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>
diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index d87f77f..2d3db81 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -56,6 +56,7 @@
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 @@
{
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 @@
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 @@
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 @@
}
}
+ /* 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 @@
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 @@
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;