mfd: max597x: Add support for MAX5970 and MAX5978

Implement a regulator driver with IRQ support for fault management.
Written against documentation [1] and [2] and tested on real hardware.

Every channel has it's own regulator supply nammed 'vss1-supply' and
'vss2-supply'. The regulator supply is used to determine the output
voltage, as the smart switch provides no output regulation.
The driver requires the 'shunt-resistor-micro-ohms' to be present in
the devicetree to properly calculate current related values.

You must specify compatible devictree layout:

regulator@3a {
        reg = <0x3a>;
        vss1-supply = <&p3v3>;
        compatible = "maxim,max5978";

        ...

        regulators {
                sw0_ref: SW0 {
                        regulator-compatible = "SW0";
                        shunt-resistor-micro-ohms = <12000>;
                        ...
                }
        }
}

1: https://datasheets.maximintegrated.com/en/ds/MAX5970.pdf
2: https://datasheets.maximintegrated.com/en/ds/MAX5978.pdf

...
Changes in V12:
- Use simple_mfd_i2c driver and remove previous implementation.
- Remove newline
- Use _MFD_MAX597X_H in header file
- Successfull build need following patch from regulator:
https://lore.kernel.org/r/20230216075302.68935-1-Naresh.Solanki@9elements.com
https://lore.kernel.org/r/20230210163225.1208035-1-Naresh.Solanki@9elements.com

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230307121246.127425-2-Naresh.Solanki@9elements.com

2 files changed, 23 insertions, 0 deletions

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index fcc141e067b9..d381d0e63455 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -266,6 +266,16 @@ config MFD_MADERA_SPI
 	  Support for the Cirrus Logic Madera platform audio SoC
 	  core functionality controlled via SPI.
 
+config MFD_MAX597X
+	tristate "Maxim 597x power switch and monitor"
+	depends on (I2C && OF)
+	select MFD_SIMPLE_MFD_I2C
+	help
+	  This driver controls a Maxim 5970/5978 switch via I2C bus.
+	  The MAX5970/5978 is a smart switch with no output regulation, but
+	  fault protection and voltage and current monitoring capabilities.
+	  Also it supports upto 4 indication leds.
+
 config MFD_CS47L15
 	bool "Cirrus Logic CS47L15"
 	select PINCTRL_CS47L15
diff --git a/drivers/mfd/simple-mfd-i2c.c b/drivers/mfd/simple-mfd-i2c.c
index e31f13fd6a79..20782b4dd172 100644
--- a/drivers/mfd/simple-mfd-i2c.c
+++ b/drivers/mfd/simple-mfd-i2c.c
@@ -72,9 +72,22 @@ static const struct simple_mfd_data silergy_sy7636a = {
 	.mfd_cell_size = ARRAY_SIZE(sy7636a_cells),
 };
 
+static const struct mfd_cell max597x_cells[] = {
+	{ .name = "max597x-regulator", },
+	{ .name = "max597x-iio", },
+	{ .name = "max597x-led", },
+};
+
+static const struct simple_mfd_data maxim_max597x = {
+	.mfd_cell = max597x_cells,
+	.mfd_cell_size = ARRAY_SIZE(max597x_cells),
+};
+
 static const struct of_device_id simple_mfd_i2c_of_match[] = {
 	{ .compatible = "kontron,sl28cpld" },
 	{ .compatible = "silergy,sy7636a", .data = &silergy_sy7636a},
+	{ .compatible = "maxim,max5970", .data = &maxim_max597x},
+	{ .compatible = "maxim,max5978", .data = &maxim_max597x},
 	{}
 };
 MODULE_DEVICE_TABLE(of, simple_mfd_i2c_of_match);