[PATCH] rtc: abx80x: Implement procfs interface

[Marek Vasut <marex@denx.de>]

Implement procfs interface for polling battery status of the RTC
via /proc/driver/rtc .

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
 drivers/rtc/rtc-abx80x.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
index 73830670a41f..4fab024fb508 100644
--- a/drivers/rtc/rtc-abx80x.c
+++ b/drivers/rtc/rtc-abx80x.c
@@ -78,6 +78,10 @@
 
 #define ABX8XX_REG_ID0		0x28
 
+#define ABX8XX_REG_ANA_STATUS	0x2f
+#define ABX8XX_ANA_BREFD	BIT(7)
+#define ABX8XX_ANA_BMIN		BIT(6)
+
 #define ABX8XX_REG_OUT_CTRL	0x30
 #define ABX8XX_OUT_CTRL_EXDS	BIT(4)
 
@@ -548,6 +552,25 @@ static int abx80x_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 	}
 }
 
+static int abx80x_proc(struct device *dev, struct seq_file *seq)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int status, tmp;
+
+	status = i2c_smbus_read_byte_data(client, ABX8XX_REG_ANA_STATUS);
+	if (status < 0)
+		return status;
+
+	if (status & ABX8XX_ANA_BREFD)
+		seq_printf(seq, "battery\t\t: ok\n");
+	else if (status & ABX8XX_ANA_BMIN)
+		seq_printf(seq, "battery\t\t: low\n");
+	else
+		seq_printf(seq, "battery\t\t: exhausted\n");
+
+	return 0;
+}
+
 static const struct rtc_class_ops abx80x_rtc_ops = {
 	.read_time	= abx80x_rtc_read_time,
 	.set_time	= abx80x_rtc_set_time,
@@ -555,6 +578,7 @@ static const struct rtc_class_ops abx80x_rtc_ops = {
 	.set_alarm	= abx80x_set_alarm,
 	.alarm_irq_enable = abx80x_alarm_irq_enable,
 	.ioctl		= abx80x_ioctl,
+	.proc		= abx80x_proc,
 };
 
 static int abx80x_dt_trickle_cfg(struct device_node *np)
-- 
2.20.1