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authorGuenter Roeck <guenter.roeck@ericsson.com>2011-08-26 08:01:51 -0700
committerGuenter Roeck <guenter.roeck@ericsson.com>2011-10-24 11:09:33 -0700
commit20fcfe172190704918969695a16cf621e2f4ce25 (patch)
tree603eeef49ea33bdb4817666f718356cc215e3ea4 /drivers
parent363a12a49968103ea2c5493932d417d73bc099b7 (diff)
downloadlinux-20fcfe172190704918969695a16cf621e2f4ce25.tar.bz2
hwmon: (pmbus) Add comments explaining internal driver API return values
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/hwmon/pmbus/pmbus.h18
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index a6ae20ffef6b..8751f4073ec2 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -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);