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eeprom: at24: extend driver to allow writing via i2c_smbus_write_byte_data 

I have a at24 EEPROM connected via i2c bus provided by ISCH i2c
bus driver. This bus driver does not support
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK and so I was looking for a way
to be able to write the eeprom. This patch adds support for
I2C_SMBUS_BYTE_DATA writing via i2c_smbus_write_byte_data.
It is quite slow, but it works.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
[wsa: s/use_smbuse_write/use_smbus_write/]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Christian Gmeiner 2014-10-09 11:07:58 +02:00 коммит произвёл Wolfram Sang
Родитель 3eee1799ae
Коммит a839ce663b
1 изменённых файлов: 29 добавлений и 6 удалений
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35
drivers/misc/eeprom/at24.c
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@ -56,6 +56,7 @@ struct at24_data {
struct at24_platform_data chip;
struct memory_accessor macc;
int use_smbus;
int use_smbus_write;
/*
* Lock protects against activities from other Linux tasks,
@ -324,7 +325,7 @@ static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
{
struct i2c_client *client;
struct i2c_msg msg;
ssize_t status;
ssize_t status = 0;
unsigned long timeout, write_time;
unsigned next_page;
@ -365,9 +366,18 @@ static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
timeout = jiffies + msecs_to_jiffies(write_timeout);
do {
write_time = jiffies;
if (at24->use_smbus) {
status = i2c_smbus_write_i2c_block_data(client,
offset, count, buf);
if (at24->use_smbus_write) {
switch (at24->use_smbus_write) {
case I2C_SMBUS_I2C_BLOCK_DATA:
status = i2c_smbus_write_i2c_block_data(client,
offset, count, buf);
break;
case I2C_SMBUS_BYTE_DATA:
status = i2c_smbus_write_byte_data(client,
offset, buf[0]);
break;
}
if (status == 0)
status = count;
} else {
@ -487,6 +497,7 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
struct at24_platform_data chip;
bool writable;
int use_smbus = 0;
int use_smbus_write = 0;
struct at24_data *at24;
int err;
unsigned i, num_addresses;
@ -546,6 +557,18 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
}
}
/* Use I2C operations unless we're stuck with SMBus extensions. */
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
if (i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
use_smbus_write = I2C_SMBUS_I2C_BLOCK_DATA;
} else if (i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
use_smbus_write = I2C_SMBUS_BYTE_DATA;
chip.page_size = 1;
}
}
if (chip.flags & AT24_FLAG_TAKE8ADDR)
num_addresses = 8;
else
@ -559,6 +582,7 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
mutex_init(&at24->lock);
at24->use_smbus = use_smbus;
at24->use_smbus_write = use_smbus_write;
at24->chip = chip;
at24->num_addresses = num_addresses;
@ -576,8 +600,7 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
writable = !(chip.flags & AT24_FLAG_READONLY);
if (writable) {
if (!use_smbus || i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
if (!use_smbus || use_smbus_write) {
unsigned write_max = chip.page_size;