hwmon: (pmbus/tps53679) Add support for TPS536C7

TPS536C7 is a dual-channel D-CAP+ step-down controller whose channels are
distributed across a configurable number of phases (N+M, up to 12 total).
Whether channel B (PMBus page 1) exists depends on the phase configuration
register, so the page count is derived at probe time.

Factor the TPS53676 phase-map parsing into a shared helper and reuse it
for TPS536C7. Only aggregate per-channel telemetry is exposed: leave
info->phases[] unset so the PMBus core never programs the PHASE selector
on every read (and because TPS536C7 can place up to 12 phases on channel
A, exceeding PMBUS_PHASES). Report VOUT in linear format like TPS53676.

Since the core never programs PHASE, set it to 0xff on each populated
page so READ_IOUT reports the aggregate channel current, and verify it
(PHASE can be write-protected). Fail identification if aggregate
selection cannot be established, since otherwise a single phase current
could be reported as the channel total.

A configuration with no channel-A phase is rejected with -EOPNOTSUPP:
the PMBus core models pages as the contiguous range 0..pages-1 and
cannot represent a channel-A-absent topology.

On the tested TPS536C7 (device ID 54 49 53 6c 70 00, CAPABILITY 0xd0),
block reads of IC_DEVICE_ID and USER_DATA_03 return -EBADMSG with PEC
enabled, while retrying those two reads without PEC returns the expected
6- and 24-byte payloads. Standard byte/word telemetry keeps using PEC,
so only those two identification reads fall back to no-PEC.

Co-developed-by: Senthil Muniyappan <smuniyappan@juniper.net>
Co-developed-by: Vaibhav Agarwal <avaibhav@juniper.net>
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://patch.msgid.link/20260915164823.160977-4-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

0 files changed, 0 insertions, 0 deletions