rtc: max77686: Add support for MAX20024/MAX77620 RTC IP

Maxim Semiconductor's PMIC MAX77686 has RTC IP which is
reused in the MAX77620/MAX20024 PMICs.

Add support for these devices in MAX77686 RTC driver. This
device does not have RTC alarm pending status outside of
RTC IP. The RTC IP is having separate I2C address for its
register access.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/Kconfig

@@ -326,10 +326,10 @@ config RTC_DRV_MAX8997
 
 config RTC_DRV_MAX77686
 	tristate "Maxim MAX77686"
-	depends on MFD_MAX77686
+	depends on MFD_MAX77686 || MFD_MAX77620
 	help
 	  If you say yes here you will get support for the
-	  RTC of Maxim MAX77686 PMIC.
+	  RTC of Maxim MAX77686/MAX77620/MAX77802 PMIC.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-max77686.

drivers/rtc/rtc-max77686.c

@@ -24,8 +24,12 @@
 #include <linux/regmap.h>
 
 #define MAX77686_I2C_ADDR_RTC		(0x0C >> 1)
+#define MAX77620_I2C_ADDR_RTC		0x68
 #define MAX77686_INVALID_I2C_ADDR	(-1)
 
+/* Define non existing register */
+#define MAX77686_INVALID_REG		(-1)
+
 /* RTC Control Register */
 #define BCD_EN_SHIFT			0
 #define BCD_EN_MASK			BIT(BCD_EN_SHIFT)
@@ -74,6 +78,10 @@ struct max77686_rtc_driver_data {
 	bool			alarm_enable_reg;
 	/* I2C address for RTC block */
 	int			rtc_i2c_addr;
+	/* RTC interrupt via platform resource */
+	bool			rtc_irq_from_platform;
+	/* Pending alarm status register */
+	int			alarm_pending_status_reg;
 	/* RTC IRQ CHIP for regmap */
 	const struct regmap_irq_chip *rtc_irq_chip;
 };
@@ -185,10 +193,23 @@ static const struct max77686_rtc_driver_data max77686_drv_data = {
 	.mask  = 0x7f,
 	.map   = max77686_map,
 	.alarm_enable_reg  = false,
+	.rtc_irq_from_platform = false,
+	.alarm_pending_status_reg = MAX77686_REG_STATUS2,
 	.rtc_i2c_addr = MAX77686_I2C_ADDR_RTC,
 	.rtc_irq_chip = &max77686_rtc_irq_chip,
 };
 
+static const struct max77686_rtc_driver_data max77620_drv_data = {
+	.delay = 16000,
+	.mask  = 0x7f,
+	.map   = max77686_map,
+	.alarm_enable_reg  = false,
+	.rtc_irq_from_platform = true,
+	.alarm_pending_status_reg = MAX77686_INVALID_REG,
+	.rtc_i2c_addr = MAX77620_I2C_ADDR_RTC,
+	.rtc_irq_chip = &max77686_rtc_irq_chip,
+};
+
 static const unsigned int max77802_map[REG_RTC_END] = {
 	[REG_RTC_CONTROLM]   = MAX77802_RTC_CONTROLM,
 	[REG_RTC_CONTROL]    = MAX77802_RTC_CONTROL,
@@ -232,6 +253,8 @@ static const struct max77686_rtc_driver_data max77802_drv_data = {
 	.mask  = 0xff,
 	.map   = max77802_map,
 	.alarm_enable_reg  = true,
+	.rtc_irq_from_platform = false,
+	.alarm_pending_status_reg = MAX77686_REG_STATUS2,
 	.rtc_i2c_addr = MAX77686_INVALID_I2C_ADDR,
 	.rtc_irq_chip = &max77802_rtc_irq_chip,
 };
@@ -427,9 +450,15 @@ static int max77686_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 	}
 
 	alrm->pending = 0;
-	ret = regmap_read(info->regmap, MAX77686_REG_STATUS2, &val);
+
+	if (info->drv_data->alarm_pending_status_reg == MAX77686_INVALID_REG)
+		goto out;
+
+	ret = regmap_read(info->regmap,
+			  info->drv_data->alarm_pending_status_reg, &val);
 	if (ret < 0) {
-		dev_err(info->dev, "Fail to read status2 reg(%d)\n", ret);
+		dev_err(info->dev,
+			"Fail to read alarm pending status reg(%d)\n", ret);
 		goto out;
 	}
 
@@ -648,7 +677,18 @@ static int max77686_init_rtc_regmap(struct max77686_rtc_info *info)
 	struct i2c_client *parent_i2c = to_i2c_client(parent);
 	int ret;
 
-	info->rtc_irq = parent_i2c->irq;
+	if (info->drv_data->rtc_irq_from_platform) {
+		struct platform_device *pdev = to_platform_device(info->dev);
+
+		info->rtc_irq = platform_get_irq(pdev, 0);
+		if (info->rtc_irq < 0) {
+			dev_err(info->dev, "Failed to get rtc interrupts: %d\n",
+				info->rtc_irq);
+			return info->rtc_irq;
+		}
+	} else {
+		info->rtc_irq =  parent_i2c->irq;
+	}
 
 	info->regmap = dev_get_regmap(parent, NULL);
 	if (!info->regmap) {
@@ -802,6 +842,7 @@ static SIMPLE_DEV_PM_OPS(max77686_rtc_pm_ops,
 static const struct platform_device_id rtc_id[] = {
 	{ "max77686-rtc", .driver_data = (kernel_ulong_t)&max77686_drv_data, },
 	{ "max77802-rtc", .driver_data = (kernel_ulong_t)&max77802_drv_data, },
+	{ "max77620-rtc", .driver_data = (kernel_ulong_t)&max77620_drv_data, },
 	{},
 };
 MODULE_DEVICE_TABLE(platform, rtc_id);