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Date:	Sat, 04 Jan 2014 09:42:36 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Markus Mayer <markus.mayer@...aro.org>,
	Wim Van Sebroeck <wim@...ana.be>,
	Christian Daudt <bcm@...thebug.org>
CC:	Linaro Patches <patches@...aro.org>,
	Linux Watchdog List <linux-watchdog@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] watchdog: bcm281xx: Debugfs support

On 12/31/2013 01:22 PM, Markus Mayer wrote:
> This change introduces debugfs support for the BCM281xx watchdog driver.
>
> Signed-off-by: Markus Mayer <markus.mayer@...aro.org>
> ---
>   drivers/watchdog/Kconfig        |   10 ++++
>   drivers/watchdog/bcm_kona_wdt.c |  116 +++++++++++++++++++++++++++++++++++++--
>   2 files changed, 122 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 10d188a..9b8b96d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1152,6 +1152,16 @@ config BCM_KONA_WDT
>   	  Say 'Y' or 'M' here to enable the driver. The module will be called
>   	  bcm_kona_wdt.
>
> +config BCM_KONA_WDT_DEBUG
> +	bool "DEBUGFS support for BCM Kona Watchdog"
> +	depends on BCM_KONA_WDT
> +	help
> +	  If enabled, adds /sys/kernel/debug/bcm-kona-wdt/info which provides
> +	  access to the driver's internal data structures as well as watchdog
> +	  timer hardware registres.
> +
Unless Wim already applied this patch, I would suggest to merge the followup patch
with this one.

> +	  If in doubt, say 'N'.
> +
>   config LANTIQ_WDT
>   	tristate "Lantiq SoC watchdog"
>   	depends on LANTIQ
> diff --git a/drivers/watchdog/bcm_kona_wdt.c b/drivers/watchdog/bcm_kona_wdt.c
> index 7e41a83..d3aa473 100644
> --- a/drivers/watchdog/bcm_kona_wdt.c
> +++ b/drivers/watchdog/bcm_kona_wdt.c
> @@ -11,6 +11,7 @@
>    * GNU General Public License for more details.
>    */
>
> +#include <linux/debugfs.h>
>   #include <linux/delay.h>
>   #include <linux/err.h>
>   #include <linux/io.h>
> @@ -55,9 +56,13 @@ struct bcm_kona_wdt {
>   	 */
>   	int resolution;
>   	spinlock_t lock;
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +	unsigned long busy_count;
> +	struct dentry *debugfs;
> +#endif
>   };
>
> -static int secure_register_read(void __iomem *addr)
> +static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset)
>   {
>   	uint32_t val;
>   	unsigned count = 0;
> @@ -70,10 +75,16 @@ static int secure_register_read(void __iomem *addr)
>   	do {
>   		if (unlikely(count > 1))
>   			udelay(5);
> -		val = readl_relaxed(addr);
> +		val = readl_relaxed(wdt->base + offset);
>   		count++;
>   	} while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY);
>
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +	/* Remember the maximum number iterations due to WD_LOAD_FLAG */
> +	if (count > wdt->busy_count)
> +		wdt->busy_count = count;
> +#endif
> +
>   	/* This is the only place we return a negative value. */
>   	if (val & SECWDOG_WD_LOAD_FLAG)
>   		return -ETIMEDOUT;
> @@ -84,6 +95,80 @@ static int secure_register_read(void __iomem *addr)
>   	return val;
>   }
>
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +
> +static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data)
> +{
> +	int ctl_val, cur_val, ret;
> +	unsigned long flags;
> +	struct bcm_kona_wdt *wdt = s->private;
> +
> +	if (!wdt)
> +		return seq_puts(s, "No device pointer\n");
> +
> +	spin_lock_irqsave(&wdt->lock, flags);
> +	ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG);
> +	cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG);
> +	spin_unlock_irqrestore(&wdt->lock, flags);
> +
> +	if (ctl_val < 0 || cur_val < 0) {
> +		ret = seq_puts(s, "Error accessing hardware\n");
> +	} else {
> +		int ctl, cur, ctl_sec, cur_sec, res;
> +
> +		ctl = ctl_val & SECWDOG_COUNT_MASK;
> +		res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT;
> +		cur = cur_val & SECWDOG_COUNT_MASK;
> +		ctl_sec = TICKS_TO_SECS(ctl, wdt);
> +		cur_sec = TICKS_TO_SECS(cur, wdt);
> +		ret = seq_printf(s, "Resolution: %d / %d\n"
> +				"Control: %d s / %d (%#x) ticks\n"
> +				"Current: %d s / %d (%#x) ticks\n"
> +				"Busy count: %lu\n", res,
> +				wdt->resolution, ctl_sec, ctl, ctl, cur_sec,
> +				cur, cur, wdt->busy_count);
> +	}
> +
> +	return ret;
> +}
> +
> +static int bcm_kona_dbg_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private);
> +}
> +
> +static const struct file_operations bcm_kona_dbg_operations = {
> +	.open		= bcm_kona_dbg_open,
> +	.read		= seq_read,
> +	.llseek		= seq_lseek,
> +	.release	= single_release,
> +};
> +
> +static struct dentry *bcm_kona_wdt_debugfs_init(struct bcm_kona_wdt *wdt,
> +	struct watchdog_device *wdd)
> +{
> +	struct dentry *dir;
> +
> +	dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL);
> +	if (IS_ERR_OR_NULL(dir))
> +		return NULL;
> +
> +	if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt,
> +				&bcm_kona_dbg_operations))
> +		return dir;
> +
> +	/* Clean up */
> +	debugfs_remove_recursive(dir);
> +	return NULL;
> +}
> +
> +static void bcm_kona_debugfs_exit(struct dentry *dir)
> +{
> +	debugfs_remove_recursive(dir);
> +}
> +
> +#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
> +
>   static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
>   					unsigned mask, unsigned newval)
>   {
> @@ -93,7 +178,7 @@ static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt,
>
>   	spin_lock_irqsave(&wdt->lock, flags);
>
> -	val = secure_register_read(wdt->base + SECWDOG_CTRL_REG);
> +	val = secure_register_read(wdt, SECWDOG_CTRL_REG);
>   	if (val < 0) {
>   		ret = val;
>   	} else {
> @@ -140,7 +225,7 @@ static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog)
>   	unsigned long flags;
>
>   	spin_lock_irqsave(&wdt->lock, flags);
> -	val = secure_register_read(wdt->base + SECWDOG_COUNT_REG);
> +	val = secure_register_read(wdt, SECWDOG_COUNT_REG);
>   	spin_unlock_irqrestore(&wdt->lock, flags);
>
>   	if (val < 0)
> @@ -190,6 +275,27 @@ static void bcm_kona_wdt_shutdown(struct platform_device *pdev)
>   	bcm_kona_wdt_stop(&bcm_kona_wdt_wdd);
>   }
>
> +#ifdef CONFIG_BCM_KONA_WDT_DEBUG
> +static void bcm_kona_wdt_debug_init(struct platform_device *pdev)
> +{
> +	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
> +
> +	wdt->debugfs = bcm_kona_wdt_debugfs_init(wdt, &bcm_kona_wdt_wdd);
> +}
> +
> +static void bcm_kona_wdt_debug_exit(struct platform_device *pdev)
> +{
> +	struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
> +
> +	if (wdt->debugfs)
> +		bcm_kona_debugfs_exit(wdt->debugfs);
> +}
> +
> +#else
> +static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {}
> +static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {}
> +#endif
> +

Can you fold those functions into bcm_kona_wdt_debugfs_init() and bcm_kona_debugfs_exit() ?
Then you only need a sinfle #ifdef / #else combination. Only functional change would be to
set wdt->debugfs in bcm_kona_wdt_debugfs_init() and to check it in bcm_kona_debugfs_exit().

Thanks,
Guenter

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