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Subject[PATCH 05/14] eeprom: at24: hide the read/write loop behind a macro
Date
Before splitting the read/write routines into smaller, more
specialized functions, unduplicate some code in advance.

Use a 'for' loop instead of 'do while' when waiting for the previous
write to complete and hide it behind a macro.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/misc/eeprom/at24.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 0621937..2efb572 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -113,6 +113,22 @@ MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
((1 << AT24_SIZE_FLAGS | (_flags)) \
<< AT24_SIZE_BYTELEN | ilog2(_len))

+/*
+ * Both reads and writes fail if the previous write didn't complete yet. This
+ * macro loops a few times waiting at least long enough for one entire page
+ * write to work.
+ *
+ * It takes two parameters: a variable in which the future timeout in jiffies
+ * will be stored and a temporary variable holding the time of the last
+ * iteration of processing the request. Both should be unsigned integers
+ * holding at least 32 bits.
+ */
+#define loop_until_timeout(tout, op_time) \
+ for (tout = jiffies + msecs_to_jiffies(write_timeout), \
+ op_time = jiffies; \
+ time_before(op_time, tout); \
+ usleep_range(1000, 1500), op_time = jiffies)
+
static const struct i2c_device_id at24_ids[] = {
/* needs 8 addresses as A0-A2 are ignored */
{ "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
@@ -225,14 +241,7 @@ static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
msg[1].len = count;
}

- /*
- * Reads fail if the previous write didn't complete yet. We may
- * loop a few times until this one succeeds, waiting at least
- * long enough for one entire page write to work.
- */
- timeout = jiffies + msecs_to_jiffies(write_timeout);
- do {
- read_time = jiffies;
+ loop_until_timeout(timeout, read_time) {
if (at24->use_smbus) {
status = i2c_smbus_read_i2c_block_data_or_emulated(client, offset,
count, buf);
@@ -246,9 +255,7 @@ static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,

if (status == count)
return count;
-
- usleep_range(1000, 1500);
- } while (time_before(read_time, timeout));
+ }

return -ETIMEDOUT;
}
@@ -299,14 +306,7 @@ static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,
msg.len = i + count;
}

- /*
- * Writes fail if the previous one didn't complete yet. We may
- * loop a few times until this one succeeds, waiting at least
- * long enough for one entire page write to work.
- */
- timeout = jiffies + msecs_to_jiffies(write_timeout);
- do {
- write_time = jiffies;
+ loop_until_timeout(timeout, write_time) {
if (at24->use_smbus_write) {
switch (at24->use_smbus_write) {
case I2C_SMBUS_I2C_BLOCK_DATA:
@@ -331,9 +331,7 @@ static ssize_t at24_eeprom_write(struct at24_data *at24, const char *buf,

if (status == count)
return count;
-
- usleep_range(1000, 1500);
- } while (time_before(write_time, timeout));
+ }

return -ETIMEDOUT;
}
--
2.7.4
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