[RFC v4 13/26] watchdog: renesas_wdt: Add restart handler

[fabrizio.castro@bp.renesas.com (Fabrizio Castro)]

On iWave's boards iwg20d and iwg22d the only way to reboot the system is
by means of the watchdog.
This patch adds a restart handler to rwdt_ops, and also makes sure we
keep its priority to a medium level, in order to not override other more
effective handlers.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
---
v3->v4:
* New patch spawn out from patch 12/16. The restart handler on Gen3 is
  controversial, hopefully this patch will help finalizing the discussion.

 drivers/watchdog/renesas_wdt.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index 0a1a402..6d1c4b9 100644
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -107,6 +107,24 @@ static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
 	return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
 }
 
+static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
+			void *data)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	pm_runtime_get_sync(wdev->parent);
+
+	rwdt_write(priv, 0x00, RWTCSRB);
+	rwdt_write(priv, 0x00, RWTCSRA);
+	rwdt_write(priv, 0xffff, RWTCNT);
+
+	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
+		cpu_relax();
+
+	rwdt_write(priv, 0x80, RWTCSRA);
+	return 0;
+}
+
 static const struct watchdog_info rwdt_ident = {
 	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
 	.identity = "Renesas WDT Watchdog",
@@ -118,6 +136,7 @@ static const struct watchdog_ops rwdt_ops = {
 	.stop = rwdt_stop,
 	.ping = rwdt_init_timeout,
 	.get_timeleft = rwdt_get_timeleft,
+	.restart = rwdt_restart,
 };
 
 static int rwdt_probe(struct platform_device *pdev)
@@ -176,6 +195,7 @@ static int rwdt_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, priv);
 	watchdog_set_drvdata(&priv->wdev, priv);
 	watchdog_set_nowayout(&priv->wdev, nowayout);
+	watchdog_set_restart_priority(&priv->wdev, 128);
 
 	/* This overrides the default timeout only if DT configuration was found */
 	ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev);
-- 
2.7.4