From: Ondrej Jirman <meg...@megous.com>

SY8106A is an I2C attached single output regulator made by Silergy Corp,
which is used on several Allwinner H3/H5 SBCs to control the power
supply of the ARM cores.

Add a driver for it.

Signed-off-by: Ondrej Jirman <meg...@megous.com>
[Icenowy: Change commit message, remove enable/disable code, add default
 ramp_delay, add comment for go bit, add code for fixed mode voltage]
Signed-off-by: Icenowy Zheng <icen...@aosc.io>
Reviewed-by: Chen-Yu Tsai <w...@csie.org>
---
Changes in v4:
- Drop custom {get,set}_voltage_sel function, and force GO_BIT to be set
  when probing.

Changes in v3:
- Return the fixed voltage defined in device tree when I2C regulating
  not enabled (in this situation the register may contain no valid
  voltage data).

Changes in v2:
- Dropped the enable/disable code.
- Added default ramp_delay value.
- Added comment for the "go bit".

 MAINTAINERS                           |   6 +
 drivers/regulator/Kconfig             |   7 ++
 drivers/regulator/Makefile            |   2 +-
 drivers/regulator/sy8106a-regulator.c | 168 ++++++++++++++++++++++++++
 4 files changed, 182 insertions(+), 1 deletion(-)
 create mode 100644 drivers/regulator/sy8106a-regulator.c

diff --git a/MAINTAINERS b/MAINTAINERS
index e03887faca4f..a27b8e02c7d8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13512,6 +13512,12 @@ S:     Supported
 F:     net/switchdev/
 F:     include/net/switchdev.h
 
+SY8106A REGULATOR DRIVER
+M:     Icenowy Zheng <icen...@aosc.io>
+S:     Maintained
+F:     drivers/regulator/sy8106a-regulator.c
+F:     Documentation/devicetree/bindings/regulator/sy8106a-regulator.txt
+
 SYNC FILE FRAMEWORK
 M:     Sumit Semwal <sumit.sem...@linaro.org>
 R:     Gustavo Padovan <gust...@padovan.org>
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 097f61784a7d..4efae3b7e746 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -801,6 +801,13 @@ config REGULATOR_STW481X_VMMC
          This driver supports the internal VMMC regulator in the STw481x
          PMIC chips.
 
+config REGULATOR_SY8106A
+       tristate "Silergy SY8106A regulator"
+       depends on I2C && (OF || COMPILE_TEST)
+       select REGMAP_I2C
+       help
+         This driver supports SY8106A single output regulator.
+
 config REGULATOR_TPS51632
        tristate "TI TPS51632 Power Regulator"
        depends on I2C
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 590674fbecd7..d81fb02bd6e9 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -100,6 +100,7 @@ obj-$(CONFIG_REGULATOR_SC2731) += sc2731-regulator.o
 obj-$(CONFIG_REGULATOR_SKY81452) += sky81452-regulator.o
 obj-$(CONFIG_REGULATOR_STM32_VREFBUF) += stm32-vrefbuf.o
 obj-$(CONFIG_REGULATOR_STW481X_VMMC) += stw481x-vmmc.o
+obj-$(CONFIG_REGULATOR_SY8106A) += sy8106a-regulator.o
 obj-$(CONFIG_REGULATOR_TI_ABB) += ti-abb-regulator.o
 obj-$(CONFIG_REGULATOR_TPS6105X) += tps6105x-regulator.o
 obj-$(CONFIG_REGULATOR_TPS62360) += tps62360-regulator.o
@@ -125,5 +126,4 @@ obj-$(CONFIG_REGULATOR_WM8350) += wm8350-regulator.o
 obj-$(CONFIG_REGULATOR_WM8400) += wm8400-regulator.o
 obj-$(CONFIG_REGULATOR_WM8994) += wm8994-regulator.o
 
-
 ccflags-$(CONFIG_REGULATOR_DEBUG) += -DDEBUG
diff --git a/drivers/regulator/sy8106a-regulator.c 
b/drivers/regulator/sy8106a-regulator.c
new file mode 100644
index 000000000000..0a398be3f023
--- /dev/null
+++ b/drivers/regulator/sy8106a-regulator.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// sy8106a-regulator.c - Regulator device driver for SY8106A
+//
+// Copyright (C) 2016 Ondřej Jirman <meg...@megous.com>
+// Copyright (c) 2017-2018 Icenowy Zheng <icen...@aosc.io>
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+#define SY8106A_REG_VOUT1_SEL          0x01
+#define SY8106A_REG_VOUT_COM           0x02
+#define SY8106A_REG_VOUT1_SEL_MASK     0x7f
+#define SY8106A_DISABLE_REG            BIT(0)
+/*
+ * The I2C controlled voltage will only work when this bit is set; otherwise
+ * it will behave like a fixed regulator.
+ */
+#define SY8106A_GO_BIT                 BIT(7)
+
+struct sy8106a {
+       struct regulator_dev *rdev;
+       struct regmap *regmap;
+       u32 fixed_voltage;
+};
+
+static const struct regmap_config sy8106a_regmap_config = {
+       .reg_bits = 8,
+       .val_bits = 8,
+};
+
+static const struct regulator_ops sy8106a_ops = {
+       .set_voltage_sel = regulator_set_voltage_sel_regmap,
+       .set_voltage_time_sel = regulator_set_voltage_time_sel,
+       .get_voltage_sel = regulator_get_voltage_sel_regmap,
+       .list_voltage = regulator_list_voltage_linear,
+       /* Enabling/disabling the regulator is not yet implemented */
+};
+
+/* Default limits measured in millivolts */
+#define SY8106A_MIN_MV         680
+#define SY8106A_MAX_MV         1950
+#define SY8106A_STEP_MV                10
+
+static const struct regulator_desc sy8106a_reg = {
+       .name = "SY8106A",
+       .id = 0,
+       .ops = &sy8106a_ops,
+       .type = REGULATOR_VOLTAGE,
+       .n_voltages = ((SY8106A_MAX_MV - SY8106A_MIN_MV) / SY8106A_STEP_MV) + 1,
+       .min_uV = (SY8106A_MIN_MV * 1000),
+       .uV_step = (SY8106A_STEP_MV * 1000),
+       .vsel_reg = SY8106A_REG_VOUT1_SEL,
+       .vsel_mask = SY8106A_REG_VOUT1_SEL_MASK,
+       /*
+        * This ramp_delay is a conservative default value which works on
+        * H3/H5 boards VDD-CPUX situations.
+        */
+       .ramp_delay = 200,
+       .owner = THIS_MODULE,
+};
+
+/*
+ * I2C driver interface functions
+ */
+static int sy8106a_i2c_probe(struct i2c_client *i2c,
+                           const struct i2c_device_id *id)
+{
+       struct sy8106a *chip;
+       struct device *dev = &i2c->dev;
+       struct regulator_dev *rdev = NULL;
+       struct regulator_config config = { };
+       unsigned int reg, vsel;
+       int error;
+
+       chip = devm_kzalloc(&i2c->dev, sizeof(struct sy8106a), GFP_KERNEL);
+       if (!chip)
+               return -ENOMEM;
+
+       error = of_property_read_u32(dev->of_node, "silergy,fixed-microvolt",
+                                    &chip->fixed_voltage);
+       if (error)
+               return error;
+
+       if (chip->fixed_voltage < SY8106A_MIN_MV * 1000 ||
+           chip->fixed_voltage > SY8106A_MAX_MV * 1000)
+               return -EINVAL;
+
+       chip->regmap = devm_regmap_init_i2c(i2c, &sy8106a_regmap_config);
+       if (IS_ERR(chip->regmap)) {
+               error = PTR_ERR(chip->regmap);
+               dev_err(dev, "Failed to allocate register map: %d\n", error);
+               return error;
+       }
+
+       config.dev = &i2c->dev;
+       config.regmap = chip->regmap;
+       config.driver_data = chip;
+
+       config.of_node = dev->of_node;
+       config.init_data = of_get_regulator_init_data(dev, dev->of_node,
+                                                     &sy8106a_reg);
+
+       if (!config.init_data)
+               return -ENOMEM;
+
+       /* Ensure GO_BIT is enabled when probing */
+       error = regmap_read(chip->regmap, SY8106A_REG_VOUT1_SEL, &reg);
+       if (error)
+               return error;
+
+       if (!(reg & SY8106A_GO_BIT)) {
+               vsel = (chip->fixed_voltage / 1000 - SY8106A_MIN_MV) /
+                      SY8106A_STEP_MV;
+
+               error = regmap_write(chip->regmap, SY8106A_REG_VOUT1_SEL,
+                                    vsel | SY8106A_GO_BIT);
+               if (error)
+                       return error;
+       }
+
+       /* Probe regulator */
+       rdev = devm_regulator_register(&i2c->dev, &sy8106a_reg, &config);
+       if (IS_ERR(rdev)) {
+               error = PTR_ERR(rdev);
+               dev_err(&i2c->dev, "Failed to register SY8106A regulator: 
%d\n", error);
+               return error;
+       }
+
+       chip->rdev = rdev;
+
+       i2c_set_clientdata(i2c, chip);
+
+       return 0;
+}
+
+static const struct of_device_id sy8106a_i2c_of_match[] = {
+       { .compatible = "silergy,sy8106a" },
+       { },
+};
+MODULE_DEVICE_TABLE(of, sy8106a_i2c_of_match);
+
+static const struct i2c_device_id sy8106a_i2c_id[] = {
+       { "sy8106a", 0 },
+       { },
+};
+MODULE_DEVICE_TABLE(i2c, sy8106a_i2c_id);
+
+static struct i2c_driver sy8106a_regulator_driver = {
+       .driver = {
+               .name = "sy8106a",
+               .of_match_table = of_match_ptr(sy8106a_i2c_of_match),
+       },
+       .probe = sy8106a_i2c_probe,
+       .id_table = sy8106a_i2c_id,
+};
+
+module_i2c_driver(sy8106a_regulator_driver);
+
+MODULE_AUTHOR("Ondřej Jirman <meg...@megous.com>");
+MODULE_AUTHOR("Icenowy Zheng <icen...@aosc.io>");
+MODULE_DESCRIPTION("Regulator device driver for Silergy SY8106A");
+MODULE_LICENSE("GPL");
-- 
2.17.0

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