rtc: bd70528: Support RTC on ROHM BD71815

BD71815 contains similar RTC block as BD71828. Only the address offsets
seem different. Support also BD71815 RTC using rtc-bd70528.
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/rtc/Kconfig

@@ -501,11 +501,11 @@ config RTC_DRV_M41T80_WDT
 	  watchdog timer in the ST M41T60 and M41T80 RTC chips series.
 
 config RTC_DRV_BD70528
-	tristate "ROHM BD70528 PMIC RTC"
-	depends on MFD_ROHM_BD70528 && (BD70528_WATCHDOG || !BD70528_WATCHDOG)
+	tristate "ROHM BD70528, BD71815 and BD71828 PMIC RTC"
+	depends on MFD_ROHM_BD71828 || MFD_ROHM_BD70528 && (BD70528_WATCHDOG || !BD70528_WATCHDOG)
 	help
 	  If you say Y here you will get support for the RTC
-	  block on ROHM BD70528 and BD71828 Power Management IC.
+	  block on ROHM BD70528, BD71815 and BD71828 Power Management IC.
 
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-bd70528.

drivers/rtc/rtc-bd70528.c

@@ -6,6 +6,7 @@
 
 #include <linux/bcd.h>
 #include <linux/mfd/rohm-bd70528.h>
+#include <linux/mfd/rohm-bd71815.h>
 #include <linux/mfd/rohm-bd71828.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -13,6 +14,12 @@
 #include <linux/regmap.h>
 #include <linux/rtc.h>
 
+/*
+ * On BD71828 and BD71815 the ALM0 MASK is 14 bytes after the ALM0
+ * block start
+ */
+#define BD718XX_ALM_EN_OFFSET 14
+
 /*
  * We read regs RTC_SEC => RTC_YEAR
  * this struct is ordered according to chip registers.
@@ -55,6 +62,7 @@ struct bd70528_rtc {
 	struct regmap *regmap;
 	struct device *dev;
 	u8 reg_time_start;
+	u8 bd718xx_alm_block_start;
 	bool has_rtc_timers;
 };
 
@@ -236,8 +244,8 @@ static int bd71828_set_alarm(struct device *dev, struct rtc_wkalrm *a)
 	struct bd71828_rtc_alm alm;
 	struct bd70528_rtc *r = dev_get_drvdata(dev);
 
-	ret = regmap_bulk_read(r->regmap, BD71828_REG_RTC_ALM_START,
-			       &alm, sizeof(alm));
+	ret = regmap_bulk_read(r->regmap, r->bd718xx_alm_block_start, &alm,
+			       sizeof(alm));
 	if (ret) {
 		dev_err(dev, "Failed to read alarm regs\n");
 		return ret;
@@ -250,8 +258,8 @@ static int bd71828_set_alarm(struct device *dev, struct rtc_wkalrm *a)
 	else
 		alm.alm_mask |= BD70528_MASK_ALM_EN;
 
-	ret = regmap_bulk_write(r->regmap, BD71828_REG_RTC_ALM_START,
-				&alm, sizeof(alm));
+	ret = regmap_bulk_write(r->regmap, r->bd718xx_alm_block_start, &alm,
+				sizeof(alm));
 	if (ret)
 		dev_err(dev, "Failed to set alarm time\n");
 
@@ -311,8 +319,8 @@ static int bd71828_read_alarm(struct device *dev, struct rtc_wkalrm *a)
 	struct bd71828_rtc_alm alm;
 	struct bd70528_rtc *r = dev_get_drvdata(dev);
 
-	ret = regmap_bulk_read(r->regmap, BD71828_REG_RTC_ALM_START,
-			       &alm, sizeof(alm));
+	ret = regmap_bulk_read(r->regmap, r->bd718xx_alm_block_start, &alm,
+			       sizeof(alm));
 	if (ret) {
 		dev_err(dev, "Failed to read alarm regs\n");
 		return ret;
@@ -453,8 +461,9 @@ static int bd71828_alm_enable(struct device *dev, unsigned int enabled)
 	if (!enabled)
 		enableval = 0;
 
-	ret = regmap_update_bits(r->regmap, BD71828_REG_RTC_ALM0_MASK,
-				 BD70528_MASK_ALM_EN, enableval);
+	ret = regmap_update_bits(r->regmap, r->bd718xx_alm_block_start +
+				 BD718XX_ALM_EN_OFFSET, BD70528_MASK_ALM_EN,
+				 enableval);
 	if (ret)
 		dev_err(dev, "Failed to change alarm state\n");
 
@@ -524,9 +533,28 @@ static int bd70528_probe(struct platform_device *pdev)
 		enable_main_irq = true;
 		rtc_ops = &bd70528_rtc_ops;
 		break;
+	case ROHM_CHIP_TYPE_BD71815:
+		irq_name = "bd71815-rtc-alm-0";
+		bd_rtc->reg_time_start = BD71815_REG_RTC_START;
+
+		/*
+		 * See also BD718XX_ALM_EN_OFFSET:
+		 * This works for BD71828 and BD71815 as they have same offset
+		 * between ALM0 start and ALM0_MASK. If new ICs are to be
+		 * added this requires proper check as ALM0_MASK is not located
+		 * at the end of ALM0 block - but after all ALM blocks so if
+		 * amount of ALMs differ the offset to enable/disable is likely
+		 * to be incorrect and enable/disable must be given as own
+		 * reg address here.
+		 */
+		bd_rtc->bd718xx_alm_block_start = BD71815_REG_RTC_ALM_START;
+		hour_reg = BD71815_REG_HOUR;
+		rtc_ops = &bd71828_rtc_ops;
+		break;
 	case ROHM_CHIP_TYPE_BD71828:
 		irq_name = "bd71828-rtc-alm-0";
 		bd_rtc->reg_time_start = BD71828_REG_RTC_START;
+		bd_rtc->bd718xx_alm_block_start = BD71828_REG_RTC_ALM_START;
 		hour_reg = BD71828_REG_RTC_HOUR;
 		rtc_ops = &bd71828_rtc_ops;
 		break;
@@ -605,6 +633,7 @@ static int bd70528_probe(struct platform_device *pdev)
 static const struct platform_device_id bd718x7_rtc_id[] = {
 	{ "bd70528-rtc", ROHM_CHIP_TYPE_BD70528 },
 	{ "bd71828-rtc", ROHM_CHIP_TYPE_BD71828 },
+	{ "bd71815-rtc", ROHM_CHIP_TYPE_BD71815 },
 	{ },
 };
 MODULE_DEVICE_TABLE(platform, bd718x7_rtc_id);