ab8500-charger: Add backup battery charge voltages on the ab8540

Add 2.7v, 2.9v, 3.0v, 3.2v and 3.3v charging voltages for backup
battery. Before that only 2.5v, 2.6v, 2.8v, 3.1v were available.
Signed-off-by: Yang QU <yang.qu@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Maxime COQUELIN <maxime.coquelin@stericsson.com>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Tested-by: Xiao Mei ZHANG <xiaomei.zhang@stericsson.com>

drivers/power/ab8500_charger.c

@@ -2836,6 +2836,7 @@ static int ab8500_charger_usb_get_property(struct power_supply *psy,
 static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
 {
 	int ret = 0;
+	u8 bup_vch_range = 0, vbup33_vrtcn = 0;
 
 	/* Setup maximum charger current and voltage for ABB cut2.0 */
 	if (!is_ab8500_1p1_or_earlier(di->parent)) {
@@ -2945,15 +2946,29 @@ static int ab8500_charger_init_hw_registers(struct ab8500_charger *di)
 	}
 
 	/* Backup battery voltage and current */
+	if (di->bm->bkup_bat_v > BUP_VCH_SEL_3P1V)
+		bup_vch_range = BUP_VCH_RANGE;
+	if (di->bm->bkup_bat_v == BUP_VCH_SEL_3P3V)
+		vbup33_vrtcn = VBUP33_VRTCN;
+
 	ret = abx500_set_register_interruptible(di->dev,
 		AB8500_RTC,
 		AB8500_RTC_BACKUP_CHG_REG,
-		di->bm->bkup_bat_v |
-		di->bm->bkup_bat_i);
+		(di->bm->bkup_bat_v & 0x3) | di->bm->bkup_bat_i);
 	if (ret) {
 		dev_err(di->dev, "failed to setup backup battery charging\n");
 		goto out;
 	}
+	if (is_ab8540(di->parent)) {
+		ret = abx500_set_register_interruptible(di->dev,
+			AB8500_RTC,
+			AB8500_RTC_CTRL1_REG,
+			bup_vch_range | vbup33_vrtcn);
+		if (ret) {
+			dev_err(di->dev, "failed to setup backup battery charging\n");
+			goto out;
+		}
+	}
 
 	/* Enable backup battery charging */
 	abx500_mask_and_set_register_interruptible(di->dev,

include/linux/mfd/abx500/ab8500-bm.h

@@ -105,6 +105,7 @@
 #define AB8500_RTC_BACKUP_CHG_REG	0x0C
 #define AB8500_RTC_CC_CONF_REG		0x01
 #define AB8500_RTC_CTRL_REG		0x0B
+#define AB8500_RTC_CTRL1_REG		0x11
 
 /*
  * OTP register offsets
@@ -179,10 +180,25 @@
 #define BUP_ICH_SEL_300UA		0x08
 #define BUP_ICH_SEL_700UA		0x0C
 
-#define BUP_VCH_SEL_2P5V		0x00
-#define BUP_VCH_SEL_2P6V		0x01
-#define BUP_VCH_SEL_2P8V		0x02
-#define BUP_VCH_SEL_3P1V		0x03
+enum bup_vch_sel {
+	BUP_VCH_SEL_2P5V,
+	BUP_VCH_SEL_2P6V,
+	BUP_VCH_SEL_2P8V,
+	BUP_VCH_SEL_3P1V,
+	/*
+	 * Note that the following 5 values 2.7v, 2.9v, 3.0v, 3.2v, 3.3v
+	 * are only available on ab8540. You can't choose these 5
+	 * voltage on ab8500/ab8505/ab9540.
+	 */
+	BUP_VCH_SEL_2P7V,
+	BUP_VCH_SEL_2P9V,
+	BUP_VCH_SEL_3P0V,
+	BUP_VCH_SEL_3P2V,
+	BUP_VCH_SEL_3P3V,
+};
+
+#define BUP_VCH_RANGE		0x02
+#define VBUP33_VRTCN		0x01
 
 /* Battery OVV constants */
 #define BATT_OVV_ENA			0x02