[Resent to correct linux-i2c address]
Following up to Sebastien Barre's recent patch, here I go one step
further, replacing i2c block transfers with SMBus byte transfers.
Sticking to pure SMBus makes the driver work on our board, which has an
nVidia SMBus controller driving a DS1339; nforce2 controllers
unfortunately don't support any flavor of i2c block transfer.
Reading or writing registers repeatedly until they stick is rather
nauseating but I'm aiming for correctness if not elegance. I would
appreciate any suggestions for improvement.
Signed-off-by: Ed Swierk <eswierk@xxxxxxxxxxxxxxxxxx>
Index: linux-2.6.27.4/drivers/rtc/rtc-ds1307.c
===================================================================
--- linux-2.6.27.4.orig/drivers/rtc/rtc-ds1307.c
+++ linux-2.6.27.4/drivers/rtc/rtc-ds1307.c
@@ -132,6 +132,64 @@ MODULE_DEVICE_TABLE(i2c, ds1307_id);
/*----------------------------------------------------------------------*/
+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;
+ pr_debug("ds1307_read_block_data (length=%d)\n", length);
+ ret = ds1307_read_block_data_once(client, command, length, values);
+ if (ret < 0)
+ return ret;
+ do {
+ s32 ret;
+ 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];
+ s32 ret;
+ pr_debug("ds1307_write_block_data (length=%d)\n", length);
+ ret = ds1307_read_block_data_once(client, command, length, currvalues);
+ if (ret < 0)
+ return ret;
+ do {
+ s32 i, ret;
+ 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 +266,7 @@ static int ds1307_get_time(struct device
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 +343,7 @@ static int ds1307_set_time(struct device
"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 +361,7 @@ static int ds1307_read_alarm(struct devi
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 +420,7 @@ static int ds1307_set_alarm(struct devic
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 +455,7 @@ static int ds1307_set_alarm(struct devic
}
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 +543,7 @@ ds1307_nvram_read(struct kobject *kobj,
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;
@@ -501,7 +565,7 @@ ds1307_nvram_write(struct kobject *kobj,
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;
@@ -537,8 +601,7 @@ static int __devinit ds1307_probe(struct
unsigned char *buf;
if (!i2c_check_functionality(adapter,
- I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
- I2C_FUNC_SMBUS_I2C_BLOCK))
+ I2C_FUNC_SMBUS_BYTE_DATA))
return -EIO;
if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
@@ -558,7 +621,7 @@ static int __devinit ds1307_probe(struct
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);
@@ -596,7 +659,7 @@ static int __devinit ds1307_probe(struct
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;
