[PATCH V2 3/4] watchdog: imx_sc: Add pretimeout support

[Anson Huang]

i.MX system controller watchdog can support pretimeout IRQ
via general SCU MU IRQ, it depends on IMX_SCU and driver MUST
be probed after SCU IPC ready, then enable corresponding SCU
IRQ group and register SCU IRQ notifier, when watchdog pretimeout
IRQ fires, SCU MU IRQ will be handled and watchdog pretimeout
notifier will be called to handle the event.

Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
---
Changes since V1:
        - improve imx_sc_wdt_set_pretimeout() return value and assignment sequence;
        - improve coding and logic of imx_sc_wdt_notify() function;
        - use devm_add_action() instead of .remove;
        - add local data structure to include notifier block;
        - remove the defer probe check since the watchdog node is now moved into SCU node;
        - ONLY enable pretimeout function after everything about IRQ are successfully.
---
 drivers/watchdog/Kconfig      |   1 +
 drivers/watchdog/imx_sc_wdt.c | 114 ++++++++++++++++++++++++++++++++++--------
 2 files changed, 95 insertions(+), 20 deletions(-)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 44a3158..f2c2c1a 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -644,6 +644,7 @@ config IMX2_WDT
 config IMX_SC_WDT
 	tristate "IMX SC Watchdog"
 	depends on HAVE_ARM_SMCCC
+	depends on IMX_SCU
 	select WATCHDOG_CORE
 	help
 	  This is the driver for the system controller watchdog
diff --git a/drivers/watchdog/imx_sc_wdt.c b/drivers/watchdog/imx_sc_wdt.c
index 49848b6..d8493a3 100644
--- a/drivers/watchdog/imx_sc_wdt.c
+++ b/drivers/watchdog/imx_sc_wdt.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/arm-smccc.h>
+#include <linux/firmware/imx/sci.h>
 #include <linux/io.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -33,11 +34,19 @@
 
 #define SC_TIMER_WDOG_ACTION_PARTITION	0
 
+#define SC_IRQ_WDOG			1
+#define SC_IRQ_GROUP_WDOG		1
+
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0000);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+struct imx_sc_wdt_device {
+	struct watchdog_device wdd;
+	struct notifier_block wdt_notifier;
+};
+
 static int imx_sc_wdt_ping(struct watchdog_device *wdog)
 {
 	struct arm_smccc_res res;
@@ -85,24 +94,66 @@ static int imx_sc_wdt_set_timeout(struct watchdog_device *wdog,
 	return res.a0 ? -EACCES : 0;
 }
 
+static int imx_sc_wdt_set_pretimeout(struct watchdog_device *wdog,
+				     unsigned int pretimeout)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(IMX_SIP_TIMER, IMX_SIP_TIMER_SET_PRETIME_WDOG,
+		      pretimeout * 1000, 0, 0, 0, 0, 0, &res);
+	if (res.a0)
+		return -EACCES;
+
+	wdog->pretimeout = pretimeout;
+
+	return 0;
+}
+
+static int imx_sc_wdt_notify(struct notifier_block *nb,
+			     unsigned long event, void *group)
+{
+	struct imx_sc_wdt_device *imx_sc_wdd =
+				 container_of(nb,
+					      struct imx_sc_wdt_device,
+					      wdt_notifier);
+
+	if (event & SC_IRQ_WDOG &&
+	    *(u8 *)group == SC_IRQ_GROUP_WDOG)
+		watchdog_notify_pretimeout(&imx_sc_wdd->wdd);
+
+	return 0;
+}
+
+static void imx_sc_wdt_action(void *data)
+{
+	struct notifier_block *wdt_notifier = data;
+
+	imx_scu_irq_unregister_notifier(wdt_notifier);
+	imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
+				 SC_IRQ_WDOG,
+				 false);
+}
+
 static const struct watchdog_ops imx_sc_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = imx_sc_wdt_start,
 	.stop  = imx_sc_wdt_stop,
 	.ping  = imx_sc_wdt_ping,
 	.set_timeout = imx_sc_wdt_set_timeout,
+	.set_pretimeout = imx_sc_wdt_set_pretimeout,
 };
 
-static const struct watchdog_info imx_sc_wdt_info = {
+static struct watchdog_info imx_sc_wdt_info = {
 	.identity	= "i.MX SC watchdog timer",
 	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
-			  WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT,
+			  WDIOF_MAGICCLOSE,
 };
 
 static int imx_sc_wdt_probe(struct platform_device *pdev)
 {
+	struct imx_sc_wdt_device *imx_sc_wdd;
+	struct watchdog_device *wdog;
 	struct device *dev = &pdev->dev;
-	struct watchdog_device *imx_sc_wdd;
 	int ret;
 
 	imx_sc_wdd = devm_kzalloc(dev, sizeof(*imx_sc_wdd), GFP_KERNEL);
@@ -111,42 +162,65 @@ static int imx_sc_wdt_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, imx_sc_wdd);
 
-	imx_sc_wdd->info = &imx_sc_wdt_info;
-	imx_sc_wdd->ops = &imx_sc_wdt_ops;
-	imx_sc_wdd->min_timeout = 1;
-	imx_sc_wdd->max_timeout = MAX_TIMEOUT;
-	imx_sc_wdd->parent = dev;
-	imx_sc_wdd->timeout = DEFAULT_TIMEOUT;
+	wdog = &imx_sc_wdd->wdd;
+	wdog->info = &imx_sc_wdt_info;
+	wdog->ops = &imx_sc_wdt_ops;
+	wdog->min_timeout = 1;
+	wdog->max_timeout = MAX_TIMEOUT;
+	wdog->parent = dev;
+	wdog->timeout = DEFAULT_TIMEOUT;
 
-	watchdog_init_timeout(imx_sc_wdd, 0, dev);
-	watchdog_stop_on_reboot(imx_sc_wdd);
-	watchdog_stop_on_unregister(imx_sc_wdd);
+	watchdog_init_timeout(wdog, 0, dev);
+	watchdog_stop_on_reboot(wdog);
+	watchdog_stop_on_unregister(wdog);
 
-	ret = devm_watchdog_register_device(dev, imx_sc_wdd);
+	ret = devm_watchdog_register_device(dev, wdog);
 	if (ret) {
 		dev_err(dev, "Failed to register watchdog device\n");
 		return ret;
 	}
 
-	return 0;
+	ret = imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
+				       SC_IRQ_WDOG,
+				       true);
+	if (ret) {
+		dev_warn(dev, "Enable irq failed, pretimeout NOT supported\n");
+		return 0;
+	}
+
+	imx_sc_wdd->wdt_notifier.notifier_call = imx_sc_wdt_notify;
+	ret = imx_scu_irq_register_notifier(&imx_sc_wdd->wdt_notifier);
+	if (ret) {
+		imx_scu_irq_group_enable(SC_IRQ_GROUP_WDOG,
+					 SC_IRQ_WDOG,
+					 false);
+		dev_warn(dev,
+			 "Register irq notifier failed, pretimeout NOT supported\n");
+		return 0;
+	}
+
+	imx_sc_wdt_info.options |= WDIOF_PRETIMEOUT;
+	ret = devm_add_action(dev, imx_sc_wdt_action,
+			      &imx_sc_wdd->wdt_notifier);
+	return ret;
 }
 
 static int __maybe_unused imx_sc_wdt_suspend(struct device *dev)
 {
-	struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
+	struct imx_sc_wdt_device *imx_sc_wdd = dev_get_drvdata(dev);
 
-	if (watchdog_active(imx_sc_wdd))
-		imx_sc_wdt_stop(imx_sc_wdd);
+	if (watchdog_active(&imx_sc_wdd->wdd))
+		imx_sc_wdt_stop(&imx_sc_wdd->wdd);
 
 	return 0;
 }
 
 static int __maybe_unused imx_sc_wdt_resume(struct device *dev)
 {
-	struct watchdog_device *imx_sc_wdd = dev_get_drvdata(dev);
+	struct imx_sc_wdt_device *imx_sc_wdd = dev_get_drvdata(dev);
 
-	if (watchdog_active(imx_sc_wdd))
-		imx_sc_wdt_start(imx_sc_wdd);
+	if (watchdog_active(&imx_sc_wdd->wdd))
+		imx_sc_wdt_start(&imx_sc_wdd->wdd);
 
 	return 0;
 }
-- 
2.7.4