blob: 27f92a771565e96324f97c11790a25269208539b [file] [log] [blame]
From: Keerthy <j-keerthy@ti.com>
Date: Wed, 1 Jun 2016 16:19:07 +0530
Subject: rtc: ds1307: Fix relying on reset value for weekday
commit e29385fab0bf94017fac130ee32f5bb2daf74417 upstream.
The reset value of weekday is 0x1. This is wrong since
the reset values of the day/month/year make up to Jan 1 2001.
When computed weekday comes out to be Monday. On a scale
of 1-7(Sunday - Saturday) it should be 0x2. So we should not
be relying on the reset value.
Hence compute the wday using the current date/month/year values.
Check if reset wday is any different from the computed wday,
If different then set the wday which we computed using
date/month/year values.
Document Referred:
http://ww1.microchip.com/downloads/en/DeviceDoc/20002266F.pdf
Fixes: 1d1945d261a2af "drivers/rtc/rtc-ds1307.c: add alarm support for mcp7941x chips"
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
[bwh: Backported to 3.16:
- No 64-time rtc_time functions available
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/rtc/rtc-ds1307.c | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -611,6 +611,8 @@ static const struct rtc_class_ops ds13xx
* Alarm support for mcp7941x devices.
*/
+#define MCP794XX_REG_WEEKDAY 0x3
+#define MCP794XX_REG_WEEKDAY_WDAY_MASK 0x7
#define MCP7941X_REG_CONTROL 0x07
# define MCP7941X_BIT_ALM0_EN 0x10
# define MCP7941X_BIT_ALM1_EN 0x20
@@ -840,12 +842,15 @@ static int ds1307_probe(struct i2c_clien
{
struct ds1307 *ds1307;
int err = -ENODEV;
- int tmp;
+ int tmp, wday;
const struct chip_desc *chip = &chips[id->driver_data];
struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
bool want_irq = false;
unsigned char *buf;
struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
+ struct rtc_time tm;
+ unsigned long timestamp;
+
static const int bbsqi_bitpos[] = {
[ds_1337] = 0,
[ds_1339] = DS1339_BIT_BBSQI,
@@ -1115,6 +1120,27 @@ read_rtc:
return PTR_ERR(ds1307->rtc);
}
+ /*
+ * Some IPs have weekday reset value = 0x1 which might not correct
+ * hence compute the wday using the current date/month/year values
+ */
+ ds1307_get_time(&client->dev, &tm);
+ wday = tm.tm_wday;
+ rtc_tm_to_time(&tm, &timestamp);
+ rtc_time_to_tm(timestamp, &tm);
+
+ /*
+ * Check if reset wday is different from the computed wday
+ * If different then set the wday which we computed using
+ * timestamp
+ */
+ if (wday != tm.tm_wday) {
+ wday = i2c_smbus_read_byte_data(client, MCP794XX_REG_WEEKDAY);
+ wday = wday & ~MCP794XX_REG_WEEKDAY_WDAY_MASK;
+ wday = wday | (tm.tm_wday + 1);
+ i2c_smbus_write_byte_data(client, MCP794XX_REG_WEEKDAY, wday);
+ }
+
if (want_irq) {
err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
ds1307->rtc->name, client);