From 8566f70c8a90f3914b06e934852596ba94aaa381 Mon Sep 17 00:00:00 2001 From: Stefan Agner Date: Thu, 23 Mar 2017 16:54:57 -0700 Subject: [PATCH] rtc: ds1307: support m41t0 variant The m41t0 variant is very similar to the already supported m41t00 variant, with the notable exception of the oscillator fail bit. The data sheet notes: If the oscillator fail (OF) bit is internally set to a '1,' this indicates that the oscillator has either stopped, or was stopped for some period of time and can be used to judge the validity of the clock and date data. The bit will get cleared with a regular write of the system time, so no changes are needed to clear it. Signed-off-by: Stefan Agner Signed-off-by: Alexandre Belloni --- .../devicetree/bindings/i2c/trivial-devices.txt | 1 + drivers/rtc/rtc-ds1307.c | 13 +++++++++++++ 2 files changed, 14 insertions(+) diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt index ad10fbe61562..3e0a34c88e07 100644 --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt @@ -160,6 +160,7 @@ sii,s35390a 2-wire CMOS real-time clock silabs,si7020 Relative Humidity and Temperature Sensors skyworks,sky81452 Skyworks SKY81452: Six-Channel White LED Driver with Touch Panel Bias Supply st,24c256 i2c serial eeprom (24cxx) +st,m41t0 Serial real-time clock (RTC) st,m41t00 Serial real-time clock (RTC) st,m41t62 Serial real-time clock (RTC) with alarm st,m41t80 M41T80 - SERIAL ACCESS RTC WITH ALARMS diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c index f085b487bbe7..e29481391496 100644 --- a/drivers/rtc/rtc-ds1307.c +++ b/drivers/rtc/rtc-ds1307.c @@ -39,6 +39,7 @@ enum ds_type { ds_1340, ds_1388, ds_3231, + m41t0, m41t00, mcp794xx, rx_8025, @@ -53,6 +54,7 @@ enum ds_type { # define DS1340_BIT_nEOSC 0x80 # define MCP794XX_BIT_ST 0x80 #define DS1307_REG_MIN 0x01 /* 00-59 */ +# define M41T0_BIT_OF 0x80 #define DS1307_REG_HOUR 0x02 /* 00-23, or 1-12{am,pm} */ # define DS1307_BIT_12HR 0x40 /* in REG_HOUR */ # define DS1307_BIT_PM 0x20 /* in REG_HOUR */ @@ -183,6 +185,7 @@ static const struct i2c_device_id ds1307_id[] = { { "ds1388", ds_1388 }, { "ds1340", ds_1340 }, { "ds3231", ds_3231 }, + { "m41t0", m41t0 }, { "m41t00", m41t00 }, { "mcp7940x", mcp794xx }, { "mcp7941x", mcp794xx }, @@ -261,6 +264,7 @@ static const struct acpi_device_id ds1307_acpi_ids[] = { { .id = "DS1388", .driver_data = ds_1388 }, { .id = "DS1340", .driver_data = ds_1340 }, { .id = "DS3231", .driver_data = ds_3231 }, + { .id = "M41T0", .driver_data = m41t0 }, { .id = "M41T00", .driver_data = m41t00 }, { .id = "MCP7940X", .driver_data = mcp794xx }, { .id = "MCP7941X", .driver_data = mcp794xx }, @@ -456,6 +460,13 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t) dev_dbg(dev, "%s: %7ph\n", "read", ds1307->regs); + /* if oscillator fail bit is set, no data can be trusted */ + if (ds1307->type == m41t0 && + ds1307->regs[DS1307_REG_MIN] & M41T0_BIT_OF) { + dev_warn_once(dev, "oscillator failed, set time!\n"); + return -EINVAL; + } + t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f); t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f); tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f; @@ -1578,6 +1589,7 @@ static int ds1307_probe(struct i2c_client *client, tmp = ds1307->regs[DS1307_REG_SECS]; switch (ds1307->type) { case ds_1307: + case m41t0: case m41t00: /* clock halted? turn it on, so clock can tick. */ if (tmp & DS1307_BIT_CH) { @@ -1642,6 +1654,7 @@ static int ds1307_probe(struct i2c_client *client, tmp = ds1307->regs[DS1307_REG_HOUR]; switch (ds1307->type) { case ds_1340: + case m41t0: case m41t00: /* * NOTE: ignores century bits; fix before deploying