[just draft RFC] rtc: add simple pcf85363 driver

[Antony Pavlov]

Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
---
 drivers/rtc/Kconfig        |   7 ++
 drivers/rtc/Makefile       |   1 +
 drivers/rtc/rtc-pcf85363.c | 195 +++++++++++++++++++++++++++++++++++++
 3 files changed, 203 insertions(+)
 create mode 100644 drivers/rtc/rtc-pcf85363.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 9d2c6e614b..50f352f422 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -36,6 +36,13 @@ config RTC_DRV_DS1307
 config RTC_DRV_ABRACON
 	tristate "Abracon RTCs"
 
+config RTC_DRV_PCF85363
+	tristate "NXP PCF85363"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the PCF85363 RTC chip.
+
 endif # I2C
 
 config RTC_DRV_IMXDI
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 1308beff38..163264a8c6 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_RTC_DRV_ABRACON)   += rtc-abracon.o
 obj-$(CONFIG_RTC_DRV_DS1307)    += rtc-ds1307.o
 obj-$(CONFIG_RTC_DRV_IMXDI)	+= rtc-imxdi.o
 obj-$(CONFIG_RTC_DRV_JZ4740)	+= rtc-jz4740.o
+obj-$(CONFIG_RTC_DRV_PCF85363)	+= rtc-pcf85363.o
diff --git a/drivers/rtc/rtc-pcf85363.c b/drivers/rtc/rtc-pcf85363.c
new file mode 100644
index 0000000000..3c4da5a536
--- /dev/null
+++ b/drivers/rtc/rtc-pcf85363.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * drivers/rtc/rtc-pcf85363.c
+ *
+ * Driver for NXP PCF85363 real-time clock.
+ *
+ * Copyright (C) 2017 Eric Nelson
+ */
+
+#include <common.h>
+#include <driver.h>
+#include <xfuncs.h>
+#include <malloc.h>
+#include <errno.h>
+#include <i2c/i2c.h>
+#include <regmap.h>
+#include <rtc.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+/*
+ * Date/Time registers
+ */
+#define DT_100THS	0x00
+#define DT_SECS		0x01
+#define DT_MINUTES	0x02
+#define DT_HOURS	0x03
+#define DT_DAYS		0x04
+#define DT_WEEKDAYS	0x05
+#define DT_MONTHS	0x06
+#define DT_YEARS	0x07
+
+/*
+ * control registers
+ */
+#define CTRL_STOP_EN	0x2e
+
+#define STOP_EN_STOP	BIT(0)
+
+#define RESET_CPR	0xa4
+
+struct pcf85363 {
+	struct rtc_device	rtc;
+	struct regmap		*regmap;
+
+	struct i2c_client	*client;
+};
+
+
+static int pcf85363_i2c_reg_read(void *ctx, unsigned int reg, unsigned int *val)
+{
+	struct pcf85363 *pcf85363 = ctx;
+	u8 buf[1];
+	int ret;
+
+	ret = i2c_read_reg(pcf85363->client, reg, buf, 1);
+	*val = buf[0];
+
+	return ret == 1 ? 0 : ret;
+}
+
+static int pcf85363_i2c_reg_write(void *ctx, unsigned int reg, unsigned int val)
+{
+	struct pcf85363 *pcf85363 = ctx;
+	u8 buf[] = {
+		val & 0xff,
+	};
+	int ret;
+
+	ret = i2c_write_reg(pcf85363->client, reg, buf, 1);
+
+	return ret == 1 ? 0 : ret;
+}
+
+static struct regmap_bus regmap_pcf85363_i2c_bus = {
+	.reg_write = pcf85363_i2c_reg_write,
+	.reg_read = pcf85363_i2c_reg_read,
+};
+
+static inline struct pcf85363 *to_pcf85363_priv(struct rtc_device *rtcdev)
+{
+	return container_of(rtcdev, struct pcf85363, rtc);
+}
+
+static int pcf85363_rtc_read_time(struct rtc_device *rtcdev, struct rtc_time *tm)
+{
+	struct device_d *dev = rtcdev->dev;
+	struct pcf85363 *pcf85363 = to_pcf85363_priv(rtcdev);
+	unsigned char buf[DT_YEARS + 1];
+	int ret, len = sizeof(buf);
+
+	/* read the RTC date and time registers all at once */
+	ret = regmap_bulk_read(pcf85363->regmap, DT_100THS, buf, len);
+	if (ret) {
+		dev_err(dev, "%s: error %d\n", __func__, ret);
+		return ret;
+	}
+
+	tm->tm_year = bcd2bin(buf[DT_YEARS]);
+	/* adjust for 1900 base of rtc_time */
+	tm->tm_year += 100;
+
+	tm->tm_wday = buf[DT_WEEKDAYS] & 7;
+	buf[DT_SECS] &= 0x7F;
+	tm->tm_sec = bcd2bin(buf[DT_SECS]);
+	buf[DT_MINUTES] &= 0x7F;
+	tm->tm_min = bcd2bin(buf[DT_MINUTES]);
+	tm->tm_hour = bcd2bin(buf[DT_HOURS]);
+	tm->tm_mday = bcd2bin(buf[DT_DAYS]);
+	tm->tm_mon = bcd2bin(buf[DT_MONTHS]) - 1;
+
+	return 0;
+}
+
+static int pcf85363_rtc_set_time(struct rtc_device *rtcdev, struct rtc_time *tm)
+{
+	struct pcf85363 *pcf85363 = to_pcf85363_priv(rtcdev);
+	unsigned char tmp[11];
+	unsigned char *buf = &tmp[2];
+	int ret;
+
+	tmp[0] = STOP_EN_STOP;
+	tmp[1] = RESET_CPR;
+
+	buf[DT_100THS] = 0;
+	buf[DT_SECS] = bin2bcd(tm->tm_sec);
+	buf[DT_MINUTES] = bin2bcd(tm->tm_min);
+	buf[DT_HOURS] = bin2bcd(tm->tm_hour);
+	buf[DT_DAYS] = bin2bcd(tm->tm_mday);
+	buf[DT_WEEKDAYS] = tm->tm_wday;
+	buf[DT_MONTHS] = bin2bcd(tm->tm_mon + 1);
+	buf[DT_YEARS] = bin2bcd(tm->tm_year % 100);
+
+	ret = regmap_bulk_write(pcf85363->regmap, CTRL_STOP_EN,
+				tmp, 2);
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_write(pcf85363->regmap, DT_100THS,
+				buf, sizeof(tmp) - 2);
+	if (ret)
+		return ret;
+
+	return regmap_write(pcf85363->regmap, CTRL_STOP_EN, 0);
+}
+
+static const struct rtc_class_ops rtc_ops = {
+	.read_time	= pcf85363_rtc_read_time,
+	.set_time	= pcf85363_rtc_set_time,
+};
+
+static const struct regmap_config pcf85363_regmap_i2c_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = 0x7f,
+};
+
+
+static int pcf85363_probe(struct device_d *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct pcf85363 *pcf85363;
+	int ret;
+
+	pcf85363 = xzalloc(sizeof(struct pcf85363));
+
+	pcf85363->regmap = regmap_init(dev, &regmap_pcf85363_i2c_bus,
+			     pcf85363, &pcf85363_regmap_i2c_config);
+
+	pcf85363->client = client;
+	i2c_set_clientdata(client, pcf85363);
+
+	pcf85363->rtc.ops = &rtc_ops;
+	pcf85363->rtc.dev = dev;
+
+	ret = rtc_register(&pcf85363->rtc);
+
+	return ret;
+}
+
+static struct platform_device_id dev_ids[] = {
+	{ .name = "pcf85363" },
+	{ /* sentinel */ }
+};
+
+static struct driver_d pcf85363_driver = {
+	.name		= "pcf85363",
+	.probe		= pcf85363_probe,
+	.id_table	= dev_ids,
+};
+device_i2c_driver(pcf85363_driver);
+
+MODULE_AUTHOR("Eric Nelson");
+MODULE_DESCRIPTION("pcf85363 I2C RTC driver");
+MODULE_LICENSE("GPL");
-- 
2.33.0