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
(cherry picked from commit c11b5748efb4f3cbf51bc4f25e5b59f3bddfffa8)
Reviewed-on: https://git-master.nvidia.com/r/1526898
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>

1 files changed, 27 insertions, 9 deletions

diff --git a/drivers/watchdog/tegra_wdt.c b/drivers/watchdog/tegra_wdt.c
index 0a2b897f1..3871cd0cf 100644
--- 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;
 }