[U-Boot] [PATCH v2] rtc: ds3232/ds3231: Add support to generate 32KHz output for driver module

[Chuanhua Han]

This patch add an implementation of the rtc_enable_32khz_output() that
uses the driver model i2c APIs.

Signed-off-by: Chuanhua Han <chuanhua.han at nxp.com>
---
Change in v2:
	- Add RTC_ENABLE_32KHZ_OUTPUT option so this code compiles only 
in that cases where it is really useful.

 drivers/rtc/Kconfig  | 10 ++++++++++
 drivers/rtc/ds3231.c | 21 +++++++++++++++++++++
 include/rtc.h        |  6 ++++++
 3 files changed, 37 insertions(+)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index fd0009b..040d241 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -31,6 +31,12 @@ config TPL_DM_RTC
 	  drivers to perform the actual functions. See rtc.h for a
 	  description of the API.
 
+config RTC_ENABLE_32KHZ_OUTPUT
+	bool "Enable RTC 32Khz output"
+	help
+	   Some real-time clocks support the output of 32kHz square waves (such as ds3231),
+	   the config symbol choose Real Time Clock device 32Khz output feature.
+
 config RTC_PCF2127
 	bool "Enable PCF2127 driver"
 	depends on DM_RTC
@@ -41,6 +47,10 @@ config RTC_PCF2127
 	  has a selectable I2C-bus or SPI-bus, a backup battery switch-over circuit, a
 	  programmable watchdog function, a timestamp function, and many other features.
 
+config DS3231_BUS_NUM
+	hex "I2C bus of the DS3231 device"
+	default 0
+
 config RTC_DS1307
 	bool "Enable DS1307 driver"
 	depends on DM_RTC
diff --git a/drivers/rtc/ds3231.c b/drivers/rtc/ds3231.c
index 79b026a..dbd77a6 100644
--- a/drivers/rtc/ds3231.c
+++ b/drivers/rtc/ds3231.c
@@ -148,11 +148,13 @@ void rtc_reset (void)
 /*
  * Enable 32KHz output
  */
+#ifdef CONFIG_RTC_ENABLE_32KHZ_OUTPUT
 void rtc_enable_32khz_output(void)
 {
 	rtc_write(RTC_STAT_REG_ADDR,
 		  RTC_STAT_BIT_BB32KHZ | RTC_STAT_BIT_EN32KHZ);
 }
+#endif
 
 /*
  * Helper functions
@@ -251,6 +253,25 @@ static int ds3231_probe(struct udevice *dev)
 	return 0;
 }
 
+#ifdef CONFIG_RTC_ENABLE_32KHZ_OUTPUT
+void rtc_enable_32khz_output(void)
+{
+	int ret;
+	struct udevice *dev;
+
+#ifdef CONFIG_DS3231_BUS_NUM
+	ret = i2c_get_chip_for_busnum(CONFIG_DS3231_BUS_NUM,
+				      CONFIG_SYS_I2C_RTC_ADDR, 1, &dev);
+#else
+	ret = i2c_get_chip_for_busnum(0, CONFIG_SYS_I2C_RTC_ADDR, 1, &dev);
+#endif
+	if (!ret)
+		dm_i2c_reg_write(dev, RTC_STAT_REG_ADDR,
+				 RTC_STAT_BIT_BB32KHZ |
+				 RTC_STAT_BIT_EN32KHZ);
+}
+#endif
+
 static const struct rtc_ops ds3231_rtc_ops = {
 	.get = ds3231_rtc_get,
 	.set = ds3231_rtc_set,
diff --git a/include/rtc.h b/include/rtc.h
index b255bdc..df7de09 100644
--- a/include/rtc.h
+++ b/include/rtc.h
@@ -166,11 +166,17 @@ int rtc_read32(struct udevice *dev, unsigned int reg, u32 *valuep);
  */
 int rtc_write32(struct udevice *dev, unsigned int reg, u32 value);
 
+#ifdef CONFIG_RTC_ENABLE_32KHZ_OUTPUT
+void rtc_enable_32khz_output(void);
+#endif
+
 #else
 int rtc_get (struct rtc_time *);
 int rtc_set (struct rtc_time *);
 void rtc_reset (void);
+#ifdef CONFIG_RTC_ENABLE_32KHZ_OUTPUT
 void rtc_enable_32khz_output(void);
+#endif
 
 /**
  * rtc_read8() - Read an 8-bit register
-- 
2.9.5