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path: root/drivers/watchdog/sama5d4_wdt.c
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Diffstat (limited to 'drivers/watchdog/sama5d4_wdt.c')
-rw-r--r--drivers/watchdog/sama5d4_wdt.c77
1 files changed, 57 insertions, 20 deletions
diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index f709962018ac..362fd229786d 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -6,6 +6,7 @@
* Licensed under GPLv2.
*/
+#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
@@ -29,6 +30,7 @@ struct sama5d4_wdt {
struct watchdog_device wdd;
void __iomem *reg_base;
u32 mr;
+ unsigned long last_ping;
};
static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
@@ -44,11 +46,34 @@ MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
+
#define wdt_read(wdt, field) \
readl_relaxed((wdt)->reg_base + (field))
-#define wdt_write(wtd, field, val) \
- writel_relaxed((val), (wdt)->reg_base + (field))
+/* 4 slow clock periods is 4/32768 = 122.07µs*/
+#define WDT_DELAY usecs_to_jiffies(123)
+
+static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
+{
+ /*
+ * WDT_CR and WDT_MR must not be modified within three slow clock
+ * periods following a restart of the watchdog performed by a write
+ * access in WDT_CR.
+ */
+ while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
+ usleep_range(30, 125);
+ writel_relaxed(val, wdt->reg_base + field);
+ wdt->last_ping = jiffies;
+}
+
+static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
+{
+ if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
+ udelay(123);
+ writel_relaxed(val, wdt->reg_base + field);
+ wdt->last_ping = jiffies;
+}
static int sama5d4_wdt_start(struct watchdog_device *wdd)
{
@@ -89,7 +114,16 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
wdt->mr &= ~AT91_WDT_WDD;
wdt->mr |= AT91_WDT_SET_WDV(value);
wdt->mr |= AT91_WDT_SET_WDD(value);
- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+
+ /*
+ * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
+ * setting the WDDIS bit, and while it is set, the fields WDV and WDD
+ * must not be modified.
+ * If the watchdog is enabled, then the timeout can be updated. Else,
+ * wait that the user enables it.
+ */
+ if (wdt_enabled)
+ wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
wdd->timeout = timeout;
@@ -145,23 +179,21 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
{
- struct watchdog_device *wdd = &wdt->wdd;
- u32 value = WDT_SEC2TICKS(wdd->timeout);
u32 reg;
-
/*
- * Because the fields WDV and WDD must not be modified when the WDDIS
- * bit is set, so clear the WDDIS bit before writing the WDT_MR.
+ * When booting and resuming, the bootloader may have changed the
+ * watchdog configuration.
+ * If the watchdog is already running, we can safely update it.
+ * Else, we have to disable it properly.
*/
- reg = wdt_read(wdt, AT91_WDT_MR);
- reg &= ~AT91_WDT_WDDIS;
- wdt_write(wdt, AT91_WDT_MR, reg);
-
- wdt->mr |= AT91_WDT_SET_WDD(value);
- wdt->mr |= AT91_WDT_SET_WDV(value);
-
- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
-
+ if (wdt_enabled) {
+ wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
+ } else {
+ reg = wdt_read(wdt, AT91_WDT_MR);
+ if (!(reg & AT91_WDT_WDDIS))
+ wdt_write_nosleep(wdt, AT91_WDT_MR,
+ reg | AT91_WDT_WDDIS);
+ }
return 0;
}
@@ -172,6 +204,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
struct resource *res;
void __iomem *regs;
u32 irq = 0;
+ u32 timeout;
int ret;
wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
@@ -184,6 +217,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
wdd->ops = &sama5d4_wdt_ops;
wdd->min_timeout = MIN_WDT_TIMEOUT;
wdd->max_timeout = MAX_WDT_TIMEOUT;
+ wdt->last_ping = jiffies;
watchdog_set_drvdata(wdd, wdt);
@@ -221,6 +255,11 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
return ret;
}
+ timeout = WDT_SEC2TICKS(wdd->timeout);
+
+ wdt->mr |= AT91_WDT_SET_WDD(timeout);
+ wdt->mr |= AT91_WDT_SET_WDV(timeout);
+
ret = sama5d4_wdt_init(wdt);
if (ret)
return ret;
@@ -263,9 +302,7 @@ static int sama5d4_wdt_resume(struct device *dev)
{
struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
- wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
- if (wdt->mr & AT91_WDT_WDDIS)
- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+ sama5d4_wdt_init(wdt);
return 0;
}