[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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