/*
 * Marvell Orion SPI controller driver
 *
 * Author: Shadi Ammouri <shadi@marvell.com>
 * Copyright (C) 2007-2008 Marvell Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/clk.h>
#include <linux/sizes.h>
#include <asm/unaligned.h>

#define DRIVER_NAME                     "orion_spi"

/* Runtime PM autosuspend timeout: PM is fairly light on this driver */
#define SPI_AUTOSUSPEND_TIMEOUT         200

/* Some SoCs using this driver support up to 8 chip selects.
 * It is up to the implementer to only use the chip selects
 * that are available.
 */
#define ORION_NUM_CHIPSELECTS           8

#define ORION_SPI_WAIT_RDY_MAX_LOOP     2000 /* in usec */

#define ORION_SPI_IF_CTRL_REG           0x00
#define ORION_SPI_IF_CONFIG_REG         0x04
#define ORION_SPI_DATA_OUT_REG          0x08
#define ORION_SPI_DATA_IN_REG           0x0c
#define ORION_SPI_INT_CAUSE_REG         0x10
#define ORION_SPI_TIMING_PARAMS_REG     0x18

#define ORION_SPI_TMISO_SAMPLE_MASK     (0x3 << 6)
#define ORION_SPI_TMISO_SAMPLE_1        (1 << 6)
#define ORION_SPI_TMISO_SAMPLE_2        (2 << 6)

#define ORION_SPI_MODE_CPOL             (1 << 11)
#define ORION_SPI_MODE_CPHA             (1 << 12)
#define ORION_SPI_IF_8_16_BIT_MODE      (1 << 5)
#define ORION_SPI_CLK_PRESCALE_MASK     0x1F
#define ARMADA_SPI_CLK_PRESCALE_MASK    0xDF
#define ORION_SPI_MODE_MASK             (ORION_SPI_MODE_CPOL | \
                                         ORION_SPI_MODE_CPHA)
#define ORION_SPI_CS_MASK       0x1C
#define ORION_SPI_CS_SHIFT      2
#define ORION_SPI_CS(cs)        ((cs << ORION_SPI_CS_SHIFT) & \
                                        ORION_SPI_CS_MASK)

enum orion_spi_type {
        ORION_SPI,
        ARMADA_SPI,
};

struct orion_spi_dev {
        enum orion_spi_type     typ;
        /*
         * min_divisor and max_hz should be exclusive, the only we can
         * have both is for managing the armada-370-spi case with old
         * device tree
         */
        unsigned long           max_hz;
        unsigned int            min_divisor;
        unsigned int            max_divisor;
        u32                     prescale_mask;
        bool                    is_errata_50mhz_ac;
};

struct orion_spi {
        struct spi_master       *master;
        void __iomem            *base;
        struct clk              *clk;
        const struct orion_spi_dev *devdata;
};

static inline void __iomem *spi_reg(struct orion_spi *orion_spi, u32 reg)
{
        return orion_spi->base + reg;
}

static inline void
orion_spi_setbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
{
        void __iomem *reg_addr = spi_reg(orion_spi, reg);
        u32 val;

        val = readl(reg_addr);
        val |= mask;
        writel(val, reg_addr);
}

static inline void
orion_spi_clrbits(struct orion_spi *orion_spi, u32 reg, u32 mask)
{
        void __iomem *reg_addr = spi_reg(orion_spi, reg);
        u32 val;

        val = readl(reg_addr);
        val &= ~mask;
        writel(val, reg_addr);
}

static int orion_spi_baudrate_set(struct spi_device *spi, unsigned int speed)
{
        u32 tclk_hz;
        u32 rate;
        u32 prescale;
        u32 reg;
        struct orion_spi *orion_spi;
        const struct orion_spi_dev *devdata;

        orion_spi = spi_master_get_devdata(spi->master);
        devdata = orion_spi->devdata;

        tclk_hz = clk_get_rate(orion_spi->clk);

        if (devdata->typ == ARMADA_SPI) {
                unsigned int clk, spr, sppr, sppr2, err;
                unsigned int best_spr, best_sppr, best_err;

                best_err = speed;
                best_spr = 0;
                best_sppr = 0;

                /* Iterate over the valid range looking for best fit */
                for (sppr = 0; sppr < 8; sppr++) {
                        sppr2 = 0x1 << sppr;

                        spr = tclk_hz / sppr2;
                        spr = DIV_ROUND_UP(spr, speed);
                        if ((spr == 0) || (spr > 15))
                                continue;

                        clk = tclk_hz / (spr * sppr2);
                        err = speed - clk;

                        if (err < best_err) {
                                best_spr = spr;
                                best_sppr = sppr;
                                best_err = err;
                        }
                }

                if ((best_sppr == 0) && (best_spr == 0))
                        return -EINVAL;

                prescale = ((best_sppr & 0x6) << 5) |
                        ((best_sppr & 0x1) << 4) | best_spr;
        } else {
                /*
                 * the supported rates are: 4,6,8...30
                 * round up as we look for equal or less speed
                 */
                rate = DIV_ROUND_UP(tclk_hz, speed);
                rate = roundup(rate, 2);

                /* check if requested speed is too small */
                if (rate > 30)
                        return -EINVAL;

                if (rate < 4)
                        rate = 4;

                /* Convert the rate to SPI clock divisor value. */
                prescale = 0x10 + rate/2;
        }

        reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
        reg = ((reg & ~devdata->prescale_mask) | prescale);
        writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));

        return 0;
}

static void
orion_spi_mode_set(struct spi_device *spi)
{
        u32 reg;
        struct orion_spi *orion_spi;

        orion_spi = spi_master_get_devdata(spi->master);

        reg = readl(spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
        reg &= ~ORION_SPI_MODE_MASK;
        if (spi->mode & SPI_CPOL)
                reg |= ORION_SPI_MODE_CPOL;
        if (spi->mode & SPI_CPHA)
                reg |= ORION_SPI_MODE_CPHA;
        writel(reg, spi_reg(orion_spi, ORION_SPI_IF_CONFIG_REG));
}

static void
orion_spi_50mhz_ac_timing_erratum(struct spi_device *spi, unsigned int speed)
{
        u32 reg;
        struct orion_spi *orion_spi;

        orion_spi = spi_master_get_devdata(spi->master);

        /*
         * Erratum description: (Erratum NO. FE-9144572) The device
         * SPI interface supports frequencies of up to 50 MHz.
         * However, due to this erratum, when the device core clock is
         * 250 MHz and the SPI interfaces is configured for 50MHz SPI
         * clock and CPOL=CPHA=1 there might occur data corruption on
         * reads from the SPI device.
         * Erratum Workaround:
         * Work in one of the following configurations:
         * 1. Set CPOL=CPHA=0 in "SPI Interface Configuration
         * Register".
         * 2. Set TMISO_SAMPLE value to 0x2 in "SPI Timing Parameters 1
         * Register" before setting the interface.
         */
        reg = readl(spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
        reg &= ~ORION_SPI_TMISO_SAMPLE_MASK;

        if (clk_get_rate(orion_spi->clk) == 250000000 &&
                        speed == 50000000 && spi->mode & SPI_CPOL &&
                        spi->mode & SPI_CPHA)
                reg |= ORION_SPI_TMISO_SAMPLE_2;
        else
                reg |= ORION_SPI_TMISO_SAMPLE_1; /* This is the default value */

        writel(reg, spi_reg(orion_spi, ORION_SPI_TIMING_PARAMS_REG));
}

/*
 * called only when no transfer is active on the bus
 */
static int
orion_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
{
        struct orion_spi *orion_spi;
        unsigned int speed = spi->max_speed_hz;
        unsigned int bits_per_word = spi->bits_per_word;
        int     rc;

        orion_spi = spi_master_get_devdata(spi->master);

        if ((t != NULL) && t->speed_hz)
                speed = t->speed_hz;

        if ((t != NULL) && t->bits_per_word)
                bits_per_word = t->bits_per_word;

        orion_spi_mode_set(spi);

        if (orion_spi->devdata->is_errata_50mhz_ac)
                orion_spi_50mhz_ac_timing_erratum(spi, speed);

        rc = orion_spi_baudrate_set(spi, speed);
        if (rc)
                return rc;

        if (bits_per_word == 16)
                orion_spi_setbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
                                  ORION_SPI_IF_8_16_BIT_MODE);
        else
                orion_spi_clrbits(orion_spi, ORION_SPI_IF_CONFIG_REG,
                                  ORION_SPI_IF_8_16_BIT_MODE);

        return 0;
}

static void orion_spi_set_cs(struct spi_device *spi, bool enable)
{
        struct orion_spi *orion_spi;

        orion_spi = spi_master_get_devdata(spi->master);

        orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, ORION_SPI_CS_MASK);
        orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG,
                                ORION_SPI_CS(spi->chip_select));

        /* Chip select logic is inverted from spi_set_cs */
        if (!enable)
                orion_spi_setbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
        else
                orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
}

static inline int orion_spi_wait_till_ready(struct orion_spi *orion_spi)
{
        int i;

        for (i = 0; i < ORION_SPI_WAIT_RDY_MAX_LOOP; i++) {
                if (readl(spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG)))
                        return 1;

                udelay(1);
        }

        return -1;
}

static inline int
orion_spi_write_read_8bit(struct spi_device *spi,
                          const u8 **tx_buf, u8 **rx_buf)
{
        void __iomem *tx_reg, *rx_reg, *int_reg;
        struct orion_spi *orion_spi;

        orion_spi = spi_master_get_devdata(spi->master);
        tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
        rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
        int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);

        /* clear the interrupt cause register */
        writel(0x0, int_reg);

        if (tx_buf && *tx_buf)
                writel(*(*tx_buf)++, tx_reg);
        else
                writel(0, tx_reg);

        if (orion_spi_wait_till_ready(orion_spi) < 0) {
                dev_err(&spi->dev, "TXS timed out\n");
                return -1;
        }

        if (rx_buf && *rx_buf)
                *(*rx_buf)++ = readl(rx_reg);

        return 1;
}

static inline int
orion_spi_write_read_16bit(struct spi_device *spi,
                           const u16 **tx_buf, u16 **rx_buf)
{
        void __iomem *tx_reg, *rx_reg, *int_reg;
        struct orion_spi *orion_spi;

        orion_spi = spi_master_get_devdata(spi->master);
        tx_reg = spi_reg(orion_spi, ORION_SPI_DATA_OUT_REG);
        rx_reg = spi_reg(orion_spi, ORION_SPI_DATA_IN_REG);
        int_reg = spi_reg(orion_spi, ORION_SPI_INT_CAUSE_REG);

        /* clear the interrupt cause register */
        writel(0x0, int_reg);

        if (tx_buf && *tx_buf)
                writel(__cpu_to_le16(get_unaligned((*tx_buf)++)), tx_reg);
        else
                writel(0, tx_reg);

        if (orion_spi_wait_till_ready(orion_spi) < 0) {
                dev_err(&spi->dev, "TXS timed out\n");
                return -1;
        }

        if (rx_buf && *rx_buf)
                put_unaligned(__le16_to_cpu(readl(rx_reg)), (*rx_buf)++);

        return 1;
}

static unsigned int
orion_spi_write_read(struct spi_device *spi, struct spi_transfer *xfer)
{
        unsigned int count;
        int word_len;

        word_len = spi->bits_per_word;
        count = xfer->len;

        if (word_len == 8) {
                const u8 *tx = xfer->tx_buf;
                u8 *rx = xfer->rx_buf;

                do {
                        if (orion_spi_write_read_8bit(spi, &tx, &rx) < 0)
                                goto out;
                        count--;
                } while (count);
        } else if (word_len == 16) {
                const u16 *tx = xfer->tx_buf;
                u16 *rx = xfer->rx_buf;

                do {
                        if (orion_spi_write_read_16bit(spi, &tx, &rx) < 0)
                                goto out;
                        count -= 2;
                } while (count);
        }

out:
        return xfer->len - count;
}

static int orion_spi_transfer_one(struct spi_master *master,
                                        struct spi_device *spi,
                                        struct spi_transfer *t)
{
        int status = 0;

        status = orion_spi_setup_transfer(spi, t);
        if (status < 0)
                return status;

        if (t->len)
                orion_spi_write_read(spi, t);

        return status;
}

static int orion_spi_setup(struct spi_device *spi)
{
        return orion_spi_setup_transfer(spi, NULL);
}

static int orion_spi_reset(struct orion_spi *orion_spi)
{
        /* Verify that the CS is deasserted */
        orion_spi_clrbits(orion_spi, ORION_SPI_IF_CTRL_REG, 0x1);
        return 0;
}

static const struct orion_spi_dev orion_spi_dev_data = {
        .typ = ORION_SPI,
        .min_divisor = 4,
        .max_divisor = 30,
        .prescale_mask = ORION_SPI_CLK_PRESCALE_MASK,
};

static const struct orion_spi_dev armada_370_spi_dev_data = {
        .typ = ARMADA_SPI,
        .min_divisor = 4,
        .max_divisor = 1920,
        .max_hz = 50000000,
        .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
};

static const struct orion_spi_dev armada_xp_spi_dev_data = {
        .typ = ARMADA_SPI,
        .max_hz = 50000000,
        .max_divisor = 1920,
        .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
};

static const struct orion_spi_dev armada_375_spi_dev_data = {
        .typ = ARMADA_SPI,
        .min_divisor = 15,
        .max_divisor = 1920,
        .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
};

static const struct orion_spi_dev armada_380_spi_dev_data = {
        .typ = ARMADA_SPI,
        .max_hz = 50000000,
        .max_divisor = 1920,
        .prescale_mask = ARMADA_SPI_CLK_PRESCALE_MASK,
        .is_errata_50mhz_ac = true,
};

static const struct of_device_id orion_spi_of_match_table[] = {
        {
                .compatible = "marvell,orion-spi",
                .data = &orion_spi_dev_data,
        },
        {
                .compatible = "marvell,armada-370-spi",
                .data = &armada_370_spi_dev_data,
        },
        {
                .compatible = "marvell,armada-375-spi",
                .data = &armada_375_spi_dev_data,
        },
        {
                .compatible = "marvell,armada-380-spi",
                .data = &armada_380_spi_dev_data,
        },
        {
                .compatible = "marvell,armada-390-spi",
                .data = &armada_xp_spi_dev_data,
        },
        {
                .compatible = "marvell,armada-xp-spi",
                .data = &armada_xp_spi_dev_data,
        },

        {}
};
MODULE_DEVICE_TABLE(of, orion_spi_of_match_table);

static int orion_spi_probe(struct platform_device *pdev)
{
        const struct of_device_id *of_id;
        const struct orion_spi_dev *devdata;
        struct spi_master *master;
        struct orion_spi *spi;
        struct resource *r;
        unsigned long tclk_hz;
        int status = 0;

        master = spi_alloc_master(&pdev->dev, sizeof(*spi));
        if (master == NULL) {
                dev_dbg(&pdev->dev, "master allocation failed\n");
                return -ENOMEM;
        }

        if (pdev->id != -1)
                master->bus_num = pdev->id;
        if (pdev->dev.of_node) {
                u32 cell_index;

                if (!of_property_read_u32(pdev->dev.of_node, "cell-index",
                                          &cell_index))
                        master->bus_num = cell_index;
        }

        /* we support only mode 0, and no options */
        master->mode_bits = SPI_CPHA | SPI_CPOL;
        master->set_cs = orion_spi_set_cs;
        master->transfer_one = orion_spi_transfer_one;
        master->num_chipselect = ORION_NUM_CHIPSELECTS;
        master->setup = orion_spi_setup;
        master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
        master->auto_runtime_pm = true;

        platform_set_drvdata(pdev, master);

        spi = spi_master_get_devdata(master);
        spi->master = master;

        of_id = of_match_device(orion_spi_of_match_table, &pdev->dev);
        devdata = (of_id) ? of_id->data : &orion_spi_dev_data;
        spi->devdata = devdata;

        spi->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(spi->clk)) {
                status = PTR_ERR(spi->clk);
                goto out;
        }

        status = clk_prepare_enable(spi->clk);
        if (status)
                goto out;

        tclk_hz = clk_get_rate(spi->clk);

        /*
         * With old device tree, armada-370-spi could be used with
         * Armada XP, however for this SoC the maximum frequency is
         * 50MHz instead of tclk/4. On Armada 370, tclk cannot be
         * higher than 200MHz. So, in order to be able to handle both
         * SoCs, we can take the minimum of 50MHz and tclk/4.
         */
        if (of_device_is_compatible(pdev->dev.of_node,
                                        "marvell,armada-370-spi"))
                master->max_speed_hz = min(devdata->max_hz,
                                DIV_ROUND_UP(tclk_hz, devdata->min_divisor));
        else if (devdata->min_divisor)
                master->max_speed_hz =
                        DIV_ROUND_UP(tclk_hz, devdata->min_divisor);
        else
                master->max_speed_hz = devdata->max_hz;
        master->min_speed_hz = DIV_ROUND_UP(tclk_hz, devdata->max_divisor);

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        spi->base = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(spi->base)) {
                status = PTR_ERR(spi->base);
                goto out_rel_clk;
        }

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

        status = orion_spi_reset(spi);
        if (status < 0)
                goto out_rel_pm;

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

        master->dev.of_node = pdev->dev.of_node;
        status = spi_register_master(master);
        if (status < 0)
                goto out_rel_pm;

        return status;

out_rel_pm:
        pm_runtime_disable(&pdev->dev);
out_rel_clk:
        clk_disable_unprepare(spi->clk);
out:
        spi_master_put(master);
        return status;
}


static int orion_spi_remove(struct platform_device *pdev)
{
        struct spi_master *master = platform_get_drvdata(pdev);
        struct orion_spi *spi = spi_master_get_devdata(master);

        pm_runtime_get_sync(&pdev->dev);
        clk_disable_unprepare(spi->clk);

        spi_unregister_master(master);
        pm_runtime_disable(&pdev->dev);

        return 0;
}

MODULE_ALIAS("platform:" DRIVER_NAME);

#ifdef CONFIG_PM
static int orion_spi_runtime_suspend(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct orion_spi *spi = spi_master_get_devdata(master);

        clk_disable_unprepare(spi->clk);
        return 0;
}

static int orion_spi_runtime_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct orion_spi *spi = spi_master_get_devdata(master);

        return clk_prepare_enable(spi->clk);
}
#endif

static const struct dev_pm_ops orion_spi_pm_ops = {
        SET_RUNTIME_PM_OPS(orion_spi_runtime_suspend,
                           orion_spi_runtime_resume,
                           NULL)
};

static struct platform_driver orion_spi_driver = {
        .driver = {
                .name   = DRIVER_NAME,
                .pm     = &orion_spi_pm_ops,
                .of_match_table = of_match_ptr(orion_spi_of_match_table),
        },
        .probe          = orion_spi_probe,
        .remove         = orion_spi_remove,
};

module_platform_driver(orion_spi_driver);

MODULE_DESCRIPTION("Orion SPI driver");
MODULE_AUTHOR("Shadi Ammouri <shadi@marvell.com>");
MODULE_LICENSE("GPL");