Merge tag 'rtc-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux

Pull RTC updates from Alexandre Belloni:
 "There is nothing scary this cycle, mostly driver fixes and updates.

  The core fix has been in for a while and has been tested on multiple
  kernel revisions by multiple teams.

  Core:
   - Fix setting the alarm to the next expiring timer

  New drivers:
   - Mediatek MT7622 RTC
   - NXP PCF85363
   - Spreadtrum SC27xx PMIC RTC

  Drivers updates:
   - Use generic nvmem to expose the Non volatile ram for ds1305,
     ds1511, m48t86 and omap
   - abx80x: solve possible race condition at probe
   - armada38x: support trimming the RTC oscillator
   - at91rm9200: fix reading the alarm value at boot
   - ds1511: allow waking platform
   - m41t80: rework square wave output
   - pcf8523: support trimming the RTC oscillator
   - pcf8563: fix clock output rate
   - pl031: make interrupt optional
   - xgene: fix suspend/resume"

* tag 'rtc-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux: (50 commits)
  dt-bindings: rtc: imxdi: Improve the bindings text
  rtc: sc27xx: Add Spreadtrum SC27xx PMIC RTC driver
  dt-bindings: rtc: Add Spreadtrum SC27xx RTC documentation
  rtc: at91rm9200: fix reading alarm value
  rtc: at91rm9200: stop calculating yday in at91_rtc_readalarm
  rtc: sysfs: Use time64_t variables to set time/alarm
  rtc: xgene: mark PM functions as __maybe_unused
  rtc: xgene: Fix suspend/resume
  rtc: pcf8563: don't alway enable the alarm
  rtc: pcf8563: fix output clock rate
  rtc: rx8010: Fix for incorrect return value
  rtc: rx8010: Specify correct address for RX8010_RESV31
  rtc: rx8010: Remove duplicate define
  rtc: m41t80: remove unneeded checks from m41t80_sqw_set_rate
  rtc: m41t80: avoid i2c read in m41t80_sqw_is_prepared
  rtc: m41t80: avoid i2c read in m41t80_sqw_recalc_rate
  rtc: m41t80: fix m41t80_sqw_round_rate return value
  rtc: m41t80: m41t80_sqw_set_rate should return 0 on success
  rtc: add support for NXP PCF85363 real-time clock
  rtc: omap: Support scratch registers
  ...

1 files changed, 40 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
index 28c48b3c1946..c312af0db729 100644
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -35,6 +35,9 @@
 #define REG_MONTHS   0x08
 #define REG_YEARS    0x09
 
+#define REG_OFFSET   0x0e
+#define REG_OFFSET_MODE BIT(7)
+
 struct pcf8523 {
 	struct rtc_device *rtc;
 };
@@ -272,10 +275,47 @@ static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
 #define pcf8523_rtc_ioctl NULL
 #endif
 
+static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int err;
+	u8 value;
+	s8 val;
+
+	err = pcf8523_read(client, REG_OFFSET, &value);
+	if (err < 0)
+		return err;
+
+	/* sign extend the 7-bit offset value */
+	val = value << 1;
+	*offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1);
+
+	return 0;
+}
+
+static int pcf8523_rtc_set_offset(struct device *dev, long offset)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	long reg_m0, reg_m1;
+	u8 value;
+
+	reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
+	reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);
+
+	if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
+		value = reg_m0 & 0x7f;
+	else
+		value = (reg_m1 & 0x7f) | REG_OFFSET_MODE;
+
+	return pcf8523_write(client, REG_OFFSET, value);
+}
+
 static const struct rtc_class_ops pcf8523_rtc_ops = {
 	.read_time = pcf8523_rtc_read_time,
 	.set_time = pcf8523_rtc_set_time,
 	.ioctl = pcf8523_rtc_ioctl,
+	.read_offset = pcf8523_rtc_read_offset,
+	.set_offset = pcf8523_rtc_set_offset,
 };
 
 static int pcf8523_probe(struct i2c_client *client,