rtc: dw: Add support for optional clock gating

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

Change-Id: I01b7831536efd87cc66a95060fcf1faf4a340073
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

arch/x86/platforms/quark_d2000/board.h

@@ -136,7 +136,6 @@ struct scss_interrupt {
 /* RTC */
 #define RTC_DW_INT_MASK			(SCSS_INT_BASE + 0x78)
 #define CCU_RTC_CLK_DIV_OFFSET          0x3
-#define CCU_RTC_PCLK_EN_SW              (1 << 11)
 
 
 

arch/x86/platforms/quark_se/Kconfig

@@ -179,6 +179,12 @@ endif
 if RTC
 config RTC_DW
 	def_bool y
+config RTC_DW_CLOCK_GATE
+	def_bool n
+config RTC_DW_CLOCK_GATE_DRV_NAME
+	default CLOCK_CONTROL_QUARK_SE_PERIPHERAL_DRV_NAME
+config RTC_DW_CLOCK_GATE_SUBSYS
+	default 11
 config RTC_DW_BASE_ADDR
 	default 0xB0000400
 config RTC_DW_IRQ

arch/x86/platforms/quark_se/board.h

@@ -227,7 +227,6 @@ struct scss_interrupt {
 /* RTC */
 #define RTC_DW_INT_MASK			(SCSS_INT_BASE + 0x78)
 #define CCU_RTC_CLK_DIV_OFFSET		(3)
-#define CCU_RTC_PCLK_EN_SW 		(1 << 11)
 
 /* Clock */
 #define CLOCK_PERIPHERAL_BASE_ADDR	(SCSS_REGISTER_BASE + 0x18)

drivers/rtc/Kconfig

@@ -40,6 +40,24 @@ config RTC_DW_DRV_NAME
 	help
 	Designware RTC driver instance name
 
+config RTC_DW_CLOCK_GATE
+	bool "Enable clock gating"
+	depends on RTC_DW
+	select CLOCK_CONTROL
+	default n
+	help
+	Enable clock gating on RTC DesignWare controller
+
+config RTC_DW_CLOCK_GATE_DRV_NAME
+	string "Clock gating driver name"
+	depends on RTC_DW_CLOCK_GATE
+	default ""
+
+config RTC_DW_CLOCK_GATE_SUBSYS
+	int "Clock controller's subsystem"
+	depends on RTC_DW_CLOCK_GATE
+	default 0
+
 config RTC_DW_BASE_ADDR
 	hex "Base address"
 	depends on RTC_DW

drivers/rtc/rtc_dw.c

@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <rtc.h>
 #include <init.h>
+#include <clock_control.h>
 #include "board.h"
 
 #include "rtc_dw.h"
@@ -36,6 +37,41 @@ static inline void _rtc_dw_int_unmask(void)
 #define _rtc_dw_int_unmask()
 #endif
 
+#ifdef CONFIG_RTC_DW_CLOCK_GATE
+static inline void _rtc_dw_clock_config(struct device *dev)
+{
+	char *drv = CONFIG_RTC_DW_CLOCK_GATE_DRV_NAME;
+	struct device *clk;
+
+	clk = device_get_binding(drv);
+	if (clk) {
+		struct rtc_dw_runtime *context = dev->driver_data;
+
+		context->clock = clk;
+	}
+}
+
+static inline void _rtc_dw_clock_on(struct device *dev)
+{
+	struct rtc_dw_dev_config *config = dev->config->config_info;
+	struct rtc_dw_runtime *context = dev->driver_data;
+
+	clock_control_on(context->clock, config->clock_data);
+}
+
+static inline void _rtc_dw_clock_off(struct device *dev)
+{
+	struct rtc_dw_dev_config *config = dev->config->config_info;
+	struct rtc_dw_runtime *context = dev->driver_data;
+
+	clock_control_off(context->clock, config->clock_data);
+}
+#else
+#define _rtc_dw_clock_config(...)
+#define _rtc_dw_clock_on(...)
+#define _rtc_dw_clock_off(...)
+#endif
+
 static void rtc_dw_set_div(const enum clk_rtc_div div)
 {
 	/* set default division mask */
@@ -53,10 +89,7 @@ static void rtc_dw_set_div(const enum clk_rtc_div div)
  */
 static void rtc_dw_enable(struct device *dev)
 {
-	ARG_UNUSED(dev);
+	_rtc_dw_clock_on(dev);
-
-	sys_set_bit(CLOCK_PERIPHERAL_BASE_ADDR, 11);
-	sys_set_bit(CLOCK_PERIPHERAL_BASE_ADDR, 1);
 }
 
 /**
@@ -65,9 +98,7 @@ static void rtc_dw_enable(struct device *dev)
  */
 static void rtc_dw_disable(struct device *dev)
 {
-	ARG_UNUSED(dev);
+	_rtc_dw_clock_off(dev);
-
-	sys_clear_bit(CLOCK_PERIPHERAL_BASE_ADDR, 11);
 }
 
 /**
@@ -169,6 +200,8 @@ int rtc_dw_init(struct device *dev)
 
 	_rtc_dw_int_unmask();
 
+	_rtc_dw_clock_config(dev);
+
 	dev->driver_api = &funcs;
 
 	return DEV_OK;
@@ -178,6 +211,9 @@ struct rtc_dw_runtime rtc_runtime;
 
 struct rtc_dw_dev_config rtc_dev = {
 	.base_address = CONFIG_RTC_DW_BASE_ADDR,
+#ifdef CONFIG_RTC_DW_CLOCK_GATE
+	.clock_data = UINT_TO_POINTER(CONFIG_RTC_DW_CLOCK_GATE_SUBSYS),
+#endif
 };
 
 DECLARE_DEVICE_INIT_CONFIG(rtc, CONFIG_RTC_DW_DRV_NAME,

drivers/rtc/rtc_dw.h

@@ -44,10 +44,16 @@
 
 struct rtc_dw_runtime {
 	void (*rtc_dw_cb_fn)(struct device *dev);
+#ifdef CONFIG_RTC_DW_CLOCK_GATE
+	struct device *clock;
+#endif
 };
 
 struct rtc_dw_dev_config {
 	uint32_t base_address;
+#ifdef CONFIG_RTC_DW_CLOCK_GATE
+	void *clock_data;
+#endif
 };
 
 int rtc_dw_init(struct device *dev);