[U-Boot] [PATCH v3] rtc: Add RTC chip pcf2127 support

[Meng Yi]

This driver just implemented rtc_get and rtc_set function for
the compatibility of pcf2127 and pcf2129, and didn't make use
of pcf2127's 512 bytes of general-purpose static RAM since
pcf2129 don't have any static RAM.

Signed-off-by: Meng Yi <meng.yi at nxp.com>
---
change in V3:
-fix coding style and return value check
change in V2:
-convert to using u-boot driver module
---
 drivers/rtc/Kconfig   |  10 +++++
 drivers/rtc/Makefile  |   1 +
 drivers/rtc/pcf2127.c | 109 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 120 insertions(+)
 create mode 100644 drivers/rtc/pcf2127.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index b5d9048..cb79a01 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -13,4 +13,14 @@ config DM_RTC
 	  drivers to perform the actual functions. See rtc.h for a
 	  description of the API.
 
+config RTC_PCF2127
+	bool "Enable PCF2127 driver"
+	depends on DM_RTC
+	help
+	  The PCF2127 is a CMOS Real Time Clock (RTC) and calendar with an integrated
+	  Temperature Compensated Crystal (Xtal) Oscillator (TCXO) and a 32.768 kHz quartz
+	  crystal optimized for very high accuracy and very low power consumption. The 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.
+
 endmenu
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index fc38a3f..c919427 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_RTC_MV) += mvrtc.o
 obj-$(CONFIG_RTC_MX27) += mx27rtc.o
 obj-$(CONFIG_RTC_MXS) += mxsrtc.o
 obj-$(CONFIG_RTC_PCF8563) += pcf8563.o
+obj-$(CONFIG_RTC_PCF2127) += pcf2127.o
 obj-$(CONFIG_RTC_PL031) += pl031.o
 obj-$(CONFIG_RTC_PT7C4338) += pt7c4338.o
 obj-$(CONFIG_RTC_RS5C372A) += rs5c372.o
diff --git a/drivers/rtc/pcf2127.c b/drivers/rtc/pcf2127.c
new file mode 100644
index 0000000..dcf0340
--- /dev/null
+++ b/drivers/rtc/pcf2127.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2016 by NXP Semiconductors Inc.
+ * Date & Time support for PCF2127 RTC
+ */
+
+/*	#define	DEBUG	*/
+
+#include <common.h>
+#include <command.h>
+#include <dm.h>
+#include <i2c.h>
+#include <rtc.h>
+
+#define PCF2127_REG_CTRL1	0x00
+#define PCF2127_REG_CTRL2	0x01
+#define PCF2127_REG_CTRL3	0x02
+#define PCF2127_REG_SC		0x03
+#define PCF2127_REG_MN		0x04
+#define PCF2127_REG_HR		0x05
+#define PCF2127_REG_DM		0x06
+#define PCF2127_REG_DW		0x07
+#define PCF2127_REG_MO		0x08
+#define PCF2127_REG_YR		0x09
+
+static int pcf2127_rtc_set(struct udevice *dev, const struct rtc_time *tm)
+{
+	uchar buf[8];
+	int i = 0, ret;
+
+	/* start register address */
+	buf[i++] = PCF2127_REG_SC;
+
+	/* hours, minutes and seconds */
+	buf[i++] = bin2bcd(tm->tm_sec);
+	buf[i++] = bin2bcd(tm->tm_min);
+	buf[i++] = bin2bcd(tm->tm_hour);
+	buf[i++] = bin2bcd(tm->tm_mday);
+	buf[i++] = tm->tm_wday & 0x07;
+
+	/* month, 1 - 12 */
+	buf[i++] = bin2bcd(tm->tm_mon + 1);
+
+	/* year */
+	buf[i++] = bin2bcd(tm->tm_year % 100);
+
+	/* write register's data */
+	ret = dm_i2c_write(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
+
+	return ret;
+}
+
+static int pcf2127_rtc_get(struct udevice *dev, struct rtc_time *tm)
+{
+	int ret = 0;
+	uchar buf[10] = { PCF2127_REG_CTRL1 };
+
+	ret = dm_i2c_write(dev, PCF2127_REG_CTRL1, buf, 1);
+	if (ret < 0)
+		return ret;
+	ret = dm_i2c_read(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
+	if (ret < 0)
+		return ret;
+
+	if (buf[PCF2127_REG_CTRL3] & 0x04)
+		puts("### Warning: RTC Low Voltage - date/time not reliable\n");
+
+	tm->tm_sec  = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
+	tm->tm_min  = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
+	tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F);
+	tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
+	tm->tm_mon  = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1;
+	tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]) + 1900;
+	if (tm->tm_year < 1970)
+		tm->tm_year += 100;	/* assume we are in 1970...2069 */
+	tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
+	tm->tm_yday = 0;
+	tm->tm_isdst = 0;
+
+	debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
+	      tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
+	      tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return ret;
+}
+
+static int pcf2127_rtc_reset(struct udevice *dev)
+{
+	/*Doing nothing here*/
+
+	return 0;
+}
+
+static const struct rtc_ops pcf2127_rtc_ops = {
+	.get = pcf2127_rtc_get,
+	.set = pcf2127_rtc_set,
+	.reset = pcf2127_rtc_reset,
+};
+
+static const struct udevice_id pcf2127_rtc_ids[] = {
+	{ .compatible = "pcf2127-rtc" },
+	{ }
+};
+
+U_BOOT_DRIVER(rtc_pcf2127) = {
+	.name	= "rtc-pcf2127",
+	.id	= UCLASS_RTC,
+	.of_match = pcf2127_rtc_ids,
+	.ops	= &pcf2127_rtc_ops,
+};
-- 
2.1.0.27.g96db324