watchdog: tegra: revamp timeout calculation and usage

 - update calculation of timeout for TIMER_PTV,
 - update watchdog ping to first disable timer, update timeut value
   and then restart the timer.
 - init watchdog timeout using watchdog_init_timeout
 - program default trigger period in watchdog configuration regiter

Bug 200314562

Change-Id: Iec9e5a94c995653e5a3c653eccfa23a0877ae2e9
Signed-off-by: Shreshtha SAHU <ssahu@nvidia.com>
Reviewed-on: https://git-master/r/1515195
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Tested-by: Bibek Basu <bbasu@nvidia.com>

diff --git a/drivers/watchdog/tegra_wdt.c b/drivers/watchdog/tegra_wdt.c
index 0a2b897f182543f4d95872706550193492009223..3871cd0cfdc2e4993a659e1c12b4b8b4591a9c18 100644 (file)
--- a/drivers/watchdog/tegra_wdt.c
+++ b/drivers/watchdog/tegra_wdt.c
@@ -68,6 +68,14 @@ struct tegra_wdt {
  */
 static int expiry_count = 1;
 
+/*
+ * Period value: Trigger Value is the time period and period value determines
+ * number of periods for watchdog expiration i.e. effectively after time:
+ * "period value" * "Trigger Vaue"
+ */
+#define WDT_TRG_PERIOD 1
+static int trigger_period = WDT_TRG_PERIOD;
+
 #define WDT_HEARTBEAT 120
 static int heartbeat = WDT_HEARTBEAT;
 module_param(heartbeat, int, 0);
@@ -87,12 +95,12 @@ static int tegra_wdt_start(struct watchdog_device *wdd)
        u32 val;
 
        /*
-        * This thing has a fixed 1MHz clock.  Normally, we would set the
-        * period to 1 second by writing 1000000ul, but the watchdog system
-        * reset actually occurs on the expiry_count'th expiration of this
-        * counter, so we set the period to 1/expiry_count of this amount.
+        * The timeout needs to be divided by expiry_count here so as to
+        * keep the ultimate watchdog reset timeout the same as the program
+        * timeout requested by application. The program timeout should make
+        * sure WDT FIQ will never be asserted in a valid use case.
         */
-       val = 1000000ul / expiry_count;
+       val = (wdd->timeout * USEC_PER_SEC) / expiry_count;
        val |= (TIMER_EN | TIMER_PERIODIC);
        writel(val, wdt->tmr_regs + TIMER_PTV);
 
@@ -104,7 +112,7 @@ static int tegra_wdt_start(struct watchdog_device *wdd)
         * WDT to reset the counter before expiration, through ioctls.
         */
        val = WDT_TIMER_ID |
-             (wdd->timeout << WDT_CFG_PERIOD_SHIFT) |
+             (trigger_period << WDT_CFG_PERIOD_SHIFT) |
              WDT_CFG_PMC2CAR_RST_EN;
        writel(val, wdt->wdt_regs + WDT_CFG);
 
@@ -126,8 +134,18 @@ static int tegra_wdt_stop(struct watchdog_device *wdd)
 
 static int tegra_wdt_ping(struct watchdog_device *wdd)
 {
+       u32 val;
        struct tegra_wdt *wdt = watchdog_get_drvdata(wdd);
 
+       /* Disable timer */
+       tegra_wdt_stop(wdd);
+
+       /* Load the timeout value */
+       val = (wdd->timeout * USEC_PER_SEC) / expiry_count;
+       val |= (TIMER_EN | TIMER_PERIODIC);
+       writel(val, wdt->tmr_regs + TIMER_PTV);
+
+       /* Restart */
        writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD);
 
        return 0;
@@ -160,7 +178,6 @@ static unsigned int tegra_wdt_get_timeleft(struct watchdog_device *wdd)
 
        /* Number of expirations */
        exp = (val >> WDT_STS_EXP_SHIFT) & WDT_STS_EXP_MASK;
-
        /*
         * The entire thing is divided by expiry_count because we are ticking
         * down expiry_count times  faster due to needing to wait for the
@@ -242,6 +259,7 @@ static int tegra_wdt_probe(struct platform_device *pdev)
 
        watchdog_set_drvdata(wdd, wdt);
 
+       watchdog_init_timeout(wdd, heartbeat, &pdev->dev);
        watchdog_set_nowayout(wdd, nowayout);
 
        ret = watchdog_register_device(wdd);
@@ -254,8 +272,8 @@ static int tegra_wdt_probe(struct platform_device *pdev)
        platform_set_drvdata(pdev, wdt);
 
        dev_info(&pdev->dev,
-                "initialized (heartbeat = %d sec, nowayout = %d)\n",
-                heartbeat, nowayout);
+                "initialized (timeout = %d sec, nowayout = %d)\n",
+                wdt->wdd.timeout, nowayout);
 
        return 0;
 }