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hwmon: (pmbus) Add comments explaining internal driver API return values

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Return values for functions reading/writing manufacturer specific registers are
poorly explained. Add comments to improve documentation.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Guenter Roeck 2011-08-26 08:01:51 -07:00
parent 363a12a499
commit 20fcfe1721
1 changed files with 16 additions and 2 deletions
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18
drivers/hwmon/pmbus/pmbus.h
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@ -134,8 +134,16 @@
* Semantics:
* Virtual registers are all word size.
* READ registers are read-only; writes are either ignored or return an error.
* RESET registers are read/write. Reading returns zero (used for detection),
* writing any value causes the associated history to be reset.
* RESET registers are read/write. Reading reset registers returns zero
* (used for detection), writing any value causes the associated history to be
* reset.
* Virtual registers have to be handled in device specific driver code. Chip
* driver code returns non-negative register values if a virtual register is
* supported, or a negative error code if not. The chip driver may return
* -ENODATA or any other error code in this case, though an error code other
* than -ENODATA is handled more efficiently and thus preferred. Either case,
* the calling PMBus core code will abort if the chip driver returns an error
* code when reading or writing virtual registers.
*/
#define PMBUS_VIRT_BASE 0x100
#define PMBUS_VIRT_READ_TEMP_MIN (PMBUS_VIRT_BASE + 0)
@ -320,6 +328,12 @@ struct pmbus_driver_info {
* The following functions map manufacturing specific register values
* to PMBus standard register values. Specify only if mapping is
* necessary.
* Functions return the register value (read) or zero (write) if
* successful. A return value of -ENODATA indicates that there is no
* manufacturer specific register, but that a standard PMBus register
* may exist. Any other negative return value indicates that the
* register does not exist, and that no attempt should be made to read
* the standard register.
*/
int (*read_byte_data)(struct i2c_client *client, int page, int reg);
int (*read_word_data)(struct i2c_client *client, int page, int reg);