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>

1 files changed, 97 insertions, 12 deletions

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 7e5155e88ac7..1c975e6439b3 100644
--- 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;