wdt: dw: Add support for optional clock gating

Clock gating is platform specific and not mandatory. Thus making it
Kconfig based as well as generic.

Change-Id: I4ea10eadb077ac3d57c9337b43b1a9fb14763302
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

arch/x86/platforms/quark_d2000/board.h

@@ -129,9 +129,6 @@ struct scss_interrupt {
 /* Watchdog */
 #define WDT_DW_INT_MASK			(SCSS_INT_BASE + 0x7C)
 #define SCSS_PERIPH_CFG0		0x4
-#define SCSS_PERIPH_CFG0_WDT_ENABLE	(1 << 1)
-#define CCU_WDT_PCLK_EN_SW		(1 << 10)
-
 
 /* RTC */
 #define RTC_DW_INT_MASK			(SCSS_INT_BASE + 0x78)

arch/x86/platforms/quark_se/Kconfig

@@ -170,6 +170,12 @@ endif
 if WATCHDOG
 config WDT_DW
 	def_bool y
+config WDT_DW_CLOCK_GATE
+	def_bool n
+config WDT_DW_CLOCK_GATE_DRV_NAME
+	default CLOCK_CONTROL_QUARK_SE_PERIPHERAL_DRV_NAME
+config WDT_DW_CLOCK_GATE_SUBSYS
+	default 10
 config WDT_DW_BASE_ADDR
 	default 0xB0000000
 config WDT_DW_IRQ

arch/x86/platforms/quark_se/board.h

@@ -207,9 +207,6 @@ struct scss_interrupt {
 
 #define SCSS_CCU_SYS_CLK_CTL		0x38
 
-/* Peripheral Configuration */
-#define SCSS_PERIPH_CFG0		(0x4)
-
 /* Peripheral Clock Gate Control */
 #define SCSS_CCU_PERIPH_CLK_GATE_CTL	0x18
 #define CCU_PERIPH_CLK_EN 		(1 << 1)
@@ -221,8 +218,7 @@ struct scss_interrupt {
 
 /* Watchdog */
 #define WDT_DW_INT_MASK			(SCSS_INT_BASE + 0x7C)
-#define SCSS_PERIPH_CFG0_WDT_ENABLE	(1 << 1)
+#define SCSS_PERIPH_CFG0		(0x4)
-#define CCU_WDT_PCLK_EN_SW     		(1 << 10)
 
 /* RTC */
 #define RTC_DW_INT_MASK			(SCSS_INT_BASE + 0x78)

drivers/watchdog/Kconfig

@@ -33,6 +33,24 @@ config WDT_DW
 	help
 	Enable watchdog timer.
 
+config WDT_DW_CLOCK_GATE
+	bool "Enable clock gating"
+	depends on WDT_DW
+	select CLOCK_CONTROL
+	default n
+	help
+	Enable clock gating on WDT DesignWare controller
+
+config WDT_DW_CLOCK_GATE_DRV_NAME
+	string "Clock gating driver name"
+	depends on WDT_DW_CLOCK_GATE
+	default ""
+
+config WDT_DW_CLOCK_GATE_SUBSYS
+	int "Clock controller's subsystem"
+	depends on WDT_DW_CLOCK_GATE
+	default 0
+
 config WDT_DW_DRV_NAME
 	string "Driver instance name"
 	default "WDT_DW"

drivers/watchdog/wdt_dw.c

@@ -16,6 +16,7 @@
 
 #include <nanokernel.h>
 #include <init.h>
+#include <clock_control.h>
 #include "wdt_dw.h"
 
 #ifdef WDT_DW_INT_MASK
@@ -28,25 +29,60 @@ static inline void _wdt_dw_int_unmask(void)
 #define _wdt_dw_int_unmask()
 #endif
 
+#ifdef CONFIG_WDT_DW_CLOCK_GATE
+static inline void _wdt_dw_clock_config(struct device *dev)
+{
+	char *drv = CONFIG_WDT_DW_CLOCK_GATE_DRV_NAME;
+	struct device *clk;
+
+	clk = device_get_binding(drv);
+	if (clk) {
+		struct wdt_dw_runtime *context = dev->driver_data;
+
+		context->clock = clk;
+	}
+}
+
+static inline void _wdt_dw_clock_on(struct device *dev)
+{
+	struct wdt_dw_dev_config *config = dev->config->config_info;
+	struct wdt_dw_runtime *context = dev->driver_data;
+
+	clock_control_on(context->clock, config->clock_data);
+}
+
+static inline void _wdt_dw_clock_off(struct device *dev)
+{
+	struct wdt_dw_dev_config *config = dev->config->config_info;
+	struct wdt_dw_runtime *context = dev->driver_data;
+
+	clock_control_off(context->clock, config->clock_data);
+}
+#else
+#define _wdt_dw_clock_config(...)
+#define _wdt_dw_clock_on(...)
+#define _wdt_dw_clock_off(...)
+#endif
+
 /**
  * Enables the clock for the peripheral watchdog
  */
 static void wdt_dw_enable(struct device *dev)
 {
-	struct wdt_dw_dev_config *wdt_dev = dev->config->config_info;
+	_wdt_dw_clock_on(dev);
 
-	sys_set_bit(wdt_dev->base_address + WDT_CR, 0);
+#if defined(CONFIG_PLATFORM_QUARK_SE) || defined(CONFIG_PLATFORM_QUARK_D2000)
-
-	sys_set_bit(CLOCK_PERIPHERAL_BASE_ADDR, 1);
 	sys_set_bit(SCSS_PERIPHERAL_BASE + SCSS_PERIPH_CFG0, 1);
+#endif
 }
 
 static void wdt_dw_disable(struct device *dev)
 {
-	ARG_UNUSED(dev);
+	_wdt_dw_clock_off(dev);
 
-	/* Disable the clock for the peripheral watchdog */
+#if defined(CONFIG_PLATFORM_QUARK_SE) || defined(CONFIG_PLATFORM_QUARK_D2000)
 	sys_clear_bit(SCSS_PERIPHERAL_BASE + SCSS_PERIPH_CFG0, 1);
+#endif
 }
 
 void wdt_dw_isr(void *arg)
@@ -126,6 +162,8 @@ int wdt_dw_init(struct device *dev)
 
 	_wdt_dw_int_unmask();
 
+	_wdt_dw_clock_config(dev);
+
 	return 0;
 }
 
@@ -133,6 +171,9 @@ struct wdt_dw_runtime wdt_runtime;
 
 struct wdt_dw_dev_config wdt_dev = {
 	.base_address = CONFIG_WDT_DW_BASE_ADDR,
+#ifdef CONFIG_WDT_DW_CLOCK_GATE
+	.clock_data = UINT_TO_POINTER(CONFIG_WDT_DW_CLOCK_GATE_SUBSYS),
+#endif
 };
 
 DECLARE_DEVICE_INIT_CONFIG(wdt, CONFIG_WDT_DW_DRV_NAME,

drivers/watchdog/wdt_dw.h

@@ -47,10 +47,16 @@
 
 struct wdt_dw_runtime {
 	void (*cb_fn)(struct device *dev);
+#ifdef CONFIG_WDT_DW_CLOCK_GATE
+	struct device *clock;
+#endif
 };
 
 struct wdt_dw_dev_config {
 	uint32_t base_address;
+#ifdef CONFIG_WDT_DW_CLOCK_GATE
+	void *clock_data;
+#endif
 };
 
 #endif /* WDT_DW_H_ */