Re: [PATCHv6] watchdog: add support for the Synopsys DesignWare WDT

[viresh kumar <viresh.linux@xxxxxxxxx>]

On Mon, Jan 24, 2011 at 5:49 PM, Jamie Iles <jamie@xxxxxxxxxxxxx> 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. ÂThe watchdog cannot be disabled once started.
>
> Cc: Wim Van Sebroeck <wim@xxxxxxxxx>
> Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxxx>
> ---
>
> v6:
> Â Â Â Â- add a Kconfig dependency on HAVE_CLK and don't allow rate to
> Â Â Â Â Âbe set by platform data.
> v5:
> Â Â Â Â- don't select CONFIG_WATCHDOG_NOWAYOUT, use a software
> Â Â Â Â Âheartbeat to keep the wdt alive if we allow close.
> v4:
> Â Â Â Â- cleanups as suggested by Viresh Kumar and Wim
> Â Â Â Â- provide a mechanism to handle NULL clks and allow
> Â Â Â Â Âplatform_data to specify the clk_rate
> Â Â Â Â- provide open-once protection
>
> v3:
> Â Â Â Â- convert pm to dev_pm_ops
> Â Â Â Â- use devres for resource allocation
>
> v2:
> Â Â Â Â- constify fops
> Â Â Â Â- request_mem_region() before ioremap()
> Â Â Â Â- disable clk if misc_register() fails
>
> Âdrivers/watchdog/Kconfig Â| Â Â9 +
> Âdrivers/watchdog/Makefile | Â Â1 +
> Âdrivers/watchdog/dw_wdt.c | Â376 +++++++++++++++++++++++++++++++++++++++++++++
> Â3 files changed, 386 insertions(+), 0 deletions(-)
> Âcreate 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
> Â Â Â Â ÂTo compile this driver as a module, choose M here: the
> Â Â Â Â Âmodule will be called imx2_wdt.
>
> +config DW_WATCHDOG
> + Â Â Â tristate "Synopsys DesignWare watchdog"
> + Â Â Â depends on ARM && HAVE_CLK
> + Â Â Â help
> + Â Â Â Â Say Y here if to include support for the Synopsys DesignWare
> + Â Â Â Â watchdog timer found in many ARM chips.
> + Â Â Â Â To compile this driver as a module, choose M here: the
> + Â Â Â Â module will be called dw_wdt.
> +
> Â# AVR32 Architecture
>
> Âconfig 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-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
> Âobj-$(CONFIG_ADX_WATCHDOG) += adx_wdt.o
> Âobj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
> Âobj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
> +obj-$(CONFIG_DW_WATCHDOG) += dw_wdt.o
>
> Â# AVR32 Architecture
> Âobj-$(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 Â Â Â Â Â Â Â Â Â Â0x00
> +#define WDOG_CONTROL_REG_WDT_EN_MASK Â Â Â 0x01
> +#define WDOG_TIMEOUT_RANGE_REG_OFFSET Â Â Â0x04
> +#define WDOG_CURRENT_COUNT_REG_OFFSET Â Â Â0x08
> +#define WDOG_COUNTER_RESTART_REG_OFFSET Â Â 0x0c
> +#define WDOG_COUNTER_RESTART_KICK_VALUE Â Â Â Â Â Â0x76
> +
> +/* The maximum TOP (timeout period) value that can be set in the watchdog. */
> +#define DW_WDT_MAX_TOP Â Â Â Â 15
> +
> +static int nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, int, 0);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
> + Â Â Â Â Â Â Â Â"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +#define WDT_TIMEOUT Â Â Â Â Â Â(HZ / 2)
> +
> +static struct {
> +    spinlock_t       Âlock;
> +    void __iomem      Â*regs;
> +    struct clk       Â*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)
> +{
> + Â Â Â return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
> + Â Â Â Â Â Â Â WDOG_CONTROL_REG_WDT_EN_MASK;
> +}
> +
> +static inline int dw_wdt_top_in_seconds(unsigned top)
> +{
> + Â Â Â /*
> + Â Â Â Â* There are 16 possible timeout values in 0..15 where the number of
> + Â Â Â Â* cycles is 2 ^ (16 + i) and the watchdog counts down.
> + Â Â Â Â*/
> + Â Â Â return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
> +}
> +
> +static int dw_wdt_get_top(void)
> +{
> + Â Â Â int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
> +
> + Â Â Â return dw_wdt_top_in_seconds(top);
> +}
> +
> +static inline void dw_wdt_set_next_heartbeat(void)
> +{
> + Â Â Â dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
> +}
> +
> +static int dw_wdt_set_top(unsigned top_s)
> +{
> + Â Â Â int i, top_val = DW_WDT_MAX_TOP;
> +
> + Â Â Â /*
> + Â Â Â Â* Iterate over the timeout values until we find the closest match. We
> + Â Â Â Â* always look for >=.
> + Â Â Â Â*/
> + Â Â Â for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
> + Â Â Â Â Â Â Â if (dw_wdt_top_in_seconds(i) >= top_s) {
> + Â Â Â Â Â Â Â Â Â Â Â top_val = i;
> + Â Â Â Â Â Â Â Â Â Â Â break;
> + Â Â Â Â Â Â Â }
> +
> + Â Â Â /* Set the new value in the watchdog. */
> + Â Â Â writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
> +
> + Â Â Â dw_wdt_set_next_heartbeat();
> +
> + Â Â Â return dw_wdt_top_in_seconds(top_val);
> +}
> +
> +static void dw_wdt_keepalive(void)
> +{
> + Â Â Â writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
> + Â Â Â Â Â Â ÂWDOG_COUNTER_RESTART_REG_OFFSET);
> +}
> +
> +static void dw_wdt_ping(unsigned long data)
> +{
> + Â Â Â if (time_before(jiffies, dw_wdt.next_heartbeat) ||
> + Â Â Â Â Â (!nowayout && !dw_wdt.in_use)) {
> + Â Â Â Â Â Â Â dw_wdt_keepalive();
> + Â Â Â Â Â Â Â mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> + Â Â Â } else
> + Â Â Â Â Â Â Â pr_crit("keepalive missed, machine will reset\n");
> +}
> +
> +static int dw_wdt_open(struct inode *inode, struct file *filp)
> +{
> + Â Â Â if (test_and_set_bit(0, &dw_wdt.in_use))
> + Â Â Â Â Â Â Â return -EBUSY;
> +
> + Â Â Â /* Make sure we don't get unloaded. */
> + Â Â Â __module_get(THIS_MODULE);
> +
> + Â Â Â spin_lock(&dw_wdt.lock);
> + Â Â Â if (!dw_wdt_is_enabled()) {
> + Â Â Â Â Â Â Â /*
> + Â Â Â Â Â Â Â Â* The watchdog is not currently enabled. Set the timeout to
> + Â Â Â Â Â Â Â Â* the maximum and then start it.
> + Â Â Â Â Â Â Â Â*/
> + Â Â Â Â Â Â Â dw_wdt_set_top(DW_WDT_MAX_TOP);
> + Â Â Â Â Â Â Â writel(WDOG_CONTROL_REG_WDT_EN_MASK,
> + Â Â Â Â Â Â Â Â Â Â Âdw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
> + Â Â Â }
> +
> + Â Â Â dw_wdt_set_next_heartbeat();
> +
> + Â Â Â spin_unlock(&dw_wdt.lock);
> +
> + Â Â Â return nonseekable_open(inode, filp);
> +}
> +
> +ssize_t dw_wdt_write(struct file *filp, const char __user *buf, size_t len,
> + Â Â Â Â Â Â Â Â Â Âloff_t *offset)
> +{
> + Â Â Â if (!len)
> + Â Â Â Â Â Â Â return 0;
> +
> + Â Â Â if (!nowayout) {
> + Â Â Â Â Â Â Â size_t i;
> +
> + Â Â Â Â Â Â Â dw_wdt.expect_close = 0;
> +
> + Â Â Â Â Â Â Â for (i = 0; i < len; ++i) {
> + Â Â Â Â Â Â Â Â Â Â Â char c;
> +
> + Â Â Â Â Â Â Â Â Â Â Â if (get_user(c, buf + i))
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â return -EFAULT;
> +
> + Â Â Â Â Â Â Â Â Â Â Â if (c == 'V') {
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â dw_wdt.expect_close = 1;
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â break;
> + Â Â Â Â Â Â Â Â Â Â Â }
> + Â Â Â Â Â Â Â }
> + Â Â Â }
> +
> + Â Â Â dw_wdt_set_next_heartbeat();
> + Â Â Â mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> +
> + Â Â Â return len;
> +}
> +
> +static u32 dw_wdt_time_left(void)
> +{
> + Â Â Â return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
> + Â Â Â Â Â Â Â clk_get_rate(dw_wdt.clk);
> +}
> +
> +static const struct watchdog_info dw_wdt_ident = {
> +    .options    Â= WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
> + Â Â Â Â Â Â Â Â Â Â Â Â WDIOF_MAGICCLOSE,
> +    .identity    = "Synopsys DesignWare Watchdog",
> +};
> +
> +static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> +{
> + Â Â Â unsigned long val;
> + Â Â Â int timeout;
> +
> + Â Â Â switch (cmd) {
> + Â Â Â case WDIOC_GETSUPPORT:
> + Â Â Â Â Â Â Â return copy_to_user((struct watchdog_info *)arg, &dw_wdt_ident,
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â sizeof(dw_wdt_ident)) ? -EFAULT : 0;
> +
> + Â Â Â case WDIOC_GETSTATUS:
> + Â Â Â case WDIOC_GETBOOTSTATUS:
> + Â Â Â Â Â Â Â return put_user(0, (int *)arg);
> +
> + Â Â Â case WDIOC_KEEPALIVE:
> + Â Â Â Â Â Â Â dw_wdt_set_next_heartbeat();
> + Â Â Â Â Â Â Â return 0;
> +
> + Â Â Â case WDIOC_SETTIMEOUT:
> + Â Â Â Â Â Â Â if (get_user(val, (int __user *)arg))
> + Â Â Â Â Â Â Â Â Â Â Â return -EFAULT;
> + Â Â Â Â Â Â Â timeout = dw_wdt_set_top(val);
> + Â Â Â Â Â Â Â return put_user(timeout , (int __user *)arg);
> +
> + Â Â Â case WDIOC_GETTIMEOUT:
> + Â Â Â Â Â Â Â return put_user(dw_wdt_get_top(), (int __user *)arg);
> +
> + Â Â Â case WDIOC_GETTIMELEFT:
> + Â Â Â Â Â Â Â /* Get the time left until expiry. */
> + Â Â Â Â Â Â Â if (get_user(val, (int __user *)arg))
> + Â Â Â Â Â Â Â Â Â Â Â return -EFAULT;
> + Â Â Â Â Â Â Â return put_user(dw_wdt_time_left(), (int __user *)arg);
> +
> + Â Â Â default:
> + Â Â Â Â Â Â Â return -ENOTTY;
> + Â Â Â }
> +}
> +
> +static int dw_wdt_release(struct inode *inode, struct file *filp)
> +{
> + Â Â Â clear_bit(0, &dw_wdt.in_use);
> +
> + Â Â Â if (!dw_wdt.expect_close) {
> + Â Â Â Â Â Â Â del_timer(&dw_wdt.timer);
> +
> + Â Â Â Â Â Â Â if (!nowayout)
> + Â Â Â Â Â Â Â Â Â Â Â pr_crit("unexpected close, system will reboot soon\n");
> + Â Â Â Â Â Â Â else
> + Â Â Â Â Â Â Â Â Â Â Â pr_crit("watchdog cannot be disabled, system will reboot soon\n");
> + Â Â Â }
> +
> + Â Â Â dw_wdt.expect_close = 0;
> +
> + Â Â Â return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int dw_wdt_suspend(struct device *dev)
> +{
> + Â Â Â clk_disable(dw_wdt.clk);
> +
> + Â Â Â return 0;
> +}
> +
> +static int dw_wdt_resume(struct device *dev)
> +{
> + Â Â Â int err = clk_enable(dw_wdt.clk);
> +
> + Â Â Â if (err)
> + Â Â Â Â Â Â Â return err;
> +
> + Â Â Â dw_wdt_keepalive();
> +
> + Â Â Â return 0;
> +}
> +
> +static const struct dev_pm_ops dw_wdt_pm_ops = {
> +    .suspend    Â= dw_wdt_suspend,
> +    .resume     = dw_wdt_resume,
> +};
> +#endif /* CONFIG_PM */
> +
> +static const struct file_operations wdt_fops = {
> +    .owner     Â= THIS_MODULE,
> +    .llseek     = no_llseek,
> +    .open      = dw_wdt_open,
> +    .write     Â= dw_wdt_write,
> + Â Â Â .unlocked_ioctl = dw_wdt_ioctl,
> +    .release    Â= dw_wdt_release
> +};
> +
> +static struct miscdevice dw_wdt_miscdev = {
> +    .fops      = &wdt_fops,
> +    .name      = "watchdog",
> +    .minor     Â= WATCHDOG_MINOR,
> +};
> +
> +static int __devinit dw_wdt_drv_probe(struct platform_device *pdev)
> +{
> + Â Â Â int ret;
> + Â Â Â struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> + Â Â Â if (!mem)
> + Â Â Â Â Â Â Â return -EINVAL;
> +
> + Â Â Â if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
> + Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â"dw_wdt"))
> + Â Â Â Â Â Â Â return -ENOMEM;
> +
> + Â Â Â dw_wdt.regs = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
> + Â Â Â if (!dw_wdt.regs)
> + Â Â Â Â Â Â Â return -ENOMEM;
> +
> + Â Â Â dw_wdt.clk = clk_get(&pdev->dev, NULL);
> + Â Â Â if (IS_ERR(dw_wdt.clk))
> + Â Â Â Â Â Â Â return PTR_ERR(dw_wdt.clk);
> +
> + Â Â Â ret = clk_enable(dw_wdt.clk);
> + Â Â Â if (ret)
> + Â Â Â Â Â Â Â goto out_put_clk;
> +
> + Â Â Â spin_lock_init(&dw_wdt.lock);
> +
> + Â Â Â ret = misc_register(&dw_wdt_miscdev);
> + Â Â Â if (ret)
> + Â Â Â Â Â Â Â goto out_disable_clk;
> +
> + Â Â Â dw_wdt_set_next_heartbeat();
> + Â Â Â setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
> + Â Â Â mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
> +
> + Â Â Â return 0;
> +
> +out_disable_clk:
> + Â Â Â clk_disable(dw_wdt.clk);
> +out_put_clk:
> + Â Â Â clk_put(dw_wdt.clk);
> +
> + Â Â Â return ret;
> +}
> +
> +static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
> +{
> + Â Â Â misc_deregister(&dw_wdt_miscdev);
> +
> + Â Â Â clk_disable(dw_wdt.clk);
> + Â Â Â clk_put(dw_wdt.clk);
> +
> + Â Â Â return 0;
> +}
> +
> +static struct platform_driver dw_wdt_driver = {
> +    .probe     Â= dw_wdt_drv_probe,
> +    .remove     = __devexit_p(dw_wdt_drv_remove),
> +    .driver     = {
> +        .name  = "dw_wdt",
> + Â Â Â Â Â Â Â .owner Â= THIS_MODULE,
> +#ifdef CONFIG_PM
> +        .pm   = &dw_wdt_pm_ops,
> +#endif /* CONFIG_PM */
> + Â Â Â },
> +};
> +
> +static int __init dw_wdt_watchdog_init(void)
> +{
> + Â Â Â return platform_driver_register(&dw_wdt_driver);
> +}
> +module_init(dw_wdt_watchdog_init);
> +
> +static void __exit dw_wdt_watchdog_exit(void)
> +{
> + Â Â Â 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@xxxxxx>
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