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Message-ID: <AANLkTi=QiCgoswixhUEseK9+-=S0R_sZLA-AefmcC9=T@mail.gmail.com>
Date: Wed, 9 Feb 2011 08:56:48 +0100
From: Belisko Marek <marek.belisko@...il.com>
To: Tobias Klauser <tklauser@...tanz.ch>
Cc: Wim Van Sebroeck <wim@...ana.be>, linux-watchdog@...r.kernel.org,
Grant Likely <grant.likely@...retlab.ca>,
Jamie Iles <jamie@...ieiles.com>,
Walter Goossens <waltergoossens@...e.nl>,
devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
nios2-dev@...c.et.ntust.edu.tw
Subject: Re: [PATCH v3] watchdog: Add driver for Altera Watchdog Timer
On Wed, Feb 9, 2011 at 8:19 AM, Tobias Klauser <tklauser@...tanz.ch> wrote:
> This driver adds support for the Altera Timer in the Watchdog Timer
> configuration. This component is usually found on SOPC (System on
> Programmable Chip) for Altera FPGAs.
>
> Signed-off-by: Tobias Klauser <tklauser@...tanz.ch>
> Reviewed-by: Jamie Iles <jamie@...ieiles.com>
> ---
> Thanks a lot to Jamie Iles and Walter Goossens for their feedback on v2.
>
> changes for v3:
> - Make altera_wdt_setup static void (as suggested by Jamie)
> - Use const __be32 * for devicetree properties (as suggested by Walter)
> changes for v2:
> - Get driver properties from devicetree (and document them), thus the
> driver depends on OF
> - Do not select WATCHDOG_NOWAYOUT, but instead implement a software
> timer resetting the watchdog timer when the device is not open
> - Only support a single instance of the watchdog, so the private data
> can be kept in static data
> - Use devm_* functions in altera_wdt_probe to simplify cleanup and
> error handling
> - Remove empty altera_wdt_shutdown function
> - Add MODULE_LICENSE (GPL)
>
>
> .../devicetree/bindings/watchdog/altera_wdt.txt | 7 +
> drivers/watchdog/Kconfig | 8 +
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/altera_wdt.c | 309 ++++++++++++++++++++
> 4 files changed, 325 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/watchdog/altera_wdt.txt
> create mode 100644 drivers/watchdog/altera_wdt.c
>
> diff --git a/Documentation/devicetree/bindings/watchdog/altera_wdt.txt b/Documentation/devicetree/bindings/watchdog/altera_wdt.txt
> new file mode 100644
> index 0000000..16ac949
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/altera_wdt.txt
> @@ -0,0 +1,7 @@
> +Altera Watchdog Timer
> +
> +Required properties:
> +- compatible : should be "ALTR,wdt-1.0"
> +- clock-frequency : frequency of the clock input
> +- timeout : load value of the timer (number of clock ticks until watchdog
> + resets)
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index bd6a33d..ebcafb0 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -69,6 +69,14 @@ config WM8350_WATCHDOG
> Support for the watchdog in the WM8350 AudioPlus PMIC. When
> the watchdog triggers the system will be reset.
>
> +config ALTERA_WDT
> + tristate "Altera Watchdog Timer"
> + depends on OF
> + help
> + Support for the Altera Timer in the Watchdog Timer configuration. This
> + component is found on SOPC (System on Programmable Chip) for Altera
> + FPGAs.
> +
> # ALPHA Architecture
>
> # ARM Architecture
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index fd9c8c0..48a2167 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -153,4 +153,5 @@ obj-$(CONFIG_WATCHDOG_CP1XXX) += cpwd.o
> obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
> obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
> obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
> +obj-$(CONFIG_ALTERA_WDT) += altera_wdt.o
> obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
> diff --git a/drivers/watchdog/altera_wdt.c b/drivers/watchdog/altera_wdt.c
> new file mode 100644
> index 0000000..2a7f14a
> --- /dev/null
> +++ b/drivers/watchdog/altera_wdt.c
> @@ -0,0 +1,309 @@
> +/*
> + * Driver for the Altera Watchdog Timer
> + *
> + * Copyright (C) 2011 Tobias Klauser <tklauser@...tanz.ch>
> + * Copyright (C) 2005 Walter Goossens
> + *
> + * Originally based on wdt.c which is
> + *
> + * Copyright (C) 1995-1997 Alan Cox <alan@...rguk.ukuu.org.uk>
> + *
> + * Software timeout heartbeat code based on pika_wdt.c which is
> + *
> + * Copyright (c) 2008 PIKA Technologies
> + *
> + * 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.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/miscdevice.h>
> +#include <linux/watchdog.h>
> +#include <linux/platform_device.h>
> +#include <linux/fs.h>
> +#include <linux/init.h>
> +#include <linux/jiffies.h>
> +#include <linux/timer.h>
> +#include <linux/io.h>
> +#include <linux/uaccess.h>
> +#include <linux/of_platform.h>
> +
> +#define WATCHDOG_NAME "altera_wdt"
> +
> +/* Register offsets */
> +#define ALTERA_WDT_STATUS 0x00
> +#define ALTERA_WDT_CONTROL 0x04
> +#define ALTERA_WDT_PERIODL 0x08
> +#define ALTERA_WDT_PERIODH 0x0C
> +
> +#define ALTERA_WDT_RUN_BIT 0x04
> +
> +/* User land timeout */
> +#define WDT_HEARTBEAT 15
> +static int heartbeat = WDT_HEARTBEAT;
> +module_param(heartbeat, int, 0);
> +MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
> + "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
> +
> +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) ")");
> +
> +static struct {
> + void __iomem *base;
> + unsigned long wdt_timeout; /* timeout of the hardware timer */
> +
> + unsigned long next_heartbeat; /* the next_heartbeat for the timer */
> + unsigned long is_open;
> + char expect_close;
> + struct timer_list timer; /* software timer that pings the watchdog */
> +} altera_wdt_priv;
> +
> +/*
> + * Start the watchdog. Once it has been started, it cannot be stopped anymore.
> + */
> +static void altera_wdt_setup(void)
> +{
> + u32 control = readl(altera_wdt_priv.base + ALTERA_WDT_CONTROL);
> +
> + writel(control | ALTERA_WDT_RUN_BIT, altera_wdt_priv.base + ALTERA_WDT_CONTROL);
> +}
> +
> +/*
> + * Tickle the watchdog (reset the watchdog timer)
> + */
> +static void altera_wdt_reset(void)
> +{
> + /* It doesn't matter what value we write */
> + writel(1, altera_wdt_priv.base + ALTERA_WDT_PERIODL);
> +}
> +
> +/*
> + * Software timer tick
> + */
> +static void altera_wdt_ping(unsigned long data)
> +{
> + if (time_before(jiffies, altera_wdt_priv.next_heartbeat) ||
> + (!nowayout && !altera_wdt_priv.is_open)) {
> + altera_wdt_reset();
> + mod_timer(&altera_wdt_priv.timer, jiffies + altera_wdt_priv.wdt_timeout);
> + } else
> + pr_crit(WATCHDOG_NAME ": I will reset your machine!\n");
> +}
> +
> +static void altera_wdt_keepalive(void)
> +{
> + altera_wdt_priv.next_heartbeat = jiffies + heartbeat * HZ;
> +}
> +
> +static void altera_wdt_start(void)
> +{
> + altera_wdt_keepalive();
> + mod_timer(&altera_wdt_priv.timer, jiffies + altera_wdt_priv.wdt_timeout);
> +}
> +
> +static int altera_wdt_open(struct inode *inode, struct file *file)
> +{
> + /* /dev/watchdog can only be opened once */
> + if (test_and_set_bit(0, &altera_wdt_priv.is_open))
> + return -EBUSY;
> +
> + altera_wdt_start();
> +
> + return nonseekable_open(inode, file);
> +}
> +
> +static int altera_wdt_release(struct inode *inode, struct file *file)
> +{
> + /* stop internal ping */
> + if (!altera_wdt_priv.expect_close)
> + del_timer(&altera_wdt_priv.timer);
> +
> + clear_bit(0, &altera_wdt_priv.is_open);
> + altera_wdt_priv.expect_close = 0;
> +
> + return 0;
> +}
> +
> +static ssize_t altera_wdt_write(struct file *file, const char __user *data,
> + size_t len, loff_t *ppos)
> +{
> + if (!len)
> + return 0;
> +
> + /* Scan for magic character */
> + if (!nowayout) {
> + size_t i;
> +
> + altera_wdt_priv.expect_close = 0;
> +
> + for (i = 0; i < len; i++) {
> + char c;
> + if (get_user(c, data + i))
> + return -EFAULT;
> + if (c == 'V') {
> + altera_wdt_priv.expect_close = 42;
For what this value is used? Why 42? It's never checked in code to such a value.
> + break;
> + }
> + }
> + }
> +
> + altera_wdt_keepalive();
> +
> + return len;
> +}
> +
> +static const struct watchdog_info altera_wdt_info = {
> + .identity = "Altera Watchdog",
> + .options = WDIOF_SETTIMEOUT |
> + WDIOF_KEEPALIVEPING |
> + WDIOF_MAGICCLOSE,
> + .firmware_version = 1,
> +};
> +
> +static long altera_wdt_ioctl(struct file *file, unsigned int cmd,
> + unsigned long arg)
> +{
> + void __user *argp = (void __user *) arg;
> + int __user *p = argp;
> + int new_value;
> +
> + switch (cmd) {
> + case WDIOC_GETSUPPORT:
> + return copy_to_user(argp, &altera_wdt_info, sizeof(altera_wdt_info));
> +
> + case WDIOC_GETSTATUS:
> + case WDIOC_GETBOOTSTATUS:
> + return put_user(0, p);
> +
> + case WDIOC_KEEPALIVE:
> + altera_wdt_keepalive();
> + return 0;
> +
> + case WDIOC_SETTIMEOUT:
> + if (get_user(new_value, p))
> + return -EFAULT;
> +
> + heartbeat = new_value;
> + altera_wdt_keepalive();
> +
> + return put_user(new_value, p); /* return current value */
> +
> + case WDIOC_GETTIMEOUT:
> + return put_user(heartbeat, p);
> +
> + default:
> + return -ENOTTY;
> + }
> +}
> +
> +static const struct file_operations altera_wdt_fops = {
> + .owner = THIS_MODULE,
> + .llseek = no_llseek,
> + .open = altera_wdt_open,
> + .release = altera_wdt_release,
> + .write = altera_wdt_write,
> + .unlocked_ioctl = altera_wdt_ioctl,
> +};
> +
> +static struct miscdevice altera_wdt_miscdev = {
> + .minor = WATCHDOG_MINOR,
> + .name = "watchdog",
> + .fops = &altera_wdt_fops,
> +};
> +
> +static int __devinit altera_wdt_probe(struct platform_device *pdev)
> +{
> + struct resource *res, *mem;
> + const __be32 *freq_prop, *timeout_prop;
> + unsigned long timeout;
> + int ret;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -ENOENT;
> +
> + mem = devm_request_mem_region(&pdev->dev, res->start,
> + resource_size(res), pdev->name);
> + if (!mem)
> + return -EBUSY;
> +
> + altera_wdt_priv.base = devm_ioremap_nocache(&pdev->dev, mem->start,
> + resource_size(mem));
> + if (!altera_wdt_priv.base)
> + return -ENOMEM;
> +
> + freq_prop = of_get_property(pdev->dev.of_node, "clock-frequency", NULL);
> + if (!freq_prop)
> + return -ENODEV;
> +
> + timeout_prop = of_get_property(pdev->dev.of_node, "timeout", NULL);
> + if (!timeout_prop)
> + return -ENODEV;
> +
> + /* Add 1 as the timeout property actually holds the load value */
> + timeout = be32_to_cpup(timeout_prop) + 1;
> + /* Convert timeout to msecs */
> + timeout = timeout / (be32_to_cpup(freq_prop) / MSEC_PER_SEC);
> + /* Tickle the watchdog twice per timeout period */
> + altera_wdt_priv.wdt_timeout = msecs_to_jiffies(timeout / 2);
> +
> + ret = misc_register(&altera_wdt_miscdev);
> + if (ret)
> + return ret;
> +
> + altera_wdt_setup();
> + altera_wdt_priv.next_heartbeat = jiffies + heartbeat * HZ;
> + setup_timer(&altera_wdt_priv.timer, altera_wdt_ping, 0);
> + mod_timer(&altera_wdt_priv.timer, jiffies + altera_wdt_priv.wdt_timeout);
> +
> + pr_info(WATCHDOG_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n",
> + heartbeat, nowayout);
> +
> + return 0;
> +}
> +
> +static int __devexit altera_wdt_remove(struct platform_device *pdev)
> +{
> + misc_deregister(&altera_wdt_miscdev);
> + return 0;
> +}
> +
> +static struct of_device_id altera_wdt_match[] = {
> + { .compatible = "altr,wdt-1.0", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, altera_wdt_match);
> +
> +static struct platform_driver altera_wdt_driver = {
> + .probe = altera_wdt_probe,
> + .remove = __devexit_p(altera_wdt_remove),
> + .driver = {
> + .owner = THIS_MODULE,
> + .name = WATCHDOG_NAME,
> + .of_match_table = altera_wdt_match,
> + },
> +};
> +
> +static int __init altera_wdt_init(void)
> +{
> + return platform_driver_register(&altera_wdt_driver);
> +}
> +
> +static void __exit altera_wdt_exit(void)
> +{
> + platform_driver_unregister(&altera_wdt_driver);
> +}
> +
> +module_init(altera_wdt_init);
> +module_exit(altera_wdt_exit);
> +
> +MODULE_AUTHOR("Walter Goossens, Tobias Klauser <tklauser@...tanz.ch>");
> +MODULE_DESCRIPTION("Driver for Altera Watchdog Timer");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
> +MODULE_ALIAS("platform:" WATCHDOG_NAME);
> --
> 1.7.0.4
>
> --
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thanks,
marek
--
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