The driver uses i2c_smbus_read_i2c_block_data() for PMBus block commands.
Use pmbus_read_smbus_i2c_block_data() instead to enable the driver to work
with I2C controllers which do not support i2c_smbus_read_i2c_block_data().

Drop the functionality check to get an explicit error message if the
required SMBus commands are not supported.

Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

The driver tries to use both pmbus_read_smbus_i2c_block_data() and
i2c_smbus_read_i2c_block_data() for PMBus block commands.

Use pmbus_read_smbus_i2c_block_data() instead to simplify the code.

Drop the functionality check to simplify the code and to trigger a return
with -EOPNOTSUPP if SMBus block commands are not supported.

Cc: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Cc: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

The driver uses a mix of pmbus_read_smbus_i2c_block_data() and
i2c_smbus_read_i2c_block_data() for PMBus block commands.

Use pmbus_read_smbus_i2c_block_data() instead to enable the driver to work
I2C controllers which do not support both block commands.

Drop the functionality check to simplify the code and to trigger a return
with -EOPNOTSUPP if SMBus block commands are not supported.

As part of this patch, rework detection of LT7170 and LT7171. The return
length of pmbus_read_smbus_i2c_block_data() may be less than the requested
number of bytes, meaning the return length needs to be checked. Also,
checking for "LT7170-1" after checking for "LT7170" and checking for
"LT7171-1" after checking for "LT7171" is pointless since the first check
will already produce a match, so drop the second part of the check.

Cc: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Cc: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

The driver uses i2c_smbus_read_block_data() for PMBus block commands.
Use pmbus_read_smbus_i2c_block_data() instead to enable the driver to work
with I2C controllers which do not support i2c_smbus_read_block_data().

Drop the functionality check to get an explicit error message if the
required SMBus commands are not supported.

Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

PMBus drivers need support for reading SMBus block data. Unfortunately,
not all i2C controllers support this command.

Implement pmbus_read_smbus_i2c_block_data() which first tries to use
i2c_smbus_read_block_data(). If not supported, try to emulate it by calling
i2c_smbus_read_i2c_block_data(). Export the new function for use in PMBus
drivers.

Cc: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Cc: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

The write cases of debugfs entries are provisioning and bench
helpers. By designs the MPQ8646 powers the CPU core rail,
so a wrong write can brown out the board or persist a bad
setpoint into finite-cycle NVM.
Said differently: some wrong register writes can and likely
will physically damage or destroy the chip and/or the board.

To be safe, it is disabled by default behind a
CONFIG_SENSORS_MPQ8646_DEBUG_UNSAFE and we print an explicit warning
banner at probe time when they are built in.

Signed-off-by: Vincent Jardin <vjardin@free.fr>
Link: https://lore.kernel.org/r/20260730-mpq8646_v0-v7-4-e7c7ad768d5d@free.fr
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Add a new driver for the MPS MPQ8646 that is a PMBus device.

Beyond basic PMBus telemetry, the driver adds:
  - alarm acknowledge via inX_reset_history.
  - STATUS_WORD MPS-extended bit decode and the NVM-backed
    PROTECTION_LAST post-mortem, exposed as a read-only debugfs
    decoder.
  - In-driver alarm-poll fallback work item (thanks lm90) for
    boards without SMBALERT

Signed-off-by: Vincent Jardin <vjardin@free.fr>
Link: https://lore.kernel.org/r/20260730-mpq8646_v0-v7-3-e7c7ad768d5d@free.fr
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Factor of pmbus_fault_handler() into an exported helper so
drivers can notify sequence from a polling work item on boards
for which the chip's SMBALERT# pin is not wired to the
CPU. The interrupt handler becomes a thin wrapper.

Like the SMBALERT# path, the helper notifies and then clears the
latched faults unconditionally, so a polling caller inherits exactly
the interrupt semantics.

Signed-off-by: Vincent Jardin <vjardin@free.fr>
Link: https://lore.kernel.org/r/20260730-mpq8646_v0-v7-1-e7c7ad768d5d@free.fr
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Add support for MAX20830C and MAX20840 step-down DC-DC switching
regulator with PMBus interface. MAX20830C is a different packaging
for MAX20830, and MAX20840C supports 40A regulation compared to
MAX20830 that is only 30A.

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Link: https://lore.kernel.org/r/20260730-dev-max20830c-v5-4-a7553f84ee74@analog.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Implement support for external voltage divider scaling using the
adi,vout-rfb1-ohms and adi,vout-rfb2-ohms device tree properties.

When the desired output voltage exceeds VREF, a resistor divider
(RFB1 and RFB2) is used to scale down the feedback voltage. The
driver reads these resistor values from device tree and applies
the scaling formula: VOUT_actual = VOUT_measured × (1 + RFB1/RFB2)

The properties are optional. If not specified, the driver assumes
no voltage divider is present and reports the raw VOUT reading.

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Link: https://lore.kernel.org/r/20260730-dev-max20830c-v5-2-a7553f84ee74@analog.com
[groeck: Fixed minor conflicts]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>