rtc-ds1307: alarm support for ds1337/ds1339
Rodolfo Giometti [Thu, 16 Oct 2008 05:02:58 +0000 (22:02 -0700)]
Update the ds1307 driver with alarm support for ds1337/ds1339.  This uses
the first alarm (there are two), and matches on seconds, minutes, hours,
and day-of-month.  Tested on ds1339.

[dbrownell@users.sourceforge.net: add comments; fixup style, valid irq
checks, debug dumps; lock; more careful IRQ shutdown; switch BCD2BIN to
bcd2bin (and vice versa); ENOTTY not EINVAL.]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-ds1307.c

index bbf97e6..4fcf073 100644 (file)
  * to have set the chip up as a clock (turning on the oscillator and
  * setting the date and time), Linux can ignore the non-clock features.
  * That's a natural job for a factory or repair bench.
- *
- * This is currently a simple no-alarms driver.  If your board has the
- * alarm irq wired up on a ds1337 or ds1339, and you want to use that,
- * then look at the rtc-rs5c372 driver for code to steal...
  */
 enum ds_type {
        ds_1307,
@@ -67,6 +63,7 @@ enum ds_type {
 #      define DS1307_BIT_RS0           0x01
 #define DS1337_REG_CONTROL     0x0e
 #      define DS1337_BIT_nEOSC         0x80
+#      define DS1339_BIT_BBSQI         0x20
 #      define DS1337_BIT_RS2           0x10
 #      define DS1337_BIT_RS1           0x08
 #      define DS1337_BIT_INTCN         0x04
@@ -83,19 +80,22 @@ enum ds_type {
 #      define DS1337_BIT_OSF           0x80
 #      define DS1337_BIT_A2I           0x02
 #      define DS1337_BIT_A1I           0x01
+#define DS1339_REG_ALARM1_SECS 0x07
 #define DS1339_REG_TRICKLE     0x10
 
 
 
 struct ds1307 {
        u8                      reg_addr;
-       bool                    has_nvram;
-       u8                      regs[8];
+       u8                      regs[11];
        enum ds_type            type;
+       unsigned long           flags;
+#define HAS_NVRAM      0               /* bit 0 == sysfs file active */
+#define HAS_ALARM      1               /* bit 1 == irq claimed */
        struct i2c_msg          msg[2];
        struct i2c_client       *client;
-       struct i2c_client       dev;
        struct rtc_device       *rtc;
+       struct work_struct      work;
 };
 
 struct chip_desc {
@@ -132,12 +132,79 @@ static const struct i2c_device_id ds1307_id[] = {
 };
 MODULE_DEVICE_TABLE(i2c, ds1307_id);
 
+/*----------------------------------------------------------------------*/
+
+/*
+ * The IRQ logic includes a "real" handler running in IRQ context just
+ * long enough to schedule this workqueue entry.   We need a task context
+ * to talk to the RTC, since I2C I/O calls require that; and disable the
+ * IRQ until we clear its status on the chip, so that this handler can
+ * work with any type of triggering (not just falling edge).
+ *
+ * The ds1337 and ds1339 both have two alarms, but we only use the first
+ * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
+ * signal; ds1339 chips have only one alarm signal.
+ */
+static void ds1307_work(struct work_struct *work)
+{
+       struct ds1307           *ds1307;
+       struct i2c_client       *client;
+       struct mutex            *lock;
+       int                     stat, control;
+
+       ds1307 = container_of(work, struct ds1307, work);
+       client = ds1307->client;
+       lock = &ds1307->rtc->ops_lock;
+
+       mutex_lock(lock);
+       stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
+       if (stat < 0)
+               goto out;
+
+       if (stat & DS1337_BIT_A1I) {
+               stat &= ~DS1337_BIT_A1I;
+               i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
+
+               control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+               if (control < 0)
+                       goto out;
+
+               control &= ~DS1337_BIT_A1IE;
+               i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
+
+               /* rtc_update_irq() assumes that it is called
+                * from IRQ-disabled context.
+                */
+               local_irq_disable();
+               rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
+               local_irq_enable();
+       }
+
+out:
+       if (test_bit(HAS_ALARM, &ds1307->flags))
+               enable_irq(client->irq);
+       mutex_unlock(lock);
+}
+
+static irqreturn_t ds1307_irq(int irq, void *dev_id)
+{
+       struct i2c_client       *client = dev_id;
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+
+       disable_irq_nosync(irq);
+       schedule_work(&ds1307->work);
+       return IRQ_HANDLED;
+}
+
+/*----------------------------------------------------------------------*/
+
 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 {
        struct ds1307   *ds1307 = dev_get_drvdata(dev);
        int             tmp;
 
        /* read the RTC date and time registers all at once */
+       ds1307->reg_addr = 0;
        ds1307->msg[1].flags = I2C_M_RD;
        ds1307->msg[1].len = 7;
 
@@ -231,9 +298,186 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
        return 0;
 }
 
+static int ds1307_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+       struct i2c_client       *client = to_i2c_client(dev);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+       int                     ret;
+
+       if (!test_bit(HAS_ALARM, &ds1307->flags))
+               return -EINVAL;
+
+       /* read all ALARM1, ALARM2, and status registers at once */
+       ds1307->reg_addr = DS1339_REG_ALARM1_SECS;
+       ds1307->msg[1].flags = I2C_M_RD;
+       ds1307->msg[1].len = 9;
+
+       ret = i2c_transfer(to_i2c_adapter(client->dev.parent),
+                       ds1307->msg, 2);
+       if (ret != 2) {
+               dev_err(dev, "%s error %d\n", "alarm read", ret);
+               return -EIO;
+       }
+
+       dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
+                       "alarm read",
+                       ds1307->regs[0], ds1307->regs[1],
+                       ds1307->regs[2], ds1307->regs[3],
+                       ds1307->regs[4], ds1307->regs[5],
+                       ds1307->regs[6], ds1307->regs[7],
+                       ds1307->regs[8]);
+
+       /* report alarm time (ALARM1); assume 24 hour and day-of-month modes,
+        * and that all four fields are checked matches
+        */
+       t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
+       t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
+       t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
+       t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
+       t->time.tm_mon = -1;
+       t->time.tm_year = -1;
+       t->time.tm_wday = -1;
+       t->time.tm_yday = -1;
+       t->time.tm_isdst = -1;
+
+       /* ... and status */
+       t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
+       t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
+
+       dev_dbg(dev, "%s secs=%d, mins=%d, "
+               "hours=%d, mday=%d, enabled=%d, pending=%d\n",
+               "alarm read", t->time.tm_sec, t->time.tm_min,
+               t->time.tm_hour, t->time.tm_mday,
+               t->enabled, t->pending);
+
+       return 0;
+}
+
+static int ds1307_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+       struct i2c_client       *client = to_i2c_client(dev);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+       unsigned char           *buf = ds1307->regs;
+       u8                      control, status;
+       int                     ret;
+
+       if (!test_bit(HAS_ALARM, &ds1307->flags))
+               return -EINVAL;
+
+       dev_dbg(dev, "%s secs=%d, mins=%d, "
+               "hours=%d, mday=%d, enabled=%d, pending=%d\n",
+               "alarm set", t->time.tm_sec, t->time.tm_min,
+               t->time.tm_hour, t->time.tm_mday,
+               t->enabled, t->pending);
+
+       /* read current status of both alarms and the chip */
+       ds1307->reg_addr = DS1339_REG_ALARM1_SECS;
+       ds1307->msg[1].flags = I2C_M_RD;
+       ds1307->msg[1].len = 9;
+
+       ret = i2c_transfer(to_i2c_adapter(client->dev.parent),
+                       ds1307->msg, 2);
+       if (ret != 2) {
+               dev_err(dev, "%s error %d\n", "alarm write", ret);
+               return -EIO;
+       }
+       control = ds1307->regs[7];
+       status = ds1307->regs[8];
+
+       dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
+                       "alarm set (old status)",
+                       ds1307->regs[0], ds1307->regs[1],
+                       ds1307->regs[2], ds1307->regs[3],
+                       ds1307->regs[4], ds1307->regs[5],
+                       ds1307->regs[6], control, status);
+
+       /* set ALARM1, using 24 hour and day-of-month modes */
+       *buf++ = DS1339_REG_ALARM1_SECS;        /* first register addr */
+       buf[0] = bin2bcd(t->time.tm_sec);
+       buf[1] = bin2bcd(t->time.tm_min);
+       buf[2] = bin2bcd(t->time.tm_hour);
+       buf[3] = bin2bcd(t->time.tm_mday);
+
+       /* set ALARM2 to non-garbage */
+       buf[4] = 0;
+       buf[5] = 0;
+       buf[6] = 0;
+
+       /* optionally enable ALARM1 */
+       buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
+       if (t->enabled) {
+               dev_dbg(dev, "alarm IRQ armed\n");
+               buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
+       }
+       buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
+
+       ds1307->msg[1].flags = 0;
+       ds1307->msg[1].len = 10;
+
+       ret = i2c_transfer(to_i2c_adapter(client->dev.parent),
+                       &ds1307->msg[1], 1);
+       if (ret != 1) {
+               dev_err(dev, "can't set alarm time\n");
+               return -EIO;
+       }
+
+       return 0;
+}
+
+static int ds1307_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+       struct i2c_client       *client = to_i2c_client(dev);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+       int                     ret;
+
+       switch (cmd) {
+       case RTC_AIE_OFF:
+               if (!test_bit(HAS_ALARM, &ds1307->flags))
+                       return -ENOTTY;
+
+               ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+               if (ret < 0)
+                       return ret;
+
+               ret &= ~DS1337_BIT_A1IE;
+
+               ret = i2c_smbus_write_byte_data(client,
+                                               DS1337_REG_CONTROL, ret);
+               if (ret < 0)
+                       return ret;
+
+               break;
+
+       case RTC_AIE_ON:
+               if (!test_bit(HAS_ALARM, &ds1307->flags))
+                       return -ENOTTY;
+
+               ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+               if (ret < 0)
+                       return ret;
+
+               ret |= DS1337_BIT_A1IE;
+
+               ret = i2c_smbus_write_byte_data(client,
+                                               DS1337_REG_CONTROL, ret);
+               if (ret < 0)
+                       return ret;
+
+               break;
+
+       default:
+               return -ENOIOCTLCMD;
+       }
+
+       return 0;
+}
+
 static const struct rtc_class_ops ds13xx_rtc_ops = {
        .read_time      = ds1307_get_time,
        .set_time       = ds1307_set_time,
+       .read_alarm     = ds1307_read_alarm,
+       .set_alarm      = ds1307_set_alarm,
+       .ioctl          = ds1307_ioctl,
 };
 
 /*----------------------------------------------------------------------*/
@@ -327,6 +571,7 @@ static int __devinit ds1307_probe(struct i2c_client *client,
        int                     tmp;
        const struct chip_desc  *chip = &chips[id->driver_data];
        struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
+       int                     want_irq = false;
 
        if (!i2c_check_functionality(adapter,
                        I2C_FUNC_I2C | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
@@ -353,6 +598,12 @@ static int __devinit ds1307_probe(struct i2c_client *client,
        switch (ds1307->type) {
        case ds_1337:
        case ds_1339:
+               /* has IRQ? */
+               if (ds1307->client->irq > 0 && chip->alarm) {
+                       INIT_WORK(&ds1307->work, ds1307_work);
+                       want_irq = true;
+               }
+
                ds1307->reg_addr = DS1337_REG_CONTROL;
                ds1307->msg[1].len = 2;
 
@@ -369,8 +620,20 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 
                /* oscillator off?  turn it on, so clock can tick. */
                if (ds1307->regs[0] & DS1337_BIT_nEOSC)
-                       i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
-                               ds1307->regs[0] & ~DS1337_BIT_nEOSC);
+                       ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
+
+               /* Using IRQ?  Disable the square wave and both alarms.
+                * For ds1339, be sure alarms can trigger when we're
+                * running on Vbackup (BBSQI); we assume ds1337 will
+                * ignore that bit
+                */
+               if (want_irq) {
+                       ds1307->regs[0] |= DS1337_BIT_INTCN | DS1339_BIT_BBSQI;
+                       ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
+               }
+
+               i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
+                                                       ds1307->regs[0]);
 
                /* oscillator fault?  clear flag, and warn */
                if (ds1307->regs[1] & DS1337_BIT_OSF) {
@@ -495,10 +758,22 @@ read_rtc:
                goto exit_free;
        }
 
+       if (want_irq) {
+               err = request_irq(client->irq, ds1307_irq, 0,
+                         ds1307->rtc->name, client);
+               if (err) {
+                       dev_err(&client->dev,
+                               "unable to request IRQ!\n");
+                       goto exit_irq;
+               }
+               set_bit(HAS_ALARM, &ds1307->flags);
+               dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
+       }
+
        if (chip->nvram56) {
                err = sysfs_create_bin_file(&client->dev.kobj, &nvram);
                if (err == 0) {
-                       ds1307->has_nvram = true;
+                       set_bit(HAS_NVRAM, &ds1307->flags);
                        dev_info(&client->dev, "56 bytes nvram\n");
                }
        }
@@ -512,7 +787,9 @@ exit_bad:
                        ds1307->regs[2], ds1307->regs[3],
                        ds1307->regs[4], ds1307->regs[5],
                        ds1307->regs[6]);
-
+exit_irq:
+       if (ds1307->rtc)
+               rtc_device_unregister(ds1307->rtc);
 exit_free:
        kfree(ds1307);
        return err;
@@ -520,9 +797,14 @@ exit_free:
 
 static int __devexit ds1307_remove(struct i2c_client *client)
 {
-       struct ds1307   *ds1307 = i2c_get_clientdata(client);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+
+       if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
+               free_irq(client->irq, client);
+               cancel_work_sync(&ds1307->work);
+       }
 
-       if (ds1307->has_nvram)
+       if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
                sysfs_remove_bin_file(&client->dev.kobj, &nvram);
 
        rtc_device_unregister(ds1307->rtc);