watchdog: Kontron PLD watchdog timer driver

Add watchdog timer support for the on-board PLD found on some Kontron
embedded modules.

Originally-From: Michael Brunner <michael.brunner@kontron.com>
Signed-off-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Acked-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 581 insertions, 0 deletions

diff --git a/drivers/watchdog/kempld_wdt.c b/drivers/watchdog/kempld_wdt.c
new file mode 100644
index 000000000000..491419e0772a
--- /dev/null
+++ b/drivers/watchdog/kempld_wdt.c
@@ -0,0 +1,581 @@
+/*
+ * Kontron PLD watchdog driver
+ *
+ * Copyright (c) 2010-2013 Kontron Europe GmbH
+ * Author: Michael Brunner <michael.brunner@kontron.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Note: From the PLD watchdog point of view timeout and pretimeout are
+ *       defined differently than in the kernel.
+ *       First the pretimeout stage runs out before the timeout stage gets
+ *       active.
+ *
+ * Kernel/API:                     P-----| pretimeout
+ *               |-----------------------T timeout
+ * Watchdog:     |-----------------P       pretimeout_stage
+ *                                 |-----T timeout_stage
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/kempld.h>
+
+#define KEMPLD_WDT_STAGE_TIMEOUT(x)     (0x1b + (x) * 4)
+#define KEMPLD_WDT_STAGE_CFG(x)         (0x18 + (x))
+#define STAGE_CFG_GET_PRESCALER(x)      (((x) & 0x30) >> 4)
+#define STAGE_CFG_SET_PRESCALER(x)      (((x) & 0x30) << 4)
+#define STAGE_CFG_PRESCALER_MASK        0x30
+#define STAGE_CFG_ACTION_MASK           0x7
+#define STAGE_CFG_ASSERT                (1 << 3)
+
+#define KEMPLD_WDT_MAX_STAGES           2
+#define KEMPLD_WDT_KICK                 0x16
+#define KEMPLD_WDT_CFG                  0x17
+#define KEMPLD_WDT_CFG_ENABLE           0x10
+#define KEMPLD_WDT_CFG_ENABLE_LOCK      0x8
+#define KEMPLD_WDT_CFG_GLOBAL_LOCK      0x80
+
+enum {
+        ACTION_NONE = 0,
+        ACTION_RESET,
+        ACTION_NMI,
+        ACTION_SMI,
+        ACTION_SCI,
+        ACTION_DELAY,
+};
+
+enum {
+        STAGE_TIMEOUT = 0,
+        STAGE_PRETIMEOUT,
+};
+
+enum {
+        PRESCALER_21 = 0,
+        PRESCALER_17,
+        PRESCALER_12,
+};
+
+const u32 kempld_prescaler[] = {
+        [PRESCALER_21] = (1 << 21) - 1,
+        [PRESCALER_17] = (1 << 17) - 1,
+        [PRESCALER_12] = (1 << 12) - 1,
+        0,
+};
+
+struct kempld_wdt_stage {
+        unsigned int    id;
+        u32             mask;
+};
+
+struct kempld_wdt_data {
+        struct kempld_device_data       *pld;
+        struct watchdog_device          wdd;
+        unsigned int                    pretimeout;
+        struct kempld_wdt_stage         stage[KEMPLD_WDT_MAX_STAGES];
+#ifdef CONFIG_PM
+        u8                              pm_status_store;
+#endif
+};
+
+#define DEFAULT_TIMEOUT         30 /* seconds */
+#define DEFAULT_PRETIMEOUT      0
+
+static unsigned int timeout = DEFAULT_TIMEOUT;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+        "Watchdog timeout in seconds. (>=0, default="
+        __MODULE_STRING(DEFAULT_TIMEOUT) ")");
+
+static unsigned int pretimeout = DEFAULT_PRETIMEOUT;
+module_param(pretimeout, uint, 0);
+MODULE_PARM_DESC(pretimeout,
+        "Watchdog pretimeout in seconds. (>=0, default="
+        __MODULE_STRING(DEFAULT_PRETIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+        "Watchdog cannot be stopped once started (default="
+        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static int kempld_wdt_set_stage_action(struct kempld_wdt_data *wdt_data,
+                                        struct kempld_wdt_stage *stage,
+                                        u8 action)
+{
+        struct kempld_device_data *pld = wdt_data->pld;
+        u8 stage_cfg;
+
+        if (!stage || !stage->mask)
+                return -EINVAL;
+
+        kempld_get_mutex(pld);
+        stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
+        stage_cfg &= ~STAGE_CFG_ACTION_MASK;
+        stage_cfg |= (action & STAGE_CFG_ACTION_MASK);
+
+        if (action == ACTION_RESET)
+                stage_cfg |= STAGE_CFG_ASSERT;
+        else
+                stage_cfg &= ~STAGE_CFG_ASSERT;
+
+        kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
+        kempld_release_mutex(pld);
+
+        return 0;
+}
+
+static int kempld_wdt_set_stage_timeout(struct kempld_wdt_data *wdt_data,
+                                        struct kempld_wdt_stage *stage,
+                                        unsigned int timeout)
+{
+        struct kempld_device_data *pld = wdt_data->pld;
+        u32 prescaler = kempld_prescaler[PRESCALER_21];
+        u64 stage_timeout64;
+        u32 stage_timeout;
+        u32 remainder;
+        u8 stage_cfg;
+
+        if (!stage)
+                return -EINVAL;
+
+        stage_timeout64 = (u64)timeout * pld->pld_clock;
+        remainder = do_div(stage_timeout64, prescaler);
+        if (remainder)
+                stage_timeout64++;
+
+        if (stage_timeout64 > stage->mask)
+                return -EINVAL;
+
+        stage_timeout = stage_timeout64 & stage->mask;
+
+        kempld_get_mutex(pld);
+        stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
+        stage_cfg &= ~STAGE_CFG_PRESCALER_MASK;
+        stage_cfg |= STAGE_CFG_SET_PRESCALER(prescaler);
+        kempld_write8(pld, KEMPLD_WDT_STAGE_CFG(stage->id), stage_cfg);
+        kempld_write32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id),
+                        stage_timeout);
+        kempld_release_mutex(pld);
+
+        return 0;
+}
+
+/*
+ * kempld_get_mutex must be called prior to calling this function.
+ */
+static unsigned int kempld_wdt_get_timeout(struct kempld_wdt_data *wdt_data,
+                                                struct kempld_wdt_stage *stage)
+{
+        struct kempld_device_data *pld = wdt_data->pld;
+        unsigned int timeout;
+        u64 stage_timeout;
+        u32 prescaler;
+        u32 remainder;
+        u8 stage_cfg;
+
+        if (!stage->mask)
+                return 0;
+
+        stage_cfg = kempld_read8(pld, KEMPLD_WDT_STAGE_CFG(stage->id));
+        stage_timeout = kempld_read32(pld, KEMPLD_WDT_STAGE_TIMEOUT(stage->id));
+        prescaler = kempld_prescaler[STAGE_CFG_GET_PRESCALER(stage_cfg)];
+
+        stage_timeout = (stage_timeout & stage->mask) * prescaler;
+        remainder = do_div(stage_timeout, pld->pld_clock);
+        if (remainder)
+                stage_timeout++;
+
+        timeout = stage_timeout;
+        WARN_ON_ONCE(timeout != stage_timeout);
+
+        return timeout;
+}
+
+static int kempld_wdt_set_timeout(struct watchdog_device *wdd,
+                                        unsigned int timeout)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        struct kempld_wdt_stage *pretimeout_stage;
+        struct kempld_wdt_stage *timeout_stage;
+        int ret;
+
+        timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
+        pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+
+        if (pretimeout_stage->mask && wdt_data->pretimeout > 0)
+                timeout = wdt_data->pretimeout;
+
+        ret = kempld_wdt_set_stage_action(wdt_data, timeout_stage,
+                                                ACTION_RESET);
+        if (ret)
+                return ret;
+        ret = kempld_wdt_set_stage_timeout(wdt_data, timeout_stage,
+                                                timeout);
+        if (ret)
+                return ret;
+
+        wdd->timeout = timeout;
+        return 0;
+}
+
+static int kempld_wdt_set_pretimeout(struct watchdog_device *wdd,
+                                        unsigned int pretimeout)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        struct kempld_wdt_stage *pretimeout_stage;
+        u8 action = ACTION_NONE;
+        int ret;
+
+        pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+
+        if (!pretimeout_stage->mask)
+                return -ENXIO;
+
+        if (pretimeout > wdd->timeout)
+                return -EINVAL;
+
+        if (pretimeout > 0)
+                action = ACTION_NMI;
+
+        ret = kempld_wdt_set_stage_action(wdt_data, pretimeout_stage,
+                                                action);
+        if (ret)
+                return ret;
+        ret = kempld_wdt_set_stage_timeout(wdt_data, pretimeout_stage,
+                                                wdd->timeout - pretimeout);
+        if (ret)
+                return ret;
+
+        wdt_data->pretimeout = pretimeout;
+        return 0;
+}
+
+static void kempld_wdt_update_timeouts(struct kempld_wdt_data *wdt_data)
+{
+        struct kempld_device_data *pld = wdt_data->pld;
+        struct kempld_wdt_stage *pretimeout_stage;
+        struct kempld_wdt_stage *timeout_stage;
+        unsigned int pretimeout, timeout;
+
+        pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+        timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
+
+        kempld_get_mutex(pld);
+        pretimeout = kempld_wdt_get_timeout(wdt_data, pretimeout_stage);
+        timeout = kempld_wdt_get_timeout(wdt_data, timeout_stage);
+        kempld_release_mutex(pld);
+
+        if (pretimeout)
+                wdt_data->pretimeout = timeout;
+        else
+                wdt_data->pretimeout = 0;
+
+        wdt_data->wdd.timeout = pretimeout + timeout;
+}
+
+static int kempld_wdt_start(struct watchdog_device *wdd)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        struct kempld_device_data *pld = wdt_data->pld;
+        u8 status;
+        int ret;
+
+        ret = kempld_wdt_set_timeout(wdd, wdd->timeout);
+        if (ret)
+                return ret;
+
+        kempld_get_mutex(pld);
+        status = kempld_read8(pld, KEMPLD_WDT_CFG);
+        status |= KEMPLD_WDT_CFG_ENABLE;
+        kempld_write8(pld, KEMPLD_WDT_CFG, status);
+        status = kempld_read8(pld, KEMPLD_WDT_CFG);
+        kempld_release_mutex(pld);
+
+        /* Check if the watchdog was enabled */
+        if (!(status & KEMPLD_WDT_CFG_ENABLE))
+                return -EACCES;
+
+        return 0;
+}
+
+static int kempld_wdt_stop(struct watchdog_device *wdd)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        struct kempld_device_data *pld = wdt_data->pld;
+        u8 status;
+
+        kempld_get_mutex(pld);
+        status = kempld_read8(pld, KEMPLD_WDT_CFG);
+        status &= ~KEMPLD_WDT_CFG_ENABLE;
+        kempld_write8(pld, KEMPLD_WDT_CFG, status);
+        status = kempld_read8(pld, KEMPLD_WDT_CFG);
+        kempld_release_mutex(pld);
+
+        /* Check if the watchdog was disabled */
+        if (status & KEMPLD_WDT_CFG_ENABLE)
+                return -EACCES;
+
+        return 0;
+}
+
+static int kempld_wdt_keepalive(struct watchdog_device *wdd)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        struct kempld_device_data *pld = wdt_data->pld;
+
+        kempld_get_mutex(pld);
+        kempld_write8(pld, KEMPLD_WDT_KICK, 'K');
+        kempld_release_mutex(pld);
+
+        return 0;
+}
+
+static long kempld_wdt_ioctl(struct watchdog_device *wdd, unsigned int cmd,
+                                unsigned long arg)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        void __user *argp = (void __user *)arg;
+        int ret = -ENOIOCTLCMD;
+        int __user *p = argp;
+        int new_value;
+
+        switch (cmd) {
+        case WDIOC_SETPRETIMEOUT:
+                if (get_user(new_value, p))
+                        return -EFAULT;
+                ret = kempld_wdt_set_pretimeout(wdd, new_value);
+                if (ret)
+                        return ret;
+                ret = kempld_wdt_keepalive(wdd);
+                break;
+        case WDIOC_GETPRETIMEOUT:
+                ret = put_user(wdt_data->pretimeout, (int *)arg);
+                break;
+        }
+
+        return ret;
+}
+
+static int kempld_wdt_probe_stages(struct watchdog_device *wdd)
+{
+        struct kempld_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+        struct kempld_device_data *pld = wdt_data->pld;
+        struct kempld_wdt_stage *pretimeout_stage;
+        struct kempld_wdt_stage *timeout_stage;
+        u8 index, data, data_orig;
+        u32 mask;
+        int i, j;
+
+        pretimeout_stage = &wdt_data->stage[STAGE_PRETIMEOUT];
+        timeout_stage = &wdt_data->stage[STAGE_TIMEOUT];
+
+        pretimeout_stage->mask = 0;
+        timeout_stage->mask = 0;
+
+        for (i = 0; i < 3; i++) {
+                index = KEMPLD_WDT_STAGE_TIMEOUT(i);
+                mask = 0;
+
+                kempld_get_mutex(pld);
+                /* Probe each byte individually. */
+                for (j = 0; j < 4; j++) {
+                        data_orig = kempld_read8(pld, index + j);
+                        kempld_write8(pld, index + j, 0x00);
+                        data = kempld_read8(pld, index + j);
+                        /* A failed write means this byte is reserved */
+                        if (data != 0x00)
+                                break;
+                        kempld_write8(pld, index + j, data_orig);
+                        mask |= 0xff << (j * 8);
+                }
+                kempld_release_mutex(pld);
+
+                /* Assign available stages to timeout and pretimeout */
+                if (!timeout_stage->mask) {
+                        timeout_stage->mask = mask;
+                        timeout_stage->id = i;
+                } else {
+                        if (pld->feature_mask & KEMPLD_FEATURE_BIT_NMI) {
+                                pretimeout_stage->mask = timeout_stage->mask;
+                                timeout_stage->mask = mask;
+                                pretimeout_stage->id = timeout_stage->id;
+                                timeout_stage->id = i;
+                        }
+                        break;
+                }
+        }
+
+        if (!timeout_stage->mask)
+                return -ENODEV;
+
+        return 0;
+}
+
+static struct watchdog_info kempld_wdt_info = {
+        .identity       = "KEMPLD Watchdog",
+        .options        = WDIOF_SETTIMEOUT |
+                        WDIOF_KEEPALIVEPING |
+                        WDIOF_MAGICCLOSE |
+                        WDIOF_PRETIMEOUT
+};
+
+static struct watchdog_ops kempld_wdt_ops = {
+        .owner          = THIS_MODULE,
+        .start          = kempld_wdt_start,
+        .stop           = kempld_wdt_stop,
+        .ping           = kempld_wdt_keepalive,
+        .set_timeout    = kempld_wdt_set_timeout,
+        .ioctl          = kempld_wdt_ioctl,
+};
+
+static int kempld_wdt_probe(struct platform_device *pdev)
+{
+        struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
+        struct kempld_wdt_data *wdt_data;
+        struct device *dev = &pdev->dev;
+        struct watchdog_device *wdd;
+        u8 status;
+        int ret = 0;
+
+        wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
+        if (!wdt_data)
+                return -ENOMEM;
+
+        wdt_data->pld = pld;
+        wdd = &wdt_data->wdd;
+        wdd->parent = dev;
+
+        kempld_get_mutex(pld);
+        status = kempld_read8(pld, KEMPLD_WDT_CFG);
+        kempld_release_mutex(pld);
+
+        /* Enable nowayout if watchdog is already locked */
+        if (status & (KEMPLD_WDT_CFG_ENABLE_LOCK |
+                        KEMPLD_WDT_CFG_GLOBAL_LOCK)) {
+                if (!nowayout)
+                        dev_warn(dev,
+                                "Forcing nowayout - watchdog lock enabled!\n");
+                nowayout = true;
+        }
+
+        wdd->info = &kempld_wdt_info;
+        wdd->ops = &kempld_wdt_ops;
+
+        watchdog_set_drvdata(wdd, wdt_data);
+        watchdog_set_nowayout(wdd, nowayout);
+
+        ret = kempld_wdt_probe_stages(wdd);
+        if (ret)
+                return ret;
+
+        kempld_wdt_set_timeout(wdd, timeout);
+        kempld_wdt_set_pretimeout(wdd, pretimeout);
+
+        /* Check if watchdog is already enabled */
+        if (status & KEMPLD_WDT_CFG_ENABLE) {
+                /* Get current watchdog settings */
+                kempld_wdt_update_timeouts(wdt_data);
+                dev_info(dev, "Watchdog was already enabled\n");
+        }
+
+        platform_set_drvdata(pdev, wdt_data);
+        ret = watchdog_register_device(wdd);
+        if (ret)
+                return ret;
+
+        dev_info(dev, "Watchdog registered with %ds timeout\n", wdd->timeout);
+
+        return 0;
+}
+
+static void kempld_wdt_shutdown(struct platform_device *pdev)
+{
+        struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+
+        kempld_wdt_stop(&wdt_data->wdd);
+}
+
+static int kempld_wdt_remove(struct platform_device *pdev)
+{
+        struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+        struct watchdog_device *wdd = &wdt_data->wdd;
+        int ret = 0;
+
+        if (!nowayout)
+                ret = kempld_wdt_stop(wdd);
+        watchdog_unregister_device(wdd);
+
+        return ret;
+}
+
+#ifdef CONFIG_PM
+/* Disable watchdog if it is active during suspend */
+static int kempld_wdt_suspend(struct platform_device *pdev,
+                                pm_message_t message)
+{
+        struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+        struct kempld_device_data *pld = wdt_data->pld;
+        struct watchdog_device *wdd = &wdt_data->wdd;
+
+        kempld_get_mutex(pld);
+        wdt_data->pm_status_store = kempld_read8(pld, KEMPLD_WDT_CFG);
+        kempld_release_mutex(pld);
+
+        kempld_wdt_update_timeouts(wdt_data);
+
+        if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
+                return kempld_wdt_stop(wdd);
+
+        return 0;
+}
+
+/* Enable watchdog and configure it if necessary */
+static int kempld_wdt_resume(struct platform_device *pdev)
+{
+        struct kempld_wdt_data *wdt_data = platform_get_drvdata(pdev);
+        struct watchdog_device *wdd = &wdt_data->wdd;
+
+        /*
+         * If watchdog was stopped before suspend be sure it gets disabled
+         * again, for the case BIOS has enabled it during resume
+         */
+        if (wdt_data->pm_status_store & KEMPLD_WDT_CFG_ENABLE)
+                return kempld_wdt_start(wdd);
+        else
+                return kempld_wdt_stop(wdd);
+}
+#else
+#define kempld_wdt_suspend      NULL
+#define kempld_wdt_resume       NULL
+#endif
+
+static struct platform_driver kempld_wdt_driver = {
+        .driver         = {
+                .name   = "kempld-wdt",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = kempld_wdt_probe,
+        .remove         = kempld_wdt_remove,
+        .shutdown       = kempld_wdt_shutdown,
+        .suspend        = kempld_wdt_suspend,
+        .resume         = kempld_wdt_resume,
+};
+
+module_platform_driver(kempld_wdt_driver);
+
+MODULE_DESCRIPTION("KEM PLD Watchdog Driver");
+MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);