// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/watchdog/orion_wdt.c
 *
 * Watchdog driver for Orion/Kirkwood processors
 *
 * Author: Sylver Bruneau <sylver.bruneau@googlemail.com>
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_device.h>

/* RSTOUT mask register physical address for Orion5x, Kirkwood and Dove */
#define ORION_RSTOUT_MASK_OFFSET        0x20108

/* Internal registers can be configured at any 1 MiB aligned address */
#define INTERNAL_REGS_MASK              ~(SZ_1M - 1)

/*
 * Watchdog timer block registers.
 */
#define TIMER_CTRL              0x0000
#define TIMER1_FIXED_ENABLE_BIT BIT(12)
#define WDT_AXP_FIXED_ENABLE_BIT BIT(10)
#define TIMER1_ENABLE_BIT       BIT(2)

#define TIMER_A370_STATUS       0x0004
#define WDT_A370_EXPIRED        BIT(31)
#define TIMER1_STATUS_BIT       BIT(8)

#define TIMER1_VAL_OFF          0x001c

#define WDT_MAX_CYCLE_COUNT     0xffffffff

#define WDT_A370_RATIO_MASK(v)  ((v) << 16)
#define WDT_A370_RATIO_SHIFT    5
#define WDT_A370_RATIO          (1 << WDT_A370_RATIO_SHIFT)

static bool nowayout = WATCHDOG_NOWAYOUT;
static int heartbeat;           /* module parameter (seconds) */

struct orion_watchdog;

struct orion_watchdog_data {
        int wdt_counter_offset;
        int wdt_enable_bit;
        int rstout_enable_bit;
        int rstout_mask_bit;
        int (*clock_init)(struct platform_device *,
                          struct orion_watchdog *);
        int (*enabled)(struct orion_watchdog *);
        int (*start)(struct watchdog_device *);
        int (*stop)(struct watchdog_device *);
};

struct orion_watchdog {
        struct watchdog_device wdt;
        void __iomem *reg;
        void __iomem *rstout;
        void __iomem *rstout_mask;
        unsigned long clk_rate;
        struct clk *clk;
        const struct orion_watchdog_data *data;
};

static int orion_wdt_clock_init(struct platform_device *pdev,
                                struct orion_watchdog *dev)
{
        int ret;

        dev->clk = clk_get(&pdev->dev, NULL);
        if (IS_ERR(dev->clk))
                return PTR_ERR(dev->clk);
        ret = clk_prepare_enable(dev->clk);
        if (ret) {
                clk_put(dev->clk);
                return ret;
        }

        dev->clk_rate = clk_get_rate(dev->clk);
        return 0;
}

static int armada370_wdt_clock_init(struct platform_device *pdev,
                                    struct orion_watchdog *dev)
{
        int ret;

        dev->clk = clk_get(&pdev->dev, NULL);
        if (IS_ERR(dev->clk))
                return PTR_ERR(dev->clk);
        ret = clk_prepare_enable(dev->clk);
        if (ret) {
                clk_put(dev->clk);
                return ret;
        }

        /* Setup watchdog input clock */
        atomic_io_modify(dev->reg + TIMER_CTRL,
                        WDT_A370_RATIO_MASK(WDT_A370_RATIO_SHIFT),
                        WDT_A370_RATIO_MASK(WDT_A370_RATIO_SHIFT));

        dev->clk_rate = clk_get_rate(dev->clk) / WDT_A370_RATIO;
        return 0;
}

static int armada375_wdt_clock_init(struct platform_device *pdev,
                                    struct orion_watchdog *dev)
{
        int ret;

        dev->clk = of_clk_get_by_name(pdev->dev.of_node, "fixed");
        if (!IS_ERR(dev->clk)) {
                ret = clk_prepare_enable(dev->clk);
                if (ret) {
                        clk_put(dev->clk);
                        return ret;
                }

                atomic_io_modify(dev->reg + TIMER_CTRL,
                                WDT_AXP_FIXED_ENABLE_BIT,
                                WDT_AXP_FIXED_ENABLE_BIT);
                dev->clk_rate = clk_get_rate(dev->clk);

                return 0;
        }

        /* Mandatory fallback for proper devicetree backward compatibility */
        dev->clk = clk_get(&pdev->dev, NULL);
        if (IS_ERR(dev->clk))
                return PTR_ERR(dev->clk);

        ret = clk_prepare_enable(dev->clk);
        if (ret) {
                clk_put(dev->clk);
                return ret;
        }

        atomic_io_modify(dev->reg + TIMER_CTRL,
                        WDT_A370_RATIO_MASK(WDT_A370_RATIO_SHIFT),
                        WDT_A370_RATIO_MASK(WDT_A370_RATIO_SHIFT));
        dev->clk_rate = clk_get_rate(dev->clk) / WDT_A370_RATIO;

        return 0;
}

static int armadaxp_wdt_clock_init(struct platform_device *pdev,
                                   struct orion_watchdog *dev)
{
        int ret;
        u32 val;

        dev->clk = of_clk_get_by_name(pdev->dev.of_node, "fixed");
        if (IS_ERR(dev->clk))
                return PTR_ERR(dev->clk);
        ret = clk_prepare_enable(dev->clk);
        if (ret) {
                clk_put(dev->clk);
                return ret;
        }

        /* Fix the wdt and timer1 clock frequency to 25MHz */
        val = WDT_AXP_FIXED_ENABLE_BIT | TIMER1_FIXED_ENABLE_BIT;
        atomic_io_modify(dev->reg + TIMER_CTRL, val, val);

        dev->clk_rate = clk_get_rate(dev->clk);
        return 0;
}

static int orion_wdt_ping(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
        /* Reload watchdog duration */
        writel(dev->clk_rate * wdt_dev->timeout,
               dev->reg + dev->data->wdt_counter_offset);
        if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
                writel(dev->clk_rate * (wdt_dev->timeout - wdt_dev->pretimeout),
                       dev->reg + TIMER1_VAL_OFF);

        return 0;
}

static int armada375_start(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
        u32 reg;

        /* Set watchdog duration */
        writel(dev->clk_rate * wdt_dev->timeout,
               dev->reg + dev->data->wdt_counter_offset);
        if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
                writel(dev->clk_rate * (wdt_dev->timeout - wdt_dev->pretimeout),
                       dev->reg + TIMER1_VAL_OFF);

        /* Clear the watchdog expiration bit */
        atomic_io_modify(dev->reg + TIMER_A370_STATUS, WDT_A370_EXPIRED, 0);

        /* Enable watchdog timer */
        reg = dev->data->wdt_enable_bit;
        if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
                reg |= TIMER1_ENABLE_BIT;
        atomic_io_modify(dev->reg + TIMER_CTRL, reg, reg);

        /* Enable reset on watchdog */
        reg = readl(dev->rstout);
        reg |= dev->data->rstout_enable_bit;
        writel(reg, dev->rstout);

        atomic_io_modify(dev->rstout_mask, dev->data->rstout_mask_bit, 0);
        return 0;
}

static int armada370_start(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
        u32 reg;

        /* Set watchdog duration */
        writel(dev->clk_rate * wdt_dev->timeout,
               dev->reg + dev->data->wdt_counter_offset);

        /* Clear the watchdog expiration bit */
        atomic_io_modify(dev->reg + TIMER_A370_STATUS, WDT_A370_EXPIRED, 0);

        /* Enable watchdog timer */
        reg = dev->data->wdt_enable_bit;
        if (dev->wdt.info->options & WDIOF_PRETIMEOUT)
                reg |= TIMER1_ENABLE_BIT;
        atomic_io_modify(dev->reg + TIMER_CTRL, reg, reg);

        /* Enable reset on watchdog */
        reg = readl(dev->rstout);
        reg |= dev->data->rstout_enable_bit;
        writel(reg, dev->rstout);
        return 0;
}

static int orion_start(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);

        /* Set watchdog duration */
        writel(dev->clk_rate * wdt_dev->timeout,
               dev->reg + dev->data->wdt_counter_offset);

        /* Enable watchdog timer */
        atomic_io_modify(dev->reg + TIMER_CTRL, dev->data->wdt_enable_bit,
                                                dev->data->wdt_enable_bit);

        /* Enable reset on watchdog */
        atomic_io_modify(dev->rstout, dev->data->rstout_enable_bit,
                                      dev->data->rstout_enable_bit);

        return 0;
}

static int orion_wdt_start(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);

        /* There are some per-SoC quirks to handle */
        return dev->data->start(wdt_dev);
}

static int orion_stop(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);

        /* Disable reset on watchdog */
        atomic_io_modify(dev->rstout, dev->data->rstout_enable_bit, 0);

        /* Disable watchdog timer */
        atomic_io_modify(dev->reg + TIMER_CTRL, dev->data->wdt_enable_bit, 0);

        return 0;
}

static int armada375_stop(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
        u32 reg, mask;

        /* Disable reset on watchdog */
        atomic_io_modify(dev->rstout_mask, dev->data->rstout_mask_bit,
                                           dev->data->rstout_mask_bit);
        reg = readl(dev->rstout);
        reg &= ~dev->data->rstout_enable_bit;
        writel(reg, dev->rstout);

        /* Disable watchdog timer */
        mask = dev->data->wdt_enable_bit;
        if (wdt_dev->info->options & WDIOF_PRETIMEOUT)
                mask |= TIMER1_ENABLE_BIT;
        atomic_io_modify(dev->reg + TIMER_CTRL, mask, 0);

        return 0;
}

static int armada370_stop(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
        u32 reg, mask;

        /* Disable reset on watchdog */
        reg = readl(dev->rstout);
        reg &= ~dev->data->rstout_enable_bit;
        writel(reg, dev->rstout);

        /* Disable watchdog timer */
        mask = dev->data->wdt_enable_bit;
        if (wdt_dev->info->options & WDIOF_PRETIMEOUT)
                mask |= TIMER1_ENABLE_BIT;
        atomic_io_modify(dev->reg + TIMER_CTRL, mask, 0);

        return 0;
}

static int orion_wdt_stop(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);

        return dev->data->stop(wdt_dev);
}

static int orion_enabled(struct orion_watchdog *dev)
{
        bool enabled, running;

        enabled = readl(dev->rstout) & dev->data->rstout_enable_bit;
        running = readl(dev->reg + TIMER_CTRL) & dev->data->wdt_enable_bit;

        return enabled && running;
}

static int armada375_enabled(struct orion_watchdog *dev)
{
        bool masked, enabled, running;

        masked = readl(dev->rstout_mask) & dev->data->rstout_mask_bit;
        enabled = readl(dev->rstout) & dev->data->rstout_enable_bit;
        running = readl(dev->reg + TIMER_CTRL) & dev->data->wdt_enable_bit;

        return !masked && enabled && running;
}

static int orion_wdt_enabled(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);

        return dev->data->enabled(dev);
}

static unsigned int orion_wdt_get_timeleft(struct watchdog_device *wdt_dev)
{
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);
        return readl(dev->reg + dev->data->wdt_counter_offset) / dev->clk_rate;
}

static struct watchdog_info orion_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "Orion Watchdog",
};

static const struct watchdog_ops orion_wdt_ops = {
        .owner = THIS_MODULE,
        .start = orion_wdt_start,
        .stop = orion_wdt_stop,
        .ping = orion_wdt_ping,
        .get_timeleft = orion_wdt_get_timeleft,
};

static irqreturn_t orion_wdt_irq(int irq, void *devid)
{
        panic("Watchdog Timeout");
        return IRQ_HANDLED;
}

static irqreturn_t orion_wdt_pre_irq(int irq, void *devid)
{
        struct orion_watchdog *dev = devid;

        atomic_io_modify(dev->reg + TIMER_A370_STATUS,
                         TIMER1_STATUS_BIT, 0);
        watchdog_notify_pretimeout(&dev->wdt);
        return IRQ_HANDLED;
}

/*
 * The original devicetree binding for this driver specified only
 * one memory resource, so in order to keep DT backwards compatibility
 * we try to fallback to a hardcoded register address, if the resource
 * is missing from the devicetree.
 */
static void __iomem *orion_wdt_ioremap_rstout(struct platform_device *pdev,
                                              phys_addr_t internal_regs)
{
        struct resource *res;
        phys_addr_t rstout;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (res)
                return devm_ioremap(&pdev->dev, res->start,
                                    resource_size(res));

        rstout = internal_regs + ORION_RSTOUT_MASK_OFFSET;

        WARN(1, FW_BUG "falling back to hardcoded RSTOUT reg %pa\n", &rstout);
        return devm_ioremap(&pdev->dev, rstout, 0x4);
}

static const struct orion_watchdog_data orion_data = {
        .rstout_enable_bit = BIT(1),
        .wdt_enable_bit = BIT(4),
        .wdt_counter_offset = 0x24,
        .clock_init = orion_wdt_clock_init,
        .enabled = orion_enabled,
        .start = orion_start,
        .stop = orion_stop,
};

static const struct orion_watchdog_data armada370_data = {
        .rstout_enable_bit = BIT(8),
        .wdt_enable_bit = BIT(8),
        .wdt_counter_offset = 0x34,
        .clock_init = armada370_wdt_clock_init,
        .enabled = orion_enabled,
        .start = armada370_start,
        .stop = armada370_stop,
};

static const struct orion_watchdog_data armadaxp_data = {
        .rstout_enable_bit = BIT(8),
        .wdt_enable_bit = BIT(8),
        .wdt_counter_offset = 0x34,
        .clock_init = armadaxp_wdt_clock_init,
        .enabled = orion_enabled,
        .start = armada370_start,
        .stop = armada370_stop,
};

static const struct orion_watchdog_data armada375_data = {
        .rstout_enable_bit = BIT(8),
        .rstout_mask_bit = BIT(10),
        .wdt_enable_bit = BIT(8),
        .wdt_counter_offset = 0x34,
        .clock_init = armada375_wdt_clock_init,
        .enabled = armada375_enabled,
        .start = armada375_start,
        .stop = armada375_stop,
};

static const struct orion_watchdog_data armada380_data = {
        .rstout_enable_bit = BIT(8),
        .rstout_mask_bit = BIT(10),
        .wdt_enable_bit = BIT(8),
        .wdt_counter_offset = 0x34,
        .clock_init = armadaxp_wdt_clock_init,
        .enabled = armada375_enabled,
        .start = armada375_start,
        .stop = armada375_stop,
};

static const struct of_device_id orion_wdt_of_match_table[] = {
        {
                .compatible = "marvell,orion-wdt",
                .data = &orion_data,
        },
        {
                .compatible = "marvell,armada-370-wdt",
                .data = &armada370_data,
        },
        {
                .compatible = "marvell,armada-xp-wdt",
                .data = &armadaxp_data,
        },
        {
                .compatible = "marvell,armada-375-wdt",
                .data = &armada375_data,
        },
        {
                .compatible = "marvell,armada-380-wdt",
                .data = &armada380_data,
        },
        {},
};
MODULE_DEVICE_TABLE(of, orion_wdt_of_match_table);

static int orion_wdt_get_regs(struct platform_device *pdev,
                              struct orion_watchdog *dev)
{
        struct device_node *node = pdev->dev.of_node;
        struct resource *res;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENODEV;
        dev->reg = devm_ioremap(&pdev->dev, res->start,
                                resource_size(res));
        if (!dev->reg)
                return -ENOMEM;

        /* Each supported compatible has some RSTOUT register quirk */
        if (of_device_is_compatible(node, "marvell,orion-wdt")) {

                dev->rstout = orion_wdt_ioremap_rstout(pdev, res->start &
                                                       INTERNAL_REGS_MASK);
                if (!dev->rstout)
                        return -ENODEV;

        } else if (of_device_is_compatible(node, "marvell,armada-370-wdt") ||
                   of_device_is_compatible(node, "marvell,armada-xp-wdt")) {

                /* Dedicated RSTOUT register, can be requested. */
                dev->rstout = devm_platform_ioremap_resource(pdev, 1);
                if (IS_ERR(dev->rstout))
                        return PTR_ERR(dev->rstout);

        } else if (of_device_is_compatible(node, "marvell,armada-375-wdt") ||
                   of_device_is_compatible(node, "marvell,armada-380-wdt")) {

                /* Dedicated RSTOUT register, can be requested. */
                dev->rstout = devm_platform_ioremap_resource(pdev, 1);
                if (IS_ERR(dev->rstout))
                        return PTR_ERR(dev->rstout);

                res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
                if (!res)
                        return -ENODEV;
                dev->rstout_mask = devm_ioremap(&pdev->dev, res->start,
                                                resource_size(res));
                if (!dev->rstout_mask)
                        return -ENOMEM;

        } else {
                return -ENODEV;
        }

        return 0;
}

static int orion_wdt_probe(struct platform_device *pdev)
{
        struct orion_watchdog *dev;
        const struct of_device_id *match;
        unsigned int wdt_max_duration;  /* (seconds) */
        int ret, irq;

        dev = devm_kzalloc(&pdev->dev, sizeof(struct orion_watchdog),
                           GFP_KERNEL);
        if (!dev)
                return -ENOMEM;

        match = of_match_device(orion_wdt_of_match_table, &pdev->dev);
        if (!match)
                /* Default legacy match */
                match = &orion_wdt_of_match_table[0];

        dev->wdt.info = &orion_wdt_info;
        dev->wdt.ops = &orion_wdt_ops;
        dev->wdt.min_timeout = 1;
        dev->data = match->data;

        ret = orion_wdt_get_regs(pdev, dev);
        if (ret)
                return ret;

        ret = dev->data->clock_init(pdev, dev);
        if (ret) {
                dev_err(&pdev->dev, "cannot initialize clock\n");
                return ret;
        }

        wdt_max_duration = WDT_MAX_CYCLE_COUNT / dev->clk_rate;

        dev->wdt.timeout = wdt_max_duration;
        dev->wdt.max_timeout = wdt_max_duration;
        dev->wdt.parent = &pdev->dev;
        watchdog_init_timeout(&dev->wdt, heartbeat, &pdev->dev);

        platform_set_drvdata(pdev, &dev->wdt);
        watchdog_set_drvdata(&dev->wdt, dev);

        /*
         * Let's make sure the watchdog is fully stopped, unless it's
         * explicitly enabled. This may be the case if the module was
         * removed and re-inserted, or if the bootloader explicitly
         * set a running watchdog before booting the kernel.
         */
        if (!orion_wdt_enabled(&dev->wdt))
                orion_wdt_stop(&dev->wdt);
        else
                set_bit(WDOG_HW_RUNNING, &dev->wdt.status);

        /* Request the IRQ only after the watchdog is disabled */
        irq = platform_get_irq_optional(pdev, 0);
        if (irq > 0) {
                /*
                 * Not all supported platforms specify an interrupt for the
                 * watchdog, so let's make it optional.
                 */
                ret = devm_request_irq(&pdev->dev, irq, orion_wdt_irq, 0,
                                       pdev->name, dev);
                if (ret < 0) {
                        dev_err(&pdev->dev, "failed to request IRQ\n");
                        goto disable_clk;
                }
        }

        /* Optional 2nd interrupt for pretimeout */
        irq = platform_get_irq_optional(pdev, 1);
        if (irq > 0) {
                orion_wdt_info.options |= WDIOF_PRETIMEOUT;
                ret = devm_request_irq(&pdev->dev, irq, orion_wdt_pre_irq,
                                       0, pdev->name, dev);
                if (ret < 0) {
                        dev_err(&pdev->dev, "failed to request IRQ\n");
                        goto disable_clk;
                }
        }


        watchdog_set_nowayout(&dev->wdt, nowayout);
        ret = watchdog_register_device(&dev->wdt);
        if (ret)
                goto disable_clk;

        pr_info("Initial timeout %d sec%s\n",
                dev->wdt.timeout, nowayout ? ", nowayout" : "");
        return 0;

disable_clk:
        clk_disable_unprepare(dev->clk);
        clk_put(dev->clk);
        return ret;
}

static void orion_wdt_remove(struct platform_device *pdev)
{
        struct watchdog_device *wdt_dev = platform_get_drvdata(pdev);
        struct orion_watchdog *dev = watchdog_get_drvdata(wdt_dev);

        watchdog_unregister_device(wdt_dev);
        clk_disable_unprepare(dev->clk);
        clk_put(dev->clk);
}

static void orion_wdt_shutdown(struct platform_device *pdev)
{
        struct watchdog_device *wdt_dev = platform_get_drvdata(pdev);
        orion_wdt_stop(wdt_dev);
}

static struct platform_driver orion_wdt_driver = {
        .probe          = orion_wdt_probe,
        .remove         = orion_wdt_remove,
        .shutdown       = orion_wdt_shutdown,
        .driver         = {
                .name   = "orion_wdt",
                .of_match_table = orion_wdt_of_match_table,
        },
};

module_platform_driver(orion_wdt_driver);

MODULE_AUTHOR("Sylver Bruneau <sylver.bruneau@googlemail.com>");
MODULE_DESCRIPTION("Orion Processor Watchdog");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:orion_wdt");