rtc-ds1307: true SMBus compatibility

Allow the rtc-ds1307 driver to work with SMBus controllers like nforce2
that do not support i2c block transfers.

Signed-off-by: Ed Swierk <eswierk@aristanetworks.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: BARRE Sebastien <sbarre@sdelcc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 7e5155e..1c975e6 100644 (file)
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -94,6 +94,10 @@ struct ds1307 {
        struct i2c_client       *client;
        struct rtc_device       *rtc;
        struct work_struct      work;
+       s32 (*read_block_data)(struct i2c_client *client, u8 command,
+                              u8 length, u8 *values);
+       s32 (*write_block_data)(struct i2c_client *client, u8 command,
+                               u8 length, const u8 *values);
 };
 
 struct chip_desc {
@@ -132,6 +136,79 @@ MODULE_DEVICE_TABLE(i2c, ds1307_id);
 
 /*----------------------------------------------------------------------*/
 
+#define BLOCK_DATA_MAX_TRIES 10
+
+static s32 ds1307_read_block_data_once(struct i2c_client *client, u8 command,
+                                 u8 length, u8 *values)
+{
+       s32 i, data;
+
+       for (i = 0; i < length; i++) {
+               data = i2c_smbus_read_byte_data(client, command + i);
+               if (data < 0)
+                       return data;
+               values[i] = data;
+       }
+       return i;
+}
+
+static s32 ds1307_read_block_data(struct i2c_client *client, u8 command,
+                                 u8 length, u8 *values)
+{
+       u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
+       s32 ret;
+       int tries = 0;
+
+       dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
+       ret = ds1307_read_block_data_once(client, command, length, values);
+       if (ret < 0)
+               return ret;
+       do {
+               if (++tries > BLOCK_DATA_MAX_TRIES) {
+                       dev_err(&client->dev,
+                               "ds1307_read_block_data failed\n");
+                       return -EIO;
+               }
+               memcpy(oldvalues, values, length);
+               ret = ds1307_read_block_data_once(client, command, length,
+                                                 values);
+               if (ret < 0)
+                       return ret;
+       } while (memcmp(oldvalues, values, length));
+       return length;
+}
+
+static s32 ds1307_write_block_data(struct i2c_client *client, u8 command,
+                                  u8 length, const u8 *values)
+{
+       u8 currvalues[I2C_SMBUS_BLOCK_MAX];
+       int tries = 0;
+
+       dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
+       do {
+               s32 i, ret;
+
+               if (++tries > BLOCK_DATA_MAX_TRIES) {
+                       dev_err(&client->dev,
+                               "ds1307_write_block_data failed\n");
+                       return -EIO;
+               }
+               for (i = 0; i < length; i++) {
+                       ret = i2c_smbus_write_byte_data(client, command + i,
+                                                       values[i]);
+                       if (ret < 0)
+                               return ret;
+               }
+               ret = ds1307_read_block_data_once(client, command, length,
+                                                 currvalues);
+               if (ret < 0)
+                       return ret;
+       } while (memcmp(currvalues, values, length));
+       return length;
+}
+
+/*----------------------------------------------------------------------*/
+
 /*
  * The IRQ logic includes a "real" handler running in IRQ context just
  * long enough to schedule this workqueue entry.   We need a task context
@@ -202,7 +279,7 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
        int             tmp;
 
        /* read the RTC date and time registers all at once */
-       tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+       tmp = ds1307->read_block_data(ds1307->client,
                DS1307_REG_SECS, 7, ds1307->regs);
        if (tmp != 7) {
                dev_err(dev, "%s error %d\n", "read", tmp);
@@ -279,7 +356,7 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
                "write", buf[0], buf[1], buf[2], buf[3],
                buf[4], buf[5], buf[6]);
 
-       result = i2c_smbus_write_i2c_block_data(ds1307->client, 0, 7, buf);
+       result = ds1307->write_block_data(ds1307->client, 0, 7, buf);
        if (result < 0) {
                dev_err(dev, "%s error %d\n", "write", result);
                return result;
@@ -297,7 +374,7 @@ static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
                return -EINVAL;
 
        /* read all ALARM1, ALARM2, and status registers at once */
-       ret = i2c_smbus_read_i2c_block_data(client,
+       ret = ds1307->read_block_data(client,
                        DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
        if (ret != 9) {
                dev_err(dev, "%s error %d\n", "alarm read", ret);
@@ -356,7 +433,7 @@ static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
                t->enabled, t->pending);
 
        /* read current status of both alarms and the chip */
-       ret = i2c_smbus_read_i2c_block_data(client,
+       ret = ds1307->read_block_data(client,
                        DS1339_REG_ALARM1_SECS, 9, buf);
        if (ret != 9) {
                dev_err(dev, "%s error %d\n", "alarm write", ret);
@@ -391,7 +468,7 @@ static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
        }
        buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
 
-       ret = i2c_smbus_write_i2c_block_data(client,
+       ret = ds1307->write_block_data(client,
                        DS1339_REG_ALARM1_SECS, 9, buf);
        if (ret < 0) {
                dev_err(dev, "can't set alarm time\n");
@@ -479,7 +556,7 @@ ds1307_nvram_read(struct kobject *kobj, struct bin_attribute *attr,
        if (unlikely(!count))
                return count;
 
-       result = i2c_smbus_read_i2c_block_data(client, 8 + off, count, buf);
+       result = ds1307->read_block_data(client, 8 + off, count, buf);
        if (result < 0)
                dev_err(&client->dev, "%s error %d\n", "nvram read", result);
        return result;
@@ -490,9 +567,11 @@ ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
                char *buf, loff_t off, size_t count)
 {
        struct i2c_client       *client;
+       struct ds1307           *ds1307;
        int                     result;
 
        client = kobj_to_i2c_client(kobj);
+       ds1307 = i2c_get_clientdata(client);
 
        if (unlikely(off >= NVRAM_SIZE))
                return -EFBIG;
@@ -501,7 +580,7 @@ ds1307_nvram_write(struct kobject *kobj, struct bin_attribute *attr,
        if (unlikely(!count))
                return count;
 
-       result = i2c_smbus_write_i2c_block_data(client, 8 + off, count, buf);
+       result = ds1307->write_block_data(client, 8 + off, count, buf);
        if (result < 0) {
                dev_err(&client->dev, "%s error %d\n", "nvram write", result);
                return result;
@@ -535,9 +614,8 @@ static int __devinit ds1307_probe(struct i2c_client *client,
        int                     want_irq = false;
        unsigned char           *buf;
 
-       if (!i2c_check_functionality(adapter,
-                       I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
-                       I2C_FUNC_SMBUS_I2C_BLOCK))
+       if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
+           && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
                return -EIO;
 
        if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
@@ -547,6 +625,13 @@ static int __devinit ds1307_probe(struct i2c_client *client,
        i2c_set_clientdata(client, ds1307);
        ds1307->type = id->driver_data;
        buf = ds1307->regs;
+       if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
+               ds1307->read_block_data = i2c_smbus_read_i2c_block_data;
+               ds1307->write_block_data = i2c_smbus_write_i2c_block_data;
+       } else {
+               ds1307->read_block_data = ds1307_read_block_data;
+               ds1307->write_block_data = ds1307_write_block_data;
+       }
 
        switch (ds1307->type) {
        case ds_1337:
@@ -557,7 +642,7 @@ static int __devinit ds1307_probe(struct i2c_client *client,
                        want_irq = true;
                }
                /* get registers that the "rtc" read below won't read... */
-               tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+               tmp = ds1307->read_block_data(ds1307->client,
                                DS1337_REG_CONTROL, 2, buf);
                if (tmp != 2) {
                        pr_debug("read error %d\n", tmp);
@@ -595,7 +680,7 @@ static int __devinit ds1307_probe(struct i2c_client *client,
 
 read_rtc:
        /* read RTC registers */
-       tmp = i2c_smbus_read_i2c_block_data(ds1307->client, 0, 8, buf);
+       tmp = ds1307->read_block_data(ds1307->client, 0, 8, buf);
        if (tmp != 8) {
                pr_debug("read error %d\n", tmp);
                err = -EIO;