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eeprom: at24: split at24_eeprom_read() into specialized functions

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Split at24_eeprom_read() into two smaller functions - one for the
i2c operations and one for the smbus extensions. Assign them in
at24_probe() depending on the bus capabilities.

Also: in order to avoid duplications move the comments related to
offset calculations above the at24_translate_offset() routine.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Bartosz Golaszewski 2016-06-06 10:48:48 +02:00 committed by Wolfram Sang
parent 9344a81efb
commit 9afd6866bf
1 changed files with 76 additions and 59 deletions
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135
drivers/misc/eeprom/at24.c
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@ -165,6 +165,19 @@ MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
* This routine supports chips which consume multiple I2C addresses. It
* computes the addressing information to be used for a given r/w request.
* Assumes that sanity checks for offset happened at sysfs-layer.
*
* Slave address and byte offset derive from the offset. Always
* set the byte address; on a multi-master board, another master
* may have changed the chip's "current" address pointer.
*
* REVISIT some multi-address chips don't rollover page reads to
* the next slave address, so we may need to truncate the count.
* Those chips might need another quirk flag.
*
* If the real hardware used four adjacent 24c02 chips and that
* were misconfigured as one 24c08, that would be a similar effect:
* one "eeprom" file not four, but larger reads would fail when
* they crossed certain pages.
*/
static struct i2c_client *at24_translate_offset(struct at24_data *at24,
unsigned int *offset)
@ -182,74 +195,77 @@ static struct i2c_client *at24_translate_offset(struct at24_data *at24,
return at24->client[i];
}
static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
unsigned int offset, size_t count)
static ssize_t at24_eeprom_read_smbus(struct at24_data *at24, char *buf,
unsigned int offset, size_t count)
{
struct i2c_msg msg[2];
u8 msgbuf[2];
struct i2c_client *client;
unsigned long timeout, read_time;
int status, i;
struct i2c_client *client;
int status;
memset(msg, 0, sizeof(msg));
/*
* REVISIT some multi-address chips don't rollover page reads to
* the next slave address, so we may need to truncate the count.
* Those chips might need another quirk flag.
*
* If the real hardware used four adjacent 24c02 chips and that
* were misconfigured as one 24c08, that would be a similar effect:
* one "eeprom" file not four, but larger reads would fail when
* they crossed certain pages.
*/
/*
* Slave address and byte offset derive from the offset. Always
* set the byte address; on a multi-master board, another master
* may have changed the chip's "current" address pointer.
*/
client = at24_translate_offset(at24, &offset);
if (count > io_limit)
count = io_limit;
if (at24->use_smbus) {
/* Smaller eeproms can work given some SMBus extension calls */
if (count > I2C_SMBUS_BLOCK_MAX)
count = I2C_SMBUS_BLOCK_MAX;
} else {
/*
* When we have a better choice than SMBus calls, use a
* combined I2C message. Write address; then read up to
* io_limit data bytes. Note that read page rollover helps us
* here (unlike writes). msgbuf is u8 and will cast to our
* needs.
*/
i = 0;
if (at24->chip.flags & AT24_FLAG_ADDR16)
msgbuf[i++] = offset >> 8;
msgbuf[i++] = offset;
msg[0].addr = client->addr;
msg[0].buf = msgbuf;
msg[0].len = i;
msg[1].addr = client->addr;
msg[1].flags = I2C_M_RD;
msg[1].buf = buf;
msg[1].len = count;
}
/* Smaller eeproms can work given some SMBus extension calls */
if (count > I2C_SMBUS_BLOCK_MAX)
count = I2C_SMBUS_BLOCK_MAX;
loop_until_timeout(timeout, read_time) {
if (at24->use_smbus) {
status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset,
count, buf);
} else {
status = i2c_transfer(client->adapter, msg, 2);
if (status == 2)
status = count;
}
status = i2c_smbus_read_i2c_block_data_or_emulated(client,
offset,
count, buf);
dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
count, offset, status, jiffies);
if (status == count)
return count;
}
return -ETIMEDOUT;
}
static ssize_t at24_eeprom_read_i2c(struct at24_data *at24, char *buf,
unsigned int offset, size_t count)
{
unsigned long timeout, read_time;
struct i2c_client *client;
struct i2c_msg msg[2];
int status, i;
u8 msgbuf[2];
memset(msg, 0, sizeof(msg));
client = at24_translate_offset(at24, &offset);
if (count > io_limit)
count = io_limit;
/*
* When we have a better choice than SMBus calls, use a combined I2C
* message. Write address; then read up to io_limit data bytes. Note
* that read page rollover helps us here (unlike writes). msgbuf is
* u8 and will cast to our needs.
*/
i = 0;
if (at24->chip.flags & AT24_FLAG_ADDR16)
msgbuf[i++] = offset >> 8;
msgbuf[i++] = offset;
msg[0].addr = client->addr;
msg[0].buf = msgbuf;
msg[0].len = i;
msg[1].addr = client->addr;
msg[1].flags = I2C_M_RD;
msg[1].buf = buf;
msg[1].len = count;
loop_until_timeout(timeout, read_time) {
status = i2c_transfer(client->adapter, msg, 2);
if (status == 2)
status = count;
dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
count, offset, status, jiffies);
@ -520,7 +536,8 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
at24->chip = chip;
at24->num_addresses = num_addresses;
at24->read_func = at24_eeprom_read;
at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
: at24_eeprom_read_i2c;
at24->write_func = at24_eeprom_write;
writable = !(chip.flags & AT24_FLAG_READONLY);