rtc: s5m: Make register configuration per S2MPS device to remove exceptions

Before updating time and alarm the driver must set appropriate mask in
UDR register. For that purpose the driver uses common register
configuration and a lot of exceptions per device in the code. The
exceptions are not obvious, for example except the change in the logic
sometimes the fields are swapped (WUDR and AUDR between S2MPS14 and
S2MPS15). This leads to quite complicated code.

Try to make it more obvious by:
1. Documenting the UDR masks for devices and operations.
2. Adding fields in register configuration structure for each operation
   (read time, write time and alarm).
3. Splitting the configuration per S2MPS13, S2MPS14 and S2MPS15 thus
   removing exceptions for them.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-s5m.c

@@ -38,7 +38,22 @@
  */
 #define UDR_READ_RETRY_CNT	5
 
-/* Registers used by the driver which are different between chipsets. */
+/*
+ * Registers used by the driver which are different between chipsets.
+ *
+ * Operations like read time and write alarm/time require updating
+ * specific fields in UDR register. These fields usually are auto-cleared
+ * (with some exceptions).
+ *
+ * Table of operations per device:
+ *
+ * Device     | Write time | Read time | Write alarm
+ * =================================================
+ * S5M8767    | UDR + TIME |           | UDR
+ * S2MPS11/14 | WUDR       | RUDR      | WUDR + RUDR
+ * S2MPS13    | WUDR       | RUDR      | WUDR + AUDR
+ * S2MPS15    | WUDR       | RUDR      | AUDR
+ */
 struct s5m_rtc_reg_config {
 	/* Number of registers used for setting time/alarm0/alarm1 */
 	unsigned int regs_count;
@@ -58,8 +73,13 @@ struct s5m_rtc_reg_config {
 	unsigned int udr_update;
 	/* Auto-cleared mask in UDR field for writing time and alarm */
 	unsigned int autoclear_udr_mask;
-	/* Mask for UDR field in 'udr_update' register */
-	unsigned int udr_mask;
+	/*
+	 * Masks in UDR field for time and alarm operations.
+	 * The read time mask can be 0. Rest should not.
+	 */
+	unsigned int read_time_udr_mask;
+	unsigned int write_time_udr_mask;
+	unsigned int write_alarm_udr_mask;
 };
 
 /* Register map for S5M8763 and S5M8767 */
@@ -71,14 +91,44 @@ static const struct s5m_rtc_reg_config s5m_rtc_regs = {
 	.alarm1			= S5M_ALARM1_SEC,
 	.udr_update		= S5M_RTC_UDR_CON,
 	.autoclear_udr_mask	= S5M_RTC_UDR_MASK,
-	.udr_mask		= S5M_RTC_UDR_MASK,
+	.read_time_udr_mask	= 0, /* Not needed */
+	.write_time_udr_mask	= S5M_RTC_UDR_MASK | S5M_RTC_TIME_EN_MASK,
+	.write_alarm_udr_mask	= S5M_RTC_UDR_MASK,
+};
+
+/* Register map for S2MPS13 */
+static const struct s5m_rtc_reg_config s2mps13_rtc_regs = {
+	.regs_count		= 7,
+	.time			= S2MPS_RTC_SEC,
+	.ctrl			= S2MPS_RTC_CTRL,
+	.alarm0			= S2MPS_ALARM0_SEC,
+	.alarm1			= S2MPS_ALARM1_SEC,
+	.udr_update		= S2MPS_RTC_UDR_CON,
+	.autoclear_udr_mask	= S2MPS_RTC_WUDR_MASK,
+	.read_time_udr_mask	= S2MPS_RTC_RUDR_MASK,
+	.write_time_udr_mask	= S2MPS_RTC_WUDR_MASK,
+	.write_alarm_udr_mask	= S2MPS_RTC_WUDR_MASK | S2MPS13_RTC_AUDR_MASK,
+};
+
+/* Register map for S2MPS11/14 */
+static const struct s5m_rtc_reg_config s2mps14_rtc_regs = {
+	.regs_count		= 7,
+	.time			= S2MPS_RTC_SEC,
+	.ctrl			= S2MPS_RTC_CTRL,
+	.alarm0			= S2MPS_ALARM0_SEC,
+	.alarm1			= S2MPS_ALARM1_SEC,
+	.udr_update		= S2MPS_RTC_UDR_CON,
+	.autoclear_udr_mask	= S2MPS_RTC_WUDR_MASK,
+	.read_time_udr_mask	= S2MPS_RTC_RUDR_MASK,
+	.write_time_udr_mask	= S2MPS_RTC_WUDR_MASK,
+	.write_alarm_udr_mask	= S2MPS_RTC_WUDR_MASK | S2MPS_RTC_RUDR_MASK,
 };
 
 /*
- * Register map for S2MPS14.
- * It may be also suitable for S2MPS11 but this was not tested.
+ * Register map for S2MPS15 - in comparison to S2MPS14 the WUDR and AUDR bits
+ * are swapped.
  */
-static const struct s5m_rtc_reg_config s2mps_rtc_regs = {
+static const struct s5m_rtc_reg_config s2mps15_rtc_regs = {
 	.regs_count		= 7,
 	.time			= S2MPS_RTC_SEC,
 	.ctrl			= S2MPS_RTC_CTRL,
@@ -86,7 +136,9 @@ static const struct s5m_rtc_reg_config s2mps_rtc_regs = {
 	.alarm1			= S2MPS_ALARM1_SEC,
 	.udr_update		= S2MPS_RTC_UDR_CON,
 	.autoclear_udr_mask	= S2MPS_RTC_WUDR_MASK,
-	.udr_mask		= S2MPS_RTC_WUDR_MASK,
+	.read_time_udr_mask	= S2MPS_RTC_RUDR_MASK,
+	.write_time_udr_mask	= S2MPS15_RTC_WUDR_MASK,
+	.write_alarm_udr_mask	= S2MPS15_RTC_AUDR_MASK,
 };
 
 struct s5m_rtc_info {
@@ -223,21 +275,7 @@ static inline int s5m8767_rtc_set_time_reg(struct s5m_rtc_info *info)
 		return ret;
 	}
 
-	switch (info->device_type) {
-	case S5M8763X:
-	case S5M8767X:
-		data |= info->regs->udr_mask | S5M_RTC_TIME_EN_MASK;
-	case S2MPS15X:
-		/* As per UM, for write time register, set WUDR bit to high */
-		data |= S2MPS15_RTC_WUDR_MASK;
-		break;
-	case S2MPS14X:
-	case S2MPS13X:
-		data |= info->regs->udr_mask;
-		break;
-	default:
-		return -EINVAL;
-	}
+	data |= info->regs->write_time_udr_mask;
 
 	ret = regmap_write(info->regmap, info->regs->udr_update, data);
 	if (ret < 0) {
@@ -262,22 +300,16 @@ static inline int s5m8767_rtc_set_alarm_reg(struct s5m_rtc_info *info)
 		return ret;
 	}
 
-	data |= info->regs->udr_mask;
+	data |= info->regs->write_alarm_udr_mask;
 	switch (info->device_type) {
 	case S5M8763X:
 	case S5M8767X:
 		data &= ~S5M_RTC_TIME_EN_MASK;
 		break;
 	case S2MPS15X:
-		/* As per UM, for write alarm, set A_UDR(bit[4]) to high
-		 * udr_mask above sets bit[4]
-		 */
-		break;
 	case S2MPS14X:
-		data |= S2MPS_RTC_RUDR_MASK;
-		break;
 	case S2MPS13X:
-		data |= S2MPS13_RTC_AUDR_MASK;
+		/* No exceptions needed */
 		break;
 	default:
 		return -EINVAL;
@@ -338,11 +370,11 @@ static int s5m_rtc_read_time(struct device *dev, struct rtc_time *tm)
 	u8 data[info->regs->regs_count];
 	int ret;
 
-	if (info->device_type == S2MPS15X || info->device_type == S2MPS14X ||
-			info->device_type == S2MPS13X) {
+	if (info->regs->read_time_udr_mask) {
 		ret = regmap_update_bits(info->regmap,
 				info->regs->udr_update,
-				S2MPS_RTC_RUDR_MASK, S2MPS_RTC_RUDR_MASK);
+				info->regs->read_time_udr_mask,
+				info->regs->read_time_udr_mask);
 		if (ret) {
 			dev_err(dev,
 				"Failed to prepare registers for time reading: %d\n",
@@ -709,10 +741,18 @@ static int s5m_rtc_probe(struct platform_device *pdev)
 
 	switch (platform_get_device_id(pdev)->driver_data) {
 	case S2MPS15X:
+		regmap_cfg = &s2mps14_rtc_regmap_config;
+		info->regs = &s2mps15_rtc_regs;
+		alarm_irq = S2MPS14_IRQ_RTCA0;
+		break;
 	case S2MPS14X:
+		regmap_cfg = &s2mps14_rtc_regmap_config;
+		info->regs = &s2mps14_rtc_regs;
+		alarm_irq = S2MPS14_IRQ_RTCA0;
+		break;
 	case S2MPS13X:
 		regmap_cfg = &s2mps14_rtc_regmap_config;
-		info->regs = &s2mps_rtc_regs;
+		info->regs = &s2mps13_rtc_regs;
 		alarm_irq = S2MPS14_IRQ_RTCA0;
 		break;
 	case S5M8763X:

include/linux/mfd/samsung/rtc.h

@@ -105,6 +105,8 @@ enum s2mps_rtc_reg {
 #define S5M_RTC_UDR_MASK	(1 << S5M_RTC_UDR_SHIFT)
 #define S2MPS_RTC_WUDR_SHIFT	4
 #define S2MPS_RTC_WUDR_MASK	(1 << S2MPS_RTC_WUDR_SHIFT)
+#define S2MPS15_RTC_AUDR_SHIFT	4
+#define S2MPS15_RTC_AUDR_MASK	(1 << S2MPS15_RTC_AUDR_SHIFT)
 #define S2MPS13_RTC_AUDR_SHIFT	1
 #define S2MPS13_RTC_AUDR_MASK	(1 << S2MPS13_RTC_AUDR_SHIFT)
 #define S2MPS15_RTC_WUDR_SHIFT	1