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rtc-ds1307: true SMBus compatibility
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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>
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Ed Swierk authored and Linus Torvalds committed Apr 1, 2009
1 parent b250c96 commit 30e7b03
Showing 1 changed file with 97 additions and 12 deletions.
109 changes: 97 additions & 12 deletions drivers/rtc/rtc-ds1307.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 {
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
Expand All @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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");
Expand Down Expand Up @@ -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;
Expand All @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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)))
Expand All @@ -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:
Expand All @@ -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);
Expand Down Expand Up @@ -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;
Expand Down

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