[RFT PATCH v6 9/9] watchdog: dw_wdt: Convert to use watchdog infrastructure

From: Guenter Roeck
Date: Sun Nov 29 2015 - 14:29:23 EST

Convert driver to use watchdog infrastructure. This includes
infrastructure support to handle watchdog keepalive if the watchdog
is running while the watchdog device is closed.

Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>

---
v6: Added patch
---
drivers/watchdog/Kconfig | 1 +
drivers/watchdog/dw_wdt.c | 322 ++++++++++++++++------------------------------
2 files changed, 114 insertions(+), 209 deletions(-)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 7a8a6c6952e9..886468aa4d83 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -291,6 +291,7 @@ config SA1100_WATCHDOG
config DW_WATCHDOG
tristate "Synopsys DesignWare watchdog"
depends on HAS_IOMEM
+ select WATCHDOG_CORE
help
Say Y here if to include support for the Synopsys DesignWare
watchdog timer found in many chips.
diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index 6ea0634345e9..c22effe47f57 100644
--- a/drivers/watchdog/dw_wdt.c
+++ b/drivers/watchdog/dw_wdt.c
@@ -10,11 +10,6 @@
* This file implements a driver for the Synopsys DesignWare watchdog device
* in the many subsystems. The watchdog has 16 different timeout periods
* and these are a function of the input clock frequency.
- *
- * The DesignWare watchdog cannot be stopped once it has been started so we
- * use a software timer to implement a ping that will keep the watchdog alive.
- * If we receive an expected close for the watchdog then we keep the timer
- * running, otherwise the timer is stopped and the watchdog will expire.
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -22,12 +17,9 @@
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
-#include <linux/device.h>
#include <linux/err.h>
-#include <linux/fs.h>
#include <linux/io.h>
#include <linux/kernel.h>
-#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/notifier.h>
@@ -35,8 +27,6 @@
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/reboot.h>
-#include <linux/timer.h>
-#include <linux/uaccess.h>
#include <linux/watchdog.h>

#define WDOG_CONTROL_REG_OFFSET 0x00
@@ -57,53 +47,50 @@ module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

-#define WDT_TIMEOUT (HZ / 2)
-
-static struct {
+struct dw_wdt {
void __iomem *regs;
struct clk *clk;
- unsigned long in_use;
- unsigned long next_heartbeat;
- struct timer_list timer;
- int expect_close;
struct notifier_block restart_handler;
-} dw_wdt;
+ struct watchdog_device wdd;
+};

-static inline int dw_wdt_is_enabled(void)
+#define to_dw_wdt(wdd) container_of(wdd, struct dw_wdt, wdd)
+
+static inline int dw_wdt_is_enabled(struct dw_wdt *dw_wdt)
{
- return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
+ return readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET) &
WDOG_CONTROL_REG_WDT_EN_MASK;
}

-static inline int dw_wdt_top_in_seconds(unsigned top)
+static inline int dw_wdt_top_in_seconds(struct dw_wdt *dw_wdt, unsigned top)
{
/*
* There are 16 possible timeout values in 0..15 where the number of
* cycles is 2 ^ (16 + i) and the watchdog counts down.
*/
- return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
+ return (1 << (16 + top)) / clk_get_rate(dw_wdt->clk);
}

-static int dw_wdt_get_top(void)
+static int dw_wdt_get_top(struct dw_wdt *dw_wdt)
{
- int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
+ int top = readl(dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;

- return dw_wdt_top_in_seconds(top);
+ return dw_wdt_top_in_seconds(dw_wdt, top);
}

-static inline void dw_wdt_set_next_heartbeat(void)
+static int dw_wdt_ping(struct watchdog_device *wdd)
{
- dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
-}
+ struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

-static void dw_wdt_keepalive(void)
-{
- writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
+ writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs +
WDOG_COUNTER_RESTART_REG_OFFSET);
+
+ return 0;
}

-static int dw_wdt_set_top(unsigned top_s)
+static int dw_wdt_set_timeout(struct watchdog_device *wdd, unsigned int top_s)
{
+ struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
int i, top_val = DW_WDT_MAX_TOP;

/*
@@ -111,7 +98,7 @@ static int dw_wdt_set_top(unsigned top_s)
* always look for >=.
*/
for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
- if (dw_wdt_top_in_seconds(i) >= top_s) {
+ if (dw_wdt_top_in_seconds(dw_wdt, i) >= top_s) {
top_val = i;
break;
}
@@ -123,33 +110,43 @@ static int dw_wdt_set_top(unsigned top_s)
* effectively get a pat of the watchdog right here.
*/
writel(top_val | top_val << WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT,
- dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+ dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);

- /*
- * Add an explicit pat to handle versions of the watchdog that
- * don't have TOPINIT. This won't hurt on versions that have
- * it.
- */
- dw_wdt_keepalive();
+ wdd->timeout = dw_wdt_top_in_seconds(dw_wdt, top_val);

- dw_wdt_set_next_heartbeat();
+ return 0;
+}
+
+static int dw_wdt_start(struct watchdog_device *wdd)
+{
+ struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

- return dw_wdt_top_in_seconds(top_val);
+ dw_wdt_set_timeout(wdd, wdd->timeout);
+
+ set_bit(WDOG_HW_RUNNING, &wdd->status);
+
+ writel(WDOG_CONTROL_REG_WDT_EN_MASK,
+ dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
+
+ return 0;
}

static int dw_wdt_restart_handle(struct notifier_block *this,
- unsigned long mode, void *cmd)
+ unsigned long mode, void *cmd)
{
+ struct dw_wdt *dw_wdt;
u32 val;

- writel(0, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
- val = readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+ dw_wdt = container_of(this, struct dw_wdt, restart_handler);
+
+ writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+ val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);
if (val & WDOG_CONTROL_REG_WDT_EN_MASK)
- writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
- WDOG_COUNTER_RESTART_REG_OFFSET);
+ writel(WDOG_COUNTER_RESTART_KICK_VALUE,
+ dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET);
else
writel(WDOG_CONTROL_REG_WDT_EN_MASK,
- dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+ dw_wdt->regs + WDOG_CONTROL_REG_OFFSET);

/* wait for reset to assert... */
mdelay(500);
@@ -157,74 +154,12 @@ static int dw_wdt_restart_handle(struct notifier_block *this,
return NOTIFY_DONE;
}

-static void dw_wdt_ping(unsigned long data)
+static unsigned int dw_wdt_get_timeleft(struct watchdog_device *wdd)
{
- if (time_before(jiffies, dw_wdt.next_heartbeat) ||
- (!nowayout && !dw_wdt.in_use)) {
- dw_wdt_keepalive();
- mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
- } else
- pr_crit("keepalive missed, machine will reset\n");
-}
+ struct dw_wdt *dw_wdt = to_dw_wdt(wdd);

-static int dw_wdt_open(struct inode *inode, struct file *filp)
-{
- if (test_and_set_bit(0, &dw_wdt.in_use))
- return -EBUSY;
-
- /* Make sure we don't get unloaded. */
- __module_get(THIS_MODULE);
-
- if (!dw_wdt_is_enabled()) {
- /*
- * The watchdog is not currently enabled. Set the timeout to
- * something reasonable and then start it.
- */
- dw_wdt_set_top(DW_WDT_DEFAULT_SECONDS);
- writel(WDOG_CONTROL_REG_WDT_EN_MASK,
- dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
- }
-
- dw_wdt_set_next_heartbeat();
-
- return nonseekable_open(inode, filp);
-}
-
-static ssize_t dw_wdt_write(struct file *filp, const char __user *buf,
- size_t len, loff_t *offset)
-{
- if (!len)
- return 0;
-
- if (!nowayout) {
- size_t i;
-
- dw_wdt.expect_close = 0;
-
- for (i = 0; i < len; ++i) {
- char c;
-
- if (get_user(c, buf + i))
- return -EFAULT;
-
- if (c == 'V') {
- dw_wdt.expect_close = 1;
- break;
- }
- }
- }
-
- dw_wdt_set_next_heartbeat();
- dw_wdt_keepalive();
- mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
-
- return len;
-}
-
-static u32 dw_wdt_time_left(void)
-{
- return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
- clk_get_rate(dw_wdt.clk);
+ return readl(dw_wdt->regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
+ clk_get_rate(dw_wdt->clk);
}

static const struct watchdog_info dw_wdt_ident = {
@@ -233,78 +168,33 @@ static const struct watchdog_info dw_wdt_ident = {
.identity = "Synopsys DesignWare Watchdog",
};

-static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
-{
- unsigned long val;
- int timeout;
-
- switch (cmd) {
- case WDIOC_GETSUPPORT:
- return copy_to_user((void __user *)arg, &dw_wdt_ident,
- sizeof(dw_wdt_ident)) ? -EFAULT : 0;
-
- case WDIOC_GETSTATUS:
- case WDIOC_GETBOOTSTATUS:
- return put_user(0, (int __user *)arg);
-
- case WDIOC_KEEPALIVE:
- dw_wdt_set_next_heartbeat();
- return 0;
-
- case WDIOC_SETTIMEOUT:
- if (get_user(val, (int __user *)arg))
- return -EFAULT;
- timeout = dw_wdt_set_top(val);
- return put_user(timeout , (int __user *)arg);
-
- case WDIOC_GETTIMEOUT:
- return put_user(dw_wdt_get_top(), (int __user *)arg);
-
- case WDIOC_GETTIMELEFT:
- /* Get the time left until expiry. */
- if (get_user(val, (int __user *)arg))
- return -EFAULT;
- return put_user(dw_wdt_time_left(), (int __user *)arg);
-
- default:
- return -ENOTTY;
- }
-}
-
-static int dw_wdt_release(struct inode *inode, struct file *filp)
-{
- clear_bit(0, &dw_wdt.in_use);
-
- if (!dw_wdt.expect_close) {
- del_timer(&dw_wdt.timer);
-
- if (!nowayout)
- pr_crit("unexpected close, system will reboot soon\n");
- else
- pr_crit("watchdog cannot be disabled, system will reboot soon\n");
- }
-
- dw_wdt.expect_close = 0;
-
- return 0;
-}
+static const struct watchdog_ops dw_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = dw_wdt_start,
+ .ping = dw_wdt_ping,
+ .set_timeout = dw_wdt_set_timeout,
+ .get_timeleft = dw_wdt_get_timeleft,
+};

#ifdef CONFIG_PM_SLEEP
static int dw_wdt_suspend(struct device *dev)
{
- clk_disable_unprepare(dw_wdt.clk);
+ struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
+
+ clk_disable_unprepare(dw_wdt->clk);

return 0;
}

static int dw_wdt_resume(struct device *dev)
{
- int err = clk_prepare_enable(dw_wdt.clk);
+ struct dw_wdt *dw_wdt = dev_get_drvdata(dev);
+ int err = clk_prepare_enable(dw_wdt->clk);

if (err)
return err;

- dw_wdt_keepalive();
+ dw_wdt_ping(&dw_wdt->wdd);

return 0;
}
@@ -312,67 +202,81 @@ static int dw_wdt_resume(struct device *dev)

static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume);

-static const struct file_operations wdt_fops = {
- .owner = THIS_MODULE,
- .llseek = no_llseek,
- .open = dw_wdt_open,
- .write = dw_wdt_write,
- .unlocked_ioctl = dw_wdt_ioctl,
- .release = dw_wdt_release
-};
-
-static struct miscdevice dw_wdt_miscdev = {
- .fops = &wdt_fops,
- .name = "watchdog",
- .minor = WATCHDOG_MINOR,
-};
-
static int dw_wdt_drv_probe(struct platform_device *pdev)
{
+ struct device *dev = &pdev->dev;
+ struct watchdog_device *wdd;
+ struct dw_wdt *dw_wdt;
+ struct resource *mem;
int ret;
- struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

- dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem);
- if (IS_ERR(dw_wdt.regs))
- return PTR_ERR(dw_wdt.regs);
+ dw_wdt = devm_kzalloc(dev, sizeof(*dw_wdt), GFP_KERNEL);
+ if (!dw_wdt)
+ return -ENOMEM;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ dw_wdt->regs = devm_ioremap_resource(dev, mem);
+ if (IS_ERR(dw_wdt->regs))
+ return PTR_ERR(dw_wdt->regs);

- dw_wdt.clk = devm_clk_get(&pdev->dev, NULL);
- if (IS_ERR(dw_wdt.clk))
- return PTR_ERR(dw_wdt.clk);
+ dw_wdt->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(dw_wdt->clk))
+ return PTR_ERR(dw_wdt->clk);

- ret = clk_prepare_enable(dw_wdt.clk);
+ ret = clk_prepare_enable(dw_wdt->clk);
if (ret)
return ret;

- ret = misc_register(&dw_wdt_miscdev);
+ wdd = &dw_wdt->wdd;
+ wdd->info = &dw_wdt_ident;
+ wdd->ops = &dw_wdt_ops;
+ wdd->min_timeout = 1;
+ wdd->max_timeout = dw_wdt_top_in_seconds(dw_wdt, DW_WDT_MAX_TOP);
+ wdd->parent = dev;
+
+ watchdog_set_drvdata(wdd, dw_wdt);
+ watchdog_set_nowayout(wdd, nowayout);
+ watchdog_init_timeout(wdd, 0, dev);
+
+ /*
+ * If the watchdog is already running, use its already configured
+ * timeout. Otherwise use the default or the value provided through
+ * devicetree.
+ */
+ if (dw_wdt_is_enabled(dw_wdt)) {
+ wdd->timeout = dw_wdt_get_top(dw_wdt);
+ set_bit(WDOG_HW_RUNNING, &wdd->status);
+ } else {
+ wdd->timeout = DW_WDT_DEFAULT_SECONDS;
+ watchdog_init_timeout(wdd, 0, dev);
+ }
+
+ platform_set_drvdata(pdev, dw_wdt);
+
+ ret = watchdog_register_device(wdd);
if (ret)
goto out_disable_clk;

- dw_wdt.restart_handler.notifier_call = dw_wdt_restart_handle;
- dw_wdt.restart_handler.priority = 128;
- ret = register_restart_handler(&dw_wdt.restart_handler);
+ dw_wdt->restart_handler.notifier_call = dw_wdt_restart_handle;
+ dw_wdt->restart_handler.priority = 128;
+ ret = register_restart_handler(&dw_wdt->restart_handler);
if (ret)
pr_warn("cannot register restart handler\n");

- dw_wdt_set_next_heartbeat();
- setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
- mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
-
return 0;

out_disable_clk:
- clk_disable_unprepare(dw_wdt.clk);
-
+ clk_disable_unprepare(dw_wdt->clk);
return ret;
}

static int dw_wdt_drv_remove(struct platform_device *pdev)
{
- unregister_restart_handler(&dw_wdt.restart_handler);
-
- misc_deregister(&dw_wdt_miscdev);
+ struct dw_wdt *dw_wdt = platform_get_drvdata(pdev);

- clk_disable_unprepare(dw_wdt.clk);
+ unregister_restart_handler(&dw_wdt->restart_handler);
+ watchdog_unregister_device(&dw_wdt->wdd);
+ clk_disable_unprepare(dw_wdt->clk);

return 0;
}
--
2.1.4

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