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Date: Fri, 5 Nov 2021 01:40:49 +0100
From: Pavel Modilaynen <pavel.modilaynen@...s.com>
To: <a.zummo@...ertech.it>, <alexandre.belloni@...tlin.com>
CC: <linux-rtc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<kernel@...s.com>, Pavel Modilaynen <pavelmn@...s.com>
Subject: [PATCH] rtc: rs5c372: Add support of RTC_VL_READ ioctl
From: Pavel Modilaynen <pavelmn@...pavelmn.se.axis.com>
Read, cache and expose with RTC_VL_READ ioctl low voltage
detection flag. It is supported on all devices except RS5C372A/B,
for which osciallation halt detection bit is interpreted
as low voltage condition.
Add RTC_VL_CLEAR ioctl to clear the cached value.
Signed-off-by: Pavel Modilaynen <pavelmn@...pavelmn.se.axis.com>
---
drivers/rtc/rtc-rs5c372.c | 46 +++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
index 80980414890c..68d2ed9670c4 100644
--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -126,6 +126,7 @@ struct rs5c372 {
unsigned smbus:1;
char buf[17];
char *regs;
+ int voltage_low;
};
static int rs5c_get_regs(struct rs5c372 *rs5c)
@@ -216,22 +217,40 @@ static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)
if (status < 0)
return status;
+ /* check the warning bits */
switch (rs5c->type) {
case rtc_r2025sd:
case rtc_r2221tl:
if ((rs5c->type == rtc_r2025sd && !(ctrl2 & R2x2x_CTRL2_XSTP)) ||
(rs5c->type == rtc_r2221tl && (ctrl2 & R2x2x_CTRL2_XSTP))) {
dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.\n");
+ /* keep it as indicator of low/dead battery */
+ rs5c->voltage_low = 1;
return -EINVAL;
}
break;
default:
if (ctrl2 & RS5C_CTRL2_XSTP) {
dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.\n");
+ /* keep it as indicator of low/dead battery */
+ rs5c->voltage_low = 1;
return -EINVAL;
}
}
+
+ switch (rs5c->type) {
+ case rtc_rs5c372a:
+ case rtc_rs5c372b:
+ break;
+ default:
+ if (ctrl2 & R2x2x_CTRL2_VDET) {
+ rs5c->voltage_low = 1;
+ dev_warn(&client->dev, "low voltage detected\n");
+ }
+ break;
+ }
+
tm->tm_sec = bcd2bin(rs5c->regs[RS5C372_REG_SECS] & 0x7f);
tm->tm_min = bcd2bin(rs5c->regs[RS5C372_REG_MINS] & 0x7f);
tm->tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C372_REG_HOURS]);
@@ -485,6 +504,32 @@ static int rs5c372_rtc_proc(struct device *dev, struct seq_file *seq)
#define rs5c372_rtc_proc NULL
#endif
+#ifdef CONFIG_RTC_INTF_DEV
+static int rs5c372_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+ struct rs5c372 *rs5c = i2c_get_clientdata(to_i2c_client(dev));
+
+ dev_dbg(dev, "%s: cmd=%x\n", __func__, cmd);
+
+ switch (cmd) {
+ case RTC_VL_READ:
+ if (rs5c->voltage_low)
+ dev_info(dev, "low voltage detected, date/time is not reliable.\n");
+
+ return put_user(rs5c->voltage_low, (unsigned int __user *)arg);
+ case RTC_VL_CLR:
+ /* Clear the cached value. */
+ rs5c->voltage_low = 0;
+ return 0;
+ default:
+ return -ENOIOCTLCMD;
+ }
+ return 0;
+}
+#else
+#define rs5c372_ioctl NULL
+#endif
+
static const struct rtc_class_ops rs5c372_rtc_ops = {
.proc = rs5c372_rtc_proc,
.read_time = rs5c372_rtc_read_time,
@@ -492,6 +537,7 @@ static const struct rtc_class_ops rs5c372_rtc_ops = {
.read_alarm = rs5c_read_alarm,
.set_alarm = rs5c_set_alarm,
.alarm_irq_enable = rs5c_rtc_alarm_irq_enable,
+ .ioctl = rs5c372_ioctl,
};
#if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)
--
2.20.1
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