hwmon: ltc2947: constify pointers to hwmon_channel_info

Statically allocated array of pointed to hwmon_channel_info can be made
const for safety.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

hwmon: (ltc2947) fix temperature scaling

The LTC2947 datasheet (Rev. B) calls out in the section "Register
Description: Non-Accumulated Result Registers" (pg. 30) that "To
calculate temperature, multiply the TEMP register value by 0.204°C
and add 5.5°C". Fix to add 5.5C and not 0.55C.

Fixes: 9f90fd652bed ("hwmon: Add support for ltc2947")
Signed-off-by: Derek Nguyen <derek.nguyen@collins.com>
Signed-off-by: Brandon Maier <brandon.maier@collins.com>
Link: https://lore.kernel.org/r/20221110192108.20624-1-brandon.maier@collins.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

hwmon: (ltc2947) Switch to EXPORT_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr()

These newer PM macros allow the compiler to see what code it can remove
if !CONFIG_PM_SLEEP. This allows the removal of __maybe_unused markings
whilst achieving the same result. In this case it also lets the
structure itself be removed.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220925172759.3573439-9-jic23@kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

hwmon: Make use of devm_clk_get_enabled()

Several drivers manually register a devm handler to disable their clk.
Convert them to devm_clk_get_enabled().

Acked-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

hwmon: (ltc2947) Properly handle errors when looking for the external clock

The return value of devm_clk_get should in general be propagated to
upper layer. In this case the clk is optional, use the appropriate
wrapper instead of interpreting all errors as "The optional clk is not
available".

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20210923201113.398932-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

hwmon: Add support for ltc2947

The ltc2947 is a high precision power and energy monitor with an
internal sense resistor supporting up to +/- 30A. Three internal no
Latency ADCs ensure accurate measurement of voltage and current, while
high-bandwidth analog multiplication of voltage and current provides
accurate power measurement in a wide range of applications. Internal or
external clocking options enable precise charge and energy measurements.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20191021154115.319073-1-nuno.sa@analog.com
[groeck: Removed unnecessary checks when reading temperature and energy;
PAGE{0,1} -> LTC2947_PAGE_{0,1}]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>