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Subject[PATCH 2/3] mfd: axp20x: Add support for backup battery charging
Date
This adds support for backup battery charging for axp20x PMICs, that is
configured through a dedicated device-tree property.

It supports 4 different charging voltages and as many charging currents.
This is especially useful to allow the on-chip RTC (on the SoC side) to
be powered when the rest of the system is off.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>

diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
index 2468b431bb22..7847f5d0b979 100644
--- a/drivers/mfd/axp20x.c
+++ b/drivers/mfd/axp20x.c
@@ -34,6 +34,16 @@
#define AXP806_REG_ADDR_EXT_ADDR_MASTER_MODE 0
#define AXP806_REG_ADDR_EXT_ADDR_SLAVE_MODE BIT(4)

+#define AXP20X_CHRG_BAK_CTRL_ENABLE BIT(7)
+#define AXP20X_CHRG_BAK_VOLTAGE_3100_MV (0 << 5)
+#define AXP20X_CHRG_BAK_VOLTAGE_3000_MV (1 << 5)
+#define AXP20X_CHRG_BAK_VOLTAGE_3600_MV (2 << 5)
+#define AXP20X_CHRG_BAK_VOLTAGE_2500_MV (3 << 5)
+#define AXP20X_CHRG_BAK_CURRENT_50_UA (0 << 0)
+#define AXP20X_CHRG_BAK_CURRENT_100_UA (1 << 0)
+#define AXP20X_CHRG_BAK_CURRENT_200_UA (2 << 0)
+#define AXP20X_CHRG_BAK_CURRENT_400_UA (3 << 0)
+
static const char * const axp20x_model_names[] = {
"AXP152",
"AXP202",
@@ -894,6 +904,63 @@ static void axp20x_power_off(void)
msleep(500);
}

+static void axp20x_backup_setup(struct axp20x_dev *axp20x)
+{
+ u32 backup[2];
+ int reg;
+ int ret;
+
+ ret = of_property_read_u32_array(axp20x->dev->of_node, "backup", backup,
+ 2);
+ if (ret != 0)
+ return;
+
+ switch (axp20x->variant) {
+ case AXP202_ID:
+ case AXP209_ID:
+ reg = AXP20X_CHRG_BAK_CTRL_ENABLE;
+
+ /* Charging voltage. */
+ switch (backup[0]) {
+ case 2500:
+ reg |= AXP20X_CHRG_BAK_VOLTAGE_2500_MV;
+ break;
+ case 3000:
+ reg |= AXP20X_CHRG_BAK_VOLTAGE_3000_MV;
+ break;
+ case 3100:
+ reg |= AXP20X_CHRG_BAK_VOLTAGE_3100_MV;
+ break;
+ case 3600:
+ reg |= AXP20X_CHRG_BAK_VOLTAGE_3600_MV;
+ break;
+ default:
+ return;
+ }
+
+ /* Charging current. */
+ switch (backup[1]) {
+ case 50:
+ reg |= AXP20X_CHRG_BAK_CURRENT_50_UA;
+ break;
+ case 100:
+ reg |= AXP20X_CHRG_BAK_CURRENT_100_UA;
+ break;
+ case 200:
+ reg |= AXP20X_CHRG_BAK_CURRENT_200_UA;
+ break;
+ case 400:
+ reg |= AXP20X_CHRG_BAK_CURRENT_400_UA;
+ break;
+ default:
+ return;
+ }
+
+ regmap_write(axp20x->regmap, AXP20X_CHRG_BAK_CTRL, reg);
+ break;
+ }
+}
+
int axp20x_match_device(struct axp20x_dev *axp20x)
{
struct device *dev = axp20x->dev;
@@ -1023,6 +1090,9 @@ int axp20x_device_probe(struct axp20x_dev *axp20x)
AXP806_REG_ADDR_EXT_ADDR_SLAVE_MODE);
}

+ /* Backup RTC battery. */
+ axp20x_backup_setup(axp20x);
+
ret = regmap_add_irq_chip(axp20x->regmap, axp20x->irq,
IRQF_ONESHOT | IRQF_SHARED | axp20x->irq_flags,
-1, axp20x->regmap_irq_chip, &axp20x->regmap_irqc);
--
2.15.1
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