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Date: Sat, 28 Dec 2013 21:40:39 +0100
From: Wim Van Sebroeck <wim@...ana.be>
To: Markus Mayer <markus.mayer@...aro.org>
Cc: Guenter Roeck <linux@...ck-us.net>,
Christian Daudt <bcm@...thebug.org>,
Linaro Patches <patches@...aro.org>,
Matt Porter <matt.porter@...aro.org>,
One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
Linux Watchdog List <linux-watchdog@...r.kernel.org>,
ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 0/2] watchdog: bcm281xx: Watchdog Driver
Hi Markus,
> This is version 5 of the watchdog driver for the BCM281xx family of mobile
> SoCs.
I applied the patches but without the BCM_KONA_WDT_DEBUG part, because I
still have some questions about it. So what is left is the following patch:
diff --git a/arch/arm/configs/bcm_defconfig b/arch/arm/configs/bcm_defconfig
index 10d1392..d4d0083 100644
--- a/arch/arm/configs/bcm_defconfig
+++ b/arch/arm/configs/bcm_defconfig
@@ -128,3 +128,4 @@ CONFIG_XZ_DEC=y
CONFIG_AVERAGE=y
CONFIG_WATCHDOG=y
CONFIG_BCM_KONA_WDT=y
+CONFIG_BCM_KONA_WDT_DEBUG=y
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 042e452..24bc93a 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1151,6 +1151,16 @@ 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.
+
+ 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..9fe174b 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>
@@ -55,8 +56,15 @@ struct bcm_kona_wdt {
*/
int resolution;
spinlock_t lock;
+#ifdef CONFIG_BCM_KONA_WDT_DEBUG
+ struct dentry *debugfs;
+#endif
};
+#ifdef CONFIG_BCM_KONA_WDT_DEBUG
+static unsigned long busy_count;
+#endif
+
static int secure_register_read(void __iomem *addr)
{
uint32_t val;
@@ -74,6 +82,12 @@ static int secure_register_read(void __iomem *addr)
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 > busy_count)
+ busy_count = count;
+#endif
+
/* This is the only place we return a negative value. */
if (val & SECWDOG_WD_LOAD_FLAG)
return -ETIMEDOUT;
@@ -84,6 +98,80 @@ 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->base + SECWDOG_CTRL_REG);
+ cur_val = secure_register_read(wdt->base + 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, 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)
{
@@ -229,6 +317,9 @@ static int bcm_kona_wdt_probe(struct platform_device *pdev)
return ret;
}
+#ifdef CONFIG_BCM_KONA_WDT_DEBUG
+ wdt->debugfs = bcm_kona_wdt_debugfs_init(wdt, &bcm_kona_wdt_wdd);
+#endif
dev_dbg(dev, "Broadcom Kona Watchdog Timer");
return 0;
@@ -236,6 +327,12 @@ static int bcm_kona_wdt_probe(struct platform_device *pdev)
static int bcm_kona_wdt_remove(struct platform_device *pdev)
{
+#ifdef CONFIG_BCM_KONA_WDT_DEBUG
+ struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev);
+
+ if (wdt->debugfs)
+ bcm_kona_debugfs_exit(wdt->debugfs);
+#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
bcm_kona_wdt_shutdown(pdev);
watchdog_unregister_device(&bcm_kona_wdt_wdd);
dev_dbg(&pdev->dev, "Watchdog driver disabled");
Questions/remarks I still have:
1) *debugfs is defined in the bcm_kona_wdt struct, but busy_count isn't.
Seems odd to me. What's the reason?
2) I don't like the #ifdef pieces in the probe and remove functions.
The preferred method is to not have the #ifdefs there, but to have an
init and exit function that is defined in a similar way:
#ifdef CONFIG_BCM_KONA_WDT_DEBUG
...
static void bcm_kona_wdt_debug_init(struct bcm_kona_wdt *wdt)
{
wdt->debugfs = bcm_kona_wdt_debugfs_init(wdt, &bcm_kona_wdt_wdd);
}
...
#else /* !CONFIG_BCM_KONA_WDT_DEBUG */
static void bcm_kona_wdt_debug_init(struct bcm_kona_wdt *wdt) {}
...
#endif /* CONFIG_BCM_KONA_WDT_DEBUG */
Goal is to have as little #ifdef's as possible and to improve readability of the code.
So can you do the necessary?
Thanks in advance,
Wim.
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