[PATCHv6] watchdog: add support for the Synopsys DesignWare WDT
viresh kumar
viresh.linux at gmail.com
Fri Feb 11 05:50:39 EST 2011
On Mon, Jan 24, 2011 at 5:49 PM, Jamie Iles <jamie at jamieiles.com> wrote:
> 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);
Sorry for being late!!!
Acked-by: Viresh Kumar <viresh.kumar at st.com>
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