sandbox: add: sandbox PMIC device drivers: I2C emul, pmic, regulator

This commit adds emulation of sandbox PMIC device, which includes:
- PMIC I2C emulation driver
- PMIC I/O driver (UCLASS_PMIC)
- PMIC regulator driver (UCLASS_REGULATOR)

The sandbox PMIC has 12 significant registers and 4 as padding to 16 bytes,
which allows using 'i2c md' command with the default count (16).

The sandbox PMIC provides regulators:
- 2x BUCK
- 2x LDO

Each, with adjustable output:
- Enable state
- Voltage
- Current limit (LDO1/BUCK1 only)
- Operation mode (different for BUCK and LDO)

Each attribute has it's own register, beside the enable state, which depends
on operation mode.

The header file: sandbox_pmic.h includes PMIC's default register values,
which are set on i2c pmic emul driver's probe() method.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested on sandbox:
Tested-by: Simon Glass <sjg@chromium.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/doc/device-tree-bindings/pmic/sandbox.txt b/doc/device-tree-bindings/pmic/sandbox.txt
new file mode 100644
index 0000000000..d84c97717b
--- /dev/null
+++ b/doc/device-tree-bindings/pmic/sandbox.txt
@@ -0,0 +1,35 @@
+Sandbox pmic
+
+This device uses two drivers:
+- drivers/power/pmic/sandbox.c (for parent device)
+- drivers/power/regulator/sandbox.c (for child regulators)
+
+This file describes the binding info for the PMIC driver.
+
+To bind the regulators, please read the regulator binding info:
+- doc/device-tree-bindings/regulator/sandbox.txt
+
+Required PMIC node properties:
+- compatible: "sandbox,pmic"
+- reg = 0x40
+
+Required PMIC's "emul" subnode,  with property:
+- compatible: "sandbox,i2c-pmic"
+
+With the above properties, the pmic device can be used for read/write only.
+To bind each regulator, the optional regulator subnodes should exists.
+
+Optional subnodes:
+- ldo/buck subnodes of each device's regulator (see regulator binding info)
+
+Example:
+
+sandbox_pmic {
+	compatible = "sandbox,pmic";
+	reg = <0x40>;
+
+	/* Mandatory for I/O */
+	emul {
+		compatible = "sandbox,i2c-pmic";
+	};
+};