In the datasheet, the new feature is describled as
"WDT_MR can be written until a LOCKMR command is issued in WDT_CR".
That is to say, as long as the bootstrap and u-boot don't issue a LOCKMR
command, WDT_MR can be written in kernel.
So the driver can enable/disable the watchdog timer hardware,
set WDV(Watchdog Counter Value) and WDD(Watchdog Delta Value) fields
of WDT_MR register to set the watchdog timer timeout.
The timer is not necessary that regularly sends a keepalive ping to
the watchdog timer hardware.
It is introduced from sama5d4 SoCs.
Signed-off-by: Wenyou Yang <wenyou.yang@xxxxxxxxx>
---
drivers/watchdog/at91sam9_wdt.c | 255 ++++++++++++++++++++++++++++-----------
drivers/watchdog/at91sam9_wdt.h | 4 +
2 files changed, 190 insertions(+), 69 deletions(-)
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 1443b3c..6b61084 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -10,9 +10,12 @@
*/
/*
+ * For AT91SAM9x SoCs, the Watchdog Timer has the following constraint.
* The Watchdog Timer Mode Register can be only written to once. If the
* timeout need to be set from Linux, be sure that the bootstrap or the
* bootloader doesn't write to this register.
+ * From SAMA5D4, the Watchdog Timer Mode Register can be written
+ * until a LOCKMR command is issued in WDT_CR.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -80,6 +83,11 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
#define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
+
+struct at91wdt_variant {
+ bool mr_writable;
+};
+
struct at91wdt {
struct watchdog_device wdd;
void __iomem *base;
@@ -90,6 +98,9 @@ struct at91wdt {
unsigned long heartbeat; /* WDT heartbeat in jiffies */
bool nowayout;
unsigned int irq;
+ bool use_timer;
+ bool enabled;
+ struct at91wdt_variant *drv_data;
};
/* ......................................................................... */
@@ -133,21 +144,67 @@ static void at91_ping(unsigned long data)
static int at91_wdt_start(struct watchdog_device *wdd)
{
struct at91wdt *wdt = to_wdt(wdd);
- /* calculate when the next userspace timeout will be */
- wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
+ u32 reg;
+
+ if (wdt->drv_data->mr_writable) {
+ reg = wdt_read(wdt, AT91_WDT_MR);
+ reg &= ~AT91_WDT_WDDIS;
+ wdt_write(wdt, AT91_WDT_MR, reg);
+ } else {
+ /* calculate when the next userspace timeout will be */
+ wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
+ }
+
return 0;
}
static int at91_wdt_stop(struct watchdog_device *wdd)
{
- /* The watchdog timer hardware can not be stopped... */
+ struct at91wdt *wdt = to_wdt(wdd);
+ u32 reg;
+
+ if (wdt->drv_data->mr_writable) {
+ reg = wdt_read(wdt, AT91_WDT_MR);
+ reg |= AT91_WDT_WDDIS;
+ wdt_write(wdt, AT91_WDT_MR, reg);
+ }
+
+ return 0;
+}
+
+static int at91_wdt_ping(struct watchdog_device *wdd)
+{
+ struct at91wdt *wdt = to_wdt(wdd);
+
+ wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
+
return 0;
}
static int at91_wdt_set_timeout(struct watchdog_device *wdd, unsigned int new_timeout)
{
- wdd->timeout = new_timeout;
- return at91_wdt_start(wdd);
+ struct at91wdt *wdt = to_wdt(wdd);
+ u32 reg, timeout;
+
+ if (wdt->drv_data->mr_writable) {
+ timeout = secs_to_ticks(new_timeout);
+ if (timeout > WDT_COUNTER_MAX_TICKS)
+ return -EINVAL;
+
+ reg = wdt_read(wdt, AT91_WDT_MR);
+ reg &= ~AT91_WDT_WDV;
+ reg |= AT91_WDT_WDV_(timeout);
+ reg &= ~AT91_WDT_WDD;
+ reg |= AT91_WDT_WDD_(timeout);
+ wdt_write(wdt, AT91_WDT_MR, reg);
+
+ wdd->timeout = new_timeout;
+
+ return 0;
+ } else {
+ wdd->timeout = new_timeout;
+ return at91_wdt_start(wdd);
+ }
}
static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
@@ -161,50 +218,65 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
unsigned long max_heartbeat;
struct device *dev = &pdev->dev;
- tmp = wdt_read(wdt, AT91_WDT_MR);
- if ((tmp & mask) != (wdt->mr & mask)) {
- if (tmp == WDT_MR_RESET) {
- wdt_write(wdt, AT91_WDT_MR, wdt->mr);
- tmp = wdt_read(wdt, AT91_WDT_MR);
+ if (wdt->drv_data->mr_writable) {
+ wdt->use_timer = false;
+
+ wdt_write(wdt, AT91_WDT_MR, wdt->mr | AT91_WDT_WDDIS);
+ } else {
+ wdt->use_timer = true;
+
+ tmp = wdt_read(wdt, AT91_WDT_MR);
+ if ((tmp & mask) != (wdt->mr & mask)) {
+ if (tmp == WDT_MR_RESET) {
+ wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+ tmp = wdt_read(wdt, AT91_WDT_MR);
+ }
}
- }
- if (tmp & AT91_WDT_WDDIS) {
- if (wdt->mr & AT91_WDT_WDDIS)
- return 0;
- dev_err(dev, "watchdog is disabled\n");
- return -EINVAL;
+ if (tmp & AT91_WDT_WDDIS) {
+ if (wdt->mr & AT91_WDT_WDDIS)
+ return 0;
+
+ dev_err(dev, "watchdog is disabled\n");
+ return -EINVAL;
+ }
}
- value = tmp & AT91_WDT_WDV;
- delta = (tmp & AT91_WDT_WDD) >> 16;
+ tmp = wdt_read(wdt, AT91_WDT_MR);
+ wdt->enabled = (tmp & AT91_WDT_WDDIS) ? false : true;
- if (delta < value)
- min_heartbeat = ticks_to_hz_roundup(value - delta);
+ if (wdt->use_timer) {
+ value = tmp & AT91_WDT_WDV;
+ delta = (tmp & AT91_WDT_WDD) >> 16;
- max_heartbeat = ticks_to_hz_rounddown(value);
- if (!max_heartbeat) {
- dev_err(dev,
- "heartbeat is too small for the system to handle it correctly\n");
- return -EINVAL;
- }
+ if (delta < value)
+ min_heartbeat = ticks_to_hz_roundup(value - delta);
- /*
- * Try to reset the watchdog counter 4 or 2 times more often than
- * actually requested, to avoid spurious watchdog reset.
- * If this is not possible because of the min_heartbeat value, reset
- * it at the min_heartbeat period.
- */
- if ((max_heartbeat / 4) >= min_heartbeat)
- wdt->heartbeat = max_heartbeat / 4;
- else if ((max_heartbeat / 2) >= min_heartbeat)
- wdt->heartbeat = max_heartbeat / 2;
- else
- wdt->heartbeat = min_heartbeat;
-
- if (max_heartbeat < min_heartbeat + 4)
- dev_warn(dev,
- "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
+ max_heartbeat = ticks_to_hz_rounddown(value);
+ if (!max_heartbeat) {
+ dev_err(dev,
+ "heartbeat is too small for the system to handle it correctly\n");
+ return -EINVAL;
+ }
+
+ /*
+ * Try to reset the watchdog counter 4 or 2 times more often than
+ * actually requested, to avoid spurious watchdog reset.
+ * If this is not possible because of the min_heartbeat value, reset
+ * it at the min_heartbeat period.
+ */
+ if ((max_heartbeat / 4) >= min_heartbeat)
+ wdt->heartbeat = max_heartbeat / 4;
+ else if ((max_heartbeat / 2) >= min_heartbeat)
+ wdt->heartbeat = max_heartbeat / 2;
+ else
+ wdt->heartbeat = min_heartbeat;
+
+ if (max_heartbeat < min_heartbeat + 4) {
+ dev_warn(dev,
+ "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n");
+ }
+ }
if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
err = request_irq(wdt->irq, wdt_interrupt,
@@ -215,21 +287,24 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
return err;
}
- if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
- dev_warn(dev,
- "watchdog already configured differently (mr = %x expecting %x)\n",
- tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
+ if (wdt->use_timer) {
+ if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask)) {
+ dev_warn(dev,
+ "watchdog already configured differently (mr = %x expecting %x)\n",
+ tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
+ }
- setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
+ setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
- /*
- * Use min_heartbeat the first time to avoid spurious watchdog reset:
- * we don't know for how long the watchdog counter is running, and
- * - resetting it right now might trigger a watchdog fault reset
- * - waiting for heartbeat time might lead to a watchdog timeout
- * reset
- */
- mod_timer(&wdt->timer, jiffies + min_heartbeat);
+ /*
+ * Use min_heartbeat the first time to avoid spurious watchdog reset:
+ * we don't know for how long the watchdog counter is running, and
+ * - resetting it right now might trigger a watchdog fault reset
+ * - waiting for heartbeat time might lead to a watchdog timeout
+ * reset
+ */
+ mod_timer(&wdt->timer, jiffies + min_heartbeat);
+ }
/* Try to set timeout from device tree first */
if (watchdog_init_timeout(&wdt->wdd, 0, dev))
@@ -239,12 +314,14 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
if (err)
goto out_stop_timer;
- wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;
+ if (wdt->use_timer)
+ wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;
return 0;
out_stop_timer:
- del_timer(&wdt->timer);
+ if (wdt->use_timer)
+ del_timer(&wdt->timer);
return err;
}
@@ -256,13 +333,54 @@ static const struct watchdog_info at91_wdt_info = {
WDIOF_MAGICCLOSE,
};
-static const struct watchdog_ops at91_wdt_ops = {
+static struct watchdog_ops at91_wdt_ops = {
.owner = THIS_MODULE,
.start = at91_wdt_start,
.stop = at91_wdt_stop,
.set_timeout = at91_wdt_set_timeout,
};
+static const struct at91wdt_variant drv_data_at91sam9260 = {
+ .mr_writable = false,
+};
+
+#if defined(CONFIG_OF)
+static const struct at91wdt_variant drv_data_sama5d4 = {
+ .mr_writable = true,
+};
+
+static const struct of_device_id at91_wdt_dt_ids[] = {
+ { .compatible = "atmel,at91sam9260-wdt",
+ .data = &drv_data_at91sam9260 },
+ { .compatible = "atmel,sama5d4-wdt",
+ .data = &drv_data_sama5d4 },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
+#endif
+
+static const struct platform_device_id at91wdt_ids[] = {
+ {
+ .name = "at91_wdt",
+ .driver_data = (unsigned long)&drv_data_at91sam9260,
+ },
+ {}
+};
+MODULE_DEVICE_TABLE(platform, at91wdt_ids);
+
+static struct at91wdt_variant *at91wdt_get_drv_data(struct platform_device *pdev)
+{
+ const struct of_device_id *match;
+
+ if (pdev->dev.of_node) {
+ match = of_match_node(at91_wdt_dt_ids, pdev->dev.of_node);
+ return (struct at91wdt_variant *)match->data;
+ } else {
+ return (struct at91wdt_variant *)
+ platform_get_device_id(pdev)->driver_data;
+ }
+}
+
#if defined(CONFIG_OF)
static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
{
@@ -336,6 +454,10 @@ static int __init at91wdt_probe(struct platform_device *pdev)
if (!wdt)
return -ENOMEM;
+ wdt->drv_data = at91wdt_get_drv_data(pdev);
+ if (wdt->drv_data->mr_writable)
+ at91_wdt_ops.ping = at91_wdt_ping;
+
wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN | AT91_WDT_WDD |
AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
wdt->mr_mask = 0x3FFFFFFF;
@@ -364,8 +486,12 @@ static int __init at91wdt_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, wdt);
- pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
- wdt->wdd.timeout, wdt->nowayout);
+ if (wdt->enabled) {
+ dev_info(&pdev->dev, "enabled (heartbeat=%d sec, nowayout=%d)\n",
+ wdt->wdd.timeout, wdt->nowayout);
+ } else {
+ dev_info(&pdev->dev, "not enabled\n");
+ }
return 0;
}
@@ -381,15 +507,6 @@ static int __exit at91wdt_remove(struct platform_device *pdev)
return 0;
}
-#if defined(CONFIG_OF)
-static const struct of_device_id at91_wdt_dt_ids[] = {
- { .compatible = "atmel,at91sam9260-wdt" },
- { /* sentinel */ }
-};
-
-MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
-#endif
-
static struct platform_driver at91wdt_driver = {
.remove = __exit_p(at91wdt_remove),
.driver = {
diff --git a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
index c6fbb2e6..79add4f 100644
--- a/drivers/watchdog/at91sam9_wdt.h
+++ b/drivers/watchdog/at91sam9_wdt.h
@@ -22,11 +22,15 @@
#define AT91_WDT_MR 0x04 /* Watchdog Mode Register */
#define AT91_WDT_WDV (0xfff << 0) /* Counter Value */
+#define AT91_WDT_WDV_MSK (0xfff)
+#define AT91_WDT_WDV_(x) (((x) & AT91_WDT_WDV_MSK) << 0)
#define AT91_WDT_WDFIEN (1 << 12) /* Fault Interrupt Enable */
#define AT91_WDT_WDRSTEN (1 << 13) /* Reset Processor */
#define AT91_WDT_WDRPROC (1 << 14) /* Timer Restart */
#define AT91_WDT_WDDIS (1 << 15) /* Watchdog Disable */
#define AT91_WDT_WDD (0xfff << 16) /* Delta Value */
+#define AT91_WDT_WDD_MSK (0xfff)
+#define AT91_WDT_WDD_(x) (((x) & AT91_WDT_WDD_MSK) << 16)
#define AT91_WDT_WDDBGHLT (1 << 28) /* Debug Halt */
#define AT91_WDT_WDIDLEHLT (1 << 29) /* Idle Halt */
--
1.7.9.5
--
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