drivers: rtc: add max313xx series rtc driver

Adding support for Analog Devices MAX313XX series RTCs.

This is ported from the Linux driver and adapted for use in u-boot.
Notable differences are
- handling of tm_year and tm_mon differ
- clock source support is omitted
- hwmon support for the MAX31328 and MAX31343 is omitted
- rtc_ops->reset is added

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

3 files changed, 473 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index fcfda2847c..23173139e0 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -134,6 +134,19 @@ config RTC_ISL1208
 	  This driver supports reading and writing the RTC/calendar and detects
 	  total power failures.
 
+config RTC_MAX313XX
+	bool "Analog Devices MAX313XX RTC driver"
+	depends on DM_RTC
+	depends on DM_I2C
+	help
+	  If you say yes here you will get support for the
+	  Analog Devices MAX313XX series RTC family.
+
+	  Chip features not currently supported:
+	  - Timestamp registers as SRAM
+	  - Temperature sensor
+	  - CLKOUT generation
+
 config RTC_PCF8563
 	tristate "Philips PCF8563"
 	help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index b6c9029c8f..308fab8da9 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_RTC_HT1380) += ht1380.o
 obj-$(CONFIG_$(SPL_TPL_)RTC_SANDBOX) += i2c_rtc_emul.o
 obj-$(CONFIG_RTC_ISL1208) += isl1208.o
 obj-$(CONFIG_RTC_M41T62) += m41t62.o
+obj-$(CONFIG_RTC_MAX313XX) += max313xx.o
 obj-$(CONFIG_RTC_MC13XXX) += mc13xxx-rtc.o
 obj-$(CONFIG_RTC_MC146818) += mc146818.o
 obj-$(CONFIG_MCFRTC) += mcfrtc.o
diff --git a/drivers/rtc/max313xx.c b/drivers/rtc/max313xx.c
new file mode 100644
index 0000000000..748f3c42c3
--- /dev/null
+++ b/drivers/rtc/max313xx.c
@@ -0,0 +1,459 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Analog Devices MAX313XX series I2C RTC driver
+ *
+ * Copyright 2022 Analog Devices Inc.
+ */
+#include <bcd.h>
+#include <dm.h>
+#include <i2c.h>
+#include <rtc.h>
+#include <dm/device_compat.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/kernel.h>
+
+/* common registers */
+#define MAX313XX_INT_ALARM1		BIT(0)
+#define MAX313XX_INT_ALARM2		BIT(1)
+#define MAX313XX_HRS_F_12_24		BIT(6)
+#define MAX313XX_HRS_F_AM_PM		BIT(5)
+#define MAX313XX_MONTH_CENTURY		BIT(7)
+
+#define MAX313XX_TMR_CFG_ENABLE		BIT(4)
+#define MAX313XX_TMR_CFG_FREQ_MASK	GENMASK(1, 0)
+#define MAX313XX_TMR_CFG_FREQ_16HZ	0x03
+
+#define MAX313XX_REG_MINUTE		0x01
+#define MAX313XX_REG_HOUR		0x02
+
+#define MAX313XX_TIME_SIZE		0x07
+
+/* device specific registers */
+#define MAX3134X_CFG2_REG		0x01
+#define MAX3134X_CFG2_SET_RTC		BIT(1)
+
+#define MAX31341_TRICKLE_RES_MASK	GENMASK(1, 0)
+#define MAX31341_TRICKLE_DIODE_EN	BIT(2)
+#define MAX31341_TRICKLE_ENABLE_BIT	BIT(3)
+#define MAX31341_POWER_MGMT_REG		0x56
+#define MAX31341_POWER_MGMT_TRICKLE_BIT	BIT(0)
+
+#define MAX3133X_TRICKLE_RES_MASK	GENMASK(2, 1)
+#define MAX3133X_TRICKLE_DIODE_EN	BIT(3)
+#define MAX3133X_TRICKLE_ENABLE_BIT	BIT(0)
+
+#define MAX31329_TRICKLE_ENABLE_BIT	BIT(7)
+#define MAX31343_TRICKLE_ENABLE_MASK	GENMASK(7, 4)
+#define MAX31343_TRICKLE_ENABLE_CODE	5
+#define MAX31329_43_TRICKLE_RES_MASK	GENMASK(1, 0)
+#define MAX31329_43_TRICKLE_DIODE_EN	BIT(2)
+
+#define MAX31329_CONFIG2_REG		0x04
+#define MAX31329_CONFIG2_CLKIN_EN	BIT(2)
+#define MAX31329_CONFIG2_CLKIN_FREQ	GENMASK(1, 0)
+
+#define MAX31341_42_CONFIG1_REG		0x00
+#define MAX31341_42_CONFIG1_CLKIN_EN	BIT(7)
+#define MAX31341_42_CONFIG1_CLKIN_FREQ	GENMASK(5, 4)
+#define MAX31341_42_CONFIG1_OSC_DISABLE	BIT(3)
+#define MAX31341_42_CONFIG1_SWRST	BIT(0)
+
+enum max313xx_ids {
+	ID_MAX31328,
+	ID_MAX31329,
+	ID_MAX31331,
+	ID_MAX31334,
+	ID_MAX31341,
+	ID_MAX31342,
+	ID_MAX31343,
+	MAX313XX_ID_NR
+};
+
+/**
+ * struct chip_desc - descriptor for MAX313xx variants
+ * @sec_reg: Offset to seconds register. Used to denote the start of the
+ *           current time registers.
+ * @alarm1_sec_reg: Offset to Alarm1 seconds register. Used to denote the
+ *                  start of the alarm registers.
+ * @int_en_reg: Offset to the interrupt enable register.
+ * @int_status_reg: Offset to the interrupt status register.
+ * @ram_reg: Offset to the timestamp RAM (which can be used as SRAM).
+ * @ram_size: Size of the timestamp RAM.
+ * @temp_reg: Offset to the temperature register (or 0 if temperature
+ *            sensor is not supported).
+ * @trickle_reg: Offset to the trickle charger configuration register (or
+ *                0 if trickle charger is not supported).
+ * @rst_reg: Offset to the reset register.
+ * @rst_bit: Bit within the reset register for the software reset.
+ */
+struct chip_desc {
+	u8 sec_reg;
+	u8 alarm1_sec_reg;
+
+	u8 int_en_reg;
+	u8 int_status_reg;
+
+	u8 ram_reg;
+	u8 ram_size;
+
+	u8 temp_reg;
+
+	u8 trickle_reg;
+
+	u8 rst_reg;
+	u8 rst_bit;
+};
+
+struct max313xx_priv {
+	enum max313xx_ids id;
+	const struct chip_desc *chip;
+};
+
+static const struct chip_desc chip[MAX313XX_ID_NR] = {
+	[ID_MAX31328] = {
+		.int_en_reg = 0x0E,
+		.int_status_reg = 0x0F,
+		.sec_reg = 0x00,
+		.alarm1_sec_reg = 0x07,
+		.temp_reg = 0x11,
+	},
+	[ID_MAX31329] = {
+		.int_en_reg = 0x01,
+		.int_status_reg = 0x00,
+		.sec_reg = 0x06,
+		.alarm1_sec_reg = 0x0D,
+		.ram_reg = 0x22,
+		.ram_size = 64,
+		.trickle_reg = 0x19,
+		.rst_reg = 0x02,
+		.rst_bit = BIT(0),
+	},
+	[ID_MAX31331] = {
+		.int_en_reg = 0x01,
+		.int_status_reg = 0x00,
+		.sec_reg = 0x08,
+		.alarm1_sec_reg = 0x0F,
+		.ram_reg = 0x20,
+		.ram_size = 32,
+		.trickle_reg = 0x1B,
+		.rst_reg = 0x02,
+		.rst_bit = BIT(0),
+	},
+	[ID_MAX31334] = {
+		.int_en_reg = 0x01,
+		.int_status_reg = 0x00,
+		.sec_reg = 0x09,
+		.alarm1_sec_reg = 0x10,
+		.ram_reg = 0x30,
+		.ram_size = 32,
+		.trickle_reg = 0x1E,
+		.rst_reg = 0x02,
+		.rst_bit = BIT(0),
+	},
+	[ID_MAX31341] = {
+		.int_en_reg = 0x04,
+		.int_status_reg = 0x05,
+		.sec_reg = 0x06,
+		.alarm1_sec_reg = 0x0D,
+		.ram_reg = 0x16,
+		.ram_size = 64,
+		.trickle_reg = 0x57,
+		.rst_reg = 0x00,
+		.rst_bit = BIT(0),
+	},
+	[ID_MAX31342] = {
+		.int_en_reg = 0x04,
+		.int_status_reg = 0x05,
+		.sec_reg = 0x06,
+		.alarm1_sec_reg = 0x0D,
+		.rst_reg = 0x00,
+		.rst_bit = BIT(0),
+	},
+	[ID_MAX31343] = {
+		.int_en_reg = 0x01,
+		.int_status_reg = 0x00,
+		.sec_reg = 0x06,
+		.alarm1_sec_reg = 0x0D,
+		.ram_reg = 0x22,
+		.ram_size = 64,
+		.temp_reg = 0x1A,
+		.trickle_reg = 0x19,
+		.rst_reg = 0x02,
+		.rst_bit = BIT(0),
+	},
+};
+
+static const u32 max313xx_trickle_ohms[] = { 3000, 6000, 11000 };
+
+static int max313xx_set_bits(struct udevice *dev, unsigned int reg, unsigned int bits)
+{
+	int ret;
+
+	ret = dm_i2c_reg_read(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	return dm_i2c_reg_write(dev, reg, ret | bits);
+}
+
+static int max313xx_clear_bits(struct udevice *dev, unsigned int reg, unsigned int bits)
+{
+	int ret;
+
+	ret = dm_i2c_reg_read(dev, reg);
+	if (ret < 0)
+		return ret;
+
+	return dm_i2c_reg_write(dev, reg, ret & ~bits);
+}
+
+static int max313xx_get_hour(u8 hour_reg)
+{
+	int hour;
+
+	/* 24Hr mode */
+	if (!FIELD_GET(MAX313XX_HRS_F_12_24, hour_reg))
+		return bcd2bin(hour_reg & 0x3f);
+
+	/* 12Hr mode */
+	hour = bcd2bin(hour_reg & 0x1f);
+	if (hour == 12)
+		hour = 0;
+
+	if (FIELD_GET(MAX313XX_HRS_F_AM_PM, hour_reg))
+		hour += 12;
+
+	return hour;
+}
+
+static int max313xx_read_time(struct udevice *dev, struct rtc_time *t)
+{
+	struct max313xx_priv *rtc = dev_get_priv(dev);
+	u8 regs[7];
+	int ret;
+
+	ret = dm_i2c_read(dev, rtc->chip->sec_reg, regs, 7);
+	if (ret)
+		return ret;
+
+	t->tm_sec = bcd2bin(regs[0] & 0x7f);
+	t->tm_min = bcd2bin(regs[1] & 0x7f);
+	t->tm_hour = max313xx_get_hour(regs[2]);
+	t->tm_wday = bcd2bin(regs[3] & 0x07) - 1;
+	t->tm_mday = bcd2bin(regs[4] & 0x3f);
+	t->tm_mon = bcd2bin(regs[5] & 0x1f);
+	t->tm_year = bcd2bin(regs[6]) + 2000;
+
+	if (FIELD_GET(MAX313XX_MONTH_CENTURY, regs[5]))
+		t->tm_year += 100;
+
+	dev_dbg(dev, "read %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n",
+		t->tm_year, t->tm_mon, t->tm_mday,
+		t->tm_wday, t->tm_hour, t->tm_min, t->tm_sec);
+
+	return 0;
+}
+
+static int max313xx_set_time(struct udevice *dev, const struct rtc_time *t)
+{
+	struct max313xx_priv *rtc = dev_get_priv(dev);
+	u8 regs[7];
+	int ret;
+
+	dev_dbg(dev, "set %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n",
+		t->tm_year, t->tm_mon, t->tm_mday,
+		t->tm_wday, t->tm_hour, t->tm_min, t->tm_sec);
+
+	if (t->tm_year < 2000) {
+		dev_err(dev, "year %d (before 2000) not supported\n",
+			t->tm_year);
+		return -EINVAL;
+	}
+
+	if (rtc->chip->rst_bit) {
+		ret = max313xx_clear_bits(dev, rtc->chip->rst_reg, rtc->chip->rst_bit);
+		if (ret)
+			return ret;
+	}
+
+	regs[0] = bin2bcd(t->tm_sec);
+	regs[1] = bin2bcd(t->tm_min);
+	regs[2] = bin2bcd(t->tm_hour);
+	regs[3] = bin2bcd(t->tm_wday + 1);
+	regs[4] = bin2bcd(t->tm_mday);
+	regs[5] = bin2bcd(t->tm_mon);
+	regs[6] = bin2bcd((t->tm_year - 2000) % 100);
+
+	if ((t->tm_year - 2000) >= 200)
+		regs[5] |= FIELD_PREP(MAX313XX_MONTH_CENTURY, 1);
+
+	ret = dm_i2c_write(dev, rtc->chip->sec_reg, regs, 7);
+	if (ret)
+		return ret;
+
+	switch (rtc->id) {
+	case ID_MAX31341:
+	case ID_MAX31342:
+		ret = max313xx_set_bits(dev, MAX3134X_CFG2_REG,
+					MAX3134X_CFG2_SET_RTC);
+		if (ret)
+			return ret;
+
+		udelay(10000);
+
+		ret = max313xx_clear_bits(dev, MAX3134X_CFG2_REG,
+					  MAX3134X_CFG2_SET_RTC);
+		if (ret)
+			return ret;
+
+		break;
+	default:
+		break;
+	}
+
+	return ret;
+}
+
+static int max313xx_reset(struct udevice *dev)
+{
+	struct max313xx_priv *rtc = dev_get_priv(dev);
+	int ret = -EINVAL;
+
+	if (rtc->chip->rst_bit)
+		ret = max313xx_set_bits(dev, rtc->chip->rst_reg, rtc->chip->rst_bit);
+
+	return ret;
+}
+
+static const struct rtc_ops max3133x_rtc_ops = {
+	.get	= max313xx_read_time,
+	.set	= max313xx_set_time,
+	.reset  = max313xx_reset,
+};
+
+static int max313xx_init(struct udevice *dev)
+{
+	struct max313xx_priv *rtc = dev_get_priv(dev);
+	int ret;
+
+	switch (rtc->id) {
+	case ID_MAX31341:
+	case ID_MAX31342:
+		ret = max313xx_clear_bits(dev, MAX31341_42_CONFIG1_REG,
+					  MAX31341_42_CONFIG1_OSC_DISABLE);
+		if (ret)
+			return ret;
+
+		return max313xx_set_bits(dev, MAX31341_42_CONFIG1_REG,
+				       MAX31341_42_CONFIG1_SWRST);
+	default:
+		return 0;
+	}
+}
+
+static int max313xx_trickle_charger_setup(struct udevice *dev)
+{
+	struct max313xx_priv *rtc = dev_get_priv(dev);
+	bool diode;
+	int index, reg;
+	u32 ohms;
+	u32 chargeable;
+	int ret;
+
+	if (dev_read_u32(dev, "trickle-resistor-ohms", &ohms) ||
+	    dev_read_u32(dev, "aux-voltage-chargeable", &chargeable))
+		return 0;
+
+	switch (chargeable) {
+	case 0:
+		diode = false;
+		break;
+	case 1:
+		diode = true;
+		break;
+	default:
+		dev_dbg(dev, "unsupported aux-voltage-chargeable value\n");
+		return -EINVAL;
+	}
+
+	if (!rtc->chip->trickle_reg) {
+		dev_warn(dev, "device does not have trickle charger\n");
+		return -ENOTSUPP;
+	}
+
+	index = find_closest(ohms, max313xx_trickle_ohms,
+			     ARRAY_SIZE(max313xx_trickle_ohms)) + 1;
+
+	switch (rtc->id) {
+	case ID_MAX31329:
+		reg = FIELD_PREP(MAX31329_TRICKLE_ENABLE_BIT, 1) |
+		      FIELD_PREP(MAX31329_43_TRICKLE_RES_MASK, index) |
+		      FIELD_PREP(MAX31329_43_TRICKLE_DIODE_EN, diode);
+		break;
+	case ID_MAX31331:
+	case ID_MAX31334:
+		reg = FIELD_PREP(MAX3133X_TRICKLE_ENABLE_BIT, 1) |
+		      FIELD_PREP(MAX3133X_TRICKLE_DIODE_EN, diode) |
+		      FIELD_PREP(MAX3133X_TRICKLE_RES_MASK, index);
+		break;
+	case ID_MAX31341:
+		if (index == 1)
+			index = 0;
+		reg = FIELD_PREP(MAX31341_TRICKLE_ENABLE_BIT, 1) |
+		      FIELD_PREP(MAX31341_TRICKLE_DIODE_EN, diode) |
+		      FIELD_PREP(MAX31341_TRICKLE_RES_MASK, index);
+
+		ret = max313xx_set_bits(dev, MAX31341_POWER_MGMT_REG,
+					MAX31341_POWER_MGMT_TRICKLE_BIT);
+		if (ret)
+			return ret;
+
+		break;
+	case ID_MAX31343:
+		reg = FIELD_PREP(MAX31329_43_TRICKLE_RES_MASK, index) |
+		      FIELD_PREP(MAX31329_43_TRICKLE_DIODE_EN, diode) |
+		      FIELD_PREP(MAX31343_TRICKLE_ENABLE_MASK,
+				 MAX31343_TRICKLE_ENABLE_CODE);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return dm_i2c_reg_write(dev, rtc->chip->trickle_reg, reg);
+}
+
+static int max313xx_probe(struct udevice *dev)
+{
+	struct max313xx_priv *max313xx = dev_get_priv(dev);
+	int ret;
+
+	max313xx->id = dev_get_driver_data(dev);
+	max313xx->chip = &chip[max313xx->id];
+
+	ret = max313xx_init(dev);
+	if (ret)
+		return ret;
+
+	return max313xx_trickle_charger_setup(dev);
+}
+
+static const struct udevice_id max313xx_of_id[] = {
+	{ .compatible = "adi,max31328", .data = ID_MAX31328 },
+	{ .compatible = "adi,max31329", .data = ID_MAX31329 },
+	{ .compatible = "adi,max31331", .data = ID_MAX31331 },
+	{ .compatible = "adi,max31334", .data = ID_MAX31334 },
+	{ .compatible = "adi,max31341", .data = ID_MAX31341 },
+	{ .compatible = "adi,max31342", .data = ID_MAX31342 },
+	{ .compatible = "adi,max31343", .data = ID_MAX31343 },
+	{ }
+};
+
+U_BOOT_DRIVER(rtc_max313xx) = {
+	.name	= "rtc-max313xx",
+	.id     = UCLASS_RTC,
+	.probe  = max313xx_probe,
+	.of_match = max313xx_of_id,
+	.priv_auto = sizeof(struct max313xx_priv),
+	.ops    = &max3133x_rtc_ops,
+};