[PATCH 1/2] ep93xx: implemented watchdog timer driver for TS-72xx SBCs

Mika Westerberg mika.westerberg at iki.fi
Fri Dec 4 01:10:36 EST 2009


Hi Ryan,

On Fri, Dec 04, 2009 at 09:07:10AM +1300, Ryan Mallon wrote:
> Mika Westerberg wrote:
> > Technologic Systems TS-72xx SBCs have external glue logic
> > CPLD which includes watchdog timer. This driver implements
> > kernel support for that.
> 
> Hi Mika, looks good. Some comments below.

Thank you very much for your comments. My answers to the comments are
below.

I'll wait a bit if someone else still has comments and then prepare
version 2 of the patches.

Thanks,
MW

> 
> > Signed-off-by: Mika Westerberg <mika.westerberg at iki.fi>
> > ---
> >  drivers/watchdog/Kconfig      |   11 +
> >  drivers/watchdog/Makefile     |    1 +
> >  drivers/watchdog/ts72xx_wdt.c |  458 +++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 470 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/watchdog/ts72xx_wdt.c
> > 
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> > index 3711b88..5204612 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -289,6 +289,17 @@ config ADX_WATCHDOG
> >  	  Say Y here if you want support for the watchdog timer on Avionic
> >  	  Design Xanthos boards.
> >  
> > +config TS72XX_WATCHDOG
> > +	tristate "TS-72XX SBC Watchdog"
> > +	depends on MACH_TS72XX
> > +	help
> > +	  Technologic Systems TS-7200, TS-7250 and TS-7260 boards have
> > +	  watchdog timer implemented in a external CPLD chip. Say Y here
> > +	  if you want to support for the watchdog timer on TS-72XX boards.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called ts72xx_wdt.
> > +
> >  # AVR32 Architecture
> >  
> >  config AT32AP700X_WDT
> > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> > index 699199b..8e8a9b4 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -46,6 +46,7 @@ obj-$(CONFIG_COH901327_WATCHDOG) += coh901327_wdt.o
> >  obj-$(CONFIG_STMP3XXX_WATCHDOG) += stmp3xxx_wdt.o
> >  obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
> >  obj-$(CONFIG_ADX_WATCHDOG) += adx_wdt.o
> > +obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
> >  
> >  # AVR32 Architecture
> >  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> > diff --git a/drivers/watchdog/ts72xx_wdt.c b/drivers/watchdog/ts72xx_wdt.c
> > new file mode 100644
> > index 0000000..88b75b9
> > --- /dev/null
> > +++ b/drivers/watchdog/ts72xx_wdt.c
> > @@ -0,0 +1,458 @@
> > +/*
> > + * Watchdog driver for Technologic Systems TS-72xx based SBCs
> > + * (TS-7200, TS-7250 and TS-7260). These boards have external
> > + * glue logic CPLD chip, which includes programmable watchdog
> > + * timer.
> > + *
> > + * Copyright (c) 2009 Mika Westerberg <mika.westerberg at iki.fi>
> > + *
> > + * This driver is based on ep93xx_wdt and wm831x_wdt drivers.
> > + *
> > + * This file is licensed under the terms of the GNU General Public
> > + * License version 2. This program is licensed "as is" without any
> > + * warranty of any kind, whether express or implied.
> > + */
> 
> Nitpick: Space between top comment and first line of includes.

Will fix to v2.

> 
> > +#include <linux/fs.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/moduleparam.h>
> > +#include <linux/miscdevice.h>
> > +#include <linux/mutex.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/watchdog.h>
> > +#include <linux/uaccess.h>
> > +
> > +#define TS72XX_WDT_FEED_VAL		0x05
> > +#define TS72XX_WDT_DEFAULT_TIMEOUT	8
> > +
> > +static int timeout = TS72XX_WDT_DEFAULT_TIMEOUT;
> > +module_param(timeout, int, 0);
> > +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. "
> > +			  "(1 <= timeout <= 8, default="
> > +			  __MODULE_STRING(TS72XX_WDT_DEFAULT_TIMEOUT)
> > +			  ")");
> > +
> > +static int nowayout = WATCHDOG_NOWAYOUT;
> > +module_param(nowayout, int, 0);
> > +MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
> > +
> > +/**
> > + * struct ts72xx_wdt - watchdog control structure
> > + * @lock: lock that protects this structure
> > + * @flags: flags controlling watchdog device state
> > + * @control_reg: watchdog control register
> > + * @feed_reg: watchdog feed register
> > + * @pdev: back pointer to platform dev
> > + */
> > +struct ts72xx_wdt {
> > +	struct mutex	lock;
> > +	int		timeout;
> > +
> > +#define TS72XX_WDT_BUSY_FLAG		1
> > +#define TS72XX_WDT_EXPECT_CLOSE_FLAG	2
> > +	int		flags;
> > +
> > +	void __iomem	*control_reg;
> > +	void __iomem	*feed_reg;
> > +
> > +	struct platform_device *pdev;
> > +};
> > +
> > +struct platform_device *ts72xx_wdt_pdev;
> > +
> > +/*
> > + * TS-72xx Watchdog supports following timeouts (value written
> > + * to control register):
> > + *	value	description
> > + *	-------------------------
> > + * 	0x00	watchdog disabled
> > + *	0x01	250ms
> > + *	0x02	500ms
> > + *	0x03	1s
> > + *	0x04	reserved
> > + *	0x05	2s
> > + *	0x06	4s
> > + *	0x07	8s
> > + *
> > + * Timeouts below 1s are not very usable so we don't
> > + * allow them at all.
> > + */
> > +static const struct {
> > +	int	timeout;
> > +	u8	ctrval;
> > +} ts72xx_wdt_map[] = {
> > +	{ 1, 3 },
> > +	{ 2, 5 },
> > +	{ 4, 6 },
> > +	{ 8, 7 },
> > +};
> > +
> > +/**
> > + * normalize_timeout() - normalizes given timeout
> > + * @new_timeout: timeout in seconds to be normalized
> > + *
> > + * This function normalizes given timeout value (in seconds)
> > + * to value that is valid to TS-72xx watchdog timer. Valid
> > + * values are 1, 2, 4 and 8 seconds. Timeout is rounded up
> > + * to nearest valid timeout so for example value 3 yields
> > + * 4 etc.
> > + */
> > +static int normalize_timeout(int new_timeout)
> > +{
> > +	int i;
> > +
> > +	/* first limit it to 1 - 8 seconds */
> > +	if (new_timeout < 1)
> > +		new_timeout = 1;
> > +	else if (new_timeout > 8)
> > +		new_timeout = 8;
> 
> You can do:
> 
> 	new_timeout = clamp_val(new_timeout, 1, 8);
> 
> for the same effect here.

Wow, I didn't even know that such functions (macros) exists
in kernel :) I will fix this in v2.

> 
> > +
> > +	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
> > +		if (ts72xx_wdt_map[i].timeout >= new_timeout)
> > +			return ts72xx_wdt_map[i].timeout;
> > +	}
> > +
> > +	BUG();
> > +	/*NOTREACHED*/
> 
> This is reached if !CONFIG_BUG, you should return -EINVAL, and handle it
> gracefully in the caller.

OK. Will be fixed in v2.

> 
> > +}
> > +
> > +/**
> > + * timeout_to_ctrval() - converts given timeout to control register value
> > + * @new_timeout: timeout in seconds to be converted (1, 2, 4 or 8)
> > + *
> > + * This function converts timeout in seconds to valid control register
> > + * value. Note that @new_timeout must be normalized first with call to
> > + * normalize_timeout().
> > + */
> 
> If you must call normalize timeout first, the can the two functions be
> combined so that you only need to do the loop once?

Yeah, that's probably better way. I'll try to combine them
in v2.

> 
> > +static u8 timeout_to_ctrval(int new_timeout)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < ARRAY_SIZE(ts72xx_wdt_map); i++) {
> > +		if (ts72xx_wdt_map[i].timeout == new_timeout)
> > +			return ts72xx_wdt_map[i].ctrval;
> > +	}
> > +
> > +	BUG();
> > +	/*NOTREACHED*/
> 
> Same as above, should return -EINVAL

Will fix in v2.

> 
> > +}
> > +
> > +/**
> > + * ts72xx_wdt_kick() - kick the watchdog
> > + * @wdt: watchdog to be kicked
> > + *
> > + * Called with @wdt->lock held.
> > + */
> > +static void ts72xx_wdt_kick(struct ts72xx_wdt *wdt)
> 
> Should probably be marked inline.

Ok. Will do.

> 
> > +{
> > +	__raw_writeb(TS72XX_WDT_FEED_VAL, wdt->feed_reg);
> > +}
> > +
> > +/**
> > + * ts72xx_wdt_start() - starts the watchdog timer
> > + * @wdt: watchdog to be started
> > + *
> > + * This function programs timeout to watchdog timer
> > + * and starts it.
> > + *
> > + * Called with @wdt->lock held.
> > + */
> > +static void ts72xx_wdt_start(struct ts72xx_wdt *wdt)
> > +{
> > +	/*
> > +	 * To program the wdt, it first must be "fed" and
> > +	 * only after that (within 30 usecs) the configuration
> > +	 * can be changed.
> > +	 */
> > +	ts72xx_wdt_kick(wdt);
> > +	__raw_writeb(timeout_to_ctrval(wdt->timeout), wdt->control_reg);
> > +}
> > +
> > +/**
> > + * ts72xx_wdt_stop() - stops the watchdog timer
> > + * @wdt: watchdog to be stopped
> > + *
> > + * Called with @wdt->lock held.
> > + */
> > +static void ts72xx_wdt_stop(struct ts72xx_wdt *wdt)
> > +{
> > +	ts72xx_wdt_kick(wdt);
> > +	__raw_writeb(0, wdt->control_reg);
> > +}
> > +
> > +static int ts72xx_wdt_open(struct inode *inode, struct file *file)
> > +{
> > +	struct ts72xx_wdt *wdt = platform_get_drvdata(ts72xx_wdt_pdev);
> > +
> > +	if (mutex_lock_interruptible(&wdt->lock))
> > +		return -ERESTARTSYS;
> > +
> > +	if ((wdt->flags & TS72XX_WDT_BUSY_FLAG) != 0) {
> > +		mutex_unlock(&wdt->lock);
> > +		return -EBUSY;
> > +	}
> > +
> > +	wdt->flags = TS72XX_WDT_BUSY_FLAG;
> > +	wdt->timeout = normalize_timeout(timeout);
> > +	file->private_data = wdt;
> > +
> > +	ts72xx_wdt_start(wdt);
> > +
> > +	mutex_unlock(&wdt->lock);
> > +	return nonseekable_open(inode, file);
> > +}
> > +
> > +static int ts72xx_wdt_release(struct inode *inode, struct file *file)
> > +{
> > +	struct ts72xx_wdt *wdt = (struct ts72xx_wdt *)file->private_data;
> > +
> > +	if (mutex_lock_interruptible(&wdt->lock))
> > +		return -ERESTARTSYS;
> > +
> > +	if ((wdt->flags & TS72XX_WDT_EXPECT_CLOSE_FLAG) != 0) {
> > +		ts72xx_wdt_stop(wdt);
> > +	} else {
> > +		dev_warn(&wdt->pdev->dev,
> > +			 "TS-72XX WDT device closed unexpectly. "
> > +			 "Watchdog timer will not stop!\n");
> > +		/*
> > +		 * Kick it one more time, to give userland some time
> > +		 * to recover (for example, respawning the kicker
> > +		 * daemon).
> > +		 */
> > +		ts72xx_wdt_kick(wdt);
> > +	}
> > +
> > +	wdt->flags = 0;
> > +
> > +	mutex_unlock(&wdt->lock);
> > +	return 0;
> > +}
> > +
> > +static ssize_t ts72xx_wdt_write(struct file *file,
> > +				const char __user *data,
> > +				size_t len,
> > +				loff_t *ppos)
> > +{
> > +	struct ts72xx_wdt *wdt = (struct ts72xx_wdt *)file->private_data;
> > +
> > +	if (!len)
> > +		return 0;
> > +
> > +	if (mutex_lock_interruptible(&wdt->lock))
> > +		return -ERESTARTSYS;
> > +
> > +	ts72xx_wdt_kick(wdt);
> > +
> > +	/*
> > +	 * Support for magic character closing. User process
> > +	 * writes 'V' into the device, just before it is closed.
> > +	 * This means that we know that the wdt timer can be
> > +	 * stopped after user closes the device.
> > +	 */
> > +	if (!nowayout) {
> > +		int i;
> > +
> > +		for (i = 0; i < len; i++) {
> > +			char c;
> > +
> > +			/* In case it was set long ago */
> > +			wdt->flags &= ~TS72XX_WDT_EXPECT_CLOSE_FLAG;
> > +
> > +			if (get_user(c, data + i)) {
> > +				mutex_unlock(&wdt->lock);
> > +				return -EFAULT;
> > +			}
> > +			if (c == 'V') {
> > +				wdt->flags |= TS72XX_WDT_EXPECT_CLOSE_FLAG;
> > +				break;
> > +			}
> > +		}
> > +	}
> > +
> > +	mutex_unlock(&wdt->lock);
> > +	return len;
> > +}
> > +
> > +static const struct watchdog_info winfo = {
> > +	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
> > +	.firmware_version = 1,
> > +	.identity = "TS-72XX WDT",
> > +};
> 
> Nitpick: Tab align struct assignments.

Ok. Will fix in v2.

> 
> > +
> > +static long ts72xx_wdt_ioctl(struct file *file, unsigned int cmd,
> > +			     unsigned long arg)
> > +{
> > +	struct ts72xx_wdt *wdt = (struct ts72xx_wdt *)file->private_data;
> > +	void __user *argp = (void __user *)arg;
> > +	int __user *p = (int __user *)argp;
> > +	int error = 0;
> > +
> > +	if (mutex_lock_interruptible(&wdt->lock))
> > +		return -ERESTARTSYS;
> > +
> > +	switch (cmd) {
> > +	case WDIOC_GETSUPPORT:
> > +		error = copy_to_user(argp, &winfo, sizeof(winfo));
> > +		break;
> > +
> > +	case WDIOC_KEEPALIVE:
> > +		ts72xx_wdt_kick(wdt);
> > +		break;
> > +
> > +	case WDIOC_SETOPTIONS: {
> > +		int options;
> > +
> > +		if (get_user(options, p)) {
> > +			error = -EFAULT;
> > +			break;
> > +		}
> > +
> > +		error = -EINVAL;
> > +
> > +		if ((options & WDIOS_DISABLECARD) != 0) {
> > +			ts72xx_wdt_stop(wdt);
> > +			error = 0;
> > +		}
> > +		if ((options & WDIOS_ENABLECARD) != 0) {
> > +			ts72xx_wdt_start(wdt);
> > +			error = 0;
> > +		}
> > +
> > +		break;
> > +	}
> > +
> > +	case WDIOC_SETTIMEOUT: {
> > +		int new_timeout;
> > +
> > +		if (get_user(new_timeout, p)) {
> > +			error = -EFAULT;
> > +		} else {
> > +			ts72xx_wdt_stop(wdt);
> > +			wdt->timeout = normalize_timeout(new_timeout);
> > +			ts72xx_wdt_start(wdt);
> > +		}
> > +		/*FALLTHROUGH*/
> > +	}
> > +
> > +	case WDIOC_GETTIMEOUT:
> > +		if (put_user(wdt->timeout, p))
> > +			error = -EFAULT;
> > +		break;
> > +
> > +	default:
> > +		error = -ENOTTY;
> > +		break;
> > +	}
> > +
> > +	mutex_unlock(&wdt->lock);
> > +	return error;
> > +}
> > +
> > +static const struct file_operations ts72xx_wdt_fops = {
> > +	.owner		= THIS_MODULE,
> > +	.llseek		= no_llseek,
> > +	.open		= ts72xx_wdt_open,
> > +	.release	= ts72xx_wdt_release,
> > +	.write		= ts72xx_wdt_write,
> > +	.unlocked_ioctl	= ts72xx_wdt_ioctl,
> > +};
> > +
> > +static struct miscdevice ts72xx_wdt_miscdev = {
> > +	.minor		= WATCHDOG_MINOR,
> > +	.name		= "watchdog",
> > +	.fops		= &ts72xx_wdt_fops,
> > +};
> > +
> > +static __devinit int ts72xx_wdt_probe(struct platform_device *pdev)
> > +{
> > +	struct ts72xx_wdt *wdt;
> > +	struct resource *res;
> > +	int error = -EIO;
> > +
> > +	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
> 
> 	sizeof(struct ts72xx_wdt)
> 
> is the preferred style I think. If the other watchdog drivers do it this
> way just leave it though.

It seems that both styles are used in watchdog drivers. I'll change
this to the preferred style in v2.

> 
> > +	if (!wdt)
> > +		return -ENOMEM;
> > +
> > +	mutex_init(&wdt->lock);
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	if (!res)
> > +		goto fail;
> > +
> > +	wdt->control_reg = ioremap(res->start, resource_size(res));
> > +	if (!wdt->control_reg)
> > +		goto fail;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > +	if (!res)
> > +		goto fail;
> > +
> > +	wdt->feed_reg = ioremap(res->start, resource_size(res));
> > +	if (!wdt->feed_reg)
> > +		goto fail;
> > +
> > +	error = misc_register(&ts72xx_wdt_miscdev);
> > +	if (error)
> > +		goto fail;
> > +
> > +	platform_set_drvdata(pdev, wdt);
> > +	ts72xx_wdt_pdev = pdev;
> > +	wdt->pdev = pdev;
> > +
> > +	dev_info(&pdev->dev, "TS-72xx Watchdog driver\n");
> > +
> > +	return 0;
> > +
> > +fail:
> > +	platform_set_drvdata(pdev, NULL);
> 
> I don't think you need this in the error path since platform_set_drvdata
> is called after the last goto fail.

Ah, good catch. Will fix in v2.

> 
> > +	if (wdt->control_reg)
> > +		iounmap(wdt->control_reg);
> > +	if (wdt->feed_reg)
> > +		iounmap(wdt->feed_reg);
> > +
> > +	kfree(wdt);
> > +	return error;
> > +}
> > +
> > +static __devexit int ts72xx_wdt_remove(struct platform_device *pdev)
> > +{
> > +	struct ts72xx_wdt *wdt =
> > +		(struct ts72xx_wdt *)platform_get_drvdata(pdev);
> > +
> > +	if (wdt->control_reg)
> > +		iounmap(wdt->control_reg);
> > +	if (wdt->feed_reg)
> > +		iounmap(wdt->feed_reg);
> > +
> > +	kfree(wdt);
> > +
> > +	platform_set_drvdata(pdev, NULL);
> > +	return misc_deregister(&ts72xx_wdt_miscdev);
> > +}
> > +
> > +static struct platform_driver ts72xx_wdt_driver = {
> > +	.probe = ts72xx_wdt_probe,
> > +	.remove = __devexit_p(ts72xx_wdt_remove),
> > +	.driver = {
> > +		.name = "ts72xx-wdt",
> > +	},
> > +};
> > +
> > +static __init int ts72xx_wdt_init(void)
> > +{
> > +	return platform_driver_register(&ts72xx_wdt_driver);
> > +}
> > +module_init(ts72xx_wdt_init);
> > +
> > +static __exit void ts72xx_wdt_exit(void)
> > +{
> > +	platform_driver_unregister(&ts72xx_wdt_driver);
> > +}
> > +module_exit(ts72xx_wdt_exit);
> > +
> > +MODULE_AUTHOR("Mika Westerberg <mika.westerberg at iki.fi>");
> > +MODULE_DESCRIPTION("TS-72xx SBC Watchdog");
> > +MODULE_LICENSE("GPL");
> > +MODULE_ALIAS("platform:ts72xx-wdt");
> 
> 
> -- 
> Bluewater Systems Ltd - ARM Technology Solution Centre
> 
> Ryan Mallon         		5 Amuri Park, 404 Barbadoes St
> ryan at bluewatersys.com         	PO Box 13 889, Christchurch 8013
> http://www.bluewatersys.com	New Zealand
> Phone: +64 3 3779127		Freecall: Australia 1800 148 751
> Fax:   +64 3 3779135			  USA 1800 261 2934



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