
        if (WARN_ON(IS_ERR(clk)))
                return PTR_ERR(clk);

        mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
        if (!mux)
                return -ENOMEM;

        snprintf(name, sizeof(name), "%s#sel", dev_name(dev));
        init.name = name;
        init.ops = &clk_mux_ops;
        parent_data[0].hw = &spicc->pow2_div.hw;
        parent_data[1].hw = &enh_div->hw;
        init.num_parents = 2;
        init.flags = CLK_SET_RATE_PARENT;

        mux->mask = 0x1;
        mux->shift = 24;
        mux->reg = spicc->base + SPICC_ENH_CTL0;
        mux->hw.init = &init;

        spicc->clk = devm_clk_register(dev, &mux->hw);
        if (WARN_ON(IS_ERR(spicc->clk)))
                return PTR_ERR(spicc->clk);

        return 0;
}

static int meson_spicc_probe(struct platform_device *pdev)
{
        struct spi_controller *host;
        struct meson_spicc_device *spicc;
        int ret, irq;

        host = devm_spi_alloc_host(&pdev->dev, sizeof(*spicc));
        if (!host) {
                dev_err(&pdev->dev, "host allocation failed\n");
                return -ENOMEM;
        }
        spicc = spi_controller_get_devdata(host);
        spicc->host = host;

        spicc->data = of_device_get_match_data(&pdev->dev);
        if (!spicc->data) {
                dev_err(&pdev->dev, "failed to get match data\n");
                return -EINVAL;
        }

        spicc->pdev = pdev;
        platform_set_drvdata(pdev, spicc);

        init_completion(&spicc->done);

        spicc->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(spicc->base)) {
                dev_err(&pdev->dev, "io resource mapping failed\n");
                return PTR_ERR(spicc->base);
        }

        /* Set master mode and enable controller */
        writel_relaxed(SPICC_ENABLE | SPICC_MODE_MASTER,
                       spicc->base + SPICC_CONREG);

        /* Disable all IRQs */
        writel_relaxed(0, spicc->base + SPICC_INTREG);

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

        ret = devm_request_irq(&pdev->dev, irq, meson_spicc_irq,
                               0, NULL, spicc);
        if (ret) {
                dev_err(&pdev->dev, "irq request failed\n");
                return ret;
        }

        spicc->core = devm_clk_get_enabled(&pdev->dev, "core");
        if (IS_ERR(spicc->core)) {
                dev_err(&pdev->dev, "core clock request failed\n");
                return PTR_ERR(spicc->core);
        }

        if (spicc->data->has_pclk) {
                spicc->pclk = devm_clk_get_enabled(&pdev->dev, "pclk");
                if (IS_ERR(spicc->pclk)) {
                        dev_err(&pdev->dev, "pclk clock request failed\n");
                        return PTR_ERR(spicc->pclk);
                }
        }

        spicc->pinctrl = devm_pinctrl_get(&pdev->dev);
        if (IS_ERR(spicc->pinctrl))
                return PTR_ERR(spicc->pinctrl);

        device_reset_optional(&pdev->dev);

        host->num_chipselect = 4;
        host->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LOOP;
        host->flags = (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX);
        host->min_speed_hz = spicc->data->min_speed_hz;
        host->max_speed_hz = spicc->data->max_speed_hz;
        host->setup = meson_spicc_setup;
        host->cleanup = meson_spicc_cleanup;
        host->prepare_message = meson_spicc_prepare_message;
        host->unprepare_transfer_hardware = meson_spicc_unprepare_transfer;
        host->transfer_one = meson_spicc_transfer_one;
        host->use_gpio_descriptors = true;

        meson_spicc_oen_enable(spicc);

        ret = meson_spicc_pow2_clk_init(spicc);
        if (ret) {
                dev_err(&pdev->dev, "pow2 clock registration failed\n");
                return ret;
        }

        if (spicc->data->has_enhance_clk_div) {
                ret = meson_spicc_enh_clk_init(spicc);
                if (ret) {
                        dev_err(&pdev->dev, "clock registration failed\n");
                        return ret;
                }
        }

        ret = spi_register_controller(host);
        if (ret) {
                dev_err(&pdev->dev, "spi registration failed\n");
                return ret;
        }

        return 0;
}

static void meson_spicc_remove(struct platform_device *pdev)
{
        struct meson_spicc_device *spicc = platform_get_drvdata(pdev);

        spi_unregister_controller(spicc->host);

        /* Disable SPI */
        writel(0, spicc->base + SPICC_CONREG);
}

static const struct meson_spicc_data meson_spicc_gx_data = {
        .max_speed_hz           = 30000000,
        .min_speed_hz           = 325000,
        .fifo_size              = 16,
};

static const struct meson_spicc_data meson_spicc_axg_data = {
        .max_speed_hz           = 80000000,
        .min_speed_hz           = 325000,
        .fifo_size              = 16,
        .has_oen                = true,
        .has_enhance_clk_div    = true,
};

static const struct meson_spicc_data meson_spicc_g12a_data = {
        .max_speed_hz           = 166666666,
        .min_speed_hz           = 50000,
        .fifo_size              = 15,
        .has_oen                = true,
        .has_enhance_clk_div    = true,
        .has_pclk               = true,
};

static const struct of_device_id meson_spicc_of_match[] = {
        {
                .compatible     = "amlogic,meson-gx-spicc",
                .data           = &meson_spicc_gx_data,
        },
        {
                .compatible = "amlogic,meson-axg-spicc",
                .data           = &meson_spicc_axg_data,
        },
        {
                .compatible = "amlogic,meson-g12a-spicc",
                .data           = &meson_spicc_g12a_data,
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, meson_spicc_of_match);

static struct platform_driver meson_spicc_driver = {
        .probe   = meson_spicc_probe,
        .remove = meson_spicc_remove,
        .driver  = {
                .name = "meson-spicc",
                .of_match_table = of_match_ptr(meson_spicc_of_match),
        },
};

module_platform_driver(meson_spicc_driver);

MODULE_DESCRIPTION("Meson SPI Communication Controller driver");
MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
MODULE_LICENSE("GPL");