rtc-x1205: Fix alarm set

I have discovered that the current version of rtc-x1205.c does not work
correctly when asked to set the alarm time by the RTC_WKALM_SET ioctl()
call.  This happens because the alarm registers do not behave like the
current-time registers.  They are non-volatile.  Two things go wrong:

- the X1205 requires a 10 msec delay after any attempt to write to the
  non-volatile registers.  The x1205_set_datetime() routine does the write
  as 8 single-byte writes without any delay.  Only the first write
  succeeds.  The second is NAKed because the chip is busy.

- the X1205 resets the RWEL bit after any write to the non-volatile
  registers.  This would lock out any further writes after the first even
  with a 10msec delay.

I fix this by doing a single 8-byte write and then waiting 10msec for the
chip to be ready.  A side effect of this change is that it will speed up
x1205_rtc_set_time() which uses the same code.

I have also implemented the 'enable' bit in the rtc_wkalm structure, which
the existing driver does not attempt to do.  I have modified both
x1205_rtc_set_alarm() to set the AL0E bit, and x1205_rtc_read_alarm() to
return it.

I have tested this patch on a LinkSys NSLU2 under OpenWRT, but on no other
hardware.  On the NSLU2 the X1205 correctly asserts its IRQ pin when the
alarm time matches the current time.

[akpm@linux-foundation.org: clean up over-parenthesisation]
Signed-off-by: Michael Hamel <mhamel@adi.co.nz>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rtc/rtc-x1205.c b/drivers/rtc/rtc-x1205.c
index eaf55945f21bbf860318a082b24463caa8648ebc..7dcfba1bbfe131539af2aba38d361e53d036280e 100644 (file)
--- a/drivers/rtc/rtc-x1205.c
+++ b/drivers/rtc/rtc-x1205.c
@@ -71,6 +71,7 @@
 #define X1205_SR_RTCF          0x01    /* Clock failure */
 #define X1205_SR_WEL           0x02    /* Write Enable Latch */
 #define X1205_SR_RWEL          0x04    /* Register Write Enable */
+#define X1205_SR_AL0           0x20    /* Alarm 0 match */
 
 #define X1205_DTR_DTR0         0x01
 #define X1205_DTR_DTR1         0x02
@@ -78,6 +79,8 @@
 
 #define X1205_HR_MIL           0x80    /* Set in ccr.hour for 24 hr mode */
 
+#define X1205_INT_AL0E         0x20    /* Alarm 0 enable */
+
 static struct i2c_driver x1205_driver;
 
 /*
@@ -89,8 +92,8 @@ static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
                                unsigned char reg_base)
 {
        unsigned char dt_addr[2] = { 0, reg_base };
-
        unsigned char buf[8];
+       int i;
 
        struct i2c_msg msgs[] = {
                { client->addr, 0, 2, dt_addr },        /* setup read ptr */
@@ -98,7 +101,7 @@ static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
        };
 
        /* read date registers */
-       if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+       if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
                dev_err(&client->dev, "%s: read error\n", __func__);
                return -EIO;
        }
@@ -110,6 +113,11 @@ static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
                buf[0], buf[1], buf[2], buf[3],
                buf[4], buf[5], buf[6], buf[7]);
 
+       /* Mask out the enable bits if these are alarm registers */
+       if (reg_base < X1205_CCR_BASE)
+               for (i = 0; i <= 4; i++)
+                       buf[i] &= 0x7F;
+
        tm->tm_sec = BCD2BIN(buf[CCR_SEC]);
        tm->tm_min = BCD2BIN(buf[CCR_MIN]);
        tm->tm_hour = BCD2BIN(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
@@ -138,7 +146,7 @@ static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
        };
 
        /* read status register */
-       if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+       if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
                dev_err(&client->dev, "%s: read error\n", __func__);
                return -EIO;
        }
@@ -147,10 +155,11 @@ static int x1205_get_status(struct i2c_client *client, unsigned char *sr)
 }
 
 static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
-                               int datetoo, u8 reg_base)
+                       int datetoo, u8 reg_base, unsigned char alm_enable)
 {
-       int i, xfer;
+       int i, xfer, nbytes;
        unsigned char buf[8];
+       unsigned char rdata[10] = { 0, reg_base };
 
        static const unsigned char wel[3] = { 0, X1205_REG_SR,
                                                X1205_SR_WEL };
@@ -189,6 +198,11 @@ static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
                buf[CCR_Y2K] = BIN2BCD(tm->tm_year / 100);
        }
 
+       /* If writing alarm registers, set compare bits on registers 0-4 */
+       if (reg_base < X1205_CCR_BASE)
+               for (i = 0; i <= 4; i++)
+                       buf[i] |= 0x80;
+
        /* this sequence is required to unlock the chip */
        if ((xfer = i2c_master_send(client, wel, 3)) != 3) {
                dev_err(&client->dev, "%s: wel - %d\n", __func__, xfer);
@@ -200,19 +214,57 @@ static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
                return -EIO;
        }
 
+
        /* write register's data */
-       for (i = 0; i < (datetoo ? 8 : 3); i++) {
-               unsigned char rdata[3] = { 0, reg_base + i, buf[i] };
+       if (datetoo)
+               nbytes = 8;
+       else
+               nbytes = 3;
+       for (i = 0; i < nbytes; i++)
+               rdata[2+i] = buf[i];
+
+       xfer = i2c_master_send(client, rdata, nbytes+2);
+       if (xfer != nbytes+2) {
+               dev_err(&client->dev,
+                       "%s: result=%d addr=%02x, data=%02x\n",
+                       __func__,
+                        xfer, rdata[1], rdata[2]);
+               return -EIO;
+       }
+
+       /* If we wrote to the nonvolatile region, wait 10msec for write cycle*/
+       if (reg_base < X1205_CCR_BASE) {
+               unsigned char al0e[3] = { 0, X1205_REG_INT, 0 };
+
+               msleep(10);
 
-               xfer = i2c_master_send(client, rdata, 3);
+               /* ...and set or clear the AL0E bit in the INT register */
+
+               /* Need to set RWEL again as the write has cleared it */
+               xfer = i2c_master_send(client, rwel, 3);
                if (xfer != 3) {
                        dev_err(&client->dev,
-                               "%s: xfer=%d addr=%02x, data=%02x\n",
+                               "%s: aloe rwel - %d\n",
                                __func__,
-                                xfer, rdata[1], rdata[2]);
+                               xfer);
+                       return -EIO;
+               }
+
+               if (alm_enable)
+                       al0e[2] = X1205_INT_AL0E;
+
+               xfer = i2c_master_send(client, al0e, 3);
+               if (xfer != 3) {
+                       dev_err(&client->dev,
+                               "%s: al0e - %d\n",
+                               __func__,
+                               xfer);
                        return -EIO;
                }
-       };
+
+               /* and wait 10msec again for this write to complete */
+               msleep(10);
+       }
 
        /* disable further writes */
        if ((xfer = i2c_master_send(client, diswe, 3)) != 3) {
@@ -230,9 +282,9 @@ static int x1205_fix_osc(struct i2c_client *client)
 
        tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
 
-       if ((err = x1205_set_datetime(client, &tm, 0, X1205_CCR_BASE)) < 0)
-               dev_err(&client->dev,
-                       "unable to restart the oscillator\n");
+       err = x1205_set_datetime(client, &tm, 0, X1205_CCR_BASE, 0);
+       if (err < 0)
+               dev_err(&client->dev, "unable to restart the oscillator\n");
 
        return err;
 }
@@ -248,7 +300,7 @@ static int x1205_get_dtrim(struct i2c_client *client, int *trim)
        };
 
        /* read dtr register */
-       if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+       if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
                dev_err(&client->dev, "%s: read error\n", __func__);
                return -EIO;
        }
@@ -280,7 +332,7 @@ static int x1205_get_atrim(struct i2c_client *client, int *trim)
        };
 
        /* read atr register */
-       if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+       if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
                dev_err(&client->dev, "%s: read error\n", __func__);
                return -EIO;
        }
@@ -403,14 +455,33 @@ static int x1205_validate_client(struct i2c_client *client)
 
 static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
-       return x1205_get_datetime(to_i2c_client(dev),
-               &alrm->time, X1205_ALM0_BASE);
+       int err;
+       unsigned char intreg, status;
+       static unsigned char int_addr[2] = { 0, X1205_REG_INT };
+       struct i2c_client *client = to_i2c_client(dev);
+       struct i2c_msg msgs[] = {
+               { client->addr, 0, 2, int_addr },        /* setup read ptr */
+               { client->addr, I2C_M_RD, 1, &intreg },  /* read INT register */
+       };
+
+       /* read interrupt register and status register */
+       if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
+               dev_err(&client->dev, "%s: read error\n", __func__);
+               return -EIO;
+       }
+       err = x1205_get_status(client, &status);
+       if (err == 0) {
+               alrm->pending = (status & X1205_SR_AL0) ? 1 : 0;
+               alrm->enabled = (intreg & X1205_INT_AL0E) ? 1 : 0;
+               err = x1205_get_datetime(client, &alrm->time, X1205_ALM0_BASE);
+       }
+       return err;
 }
 
 static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {
        return x1205_set_datetime(to_i2c_client(dev),
-               &alrm->time, 1, X1205_ALM0_BASE);
+               &alrm->time, 1, X1205_ALM0_BASE, alrm->enabled);
 }
 
 static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
@@ -422,7 +493,7 @@ static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
 static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
        return x1205_set_datetime(to_i2c_client(dev),
-               tm, 1, X1205_CCR_BASE);
+               tm, 1, X1205_CCR_BASE, 0);
 }
 
 static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)