[PATCH 1/6] Driver for the watchdog timer on Freescale IMX2 (and later) processors.
Wolfram Sang
w.sang at pengutronix.de
Tue May 25 05:18:40 EDT 2010
Hi Wim,
thanks for the review!
On Fri, May 21, 2010 at 11:52:11PM +0200, Wim Van Sebroeck wrote:
> Hi Wolfram,
>
> > Ping. Wim, did you notice this one? Shall the driver go via your tree or via
> > the imx-tree along with the resource updates (with your ack)?
>
> I was not to happy with how the close of /dev/watchdog was being done.
> So I modified your code so that
> * the close is better supported.
> * the code is ready for when we change to the generic watchdog api.
Cool, any concrete plans for this happening?
> * the magic close feature is supported.
OK, I left it out intentionally, as I expected it to come for free with the new
api at a later stage:)
>
> I didn't compile test the code. Could you have a look at it? compile it and test it?
Will do. Some initial comments. (An incremental patch might have been easier to
check)
> Goal is to get this in during this merge window still...
The new driver-rule should apply here, no?
>
> Kind regards,
> Wim.
>
> /*
> * Watchdog driver for IMX2 and later processors
> *
> * Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <w.sang at pengutronix.de>
> *
> * some parts adapted by similar drivers from Darius Augulis and Vladimir
> * Zapolskiy.
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms of the GNU General Public License version 2 as published by
> * the Free Software Foundation.
> *
> * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
> *
> * MX1: MX2+:
> * ---- -----
> * Registers: 32-bit 16-bit
> * Stopable timer: Yes No
> * Need to enable clk: No Yes
> * Halt on suspend: Manual Can be automatic
> */
>
> #include <linux/init.h>
> #include <linux/kernel.h>
> #include <linux/miscdevice.h>
> #include <linux/module.h>
> #include <linux/moduleparam.h>
> #include <linux/platform_device.h>
> #include <linux/watchdog.h>
> #include <linux/clk.h>
> #include <linux/fs.h>
> #include <linux/io.h>
> #include <linux/uaccess.h>
> #include <linux/timer.h>
> #include <linux/jiffies.h>
> #include <mach/hardware.h>
>
> #define DRIVER_NAME "imx2-wdt"
>
> #define IMX2_WDT_WCR 0x00 /* Control Register */
> #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
> #define IMX2_WDT_WCR_WDA (1 << 5) /* -> !Watchdog Assertion */
> #define IMX2_WDT_WCR_SRS (1 << 4) /* -> !Software Reset Signal */
> #define IMX2_WDT_WCR_WRE (1 << 3) /* -> WDOG Reset Enable */
> #define IMX2_WDT_WCR_WDE (1 << 2) /* -> Watchdog Enable */
> #define IMX2_WDT_WCR_WDBG (1 << 1) /* -> Watchdog Debug Enable */
> #define IMX2_WDT_WCR_WDZST (1 << 0) /* -> Watchdog Low Power */
>
> #define IMX2_WDT_WSR 0x02 /* Service Register */
> #define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */
> #define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */
>
> #define IMX2_WDT_WRSR 0x04 /* Reset Status Register */
> #define IMX2_WDT_WRSR_PWR (1 << 4) /* -> Power-On Reset */
> #define IMX2_WDT_WRSR_EXT (1 << 3) /* -> External Reset */
> #define IMX2_WDT_WRSR_TOUT (1 << 1) /* -> WDOG Time-Out Reset */
> #define IMX2_WDT_WRSR_SFTW (1 << 0) /* -> Software Reset */
>
> #define IMX2_WDT_MAX_TIME 128
> #define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */
>
> #define WDOG_SEC_TO_COUNT(s) ((s * 2) << 8)
Any reason you dropped the '- 1' from my version here?
>
> #define IMX2_WDT_STATUS_OPEN 0
> #define IMX2_WDT_STATUS_STARTED 1
> #define IMX2_WDT_EXPECT_CLOSE 2
>
> /* Apply nand and or masks to data read from addr and write back
> * we nand first so that we can erase the timeout before setting the new one */
> #define IMX2_WDT_CHG_BITS(addr, nand, or) \
> __raw_writew((__raw_readw(addr) & ~nand) | or, addr)
I don't like such a macro very much, but well...
>
>
> static struct {
> struct clk *clk;
> void __iomem *base;
> unsigned timeout;
> unsigned long status;
> struct timer_list timer; /* Pings the watchdog when closed */
> } imx2_wdt;
>
> static struct miscdevice imx2_wdt_miscdev;
>
> 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 unsigned timeout = IMX2_WDT_DEFAULT_TIME;
> module_param(timeout, uint, 0);
> MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
> __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
>
> static const struct watchdog_info imx2_wdt_info = {
> .identity = "imx2+ watchdog",
> .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
> };
>
> static inline void imx2_wdt_init(void)
> {
> unsigned int bits_off;
> unsigned int bits_on;
>
> /* Strip the old watchdog Time-Out value */
> bits_off = IMX2_WDT_WCR_WT;
> /* Generate reset if WDOG times out */
> bits_off |= IMX2_WDT_WCR_WRE;
> /* Keep Watchdog Disabled */
> bits_off |= IMX2_WDT_WCR_WDE;
> /* Continue timer operation during DEBUG mode */
> bits_off |= IMX2_WDT_WCR_WDBG;
> /* Continue Watchdog Timer during Low Power modes */
> bits_off |= IMX2_WDT_WCR_WDZST;
>
> /* Set the watchdog's Time-Out value */
> bits_on = WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
> /* Don't set Watchdog Assertion */
> bits_on |= IMX2_WDT_WCR_WDA;
> /* Don't set Software Reset Signal */
> bits_on |= IMX2_WDT_WCR_SRS;
This is too excessive IMO. The bootloader might already have setup the watchdog
according to the board.
>
> IMX2_WDT_CHG_BITS(imx2_wdt.base + IMX2_WDT_WCR, bits_off, bits_on);
> }
>
> static inline void imx2_wdt_enable(void)
> {
> IMX2_WDT_CHG_BITS(imx2_wdt.base + IMX2_WDT_WCR, 0, IMX2_WDT_WCR_WDE);
> }
I assume this is for the easy migration to the generic watchdog API? Otherwise
I see little use for a seperate function.
>
> static inline void imx2_wdt_ping(void)
> {
> /* When enabled, the Watchdog requires that a service sequence be
> * written to the Watchdog Service Register (WSR) */
IMHO this is maybe over-commenting :)
> __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
> __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
> }
>
> static void imx2_wdt_timer_ping(void)
> {
> /* ping it every imx2_wdt.timeout / 2 seconds to prevent reboot */
> imx2_wdt_ping();
> mod_timer(&imx2_wdt.timer, jiffies + imx2_wdt.timeout * HZ / 2);
> }
>
> static void imx2_wdt_start(void)
> {
> if (!test_and_set_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
> /* at our first start we enable clock and do initialisations */
> clk_enable(imx2_wdt.clk);
>
> imx2_wdt_init();
> imx2_wdt_enable();
> } else /* delete the timer that pings the watchdog after close */
> del_timer_sync(&imx2_wdt.timer);
>
> /* Watchdog is enabled - time to reload the timeout value */
> imx2_wdt_ping();
> }
>
> static void imx2_wdt_stop(void)
> {
> /* we don't need a clk_disable, it cannot be disabled once started.
> * We use a timer to ping the watchdog while /dev/watchdog is closed */
> imx2_wdt_timer_ping();
> }
>
> static void imx2_wdt_set_timeout(int new_timeout)
> {
> /* set the new timeout value in the WSR */
> IMX2_WDT_CHG_BITS(imx2_wdt.base + IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
> WDOG_SEC_TO_COUNT(new_timeout));
> }
>
> static int imx2_wdt_open(struct inode *inode, struct file *file)
> {
> if (test_and_set_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status))
> return -EBUSY;
>
> imx2_wdt_start();
> return nonseekable_open(inode, file);
> }
>
> static int imx2_wdt_close(struct inode *inode, struct file *file)
> {
> if (test_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status) && !nowayout)
> imx2_wdt_stop();
> else {
> dev_crit(imx2_wdt_miscdev.parent,
> "Unexpected close: Expect reboot!\n");
> imx2_wdt_ping();
> }
>
> clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
> clear_bit(IMX2_WDT_STATUS_OPEN, &imx2_wdt.status);
> return 0;
> }
>
> static long imx2_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, &imx2_wdt_info,
> sizeof(struct watchdog_info)) ? -EFAULT : 0;
>
> case WDIOC_GETSTATUS:
> case WDIOC_GETBOOTSTATUS:
> return put_user(0, p);
>
> case WDIOC_KEEPALIVE:
> imx2_wdt_ping();
> return 0;
>
> case WDIOC_SETTIMEOUT:
> if (get_user(new_value, p))
> return -EFAULT;
> if ((new_value < 1) || (new_value > IMX2_WDT_MAX_TIME))
> return -EINVAL;
> imx2_wdt_set_timeout(new_value);
> imx2_wdt.timeout = new_value;
> imx2_wdt_ping();
>
> /* Fallthrough to return current value */
> case WDIOC_GETTIMEOUT:
> return put_user(imx2_wdt.timeout, p);
>
> default:
> return -ENOTTY;
> }
> }
>
> static ssize_t imx2_wdt_write(struct file *file, const char __user *data,
> size_t len, loff_t *ppos)
> {
> size_t i;
> char c;
>
> if (len == 0) /* Can we see this even ? */
> return 0;
>
> clear_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
> /* scan to see whether or not we got the magic character */
> for (i = 0; i != len; i++) {
> if (get_user(c, data + i))
> return -EFAULT;
> if (c == 'V')
> set_bit(IMX2_WDT_EXPECT_CLOSE, &imx2_wdt.status);
> }
> }
> imx2_wdt_ping();
> return len;
> }
>
> static const struct file_operations imx2_wdt_fops = {
> .owner = THIS_MODULE,
> .llseek = no_llseek,
> .unlocked_ioctl = imx2_wdt_ioctl,
> .open = imx2_wdt_open,
> .release = imx2_wdt_close,
> .write = imx2_wdt_write,
> };
>
> static struct miscdevice imx2_wdt_miscdev = {
> .minor = WATCHDOG_MINOR,
> .name = "watchdog",
> .fops = &imx2_wdt_fops,
> };
>
> static int __init imx2_wdt_probe(struct platform_device *pdev)
> {
> int ret;
> int res_size;
> struct resource *res;
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> if (!res) {
> dev_err(&pdev->dev, "can't get device resources\n");
> return -ENODEV;
> }
>
> res_size = resource_size(res);
> if (!devm_request_mem_region(&pdev->dev, res->start, res_size,
> res->name)) {
> dev_err(&pdev->dev, "can't allocate %d bytes at %d address\n",
> res_size, res->start);
> return -ENOMEM;
> }
>
> imx2_wdt.base = devm_ioremap_nocache(&pdev->dev, res->start, res_size);
> if (!imx2_wdt.base) {
> dev_err(&pdev->dev, "ioremap failed\n");
> return -ENOMEM;
> }
>
> imx2_wdt.clk = clk_get_sys("imx-wdt.0", NULL);
> if (IS_ERR(imx2_wdt.clk)) {
> dev_err(&pdev->dev, "can't get Watchdog clock\n");
> return PTR_ERR(imx2_wdt.clk);
> }
>
> imx2_wdt.timeout = clamp_t(unsigned, timeout, 1, IMX2_WDT_MAX_TIME);
> if (imx2_wdt.timeout != timeout)
> dev_warn(&pdev->dev, "Initial timeout out of range! "
> "Clamped from %u to %u\n", timeout, imx2_wdt.timeout);
>
> setup_timer(&imx2_wdt.timer, imx2_wdt_timer_ping, 0);
>
> imx2_wdt_miscdev.parent = &pdev->dev;
> ret = misc_register(&imx2_wdt_miscdev);
> if (ret)
> goto fail;
>
> dev_info(&pdev->dev,
> "IMX2+ Watchdog Timer enabled. timeout=%d sec (nowayout=%d)\n",
> imx2_wdt.timeout, nowayout);
> return 0;
>
> fail:
> imx2_wdt_miscdev.parent = NULL;
> clk_put(imx2_wdt.clk);
> return ret;
> }
>
> static int __exit imx2_wdt_remove(struct platform_device *pdev)
> {
> misc_deregister(&imx2_wdt_miscdev);
>
> if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
> del_timer_sync(&imx2_wdt.timer);
>
> dev_crit(imx2_wdt_miscdev.parent,
> "Device removed: Expect reboot!\n");
> } else
> clk_put(imx2_wdt.clk);
>
> imx2_wdt_miscdev.parent = NULL;
> return 0;
> }
>
> static void imx2_wdt_shutdown(struct platform_device *pdev)
> {
> if (test_bit(IMX2_WDT_STATUS_STARTED, &imx2_wdt.status)) {
> /* we are running, we need to delete the timer but will give
> * max timeout before reboot will take place */
> del_timer_sync(&imx2_wdt.timer);
> imx2_wdt_set_timeout(IMX2_WDT_MAX_TIME);
> imx2_wdt_ping();
>
> dev_crit(imx2_wdt_miscdev.parent,
> "Device shutdown: Expect reboot!\n");
> }
> }
>
> static struct platform_driver imx2_wdt_driver = {
> .probe = imx2_wdt_probe,
> .remove = __exit_p(imx2_wdt_remove),
> .shutdown = imx2_wdt_shutdown,
> .driver = {
> .name = DRIVER_NAME,
> .owner = THIS_MODULE,
> },
> };
>
> static int __init imx2_wdt_init(void)
> {
> return platform_driver_probe(&imx2_wdt_driver, imx2_wdt_probe);
> }
> module_init(imx2_wdt_init);
>
> static void __exit imx2_wdt_exit(void)
> {
> platform_driver_unregister(&imx2_wdt_driver);
> }
> module_exit(imx2_wdt_exit);
>
> MODULE_AUTHOR("Wolfram Sang");
> MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
> MODULE_LICENSE("GPL v2");
> MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
> MODULE_ALIAS("platform:" DRIVER_NAME);
The rest looks good, thanks for that. Some functions looks a bit too trivial
(and are called just once) for my taste, but I guess this is for easier
migration later? Oh, and a few whitespace issues, easily fixed.
Kind regards,
Wolfram
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: Digital signature
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20100525/736f6d78/attachment-0001.sig>
More information about the linux-arm-kernel
mailing list