[PATCHv6] watchdog: add support for the Synopsys DesignWare WDT
Jamie Iles
jamie at jamieiles.com
Mon Jan 24 07:19:12 EST 2011
The Synopsys DesignWare watchdog is found in several ARM based systems
and provides a choice of 16 timeout periods depending on the clock
input. The watchdog cannot be disabled once started.
Cc: Wim Van Sebroeck <wim at iguana.be>
Signed-off-by: Jamie Iles <jamie at jamieiles.com>
---
v6:
- add a Kconfig dependency on HAVE_CLK and don't allow rate to
be set by platform data.
v5:
- don't select CONFIG_WATCHDOG_NOWAYOUT, use a software
heartbeat to keep the wdt alive if we allow close.
v4:
- cleanups as suggested by Viresh Kumar and Wim
- provide a mechanism to handle NULL clks and allow
platform_data to specify the clk_rate
- provide open-once protection
v3:
- convert pm to dev_pm_ops
- use devres for resource allocation
v2:
- constify fops
- request_mem_region() before ioremap()
- disable clk if misc_register() fails
drivers/watchdog/Kconfig | 9 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/dw_wdt.c | 376 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 386 insertions(+), 0 deletions(-)
create mode 100644 drivers/watchdog/dw_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index cbd37bb..f707536 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -331,6 +331,15 @@ config IMX2_WDT
To compile this driver as a module, choose M here: the
module will be called imx2_wdt.
+config DW_WATCHDOG
+ tristate "Synopsys DesignWare watchdog"
+ depends on ARM && HAVE_CLK
+ help
+ Say Y here if to include support for the Synopsys DesignWare
+ watchdog timer found in many ARM chips.
+ To compile this driver as a module, choose M here: the
+ module will be called dw_wdt.
+
# AVR32 Architecture
config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index cd1e7fe..e2b5b10 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
obj-$(CONFIG_ADX_WATCHDOG) += adx_wdt.o
obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
+obj-$(CONFIG_DW_WATCHDOG) += dw_wdt.o
# AVR32 Architecture
obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
new file mode 100644
index 0000000..f10f8c0
--- /dev/null
+++ b/drivers/watchdog/dw_wdt.c
@@ -0,0 +1,376 @@
+/*
+ * Copyright 2010-2011 Picochip Ltd., Jamie Iles
+ * http://www.picochip.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This file implements a driver for the Synopsys DesignWare watchdog device
+ * in the many ARM 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) "dw_wdt: " fmt
+
+#include <linux/bitops.h>
+#include <linux/clk.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/pm.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+
+#define WDOG_CONTROL_REG_OFFSET 0x00
+#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
+#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
+#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
+#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
+#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
+
+/* The maximum TOP (timeout period) value that can be set in the watchdog. */
+#define DW_WDT_MAX_TOP 15
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+ "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#define WDT_TIMEOUT (HZ / 2)
+
+static struct {
+ spinlock_t lock;
+ void __iomem *regs;
+ struct clk *clk;
+ unsigned long in_use;
+ unsigned long next_heartbeat;
+ struct timer_list timer;
+ int expect_close;
+} dw_wdt;
+
+static inline int dw_wdt_is_enabled(void)
+{
+ 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)
+{
+ /*
+ * 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);
+}
+
+static int dw_wdt_get_top(void)
+{
+ int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
+
+ return dw_wdt_top_in_seconds(top);
+}
+
+static inline void dw_wdt_set_next_heartbeat(void)
+{
+ dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
+}
+
+static int dw_wdt_set_top(unsigned top_s)
+{
+ int i, top_val = DW_WDT_MAX_TOP;
+
+ /*
+ * Iterate over the timeout values until we find the closest match. We
+ * always look for >=.
+ */
+ for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
+ if (dw_wdt_top_in_seconds(i) >= top_s) {
+ top_val = i;
+ break;
+ }
+
+ /* Set the new value in the watchdog. */
+ writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
+
+ dw_wdt_set_next_heartbeat();
+
+ return dw_wdt_top_in_seconds(top_val);
+}
+
+static void dw_wdt_keepalive(void)
+{
+ writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
+ WDOG_COUNTER_RESTART_REG_OFFSET);
+}
+
+static void dw_wdt_ping(unsigned long data)
+{
+ 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");
+}
+
+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);
+
+ spin_lock(&dw_wdt.lock);
+ if (!dw_wdt_is_enabled()) {
+ /*
+ * The watchdog is not currently enabled. Set the timeout to
+ * the maximum and then start it.
+ */
+ dw_wdt_set_top(DW_WDT_MAX_TOP);
+ writel(WDOG_CONTROL_REG_WDT_EN_MASK,
+ dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
+ }
+
+ dw_wdt_set_next_heartbeat();
+
+ spin_unlock(&dw_wdt.lock);
+
+ return nonseekable_open(inode, filp);
+}
+
+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();
+ 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);
+}
+
+static const struct watchdog_info dw_wdt_ident = {
+ .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+ WDIOF_MAGICCLOSE,
+ .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((struct watchdog_info *)arg, &dw_wdt_ident,
+ sizeof(dw_wdt_ident)) ? -EFAULT : 0;
+
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(0, (int *)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;
+}
+
+#ifdef CONFIG_PM
+static int dw_wdt_suspend(struct device *dev)
+{
+ clk_disable(dw_wdt.clk);
+
+ return 0;
+}
+
+static int dw_wdt_resume(struct device *dev)
+{
+ int err = clk_enable(dw_wdt.clk);
+
+ if (err)
+ return err;
+
+ dw_wdt_keepalive();
+
+ return 0;
+}
+
+static const struct dev_pm_ops dw_wdt_pm_ops = {
+ .suspend = dw_wdt_suspend,
+ .resume = dw_wdt_resume,
+};
+#endif /* CONFIG_PM */
+
+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 __devinit dw_wdt_drv_probe(struct platform_device *pdev)
+{
+ int ret;
+ struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+ if (!mem)
+ return -EINVAL;
+
+ if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
+ "dw_wdt"))
+ return -ENOMEM;
+
+ dw_wdt.regs = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
+ if (!dw_wdt.regs)
+ return -ENOMEM;
+
+ dw_wdt.clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(dw_wdt.clk))
+ return PTR_ERR(dw_wdt.clk);
+
+ ret = clk_enable(dw_wdt.clk);
+ if (ret)
+ goto out_put_clk;
+
+ spin_lock_init(&dw_wdt.lock);
+
+ ret = misc_register(&dw_wdt_miscdev);
+ if (ret)
+ goto out_disable_clk;
+
+ 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(dw_wdt.clk);
+out_put_clk:
+ clk_put(dw_wdt.clk);
+
+ return ret;
+}
+
+static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
+{
+ misc_deregister(&dw_wdt_miscdev);
+
+ clk_disable(dw_wdt.clk);
+ clk_put(dw_wdt.clk);
+
+ return 0;
+}
+
+static struct platform_driver dw_wdt_driver = {
+ .probe = dw_wdt_drv_probe,
+ .remove = __devexit_p(dw_wdt_drv_remove),
+ .driver = {
+ .name = "dw_wdt",
+ .owner = THIS_MODULE,
+#ifdef CONFIG_PM
+ .pm = &dw_wdt_pm_ops,
+#endif /* CONFIG_PM */
+ },
+};
+
+static int __init dw_wdt_watchdog_init(void)
+{
+ return platform_driver_register(&dw_wdt_driver);
+}
+module_init(dw_wdt_watchdog_init);
+
+static void __exit dw_wdt_watchdog_exit(void)
+{
+ platform_driver_unregister(&dw_wdt_driver);
+}
+module_exit(dw_wdt_watchdog_exit);
+
+MODULE_AUTHOR("Jamie Iles");
+MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--
1.7.3.4
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