// SPDX-License-Identifier: GPL-2.0-or-later
// Copyright (C) IBM Corporation 2018
// FSI master driver for AST2600

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/fsi.h>
#include <linux/io.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/iopoll.h>
#include <linux/gpio/consumer.h>

#include "fsi-master.h"

struct fsi_master_aspeed {
        struct fsi_master       master;
        struct mutex            lock;   /* protect HW access */
        struct device           *dev;
        void __iomem            *base;
        struct clk              *clk;
        struct gpio_desc        *cfam_reset_gpio;
};

#define to_fsi_master_aspeed(m) \
        container_of(m, struct fsi_master_aspeed, master)

/* Control register (size 0x400) */
static const u32 ctrl_base = 0x80000000;

static const u32 fsi_base = 0xa0000000;

#define OPB_FSI_VER     0x00
#define OPB_TRIGGER     0x04
#define OPB_CTRL_BASE   0x08
#define OPB_FSI_BASE    0x0c
#define OPB_CLK_SYNC    0x3c
#define OPB_IRQ_CLEAR   0x40
#define OPB_IRQ_MASK    0x44
#define OPB_IRQ_STATUS  0x48

#define OPB0_SELECT     0x10
#define OPB0_RW         0x14
#define OPB0_XFER_SIZE  0x18
#define OPB0_FSI_ADDR   0x1c
#define OPB0_FSI_DATA_W 0x20
#define OPB0_STATUS     0x80
#define OPB0_FSI_DATA_R 0x84

#define OPB0_WRITE_ORDER1       0x4c
#define OPB0_WRITE_ORDER2       0x50
#define OPB1_WRITE_ORDER1       0x54
#define OPB1_WRITE_ORDER2       0x58
#define OPB0_READ_ORDER1        0x5c
#define OPB1_READ_ORDER2        0x60

#define OPB_RETRY_COUNTER       0x64

/* OPBn_STATUS */
#define STATUS_HALFWORD_ACK     BIT(0)
#define STATUS_FULLWORD_ACK     BIT(1)
#define STATUS_ERR_ACK          BIT(2)
#define STATUS_RETRY            BIT(3)
#define STATUS_TIMEOUT          BIT(4)

/* OPB_IRQ_MASK */
#define OPB1_XFER_ACK_EN BIT(17)
#define OPB0_XFER_ACK_EN BIT(16)

/* OPB_RW */
#define CMD_READ        BIT(0)
#define CMD_WRITE       0

/* OPBx_XFER_SIZE */
#define XFER_FULLWORD   (BIT(1) | BIT(0))
#define XFER_HALFWORD   (BIT(0))
#define XFER_BYTE       (0)

#define CREATE_TRACE_POINTS
#include <trace/events/fsi_master_aspeed.h>

#define FSI_LINK_ENABLE_SETUP_TIME      10      /* in mS */

/* Run the bus at maximum speed by default */
#define FSI_DIVISOR_DEFAULT            1
#define FSI_DIVISOR_CABLED             2
static u16 aspeed_fsi_divisor = FSI_DIVISOR_DEFAULT;
module_param_named(bus_div,aspeed_fsi_divisor, ushort, 0);

#define OPB_POLL_TIMEOUT                500

static int __opb_write(struct fsi_master_aspeed *aspeed, u32 addr,
                       u32 val, u32 transfer_size)
{
        void __iomem *base = aspeed->base;
        u32 reg, status;
        int ret;

        /*
         * The ordering of these writes up until the trigger
         * write does not matter, so use writel_relaxed.
         */
        writel_relaxed(CMD_WRITE, base + OPB0_RW);
        writel_relaxed(transfer_size, base + OPB0_XFER_SIZE);
        writel_relaxed(addr, base + OPB0_FSI_ADDR);
        writel_relaxed(val, base + OPB0_FSI_DATA_W);
        writel_relaxed(0x1, base + OPB_IRQ_CLEAR);
        writel(0x1, base + OPB_TRIGGER);

        ret = readl_poll_timeout(base + OPB_IRQ_STATUS, reg,
                                (reg & OPB0_XFER_ACK_EN) != 0,
                                0, OPB_POLL_TIMEOUT);

        status = readl(base + OPB0_STATUS);

        trace_fsi_master_aspeed_opb_write(addr, val, transfer_size, status, reg);

        /* Return error when poll timed out */
        if (ret)
                return ret;

        /* Command failed, master will reset */
        if (status & STATUS_ERR_ACK)
                return -EIO;

        return 0;
}

static int opb_writeb(struct fsi_master_aspeed *aspeed, u32 addr, u8 val)
{
        return __opb_write(aspeed, addr, val, XFER_BYTE);
}

static int opb_writew(struct fsi_master_aspeed *aspeed, u32 addr, __be16 val)
{
        return __opb_write(aspeed, addr, (__force u16)val, XFER_HALFWORD);
}

static int opb_writel(struct fsi_master_aspeed *aspeed, u32 addr, __be32 val)
{
        return __opb_write(aspeed, addr, (__force u32)val, XFER_FULLWORD);
}

static int __opb_read(struct fsi_master_aspeed *aspeed, uint32_t addr,
                      u32 transfer_size, void *out)
{
        void __iomem *base = aspeed->base;
        u32 result, reg;
        int status, ret;

        /*
         * The ordering of these writes up until the trigger
         * write does not matter, so use writel_relaxed.
         */
        writel_relaxed(CMD_READ, base + OPB0_RW);
        writel_relaxed(transfer_size, base + OPB0_XFER_SIZE);
        writel_relaxed(addr, base + OPB0_FSI_ADDR);
        writel_relaxed(0x1, base + OPB_IRQ_CLEAR);
        writel(0x1, base + OPB_TRIGGER);

        ret = readl_poll_timeout(base + OPB_IRQ_STATUS, reg,
                           (reg & OPB0_XFER_ACK_EN) != 0,
                           0, OPB_POLL_TIMEOUT);

        status = readl(base + OPB0_STATUS);

        result = readl(base + OPB0_FSI_DATA_R);

        trace_fsi_master_aspeed_opb_read(addr, transfer_size, result,
                        readl(base + OPB0_STATUS),
                        reg);

        /* Return error when poll timed out */
        if (ret)
                return ret;

        /* Command failed, master will reset */
        if (status & STATUS_ERR_ACK)
                return -EIO;

        if (out) {
                switch (transfer_size) {
                case XFER_BYTE:
                        *(u8 *)out = result;
                        break;
                case XFER_HALFWORD:
                        *(u16 *)out = result;
                        break;
                case XFER_FULLWORD:
                        *(u32 *)out = result;
                        break;
                default:
                        return -EINVAL;
                }

        }

        return 0;
}

static int opb_readl(struct fsi_master_aspeed *aspeed, uint32_t addr, __be32 *out)
{
        return __opb_read(aspeed, addr, XFER_FULLWORD, out);
}

static int opb_readw(struct fsi_master_aspeed *aspeed, uint32_t addr, __be16 *out)
{
        return __opb_read(aspeed, addr, XFER_HALFWORD, (void *)out);
}

static int opb_readb(struct fsi_master_aspeed *aspeed, uint32_t addr, u8 *out)
{
        return __opb_read(aspeed, addr, XFER_BYTE, (void *)out);
}

static int check_errors(struct fsi_master_aspeed *aspeed, int err)
{
        int ret;

        if (trace_fsi_master_aspeed_opb_error_enabled()) {
                __be32 mresp0, mstap0, mesrb0;

                opb_readl(aspeed, ctrl_base + FSI_MRESP0, &mresp0);
                opb_readl(aspeed, ctrl_base + FSI_MSTAP0, &mstap0);
                opb_readl(aspeed, ctrl_base + FSI_MESRB0, &mesrb0);

                trace_fsi_master_aspeed_opb_error(
                                be32_to_cpu(mresp0),
                                be32_to_cpu(mstap0),
                                be32_to_cpu(mesrb0));
        }

        if (err == -EIO) {
                /* Check MAEB (0x70) ? */

                /* Then clear errors in master */
                ret = opb_writel(aspeed, ctrl_base + FSI_MRESP0,
                                cpu_to_be32(FSI_MRESP_RST_ALL_MASTER));
                if (ret) {
                        /* TODO: log? return different code? */
                        return ret;
                }
                /* TODO: confirm that 0x70 was okay */
        }

        /* This will pass through timeout errors */
        return err;
}

static int aspeed_master_read(struct fsi_master *master, int link,
                        uint8_t id, uint32_t addr, void *val, size_t size)
{
        struct fsi_master_aspeed *aspeed = to_fsi_master_aspeed(master);
        int ret;

        if (id > 0x3)
                return -EINVAL;

        addr |= id << 21;
        addr += link * FSI_HUB_LINK_SIZE;

        mutex_lock(&aspeed->lock);

        switch (size) {
        case 1:
                ret = opb_readb(aspeed, fsi_base + addr, val);
                break;
        case 2:
                ret = opb_readw(aspeed, fsi_base + addr, val);
                break;
        case 4:
                ret = opb_readl(aspeed, fsi_base + addr, val);
                break;
        default:
                ret = -EINVAL;
                goto done;
        }

        ret = check_errors(aspeed, ret);
done:
        mutex_unlock(&aspeed->lock);
        return ret;
}

static int aspeed_master_write(struct fsi_master *master, int link,
                        uint8_t id, uint32_t addr, const void *val, size_t size)
{
        struct fsi_master_aspeed *aspeed = to_fsi_master_aspeed(master);
        int ret;

        if (id > 0x3)
                return -EINVAL;

        addr |= id << 21;
        addr += link * FSI_HUB_LINK_SIZE;

        mutex_lock(&aspeed->lock);

        switch (size) {
        case 1:
                ret = opb_writeb(aspeed, fsi_base + addr, *(u8 *)val);
                break;
        case 2:
                ret = opb_writew(aspeed, fsi_base + addr, *(__be16 *)val);
                break;
        case 4:
                ret = opb_writel(aspeed, fsi_base + addr, *(__be32 *)val);
                break;
        default:
                ret = -EINVAL;
                goto done;
        }

        ret = check_errors(aspeed, ret);
done:
        mutex_unlock(&aspeed->lock);
        return ret;
}

static int aspeed_master_link_enable(struct fsi_master *master, int link,
                                     bool enable)
{
        struct fsi_master_aspeed *aspeed = to_fsi_master_aspeed(master);
        int idx, bit, ret;
        __be32 reg;

        idx = link / 32;
        bit = link % 32;

        reg = cpu_to_be32(0x80000000 >> bit);

        mutex_lock(&aspeed->lock);

        if (!enable) {
                ret = opb_writel(aspeed, ctrl_base + FSI_MCENP0 + (4 * idx), reg);
                goto done;
        }

        ret = opb_writel(aspeed, ctrl_base + FSI_MSENP0 + (4 * idx), reg);
        if (ret)
                goto done;

        mdelay(FSI_LINK_ENABLE_SETUP_TIME);
done:
        mutex_unlock(&aspeed->lock);
        return ret;
}

static int aspeed_master_term(struct fsi_master *master, int link, uint8_t id)
{
        uint32_t addr;
        __be32 cmd;

        addr = 0x4;
        cmd = cpu_to_be32(0xecc00000);

        return aspeed_master_write(master, link, id, addr, &cmd, 4);
}

static int aspeed_master_break(struct fsi_master *master, int link)
{
        uint32_t addr;
        __be32 cmd;

        addr = 0x0;
        cmd = cpu_to_be32(0xc0de0000);

        return aspeed_master_write(master, link, 0, addr, &cmd, 4);
}

static void aspeed_master_release(struct device *dev)
{
        struct fsi_master_aspeed *aspeed =
                to_fsi_master_aspeed(to_fsi_master(dev));

        kfree(aspeed);
}

/* mmode encoders */
static inline u32 fsi_mmode_crs0(u32 x)
{
        return (x & FSI_MMODE_CRS0MASK) << FSI_MMODE_CRS0SHFT;
}

static inline u32 fsi_mmode_crs1(u32 x)
{
        return (x & FSI_MMODE_CRS1MASK) << FSI_MMODE_CRS1SHFT;
}

static int aspeed_master_init(struct fsi_master_aspeed *aspeed)
{
        __be32 reg;

        reg = cpu_to_be32(FSI_MRESP_RST_ALL_MASTER | FSI_MRESP_RST_ALL_LINK
                        | FSI_MRESP_RST_MCR | FSI_MRESP_RST_PYE);
        opb_writel(aspeed, ctrl_base + FSI_MRESP0, reg);

        /* Initialize the MFSI (hub master) engine */
        reg = cpu_to_be32(FSI_MRESP_RST_ALL_MASTER | FSI_MRESP_RST_ALL_LINK
                        | FSI_MRESP_RST_MCR | FSI_MRESP_RST_PYE);
        opb_writel(aspeed, ctrl_base + FSI_MRESP0, reg);

        reg = cpu_to_be32(FSI_MECTRL_EOAE | FSI_MECTRL_P8_AUTO_TERM);
        opb_writel(aspeed, ctrl_base + FSI_MECTRL, reg);

        reg = cpu_to_be32(FSI_MMODE_ECRC | FSI_MMODE_EPC | FSI_MMODE_RELA
                        | fsi_mmode_crs0(aspeed_fsi_divisor)
                        | fsi_mmode_crs1(aspeed_fsi_divisor)
                        | FSI_MMODE_P8_TO_LSB);
        dev_info(aspeed->dev, "mmode set to %08x (divisor %d)\n",
                        be32_to_cpu(reg), aspeed_fsi_divisor);
        opb_writel(aspeed, ctrl_base + FSI_MMODE, reg);

        reg = cpu_to_be32(0xffff0000);
        opb_writel(aspeed, ctrl_base + FSI_MDLYR, reg);

        reg = cpu_to_be32(~0);
        opb_writel(aspeed, ctrl_base + FSI_MSENP0, reg);

        /* Leave enabled long enough for master logic to set up */
        mdelay(FSI_LINK_ENABLE_SETUP_TIME);

        opb_writel(aspeed, ctrl_base + FSI_MCENP0, reg);

        opb_readl(aspeed, ctrl_base + FSI_MAEB, NULL);

        reg = cpu_to_be32(FSI_MRESP_RST_ALL_MASTER | FSI_MRESP_RST_ALL_LINK);
        opb_writel(aspeed, ctrl_base + FSI_MRESP0, reg);

        opb_readl(aspeed, ctrl_base + FSI_MLEVP0, NULL);

        /* Reset the master bridge */
        reg = cpu_to_be32(FSI_MRESB_RST_GEN);
        opb_writel(aspeed, ctrl_base + FSI_MRESB0, reg);

        reg = cpu_to_be32(FSI_MRESB_RST_ERR);
        opb_writel(aspeed, ctrl_base + FSI_MRESB0, reg);

        return 0;
}

static ssize_t cfam_reset_store(struct device *dev, struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct fsi_master_aspeed *aspeed = dev_get_drvdata(dev);

        trace_fsi_master_aspeed_cfam_reset(true);
        mutex_lock(&aspeed->lock);
        gpiod_set_value(aspeed->cfam_reset_gpio, 1);
        usleep_range(900, 1000);
        gpiod_set_value(aspeed->cfam_reset_gpio, 0);
        usleep_range(900, 1000);
        opb_writel(aspeed, ctrl_base + FSI_MRESP0, cpu_to_be32(FSI_MRESP_RST_ALL_MASTER));
        mutex_unlock(&aspeed->lock);
        trace_fsi_master_aspeed_cfam_reset(false);

        return count;
}

static DEVICE_ATTR(cfam_reset, 0200, NULL, cfam_reset_store);

static int setup_cfam_reset(struct fsi_master_aspeed *aspeed)
{
        struct device *dev = aspeed->dev;
        struct gpio_desc *gpio;
        int rc;

        gpio = devm_gpiod_get_optional(dev, "cfam-reset", GPIOD_OUT_LOW);
        if (IS_ERR(gpio))
                return PTR_ERR(gpio);
        if (!gpio)
                return 0;

        aspeed->cfam_reset_gpio = gpio;

        rc = device_create_file(dev, &dev_attr_cfam_reset);
        if (rc) {
                devm_gpiod_put(dev, gpio);
                return rc;
        }

        return 0;
}

static int tacoma_cabled_fsi_fixup(struct device *dev)
{
        struct gpio_desc *routing_gpio, *mux_gpio;
        int gpio;

        /*
         * The routing GPIO is a jumper indicating we should mux for the
         * externally connected FSI cable.
         */
        routing_gpio = devm_gpiod_get_optional(dev, "fsi-routing",
                        GPIOD_IN | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
        if (IS_ERR(routing_gpio))
                return PTR_ERR(routing_gpio);
        if (!routing_gpio)
                return 0;

        mux_gpio = devm_gpiod_get_optional(dev, "fsi-mux", GPIOD_ASIS);
        if (IS_ERR(mux_gpio))
                return PTR_ERR(mux_gpio);
        if (!mux_gpio)
                return 0;

        gpio = gpiod_get_value(routing_gpio);
        if (gpio < 0)
                return gpio;

        /* If the routing GPIO is high we should set the mux to low. */
        if (gpio) {
                /*
                 * Cable signal integrity means we should run the bus
                 * slightly slower. Do not override if a kernel param
                 * has already overridden.
                 */
                if (aspeed_fsi_divisor == FSI_DIVISOR_DEFAULT)
                        aspeed_fsi_divisor = FSI_DIVISOR_CABLED;

                gpiod_direction_output(mux_gpio, 0);
                dev_info(dev, "FSI configured for external cable\n");
        } else {
                gpiod_direction_output(mux_gpio, 1);
        }

        devm_gpiod_put(dev, routing_gpio);

        return 0;
}

static int fsi_master_aspeed_probe(struct platform_device *pdev)
{
        struct fsi_master_aspeed *aspeed;
        int rc, links, reg;
        __be32 raw;

        rc = tacoma_cabled_fsi_fixup(&pdev->dev);
        if (rc) {
                dev_err(&pdev->dev, "Tacoma FSI cable fixup failed\n");
                return rc;
        }

        aspeed = kzalloc_obj(*aspeed);
        if (!aspeed)
                return -ENOMEM;

        aspeed->dev = &pdev->dev;

        aspeed->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(aspeed->base)) {
                rc = PTR_ERR(aspeed->base);
                goto err_free_aspeed;
        }

        aspeed->clk = devm_clk_get(aspeed->dev, NULL);
        if (IS_ERR(aspeed->clk)) {
                dev_err(aspeed->dev, "couldn't get clock\n");
                rc = PTR_ERR(aspeed->clk);
                goto err_free_aspeed;
        }
        rc = clk_prepare_enable(aspeed->clk);
        if (rc) {
                dev_err(aspeed->dev, "couldn't enable clock\n");
                goto err_free_aspeed;
        }

        rc = setup_cfam_reset(aspeed);
        if (rc) {
                dev_err(&pdev->dev, "CFAM reset GPIO setup failed\n");
        }

        writel(0x1, aspeed->base + OPB_CLK_SYNC);
        writel(OPB1_XFER_ACK_EN | OPB0_XFER_ACK_EN,
                        aspeed->base + OPB_IRQ_MASK);

        /* TODO: determine an appropriate value */
        writel(0x10, aspeed->base + OPB_RETRY_COUNTER);

        writel(ctrl_base, aspeed->base + OPB_CTRL_BASE);
        writel(fsi_base, aspeed->base + OPB_FSI_BASE);

        /* Set read data order */
        writel(0x00030b1b, aspeed->base + OPB0_READ_ORDER1);

        /* Set write data order */
        writel(0x0011101b, aspeed->base + OPB0_WRITE_ORDER1);
        writel(0x0c330f3f, aspeed->base + OPB0_WRITE_ORDER2);

        /*
         * Select OPB0 for all operations.
         * Will need to be reworked when enabling DMA or anything that uses
         * OPB1.
         */
        writel(0x1, aspeed->base + OPB0_SELECT);

        rc = opb_readl(aspeed, ctrl_base + FSI_MVER, &raw);
        if (rc) {
                dev_err(&pdev->dev, "failed to read hub version\n");
                goto err_release;
        }

        reg = be32_to_cpu(raw);
        links = (reg >> 8) & 0xff;
        dev_info(&pdev->dev, "hub version %08x (%d links)\n", reg, links);

        aspeed->master.dev.parent = &pdev->dev;
        aspeed->master.dev.release = aspeed_master_release;
        aspeed->master.dev.of_node = of_node_get(dev_of_node(&pdev->dev));

        aspeed->master.n_links = links;
        aspeed->master.read = aspeed_master_read;
        aspeed->master.write = aspeed_master_write;
        aspeed->master.send_break = aspeed_master_break;
        aspeed->master.term = aspeed_master_term;
        aspeed->master.link_enable = aspeed_master_link_enable;

        dev_set_drvdata(&pdev->dev, aspeed);

        mutex_init(&aspeed->lock);
        aspeed_master_init(aspeed);

        rc = fsi_master_register(&aspeed->master);
        if (rc)
                goto err_release;

        /* At this point, fsi_master_register performs the device_initialize(),
         * and holds the sole reference on master.dev. This means the device
         * will be freed (via ->release) during any subsequent call to
         * fsi_master_unregister.  We add our own reference to it here, so we
         * can perform cleanup (in _remove()) without it being freed before
         * we're ready.
         */
        get_device(&aspeed->master.dev);
        return 0;

err_release:
        clk_disable_unprepare(aspeed->clk);
err_free_aspeed:
        kfree(aspeed);
        return rc;
}

static void fsi_master_aspeed_remove(struct platform_device *pdev)
{
        struct fsi_master_aspeed *aspeed = platform_get_drvdata(pdev);

        fsi_master_unregister(&aspeed->master);
        clk_disable_unprepare(aspeed->clk);
}

static const struct of_device_id fsi_master_aspeed_match[] = {
        { .compatible = "aspeed,ast2600-fsi-master" },
        { },
};
MODULE_DEVICE_TABLE(of, fsi_master_aspeed_match);

static struct platform_driver fsi_master_aspeed_driver = {
        .driver = {
                .name           = "fsi-master-aspeed",
                .of_match_table = fsi_master_aspeed_match,
        },
        .probe  = fsi_master_aspeed_probe,
        .remove = fsi_master_aspeed_remove,
};

module_platform_driver(fsi_master_aspeed_driver);
MODULE_DESCRIPTION("FSI master driver for AST2600");
MODULE_LICENSE("GPL");