[PATCH v2 04/15] watchdog: lantiq: access boot cause register through regmap

[Hauke Mehrtens <hauke@xxxxxxxxxx>]

This patch avoids accessing the function ltq_reset_cause() and directly
accesses the register given over the syscon interface. The syscon
interface will be implemented for the xway SoCs for the falcon SoCs the
ltq_reset_cause() function never worked, because a wrong offset was used.

Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
Acked-by: Guenter Roeck <linux@xxxxxxxxxxx>
---
 drivers/watchdog/lantiq_wdt.c | 48 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/lantiq_wdt.c b/drivers/watchdog/lantiq_wdt.c
index e0823677d8c1..d0447d8cabd0 100644
--- a/drivers/watchdog/lantiq_wdt.c
+++ b/drivers/watchdog/lantiq_wdt.c
@@ -4,6 +4,7 @@
  *  by the Free Software Foundation.
  *
  *  Copyright (C) 2010 John Crispin <john@xxxxxxxxxxx>
+ *  Copyright (C) 2017 Hauke Mehrtens <hauke@xxxxxxxxxx>
  *  Based on EP93xx wdt driver
  */
 
@@ -17,9 +18,14 @@
 #include <linux/uaccess.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
 
 #include <lantiq_soc.h>
 
+#define LTQ_RST_CAUSE_WDT_XRX		BIT(31)
+#define LTQ_RST_CAUSE_WDT_FALCON	0x02
+
 /*
  * Section 3.4 of the datasheet
  * The password sequence protects the WDT control register from unintended
@@ -186,6 +192,40 @@ static struct miscdevice ltq_wdt_miscdev = {
 	.fops	= &ltq_wdt_fops,
 };
 
+static void ltq_set_wdt_bootstatus(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct regmap *rcu_regmap;
+	u32 status_reg_offset;
+	u32 val;
+	int err;
+
+	rcu_regmap = syscon_regmap_lookup_by_phandle(np,
+						     "lantiq,rcu-syscon");
+	if (IS_ERR_OR_NULL(rcu_regmap))
+		return;
+
+	err = of_property_read_u32_index(np, "lantiq,rcu-syscon", 1,
+					 &status_reg_offset);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to get RCU reg offset\n");
+		return;
+	}
+
+	err = regmap_read(rcu_regmap, status_reg_offset, &val);
+	if (err)
+		return;
+
+	/* find out if the watchdog caused the last reboot */
+	if (of_device_is_compatible(np, "lantiq,wdt-xrx100")) {
+		if (val & LTQ_RST_CAUSE_WDT_XRX)
+			ltq_wdt_bootstatus = WDIOF_CARDRESET;
+	} else if  (of_device_is_compatible(np, "lantiq,wdt-falcon")) {
+		if ((val & 0x7) == LTQ_RST_CAUSE_WDT_FALCON)
+			ltq_wdt_bootstatus = WDIOF_CARDRESET;
+	}
+}
+
 static int
 ltq_wdt_probe(struct platform_device *pdev)
 {
@@ -205,9 +245,7 @@ ltq_wdt_probe(struct platform_device *pdev)
 	ltq_io_region_clk_rate = clk_get_rate(clk);
 	clk_put(clk);
 
-	/* find out if the watchdog caused the last reboot */
-	if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
-		ltq_wdt_bootstatus = WDIOF_CARDRESET;
+	ltq_set_wdt_bootstatus(pdev);
 
 	dev_info(&pdev->dev, "Init done\n");
 	return misc_register(&ltq_wdt_miscdev);
@@ -222,7 +260,9 @@ ltq_wdt_remove(struct platform_device *pdev)
 }
 
 static const struct of_device_id ltq_wdt_match[] = {
-	{ .compatible = "lantiq,wdt" },
+	{ .compatible = "lantiq,wdt"},
+	{ .compatible = "lantiq,wdt-xrx100"},
+	{ .compatible = "lantiq,wdt-falcon"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, ltq_wdt_match);
-- 
2.11.0