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>
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@ -134,8 +134,16 @@
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* Semantics:
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* Virtual registers are all word size.
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* READ registers are read-only; writes are either ignored or return an error.
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* RESET registers are read/write. Reading returns zero (used for detection),
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* writing any value causes the associated history to be reset.
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* RESET registers are read/write. Reading reset registers returns zero
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* (used for detection), writing any value causes the associated history to be
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* reset.
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* Virtual registers have to be handled in device specific driver code. Chip
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* driver code returns non-negative register values if a virtual register is
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* supported, or a negative error code if not. The chip driver may return
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* -ENODATA or any other error code in this case, though an error code other
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* than -ENODATA is handled more efficiently and thus preferred. Either case,
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* the calling PMBus core code will abort if the chip driver returns an error
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* code when reading or writing virtual registers.
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*/
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#define PMBUS_VIRT_BASE 0x100
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#define PMBUS_VIRT_READ_TEMP_MIN (PMBUS_VIRT_BASE + 0)
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@ -320,6 +328,12 @@ struct pmbus_driver_info {
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* The following functions map manufacturing specific register values
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* to PMBus standard register values. Specify only if mapping is
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* necessary.
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* Functions return the register value (read) or zero (write) if
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* successful. A return value of -ENODATA indicates that there is no
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* manufacturer specific register, but that a standard PMBus register
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* may exist. Any other negative return value indicates that the
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* register does not exist, and that no attempt should be made to read
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* the standard register.
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*/
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int (*read_byte_data)(struct i2c_client *client, int page, int reg);
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int (*read_word_data)(struct i2c_client *client, int page, int reg);
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