[PATCH] rtc: add support for rv3028 rtc

[Heiko Schocher <hs@denx.de>]

add support for rtc3028 rtc from microcrystal.
based on linux dirver:
commit a38fd8748464: ("Linux 5.12-rc2")

Signed-off-by: Heiko Schocher <hs@denx.de>

---
driver is based on code in linux, but with already
corrected weekday usage. linux codes the weekday
bitwise, while the weekday register has only 3 valid
bits as the app manual [1] says:

This register holds the current day of the week. Each value represents
one weekday that is assigned by the user. Values will range from 0 to 6
The weekday counter is simply a 3-bit counter which counts up to 6
and then resets to 0.

[1] https://www.microcrystal.com/fileadmin/Media/Products/RTC/App.Manual/RV-3028-C7_App-Manual.pdf

This is not a big problem, as userspace never use weekday.
Nevertheless, I will also send an update for the linux driver.

Also the nvram can be used for bootcounter purposes.

Tested this driver on "PHYTEC phyBOARD-Pollux i.MX8MP" board.

azure build:
https://dev.azure.com/hs0298/hs/_build/results?buildId=63&view=results

 drivers/rtc/Kconfig  |   6 ++
 drivers/rtc/Makefile |   1 +
 drivers/rtc/rv3028.c | 215 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 222 insertions(+)
 create mode 100644 drivers/rtc/rv3028.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index aa6d90158c..e451308b40 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -95,6 +95,12 @@ config RTC_PCF8563
 	  If you say yes here you get support for the Philips PCF8563 RTC
 	  and compatible chips.
 
+config RTC_RV3028
+	bool "Enable RV3028 driver"
+	depends on DM_RTC
+	help
+	  The MicroCrystal RV3028 is a I2C Real Time Clock (RTC)
+
 config RTC_RV3029
 	bool "Enable RV3029 driver"
 	depends on DM_RTC
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 6a45a9c874..e7acd76266 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_RTC_PCF2127) += pcf2127.o
 obj-$(CONFIG_RTC_PL031) += pl031.o
 obj-$(CONFIG_RTC_PT7C4338) += pt7c4338.o
 obj-$(CONFIG_RTC_RS5C372A) += rs5c372.o
+obj-$(CONFIG_RTC_RV3028) += rv3028.o
 obj-$(CONFIG_RTC_RV3029) += rv3029.o
 obj-$(CONFIG_RTC_RV8803) += rv8803.o
 obj-$(CONFIG_RTC_RX8025) += rx8025.o
diff --git a/drivers/rtc/rv3028.c b/drivers/rtc/rv3028.c
new file mode 100644
index 0000000000..8d8336c5f1
--- /dev/null
+++ b/drivers/rtc/rv3028.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * RTC driver for the Micro Crystal RV3028
+ *
+ * based on linux driver from
+ * Copyright (C) 2019 Micro Crystal SA
+ *
+ * Alexandre Belloni <alexandre.belloni@bootlin.com>
+ *
+ */
+
+#include <common.h>
+#include <command.h>
+#include <dm.h>
+#include <eeprom.h>
+#include <i2c.h>
+#include <log.h>
+#include <rtc.h>
+#include <dm/device_compat.h>
+#include <linux/bitops.h>
+#include <linux/delay.h>
+
+#define RV3028_SEC			0x00
+#define RV3028_MIN			0x01
+#define RV3028_HOUR			0x02
+#define RV3028_WDAY			0x03
+#define RV3028_DAY			0x04
+#define RV3028_MONTH			0x05
+#define RV3028_YEAR			0x06
+#define RV3028_ALARM_MIN		0x07
+#define RV3028_ALARM_HOUR		0x08
+#define RV3028_ALARM_DAY		0x09
+#define RV3028_STATUS			0x0E
+#define RV3028_CTRL1			0x0F
+#define RV3028_CTRL2			0x10
+#define RV3028_EVT_CTRL			0x13
+#define RV3028_TS_COUNT			0x14
+#define RV3028_TS_SEC			0x15
+#define RV3028_RAM1			0x1F
+#define RV3028_EEPROM_ADDR		0x25
+#define RV3028_EEPROM_DATA		0x26
+#define RV3028_EEPROM_CMD		0x27
+#define RV3028_CLKOUT			0x35
+#define RV3028_OFFSET			0x36
+#define RV3028_BACKUP			0x37
+
+#define RV3028_STATUS_PORF		BIT(0)
+#define RV3028_STATUS_EVF		BIT(1)
+#define RV3028_STATUS_AF		BIT(2)
+#define RV3028_STATUS_TF		BIT(3)
+#define RV3028_STATUS_UF		BIT(4)
+#define RV3028_STATUS_BSF		BIT(5)
+#define RV3028_STATUS_CLKF		BIT(6)
+#define RV3028_STATUS_EEBUSY		BIT(7)
+
+#define RV3028_CLKOUT_FD_MASK		GENMASK(2, 0)
+#define RV3028_CLKOUT_PORIE		BIT(3)
+#define RV3028_CLKOUT_CLKSY		BIT(6)
+#define RV3028_CLKOUT_CLKOE		BIT(7)
+
+#define RV3028_CTRL1_EERD		BIT(3)
+#define RV3028_CTRL1_WADA		BIT(5)
+
+#define RV3028_CTRL2_RESET		BIT(0)
+#define RV3028_CTRL2_12_24		BIT(1)
+#define RV3028_CTRL2_EIE		BIT(2)
+#define RV3028_CTRL2_AIE		BIT(3)
+#define RV3028_CTRL2_TIE		BIT(4)
+#define RV3028_CTRL2_UIE		BIT(5)
+#define RV3028_CTRL2_TSE		BIT(7)
+
+#define RV3028_EVT_CTRL_TSR		BIT(2)
+
+#define RV3028_EEPROM_CMD_UPDATE	0x11
+#define RV3028_EEPROM_CMD_WRITE		0x21
+#define RV3028_EEPROM_CMD_READ		0x22
+
+#define RV3028_EEBUSY_POLL		10000
+#define RV3028_EEBUSY_TIMEOUT		100000
+
+#define RV3028_BACKUP_TCE		BIT(5)
+#define RV3028_BACKUP_TCR_MASK		GENMASK(1, 0)
+
+#define OFFSET_STEP_PPT			953674
+
+#define RTC_RV3028_LEN			7
+
+static int rv3028_rtc_get(struct udevice *dev, struct rtc_time *tm)
+{
+	u8 regs[RTC_RV3028_LEN];
+	u8 status;
+	int ret;
+
+	ret = dm_i2c_read(dev, RV3028_STATUS, &status, 1);
+	if (ret < 0) {
+		printf("%s: error reading RTC status: %x\n", __func__, ret);
+		return -EIO;
+	}
+
+	if (status & RV3028_STATUS_PORF) {
+		printf("Voltage low, data is invalid.\n");
+		return -EINVAL;
+	}
+
+	ret = dm_i2c_read(dev, RV3028_SEC, regs, sizeof(regs));
+	if (ret < 0) {
+		printf("%s: error reading RTC: %x\n", __func__, ret);
+		return -EIO;
+	}
+
+	tm->tm_sec = bcd2bin(regs[RV3028_SEC] & 0x7f);
+	tm->tm_min = bcd2bin(regs[RV3028_MIN] & 0x7f);
+	tm->tm_hour = bcd2bin(regs[RV3028_HOUR] & 0x3f);
+	tm->tm_wday = regs[RV3028_WDAY] & 0x7;
+	tm->tm_mday = bcd2bin(regs[RV3028_DAY] & 0x3f);
+	tm->tm_mon  = bcd2bin(regs[RV3028_MONTH] & 0x1f);
+	tm->tm_year = bcd2bin(regs[RV3028_YEAR]) + 2000;
+	tm->tm_yday = 0;
+	tm->tm_isdst = 0;
+
+	debug("%s: %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n",
+	      __func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
+	      tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return 0;
+}
+
+static int rv3028_rtc_set(struct udevice *dev, const struct rtc_time *tm)
+{
+	u8 regs[RTC_RV3028_LEN];
+	u8 status;
+	int ret;
+
+	debug("%s: %4d-%02d-%02d (wday=%d( %2d:%02d:%02d\n",
+	      __func__, tm->tm_year, tm->tm_mon, tm->tm_mday,
+	      tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	if (tm->tm_year < 2000) {
+		printf("%s: year %d (before 2000) not supported\n",
+		       __func__, tm->tm_year);
+		return -EINVAL;
+	}
+
+	regs[RV3028_SEC] = bin2bcd(tm->tm_sec);
+	regs[RV3028_MIN] = bin2bcd(tm->tm_min);
+	regs[RV3028_HOUR] = bin2bcd(tm->tm_hour);
+	regs[RV3028_WDAY]  = tm->tm_wday;
+	regs[RV3028_DAY]   = bin2bcd(tm->tm_mday);
+	regs[RV3028_MONTH] = bin2bcd(tm->tm_mon);
+	regs[RV3028_YEAR]  = bin2bcd(tm->tm_year - 2000);
+
+	ret = dm_i2c_write(dev, RV3028_SEC, regs, sizeof(regs));
+	if (ret) {
+		printf("%s: set rtc error: %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = dm_i2c_read(dev, RV3028_STATUS, &status, 1);
+	if (ret < 0) {
+		printf("%s: error reading RTC status: %x\n", __func__, ret);
+		return -EIO;
+	}
+	status |= RV3028_STATUS_PORF;
+	return dm_i2c_write(dev, RV3028_STATUS, &status, 1);
+}
+
+static int rv3028_rtc_reset(struct udevice *dev)
+{
+	return 0;
+}
+
+static int rv3028_rtc_read8(struct udevice *dev, unsigned int reg)
+{
+	u8 data;
+	int ret;
+
+	ret = dm_i2c_read(dev, reg, &data, sizeof(data));
+	return ret < 0 ? ret : data;
+}
+
+static int rv3028_rtc_write8(struct udevice *dev, unsigned int reg, int val)
+{
+	u8 data = val;
+
+	return dm_i2c_write(dev, reg, &data, 1);
+}
+
+static int rv3028_probe(struct udevice *dev)
+{
+	i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS |
+				DM_I2C_CHIP_WR_ADDRESS);
+
+	return 0;
+}
+
+static const struct rtc_ops rv3028_rtc_ops = {
+	.get = rv3028_rtc_get,
+	.set = rv3028_rtc_set,
+	.read8 = rv3028_rtc_read8,
+	.write8 = rv3028_rtc_write8,
+	.reset = rv3028_rtc_reset,
+};
+
+static const struct udevice_id rv3028_rtc_ids[] = {
+	{ .compatible = "microcrystal,rv3028" },
+	{ }
+};
+
+U_BOOT_DRIVER(rtc_rv3028) = {
+	.name	= "rtc-rv3028",
+	.id	= UCLASS_RTC,
+	.probe	= rv3028_probe,
+	.of_match = rv3028_rtc_ids,
+	.ops	= &rv3028_rtc_ops,
+};
-- 
2.29.2