From 31d4d33ef431364972f4a38401f660a2ec935cde Mon Sep 17 00:00:00 2001 From: Juergen Borleis Date: Tue, 9 Feb 2016 11:57:27 +0100 Subject: [PATCH] rtc: pcf85063: fix time/date setting When setting a new time/date the RTC's clock must be stopped first, in order to write the time/date registers in an atomic manner. So, this change stops the clock first and then writes the time/date registers and the clock control register (to re-enable the clock) in one turn. Signed-off-by: Juergen Borleis Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-pcf85063.c | 78 +++++++++++++++++++++++++++----------- 1 file changed, 55 insertions(+), 23 deletions(-) diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c index e0343e6aeb31..c5db231f14de 100644 --- a/drivers/rtc/rtc-pcf85063.c +++ b/drivers/rtc/rtc-pcf85063.c @@ -19,6 +19,7 @@ #define DRV_VERSION "0.0.1" #define PCF85063_REG_CTRL1 0x00 /* status */ +#define PCF85063_REG_CTRL1_STOP BIT(5) #define PCF85063_REG_CTRL2 0x01 #define PCF85063_REG_SC 0x04 /* datetime */ @@ -40,6 +41,30 @@ struct pcf85063 { int voltage_low; /* indicates if a low_voltage was detected */ }; +static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1) +{ + s32 ret; + + ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1); + if (ret < 0) { + dev_err(&client->dev, "Failing to stop the clock\n"); + return -EIO; + } + + /* stop the clock */ + ret |= PCF85063_REG_CTRL1_STOP; + + ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret); + if (ret < 0) { + dev_err(&client->dev, "Failing to stop the clock\n"); + return -EIO; + } + + *ctrl1 = ret; + + return 0; +} + /* * In the routines that deal directly with the pcf85063 hardware, we use * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch. @@ -87,41 +112,48 @@ static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm) static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm) { - int i = 0, err = 0; - unsigned char buf[11]; + int rc; + u8 regs[8]; - /* Control & status */ - buf[PCF85063_REG_CTRL1] = 0; - buf[PCF85063_REG_CTRL2] = 5; + /* + * to accurately set the time, reset the divider chain and keep it in + * reset state until all time/date registers are written + */ + rc = pcf85063_stop_clock(client, ®s[7]); + if (rc != 0) + return rc; /* hours, minutes and seconds */ - buf[PCF85063_REG_SC] = bin2bcd(tm->tm_sec) & 0x7F; + regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */ - buf[PCF85063_REG_MN] = bin2bcd(tm->tm_min); - buf[PCF85063_REG_HR] = bin2bcd(tm->tm_hour); + regs[1] = bin2bcd(tm->tm_min); + regs[2] = bin2bcd(tm->tm_hour); /* Day of month, 1 - 31 */ - buf[PCF85063_REG_DM] = bin2bcd(tm->tm_mday); + regs[3] = bin2bcd(tm->tm_mday); /* Day, 0 - 6 */ - buf[PCF85063_REG_DW] = tm->tm_wday & 0x07; + regs[4] = tm->tm_wday & 0x07; /* month, 1 - 12 */ - buf[PCF85063_REG_MO] = bin2bcd(tm->tm_mon + 1); + regs[5] = bin2bcd(tm->tm_mon + 1); /* year and century */ - buf[PCF85063_REG_YR] = bin2bcd(tm->tm_year % 100); - - /* write register's data */ - for (i = 0; i < sizeof(buf); i++) { - unsigned char data[2] = { i, buf[i] }; - - err = i2c_master_send(client, data, sizeof(data)); - if (err != sizeof(data)) { - dev_err(&client->dev, "%s: err=%d addr=%02x, data=%02x\n", - __func__, err, data[0], data[1]); - return -EIO; - } + regs[6] = bin2bcd(tm->tm_year % 100); + + /* + * after all time/date registers are written, let the 'address auto + * increment' feature wrap around and write register CTRL1 to re-enable + * the clock divider chain again + */ + regs[7] &= ~PCF85063_REG_CTRL1_STOP; + + /* write all registers at once */ + rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC, + sizeof(regs), regs); + if (rc < 0) { + dev_err(&client->dev, "date/time register write error\n"); + return rc; } return 0; -- 2.30.2