rtc: pcf85063: simplify code to read the current time

By using i2c_smbus_read_i2c_block_data() the code is now much simpler.

While at it: when reading the RTC's seconds register, all time/date registers
are frozen until the RTC's year register is read. So it is important to read
all time/date registers in one turn to not lose a second event. Make it more
clear why the read must happen in this way.

Signed-off-by: Juergen Borleis <jbe@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index 63334cb..7f9caee 100644 (file)
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -45,39 +45,34 @@ struct pcf85063 {
  */
 static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
+       int rc;
        struct pcf85063 *pcf85063 = i2c_get_clientdata(client);
-       unsigned char buf[13] = { PCF85063_REG_CTRL1 };
-       struct i2c_msg msgs[] = {
-               {/* setup read ptr */
-                       .addr = client->addr,
-                       .len = 1,
-                       .buf = buf
-               },
-               {/* read status + date */
-                       .addr = client->addr,
-                       .flags = I2C_M_RD,
-                       .len = 13,
-                       .buf = buf
-               },
-       };
-
-       /* read registers */
-       if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
-               dev_err(&client->dev, "%s: read error\n", __func__);
+       u8 regs[7];
+
+       /*
+        * while reading, the time/date registers are blocked and not updated
+        * anymore until the access is finished. To not lose a second
+        * event, the access must be finished within one second. So, read all
+        * time/date registers in one turn.
+        */
+       rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
+                                          sizeof(regs), regs);
+       if (rc != sizeof(regs)) {
+               dev_err(&client->dev, "date/time register read error\n");
                return -EIO;
        }
 
-       tm->tm_sec = bcd2bin(buf[PCF85063_REG_SC] & 0x7F);
-       tm->tm_min = bcd2bin(buf[PCF85063_REG_MN] & 0x7F);
-       tm->tm_hour = bcd2bin(buf[PCF85063_REG_HR] & 0x3F); /* rtc hr 0-23 */
-       tm->tm_mday = bcd2bin(buf[PCF85063_REG_DM] & 0x3F);
-       tm->tm_wday = buf[PCF85063_REG_DW] & 0x07;
-       tm->tm_mon = bcd2bin(buf[PCF85063_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
-       tm->tm_year = bcd2bin(buf[PCF85063_REG_YR]);
+       tm->tm_sec = bcd2bin(regs[0] & 0x7F);
+       tm->tm_min = bcd2bin(regs[1] & 0x7F);
+       tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
+       tm->tm_mday = bcd2bin(regs[3] & 0x3F);
+       tm->tm_wday = regs[4] & 0x07;
+       tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
+       tm->tm_year = bcd2bin(regs[6]);
        if (tm->tm_year < 70)
                tm->tm_year += 100;     /* assume we are in 1970...2069 */
        /* detect the polarity heuristically. see note above. */
-       pcf85063->c_polarity = (buf[PCF85063_REG_MO] & PCF85063_MO_C) ?
+       pcf85063->c_polarity = (regs[5] & PCF85063_MO_C) ?
                (tm->tm_year >= 100) : (tm->tm_year < 100);
 
        return rtc_valid_tm(tm);