/*
 * Copyright (C) 2008, Guennadi Liakhovetski <lg@denx.de>
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <malloc.h>
#include <spi.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/gpio.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/clock.h>

#ifdef CONFIG_MX27
/* i.MX27 has a completely wrong register layout and register definitions in the
 * datasheet, the correct one is in the Freescale's Linux driver */

#error "i.MX27 CSPI not supported due to drastic differences in register definitions" \
"See linux mxc_spi driver from Freescale for details."
#endif

static unsigned long spi_bases[] = {
        MXC_SPI_BASE_ADDRESSES
};

#define OUT     MXC_GPIO_DIRECTION_OUT

#define reg_read readl
#define reg_write(a, v) writel(v, a)

struct mxc_spi_slave {
        struct spi_slave slave;
        unsigned long   base;
        u32             ctrl_reg;
#if defined(MXC_ECSPI)
        u32             cfg_reg;
#endif
        int             gpio;
        int             ss_pol;
};

static inline struct mxc_spi_slave *to_mxc_spi_slave(struct spi_slave *slave)
{
        return container_of(slave, struct mxc_spi_slave, slave);
}

void spi_cs_activate(struct spi_slave *slave)
{
        struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
        if (mxcs->gpio > 0)
                gpio_set_value(mxcs->gpio, mxcs->ss_pol);
}

void spi_cs_deactivate(struct spi_slave *slave)
{
        struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
        if (mxcs->gpio > 0)
                gpio_set_value(mxcs->gpio,
                              !(mxcs->ss_pol));
}

u32 get_cspi_div(u32 div)
{
        int i;

        for (i = 0; i < 8; i++) {
                if (div <= (4 << i))
                        return i;
        }
        return i;
}

#ifdef MXC_CSPI
static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
                unsigned int max_hz, unsigned int mode)
{
        unsigned int ctrl_reg;
        u32 clk_src;
        u32 div;

        clk_src = mxc_get_clock(MXC_CSPI_CLK);

        div = DIV_ROUND_UP(clk_src, max_hz);
        div = get_cspi_div(div);

        debug("clk %d Hz, div %d, real clk %d Hz\n",
                max_hz, div, clk_src / (4 << div));

        ctrl_reg = MXC_CSPICTRL_CHIPSELECT(cs) |
                MXC_CSPICTRL_BITCOUNT(MXC_CSPICTRL_MAXBITS) |
                MXC_CSPICTRL_DATARATE(div) |
                MXC_CSPICTRL_EN |
#ifdef CONFIG_MX35
                MXC_CSPICTRL_SSCTL |
#endif
                MXC_CSPICTRL_MODE;

        if (mode & SPI_CPHA)
                ctrl_reg |= MXC_CSPICTRL_PHA;
        if (mode & SPI_CPOL)
                ctrl_reg |= MXC_CSPICTRL_POL;
        if (mode & SPI_CS_HIGH)
                ctrl_reg |= MXC_CSPICTRL_SSPOL;
        mxcs->ctrl_reg = ctrl_reg;

        return 0;
}
#endif

#ifdef MXC_ECSPI
static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
                unsigned int max_hz, unsigned int mode)
{
        u32 clk_src = mxc_get_clock(MXC_CSPI_CLK);
        s32 reg_ctrl, reg_config;
        u32 ss_pol = 0, sclkpol = 0, sclkpha = 0, pre_div = 0, post_div = 0;
        struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;

        if (max_hz == 0) {
                printf("Error: desired clock is 0\n");
                return -1;
        }

        /*
         * Reset SPI and set all CSs to master mode, if toggling
         * between slave and master mode we might see a glitch
         * on the clock line
         */
        reg_ctrl = MXC_CSPICTRL_MODE_MASK;
        reg_write(&regs->ctrl, reg_ctrl);
        reg_ctrl |=  MXC_CSPICTRL_EN;
        reg_write(&regs->ctrl, reg_ctrl);

        if (clk_src > max_hz) {
                pre_div = (clk_src - 1) / max_hz;
                /* fls(1) = 1, fls(0x80000000) = 32, fls(16) = 5 */
                post_div = fls(pre_div);
                if (post_div > 4) {
                        post_div -= 4;
                        if (post_div >= 16) {
                                printf("Error: no divider for the freq: %d\n",
                                        max_hz);
                                return -1;
                        }
                        pre_div >>= post_div;
                } else {
                        post_div = 0;
                }
        }

        debug("pre_div = %d, post_div=%d\n", pre_div, post_div);
        reg_ctrl = (reg_ctrl & ~MXC_CSPICTRL_SELCHAN(3)) |
                MXC_CSPICTRL_SELCHAN(cs);
        reg_ctrl = (reg_ctrl & ~MXC_CSPICTRL_PREDIV(0x0F)) |
                MXC_CSPICTRL_PREDIV(pre_div);
        reg_ctrl = (reg_ctrl & ~MXC_CSPICTRL_POSTDIV(0x0F)) |
                MXC_CSPICTRL_POSTDIV(post_div);

        /* We need to disable SPI before changing registers */
        reg_ctrl &= ~MXC_CSPICTRL_EN;

        if (mode & SPI_CS_HIGH)
                ss_pol = 1;

        if (mode & SPI_CPOL)
                sclkpol = 1;

        if (mode & SPI_CPHA)
                sclkpha = 1;

        reg_config = reg_read(&regs->cfg);

        /*
         * Configuration register setup
         * The MX51 supports different setup for each SS
         */
        reg_config = (reg_config & ~(1 << (cs + MXC_CSPICON_SSPOL))) |
                (ss_pol << (cs + MXC_CSPICON_SSPOL));
        reg_config = (reg_config & ~(1 << (cs + MXC_CSPICON_POL))) |
                (sclkpol << (cs + MXC_CSPICON_POL));
        reg_config = (reg_config & ~(1 << (cs + MXC_CSPICON_PHA))) |
                (sclkpha << (cs + MXC_CSPICON_PHA));

        debug("reg_ctrl = 0x%x\n", reg_ctrl);
        reg_write(&regs->ctrl, reg_ctrl);
        debug("reg_config = 0x%x\n", reg_config);
        reg_write(&regs->cfg, reg_config);

        /* save config register and control register */
        mxcs->ctrl_reg = reg_ctrl;
        mxcs->cfg_reg = reg_config;

        /* clear interrupt reg */
        reg_write(&regs->intr, 0);
        reg_write(&regs->stat, MXC_CSPICTRL_TC | MXC_CSPICTRL_RXOVF);

        return 0;
}
#endif

int spi_xchg_single(struct spi_slave *slave, unsigned int bitlen,
        const u8 *dout, u8 *din, unsigned long flags)
{
        struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
        int nbytes = DIV_ROUND_UP(bitlen, 8);
        u32 data, cnt, i;
        struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;

        debug("%s: bitlen %d dout 0x%x din 0x%x\n",
                __func__, bitlen, (u32)dout, (u32)din);

        mxcs->ctrl_reg = (mxcs->ctrl_reg &
                ~MXC_CSPICTRL_BITCOUNT(MXC_CSPICTRL_MAXBITS)) |
                MXC_CSPICTRL_BITCOUNT(bitlen - 1);

        reg_write(&regs->ctrl, mxcs->ctrl_reg | MXC_CSPICTRL_EN);
#ifdef MXC_ECSPI
        reg_write(&regs->cfg, mxcs->cfg_reg);
#endif

        /* Clear interrupt register */
        reg_write(&regs->stat, MXC_CSPICTRL_TC | MXC_CSPICTRL_RXOVF);

        /*
         * The SPI controller works only with words,
         * check if less than a word is sent.
         * Access to the FIFO is only 32 bit
         */
        if (bitlen % 32) {
                data = 0;
                cnt = (bitlen % 32) / 8;
                if (dout) {
                        for (i = 0; i < cnt; i++) {
                                data = (data << 8) | (*dout++ & 0xFF);
                        }
                }
                debug("Sending SPI 0x%x\n", data);

                reg_write(&regs->txdata, data);
                nbytes -= cnt;
        }

        data = 0;

        while (nbytes > 0) {
                data = 0;
                if (dout) {
                        /* Buffer is not 32-bit aligned */
                        if ((unsigned long)dout & 0x03) {
                                data = 0;
                                for (i = 0; i < 4; i++)
                                        data = (data << 8) | (*dout++ & 0xFF);
                        } else {
                                data = *(u32 *)dout;
                                data = cpu_to_be32(data);
                                dout += 4;
                        }
                }
                debug("Sending SPI 0x%x\n", data);
                reg_write(&regs->txdata, data);
                nbytes -= 4;
        }

        /* FIFO is written, now starts the transfer setting the XCH bit */
        reg_write(&regs->ctrl, mxcs->ctrl_reg |
                MXC_CSPICTRL_EN | MXC_CSPICTRL_XCH);

        /* Wait until the TC (Transfer completed) bit is set */
        while ((reg_read(&regs->stat) & MXC_CSPICTRL_TC) == 0)
                ;

        /* Transfer completed, clear any pending request */
        reg_write(&regs->stat, MXC_CSPICTRL_TC | MXC_CSPICTRL_RXOVF);

        nbytes = DIV_ROUND_UP(bitlen, 8);

        cnt = nbytes % 32;

        if (bitlen % 32) {
                data = reg_read(&regs->rxdata);
                cnt = (bitlen % 32) / 8;
                data = cpu_to_be32(data) >> ((sizeof(data) - cnt) * 8);
                debug("SPI Rx unaligned: 0x%x\n", data);
                if (din) {
                        memcpy(din, &data, cnt);
                        din += cnt;
                }
                nbytes -= cnt;
        }

        while (nbytes > 0) {
                u32 tmp;
                tmp = reg_read(&regs->rxdata);
                data = cpu_to_be32(tmp);
                debug("SPI Rx: 0x%x 0x%x\n", tmp, data);
                cnt = min(nbytes, sizeof(data));
                if (din) {
                        memcpy(din, &data, cnt);
                        din += cnt;
                }
                nbytes -= cnt;
        }

        return 0;

}

int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
                void *din, unsigned long flags)
{
        int n_bytes = DIV_ROUND_UP(bitlen, 8);
        int n_bits;
        int ret;
        u32 blk_size;
        u8 *p_outbuf = (u8 *)dout;
        u8 *p_inbuf = (u8 *)din;

        if (!slave)
                return -1;

        if (flags & SPI_XFER_BEGIN)
                spi_cs_activate(slave);

        while (n_bytes > 0) {
                if (n_bytes < MAX_SPI_BYTES)
                        blk_size = n_bytes;
                else
                        blk_size = MAX_SPI_BYTES;

                n_bits = blk_size * 8;

                ret = spi_xchg_single(slave, n_bits, p_outbuf, p_inbuf, 0);

                if (ret)
                        return ret;
                if (dout)
                        p_outbuf += blk_size;
                if (din)
                        p_inbuf += blk_size;
                n_bytes -= blk_size;
        }

        if (flags & SPI_XFER_END) {
                spi_cs_deactivate(slave);
        }

        return 0;
}

void spi_init(void)
{
}

static int decode_cs(struct mxc_spi_slave *mxcs, unsigned int cs)
{
        int ret;

        /*
         * Some SPI devices require active chip-select over multiple
         * transactions, we achieve this using a GPIO. Still, the SPI
         * controller has to be configured to use one of its own chipselects.
         * To use this feature you have to call spi_setup_slave() with
         * cs = internal_cs | (gpio << 8), and you have to use some unused
         * on this SPI controller cs between 0 and 3.
         */
        if (cs > 3) {
                mxcs->gpio = cs >> 8;
                cs &= 3;
                ret = gpio_direction_output(mxcs->gpio, !(mxcs->ss_pol));
                if (ret) {
                        printf("mxc_spi: cannot setup gpio %d\n", mxcs->gpio);
                        return -EINVAL;
                }
        } else {
                mxcs->gpio = -1;
        }

        return cs;
}

struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
                        unsigned int max_hz, unsigned int mode)
{
        struct mxc_spi_slave *mxcs;
        int ret;

        if (bus >= ARRAY_SIZE(spi_bases))
                return NULL;

        mxcs = spi_alloc_slave(struct mxc_spi_slave, bus, cs);
        if (!mxcs) {
                puts("mxc_spi: SPI Slave not allocated !\n");
                return NULL;
        }

        mxcs->ss_pol = (mode & SPI_CS_HIGH) ? 1 : 0;

        ret = decode_cs(mxcs, cs);
        if (ret < 0) {
                free(mxcs);
                return NULL;
        }

        cs = ret;

        mxcs->base = spi_bases[bus];

        ret = spi_cfg_mxc(mxcs, cs, max_hz, mode);
        if (ret) {
                printf("mxc_spi: cannot setup SPI controller\n");
                free(mxcs);
                return NULL;
        }
        return &mxcs->slave;
}

void spi_free_slave(struct spi_slave *slave)
{
        struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);

        free(mxcs);
}

int spi_claim_bus(struct spi_slave *slave)
{
        struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
        struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;

        reg_write(&regs->rxdata, 1);
        udelay(1);
        reg_write(&regs->ctrl, mxcs->ctrl_reg);
        reg_write(&regs->period, MXC_CSPIPERIOD_32KHZ);
        reg_write(&regs->intr, 0);

        return 0;
}

void spi_release_bus(struct spi_slave *slave)
{
        /* TODO: Shut the controller down */
}