Documentation/hwmon/pmbus-core.rst

9 power-management protocol with a fully defined command language that facilitates
11 protocol is implemented over the industry-standard SMBus serial interface and
12 enables programming, control, and real-time monitoring of compliant power
18 promoted by the PMBus Implementers Forum (PMBus-IF), comprising 30+ adopters
22 commands, and manufacturers can add as many non-standard commands as they like.
23 Also, different PMBUs devices act differently if non-supported commands are
43 PMBus device capabilities auto-detection
46 For generic PMBus devices, code in pmbus.c attempts to auto-detect all supported
47 PMBus commands. Auto-detection is somewhat limited, since there are simply too
50 pages (see the PMBus specification for details on multi-page PMBus devices).
53 all commands can be auto-detected. The data structures in this driver can be
57 Some commands are always auto-detected. This applies to all limit commands
59 Limits and alarm attributes are auto-detected because there are simply too many
70 -----------------------
76 ----------------------
78 Virtual PMBus commands are provided to enable support for non-standard
92 - READ commands are read-only; writes are either ignored or return an error.
93 - RESET commands are read/write. Reading reset registers returns zero
98 code returns non-negative values if a virtual command is supported, or a
99 negative error code if not. The chip driver may return -ENODATA or any other
100 Linux error code in this case, though an error code other than -ENODATA is
107 ------------------------
113 - For devices supporting its data in Direct Data Format, it provides coefficients
116 - Supported chip functionality can be provided to the core driver. This may be
117   necessary for chips which react badly if non-supported commands are executed,
119 - Several function entry points are provided to support overriding and/or
121   non-standard PMBus commands to standard commands, or to augment standard
137 ---------------------------------
140 successful. A return value of -ENODATA indicates that there is no manufacturer
154 		if (status != -ENODATA)
158 		return -EINVAL;
169 <page> may be -1, which means "current page".
174   int (*read_word_data)(struct i2c_client *client, int page, int phase,
177 Read word from page <page>, phase <phase>, register <reg>. If the chip does not
178 support multiple phases, the phase parameter can be ignored. If the chip
179 supports multiple phases, a phase value of 0xff indicates all phases.
193 <page> may be -1, which means "current page".
201 pre-determined. It is currently only used by the generic pmbus driver
205 ---------------------------------
216   int pmbus_set_page(struct i2c_client *client, u8 page, u8 phase);
218 Set PMBus page register to <page> and <phase> for subsequent commands.
219 If the chip does not support multiple phases, the phase parameter is
220 ignored. Otherwise, a phase value of 0xff selects all phases.
224   int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 phase,
227 Read word data from <page>, <phase>, <reg>. Similar to
228 i2c_smbus_read_word_data(), but selects page and phase first. If the chip does
229 not support multiple phases, the phase parameter is ignored. Otherwise, a phase
245 selects page first. <page> may be -1, which means "current page".
252 selects page first. <page> may be -1, which means "current page".
321 -----
335 Some i2c controllers do not support single-byte commands (write commands with