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Subject[PATCH 07/14] eeprom: at24: split at24_eeprom_write() into specialized functions
Date
Split at24_eeprom_write() into three smaller functions - one for the
i2c operations and two for the smbus extensions (separate routines for
block and byte transfers). Assign them in at24_probe() depending on
the bus capabilities.

Also: in order to avoid duplications move code adjusting the count
argument into a separate function and use it for i2c and smbus block
writes (no need for a roll-over for byte writes as we're always
writing one byte).

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/misc/eeprom/at24.c | 134 ++++++++++++++++++++++++++++++---------------
1 file changed, 91 insertions(+), 43 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index e7db137..6acf35a 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -281,21 +281,15 @@ static ssize_t at24_eeprom_read_i2c(struct at24_data *at24, char *buf,
* chip is normally write protected. But there are plenty of product
* variants here, including OTP fuses and partial chip protect.
*
- * We only use page mode writes; the alternative is sloooow. This routine
- * writes at most one page.
+ * We only use page mode writes; the alternative is sloooow. These routines
+ * write at most one page.
*/
-static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
- unsigned int offset, size_t count)
+
+static size_t at24_adjust_write_count(struct at24_data *at24,
+ unsigned int offset, size_t count)
{
- struct i2c_client *client;
- struct i2c_msg msg;
- ssize_t status = 0;
- unsigned long timeout, write_time;
unsigned next_page;

- /* Get corresponding I2C address and adjust offset */
- client = at24_translate_offset(at24, &offset);
-
/* write_max is at most a page */
if (count > at24->write_max)
count = at24->write_max;
@@ -305,43 +299,90 @@ static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
if (offset + count > next_page)
count = next_page - offset;

- /* If we'll use I2C calls for I/O, set up the message */
- if (!at24->use_smbus) {
- int i = 0;
+ return count;
+}
+
+static ssize_t at24_eeprom_write_smbus_block(struct at24_data *at24,
+ const char *buf,
+ unsigned int offset, size_t count)
+{
+ unsigned long timeout, write_time;
+ struct i2c_client *client;
+ ssize_t status = 0;
+
+ client = at24_translate_offset(at24, &offset);
+ count = at24_adjust_write_count(at24, offset, count);

- msg.addr = client->addr;
- msg.flags = 0;
+ loop_until_timeout(timeout, write_time) {
+ status = i2c_smbus_write_i2c_block_data(client,
+ offset, count, buf);
+ if (status == 0)
+ status = count;

- /* msg.buf is u8 and casts will mask the values */
- msg.buf = at24->writebuf;
- if (at24->chip.flags & AT24_FLAG_ADDR16)
- msg.buf[i++] = offset >> 8;
+ dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
+ count, offset, status, jiffies);

- msg.buf[i++] = offset;
- memcpy(&msg.buf[i], buf, count);
- msg.len = i + count;
+ if (status == count)
+ return count;
}

+ return -ETIMEDOUT;
+}
+
+static ssize_t at24_eeprom_write_smbus_byte(struct at24_data *at24,
+ const char *buf,
+ unsigned int offset, size_t count)
+{
+ unsigned long timeout, write_time;
+ struct i2c_client *client;
+ ssize_t status = 0;
+
+ client = at24_translate_offset(at24, &offset);
+
loop_until_timeout(timeout, write_time) {
- 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 {
- status = i2c_transfer(client->adapter, &msg, 1);
- if (status == 1)
- status = count;
- }
+ status = i2c_smbus_write_byte_data(client, offset, buf[0]);
+ if (status == 0)
+ status = count;
+
+ dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
+ count, offset, status, jiffies);
+
+ if (status == count)
+ return count;
+ }
+
+ return -ETIMEDOUT;
+}
+
+static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
+ unsigned int offset, size_t count)
+{
+ unsigned long timeout, write_time;
+ struct i2c_client *client;
+ struct i2c_msg msg;
+ ssize_t status = 0;
+ int i = 0;
+
+ client = at24_translate_offset(at24, &offset);
+ count = at24_adjust_write_count(at24, offset, count);
+
+ msg.addr = client->addr;
+ msg.flags = 0;
+
+ /* msg.buf is u8 and casts will mask the values */
+ msg.buf = at24->writebuf;
+ if (at24->chip.flags & AT24_FLAG_ADDR16)
+ msg.buf[i++] = offset >> 8;
+
+ msg.buf[i++] = offset;
+ memcpy(&msg.buf[i], buf, count);
+ msg.len = i + count;
+
+ loop_until_timeout(timeout, write_time) {
+ status = i2c_transfer(client->adapter, &msg, 1);
+ if (status == 1)
+ status = count;
+
dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n",
count, offset, status, jiffies);

@@ -538,7 +579,14 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)

at24->read_func = at24->use_smbus ? at24_eeprom_read_smbus
: at24_eeprom_read_i2c;
- at24->write_func = at24_eeprom_write;
+ if (at24->use_smbus) {
+ if (at24->use_smbus_write == I2C_SMBUS_I2C_BLOCK_DATA)
+ at24->write_func = at24_eeprom_write_smbus_block;
+ else
+ at24->write_func = at24_eeprom_write_smbus_byte;
+ } else {
+ at24->write_func = at24_eeprom_write_i2c;
+ }

writable = !(chip.flags & AT24_FLAG_READONLY);
if (writable) {
--
2.7.4
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