rtc-ds1307: alarm support for ds1337/ds1339

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>

1 files changed, 295 insertions, 13 deletions

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index bbf97e65202a..4fcf0734a6ef 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -23,10 +23,6 @@
  * 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);