[PATCH 3/3] watchdog: mt7621-wdt: avoid globals and arch dependencies

[Sergio Paracuellos <sergio.paracuellos@gmail.com>]

MT7621 SoC has a system controller node. Watchdog need to access to reset
status register. Ralink architecture and related driver are old and from
the beggining they ar providing some architecture dependent operations
for accessing this shared registers through 'asm/mach-ralink/ralink_regs.h'
header file. However this is not ideal from a driver perspective which can
just access to the system controller registers in am arch independent way
using regmap syscon APIs. Hence, add a new structure for driver data and
use it along the code. This way architecture dependencies and global vars
are not needed anymore. Update Kconfig accordingly to select new added
dependencies and allow driver to be compile tested.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
---
 drivers/watchdog/Kconfig      |   4 +-
 drivers/watchdog/mt7621_wdt.c | 121 ++++++++++++++++++++++------------
 2 files changed, 83 insertions(+), 42 deletions(-)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index b64bc49c7..cf752ad64 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1865,7 +1865,9 @@ config GXP_WATCHDOG
 config MT7621_WDT
 	tristate "Mediatek SoC watchdog"
 	select WATCHDOG_CORE
-	depends on SOC_MT7620 || SOC_MT7621
+	select REGMAP_MMIO
+	select MFD_SYSCON
+	depends on SOC_MT7620 || SOC_MT7621 || COMPILE_TEST
 	help
 	  Hardware driver for the Mediatek/Ralink MT7621/8 SoC Watchdog Timer.
 
diff --git a/drivers/watchdog/mt7621_wdt.c b/drivers/watchdog/mt7621_wdt.c
index a8aa3522c..a7480fd2b 100644
--- a/drivers/watchdog/mt7621_wdt.c
+++ b/drivers/watchdog/mt7621_wdt.c
@@ -15,8 +15,8 @@
 #include <linux/moduleparam.h>
 #include <linux/platform_device.h>
 #include <linux/mod_devicetable.h>
-
-#include <asm/mach-ralink/ralink_regs.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
 
 #define SYSC_RSTSTAT			0x38
 #define WDT_RST_CAUSE			BIT(1)
@@ -31,8 +31,12 @@
 #define TMR1CTL_RESTART			BIT(9)
 #define TMR1CTL_PRESCALE_SHIFT		16
 
-static void __iomem *mt7621_wdt_base;
-static struct reset_control *mt7621_wdt_reset;
+struct mt7621_wdt_data {
+	void __iomem *base;
+	struct reset_control *rst;
+	struct regmap *sysc;
+	struct watchdog_device wdt;
+};
 
 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
@@ -40,27 +44,31 @@ MODULE_PARM_DESC(nowayout,
 		 "Watchdog cannot be stopped once started (default="
 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
-static inline void rt_wdt_w32(unsigned reg, u32 val)
+static inline void rt_wdt_w32(void __iomem *base, unsigned reg, u32 val)
 {
-	iowrite32(val, mt7621_wdt_base + reg);
+	iowrite32(val, base + reg);
 }
 
-static inline u32 rt_wdt_r32(unsigned reg)
+static inline u32 rt_wdt_r32(void __iomem *base, unsigned reg)
 {
-	return ioread32(mt7621_wdt_base + reg);
+	return ioread32(base + reg);
 }
 
 static int mt7621_wdt_ping(struct watchdog_device *w)
 {
-	rt_wdt_w32(TIMER_REG_TMRSTAT, TMR1CTL_RESTART);
+	struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(w);
+
+	rt_wdt_w32(drvdata->base, TIMER_REG_TMRSTAT, TMR1CTL_RESTART);
 
 	return 0;
 }
 
 static int mt7621_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
 {
+	struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(w);
+
 	w->timeout = t;
-	rt_wdt_w32(TIMER_REG_TMR1LOAD, t * 1000);
+	rt_wdt_w32(drvdata->base, TIMER_REG_TMR1LOAD, t * 1000);
 	mt7621_wdt_ping(w);
 
 	return 0;
@@ -68,36 +76,41 @@ static int mt7621_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
 
 static int mt7621_wdt_start(struct watchdog_device *w)
 {
+	struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(w);
 	u32 t;
 
 	/* set the prescaler to 1ms == 1000us */
-	rt_wdt_w32(TIMER_REG_TMR1CTL, 1000 << TMR1CTL_PRESCALE_SHIFT);
+	rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, 1000 << TMR1CTL_PRESCALE_SHIFT);
 
 	mt7621_wdt_set_timeout(w, w->timeout);
 
-	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
+	t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
 	t |= TMR1CTL_ENABLE;
-	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
+	rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);
 
 	return 0;
 }
 
 static int mt7621_wdt_stop(struct watchdog_device *w)
 {
+	struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(w);
 	u32 t;
 
 	mt7621_wdt_ping(w);
 
-	t = rt_wdt_r32(TIMER_REG_TMR1CTL);
+	t = rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL);
 	t &= ~TMR1CTL_ENABLE;
-	rt_wdt_w32(TIMER_REG_TMR1CTL, t);
+	rt_wdt_w32(drvdata->base, TIMER_REG_TMR1CTL, t);
 
 	return 0;
 }
 
-static int mt7621_wdt_bootcause(void)
+static int mt7621_wdt_bootcause(struct mt7621_wdt_data *d)
 {
-	if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
+	u32 val;
+
+	regmap_read(d->sysc, SYSC_RSTSTAT, &val);
+	if (val & WDT_RST_CAUSE)
 		return WDIOF_CARDRESET;
 
 	return 0;
@@ -105,7 +118,9 @@ static int mt7621_wdt_bootcause(void)
 
 static int mt7621_wdt_is_running(struct watchdog_device *w)
 {
-	return !!(rt_wdt_r32(TIMER_REG_TMR1CTL) & TMR1CTL_ENABLE);
+	struct mt7621_wdt_data *drvdata = watchdog_get_drvdata(w);
+
+	return !!(rt_wdt_r32(drvdata->base, TIMER_REG_TMR1CTL) & TMR1CTL_ENABLE);
 }
 
 static const struct watchdog_info mt7621_wdt_info = {
@@ -121,30 +136,44 @@ static const struct watchdog_ops mt7621_wdt_ops = {
 	.set_timeout = mt7621_wdt_set_timeout,
 };
 
-static struct watchdog_device mt7621_wdt_dev = {
-	.info = &mt7621_wdt_info,
-	.ops = &mt7621_wdt_ops,
-	.min_timeout = 1,
-	.max_timeout = 0xfffful / 1000,
-};
-
 static int mt7621_wdt_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	struct device *dev = &pdev->dev;
-	mt7621_wdt_base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(mt7621_wdt_base))
-		return PTR_ERR(mt7621_wdt_base);
+	struct watchdog_device *mt7621_wdt;
+	struct mt7621_wdt_data *drvdata;
+	int err;
+
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
 
-	mt7621_wdt_reset = devm_reset_control_get_exclusive(dev, NULL);
-	if (!IS_ERR(mt7621_wdt_reset))
-		reset_control_deassert(mt7621_wdt_reset);
+	drvdata->sysc = syscon_regmap_lookup_by_phandle(np, "ralink,sysctl");
+	if (IS_ERR(drvdata->sysc))
+		return PTR_ERR(drvdata->sysc);
 
-	mt7621_wdt_dev.bootstatus = mt7621_wdt_bootcause();
+	drvdata->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(drvdata->base))
+		return PTR_ERR(drvdata->base);
 
-	watchdog_init_timeout(&mt7621_wdt_dev, mt7621_wdt_dev.max_timeout,
-			      dev);
-	watchdog_set_nowayout(&mt7621_wdt_dev, nowayout);
-	if (mt7621_wdt_is_running(&mt7621_wdt_dev)) {
+	drvdata->rst = devm_reset_control_get_exclusive(dev, NULL);
+	if (!IS_ERR(drvdata->rst))
+		reset_control_deassert(drvdata->rst);
+
+	mt7621_wdt = &drvdata->wdt;
+	mt7621_wdt->info = &mt7621_wdt_info;
+	mt7621_wdt->ops = &mt7621_wdt_ops;
+	mt7621_wdt->min_timeout = 1;
+	mt7621_wdt->max_timeout = 0xfffful / 1000;
+	mt7621_wdt->parent = dev;
+
+	mt7621_wdt->bootstatus = mt7621_wdt_bootcause(drvdata);
+
+	watchdog_init_timeout(mt7621_wdt, mt7621_wdt->max_timeout, dev);
+	watchdog_set_nowayout(mt7621_wdt, nowayout);
+	watchdog_set_drvdata(mt7621_wdt, drvdata);
+
+	if (mt7621_wdt_is_running(mt7621_wdt)) {
 		/*
 		 * Make sure to apply timeout from watchdog core, taking
 		 * the prescaler of this driver here into account (the
@@ -154,17 +183,27 @@ static int mt7621_wdt_probe(struct platform_device *pdev)
 		 * we first disable the watchdog, set the new prescaler
 		 * and timeout, and then re-enable the watchdog.
 		 */
-		mt7621_wdt_stop(&mt7621_wdt_dev);
-		mt7621_wdt_start(&mt7621_wdt_dev);
-		set_bit(WDOG_HW_RUNNING, &mt7621_wdt_dev.status);
+		mt7621_wdt_stop(mt7621_wdt);
+		mt7621_wdt_start(mt7621_wdt);
+		set_bit(WDOG_HW_RUNNING, &mt7621_wdt->status);
 	}
 
-	return devm_watchdog_register_device(dev, &mt7621_wdt_dev);
+	err = devm_watchdog_register_device(dev, &drvdata->wdt);
+	if (err) {
+		dev_err(dev, "Error registering watchdog device\n");
+		return err;
+	}
+
+	platform_set_drvdata(pdev, drvdata);
+
+	return 0;
 }
 
 static void mt7621_wdt_shutdown(struct platform_device *pdev)
 {
-	mt7621_wdt_stop(&mt7621_wdt_dev);
+	struct mt7621_wdt_data *drvdata = platform_get_drvdata(pdev);
+
+	mt7621_wdt_stop(&drvdata->wdt);
 }
 
 static const struct of_device_id mt7621_wdt_match[] = {
-- 
2.25.1