[PATCH v4 3/3] watchdog: sama5d4_wdt: addition of sam9x60 compatible watchdog

[<Eugen.Hristev@microchip.com>]

From: Eugen Hristev <eugen.hristev@microchip.com>

Add support for SAM9X60 WDT into sama5d4_wdt.
This means that this driver gets a flag inside the data struct
that represents the sam9x60 support.
This flag differentiates between the two hardware blocks, and is set
according to the compatible of the driver instantiation.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v4:
- check compatible with different of_ function
- call irq parse and map only if need_irq
- changed tabbing in struct defintion

Changes in v3:
- changed need_irq to bool, instead of a single bit variable.
- the platform data config struct is gone now, changed to a pointer to a bool
to have the sam9x60_support as 'true', pointing to a static bool with true value.
Can have a better solution than this ?
- the specific sam9x60_support flag is assigned at probe time, corresponding
to the flag value in .data

 drivers/watchdog/at91sam9_wdt.h |  14 ++++++
 drivers/watchdog/sama5d4_wdt.c  | 109 +++++++++++++++++++++++++++++++---------
 2 files changed, 98 insertions(+), 25 deletions(-)

diff --git a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
index abfe34d..4b3bd1d 100644
--- a/drivers/watchdog/at91sam9_wdt.h
+++ b/drivers/watchdog/at91sam9_wdt.h
@@ -24,7 +24,10 @@
 #define AT91_WDT_MR		0x04			/* Watchdog Mode Register */
 #define  AT91_WDT_WDV		(0xfffUL << 0)		/* Counter Value */
 #define  AT91_WDT_SET_WDV(x)	((x) & AT91_WDT_WDV)
+#define  AT91_SAM9X60_PERIODRST	BIT(4)		/* Period Reset */
+#define  AT91_SAM9X60_RPTHRST	BIT(5)		/* Minimum Restart Period */
 #define  AT91_WDT_WDFIEN	BIT(12)		/* Fault Interrupt Enable */
+#define  AT91_SAM9X60_WDDIS	BIT(12)		/* Watchdog Disable */
 #define  AT91_WDT_WDRSTEN	BIT(13)		/* Reset Processor */
 #define  AT91_WDT_WDRPROC	BIT(14)		/* Timer Restart */
 #define  AT91_WDT_WDDIS		BIT(15)		/* Watchdog Disable */
@@ -37,4 +40,15 @@
 #define  AT91_WDT_WDUNF		BIT(0)		/* Watchdog Underflow */
 #define  AT91_WDT_WDERR		BIT(1)		/* Watchdog Error */
 
+#define AT91_SAM9X60_VR		0x08			/* Watchdog Timer Value Register */
+
+#define AT91_SAM9X60_WLR		0x0c
+#define  AT91_SAM9X60_COUNTER	(0xfffUL << 0)		/* Watchdog Period Value */
+#define  AT91_SAM9X60_SET_COUNTER(x)	((x) & AT91_SAM9X60_COUNTER)
+
+#define AT91_SAM9X60_IER		0x14		/* Interrupt Enable Register */
+#define  AT91_SAM9X60_PERINT		BIT(0)		/* Period Interrupt Enable */
+#define AT91_SAM9X60_IDR		0x18		/* Interrupt Disable Register */
+#define AT91_SAM9X60_ISR		0x1c		/* Interrupt Status Register */
+
 #endif
diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index d193a60..e5d11d6 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -2,7 +2,7 @@
 /*
  * Driver for Atmel SAMA5D4 Watchdog Timer
  *
- * Copyright (C) 2015 Atmel Corporation
+ * Copyright (C) 2015-2019 Microchip Technology Inc. and its subsidiaries
  */
 
 #include <linux/delay.h>
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
@@ -29,7 +30,10 @@ struct sama5d4_wdt {
 	struct watchdog_device	wdd;
 	void __iomem		*reg_base;
 	u32			mr;
+	u32			ir;
 	unsigned long		last_ping;
+	bool			need_irq;
+	bool			sam9x60_support;
 };
 
 static int wdt_timeout;
@@ -78,7 +82,12 @@ static int sama5d4_wdt_start(struct watchdog_device *wdd)
 {
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 
-	wdt->mr &= ~AT91_WDT_WDDIS;
+	if (wdt->sam9x60_support) {
+		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
+		wdt->mr &= ~AT91_SAM9X60_WDDIS;
+	} else {
+		wdt->mr &= ~AT91_WDT_WDDIS;
+	}
 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 
 	return 0;
@@ -88,7 +97,12 @@ static int sama5d4_wdt_stop(struct watchdog_device *wdd)
 {
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 
-	wdt->mr |= AT91_WDT_WDDIS;
+	if (wdt->sam9x60_support) {
+		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
+		wdt->mr |= AT91_SAM9X60_WDDIS;
+	} else {
+		wdt->mr |= AT91_WDT_WDDIS;
+	}
 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 
 	return 0;
@@ -109,6 +123,14 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 	u32 value = WDT_SEC2TICKS(timeout);
 
+	if (wdt->sam9x60_support) {
+		wdt_write(wdt, AT91_SAM9X60_WLR,
+			  AT91_SAM9X60_SET_COUNTER(value));
+
+		wdd->timeout = timeout;
+		return 0;
+	}
+
 	wdt->mr &= ~AT91_WDT_WDV;
 	wdt->mr |= AT91_WDT_SET_WDV(value);
 
@@ -143,8 +165,14 @@ static const struct watchdog_ops sama5d4_wdt_ops = {
 static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 {
 	struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
+	u32 reg;
 
-	if (wdt_read(wdt, AT91_WDT_SR)) {
+	if (wdt->sam9x60_support)
+		reg = wdt_read(wdt, AT91_SAM9X60_ISR);
+	else
+		reg = wdt_read(wdt, AT91_WDT_SR);
+
+	if (reg) {
 		pr_crit("Atmel Watchdog Software Reset\n");
 		emergency_restart();
 		pr_crit("Reboot didn't succeed\n");
@@ -157,13 +185,14 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 {
 	const char *tmp;
 
-	wdt->mr = AT91_WDT_WDDIS;
+	if (wdt->sam9x60_support)
+		wdt->mr = AT91_SAM9X60_WDDIS;
+	else
+		wdt->mr = AT91_WDT_WDDIS;
 
 	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 	    !strcmp(tmp, "software"))
-		wdt->mr |= AT91_WDT_WDFIEN;
-	else
-		wdt->mr |= AT91_WDT_WDRSTEN;
+		wdt->need_irq = true;
 
 	if (of_property_read_bool(np, "atmel,idle-halt"))
 		wdt->mr |= AT91_WDT_WDIDLEHLT;
@@ -176,21 +205,46 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 
 static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 {
-	u32 reg;
+	u32 reg, val;
+
+	val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
 	/*
 	 * When booting and resuming, the bootloader may have changed the
 	 * watchdog configuration.
 	 * If the watchdog is already running, we can safely update it.
 	 * Else, we have to disable it properly.
 	 */
-	if (wdt_enabled) {
-		wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
-	} else {
+	if (!wdt_enabled) {
 		reg = wdt_read(wdt, AT91_WDT_MR);
-		if (!(reg & AT91_WDT_WDDIS))
+		if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
+			wdt_write_nosleep(wdt, AT91_WDT_MR,
+					  reg | AT91_SAM9X60_WDDIS);
+		else if (!wdt->sam9x60_support &&
+			 (!(reg & AT91_WDT_WDDIS)))
 			wdt_write_nosleep(wdt, AT91_WDT_MR,
 					  reg | AT91_WDT_WDDIS);
 	}
+
+	if (wdt->sam9x60_support) {
+		if (wdt->need_irq)
+			wdt->ir = AT91_SAM9X60_PERINT;
+		else
+			wdt->mr |= AT91_SAM9X60_PERIODRST;
+
+		wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
+		wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val));
+	} else {
+		wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
+		wdt->mr |= AT91_WDT_SET_WDV(val);
+
+		if (wdt->need_irq)
+			wdt->mr |= AT91_WDT_WDFIEN;
+		else
+			wdt->mr |= AT91_WDT_WDRSTEN;
+	}
+
+	wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
+
 	return 0;
 }
 
@@ -201,7 +255,6 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	struct sama5d4_wdt *wdt;
 	void __iomem *regs;
 	u32 irq = 0;
-	u32 timeout;
 	int ret;
 
 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
@@ -215,6 +268,8 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	wdd->min_timeout = MIN_WDT_TIMEOUT;
 	wdd->max_timeout = MAX_WDT_TIMEOUT;
 	wdt->last_ping = jiffies;
+	wdt->sam9x60_support = of_device_is_compatible(dev->of_node,
+						       "microchip,sam9x60-wdt");
 
 	watchdog_set_drvdata(wdd, wdt);
 
@@ -224,15 +279,19 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 
 	wdt->reg_base = regs;
 
-	irq = irq_of_parse_and_map(dev->of_node, 0);
-	if (!irq)
-		dev_warn(dev, "failed to get IRQ from DT\n");
-
 	ret = of_sama5d4_wdt_init(dev->of_node, wdt);
 	if (ret)
 		return ret;
 
-	if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
+	if (wdt->need_irq) {
+		irq = irq_of_parse_and_map(dev->of_node, 0);
+		if (!irq) {
+			dev_warn(dev, "failed to get IRQ from DT\n");
+			wdt->need_irq = false;
+		}
+	}
+
+	if (wdt->need_irq) {
 		ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
 				       IRQF_SHARED | IRQF_IRQPOLL |
 				       IRQF_NO_SUSPEND, pdev->name, pdev);
@@ -244,11 +303,6 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 
 	watchdog_init_timeout(wdd, wdt_timeout, dev);
 
-	timeout = WDT_SEC2TICKS(wdd->timeout);
-
-	wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
-	wdt->mr |= AT91_WDT_SET_WDV(timeout);
-
 	ret = sama5d4_wdt_init(wdt);
 	if (ret)
 		return ret;
@@ -269,7 +323,12 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 }
 
 static const struct of_device_id sama5d4_wdt_of_match[] = {
-	{ .compatible = "atmel,sama5d4-wdt", },
+	{
+		.compatible = "atmel,sama5d4-wdt",
+	},
+	{
+		.compatible = "microchip,sam9x60-wdt",
+	},
 	{ }
 };
 MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
-- 
2.7.4