[PATCH 4/4] rtc: rv8803: Be able to set VDETOFF and SWOFF via devcie tree

[Dirk Behme <dirk.behme-V5te9oGctAVWk0Htik3J/w@public.gmane.org>]

From: Oleksij Rempel <fixed-term.Oleksij.Rempel-V5te9oGctAVWk0Htik3J/w@public.gmane.org>

There might be designs where the power supply circuit is designed
in a way that VDETOFF and SWOFF is reuqired to be set. Otherwise the
RTC detects a power loss. Add a device tree interface for this.

Signed-off-by: Carsten Resch <Carsten.Resch-V5te9oGctAVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Dirk Behme <dirk.behme-V5te9oGctAVWk0Htik3J/w@public.gmane.org>
Signed-off-by: Oleksij Rempel <fixed-term.Oleksij.Rempel-V5te9oGctAVWk0Htik3J/w@public.gmane.org>
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 drivers/rtc/rtc-rv8803.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/rtc/rtc-rv8803.c b/drivers/rtc/rtc-rv8803.c
index 62baddd..2566d67 100644
--- a/drivers/rtc/rtc-rv8803.c
+++ b/drivers/rtc/rtc-rv8803.c
@@ -50,6 +50,10 @@
 #define RV8803_CTRL_TIE			BIT(4)
 #define RV8803_CTRL_UIE			BIT(5)
 
+#define RX8900_BACKUP_CTRL		0x18
+#define RX8900_FLAG_SWOFF		BIT(2)
+#define RX8900_FLAG_VDETOFF		BIT(3)
+
 struct rv8803_data {
 	struct i2c_client *client;
 	struct rtc_device *rtc;
@@ -423,6 +427,35 @@ static struct rtc_class_ops rv8803_rtc_ops = {
 	.ioctl = rv8803_ioctl,
 };
 
+static int rx8900_trickle_charger_init(struct rv8803_data *rv8803)
+{
+	struct i2c_client *client = rv8803->client;
+	struct device_node *node = client->dev.of_node;
+	int err;
+	u8 flags;
+
+	if (!node)
+		return 0;
+
+	if (!of_device_is_compatible(node, "epson,rx8900"))
+		return 0;
+
+	err = i2c_smbus_read_byte_data(rv8803->client, RX8900_BACKUP_CTRL);
+	if (err < 0)
+		return err;
+
+	flags = ~(RX8900_FLAG_VDETOFF | RX8900_FLAG_SWOFF) & (u8)err;
+
+	if (of_property_read_bool(node, "epson,vdetoff"))
+		flags |= RX8900_FLAG_VDETOFF;
+
+	if (of_property_read_bool(node, "trickle-diode-disable"))
+		flags |= RX8900_FLAG_SWOFF;
+
+	return i2c_smbus_write_byte_data(rv8803->client, RX8900_BACKUP_CTRL,
+					 flags);
+}
+
 static int rv8803_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -498,6 +531,12 @@ static int rv8803_probe(struct i2c_client *client,
 	if (err)
 		return err;
 
+	err = rx8900_trickle_charger_init(rv8803);
+	if (err) {
+		dev_err(&client->dev, "failed to init charger\n");
+		return err;
+	}
+
 	err = device_create_bin_file(&client->dev, &rv8803_nvram_attr);
 	if (err)
 		return err;
-- 
2.8.0

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