[PATCH 1/3] iio: Add ADM1177 Hot Swap Controller and Digital Power Monitor driver

[Beniamin Bia]

From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>

ADM1177 is a Hot Swap Controller and Digital Power Monitor with
Soft Start Pin.

Datasheet:
Link: https://www.analog.com/media/en/technical-documentation/data-sheets/ADM1177.pdf

Signed-off-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
Co-developed-by: Beniamin Bia <beniamin.bia@xxxxxxxxxx>
Signed-off-by: Beniamin Bia <beniamin.bia@xxxxxxxxxx>
---
 drivers/iio/adc/Kconfig   |  12 ++
 drivers/iio/adc/Makefile  |   1 +
 drivers/iio/adc/adm1177.c | 257 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 270 insertions(+)
 create mode 100644 drivers/iio/adc/adm1177.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 9554890a3200..4db8c6dcb595 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -228,6 +228,18 @@ config ASPEED_ADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called aspeed_adc.
 
+config ADM1177
+	tristate "Analog Devices ADM1177 Digital Power Monitor driver"
+	depends on I2C
+	help
+	  Say yes here to build support for Analog Devices:
+	  ADM1177 Hot Swap Controller and Digital Power Monitor
+	  with Soft Start Pin. Provides direct access
+	  via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called adm1177.
+
 config AT91_ADC
 	tristate "Atmel AT91 ADC"
 	depends on ARCH_AT91
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 5ecc481c2967..7899d6a158f3 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_AD7887) += ad7887.o
 obj-$(CONFIG_AD7949) += ad7949.o
 obj-$(CONFIG_AD799X) += ad799x.o
 obj-$(CONFIG_ASPEED_ADC) += aspeed_adc.o
+obj-$(CONFIG_ADM1177) += adm1177.o
 obj-$(CONFIG_AT91_ADC) += at91_adc.o
 obj-$(CONFIG_AT91_SAMA5D2_ADC) += at91-sama5d2_adc.o
 obj-$(CONFIG_AXP20X_ADC) += axp20x_adc.o
diff --git a/drivers/iio/adc/adm1177.c b/drivers/iio/adc/adm1177.c
new file mode 100644
index 000000000000..daec34566a65
--- /dev/null
+++ b/drivers/iio/adc/adm1177.c
@@ -0,0 +1,257 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ADM1177 Hot Swap Controller and Digital Power Monitor with Soft Start Pin
+ *
+ * Copyright 2015-2019 Analog Devices Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+
+/*  Command Byte Operations */
+#define ADM1177_CMD_V_CONT	BIT(0)
+#define ADM1177_CMD_V_ONCE	BIT(1)
+#define ADM1177_CMD_I_CONT	BIT(2)
+#define ADM1177_CMD_I_ONCE	BIT(3)
+#define ADM1177_CMD_VRANGE	BIT(4)
+#define ADM1177_CMD_STATUS_RD	BIT(6)
+
+/* Extended Register */
+#define ADM1177_REG_ALERT_EN	1
+#define ADM1177_REG_ALERT_TH	2
+#define ADM1177_REG_CONTROL	3
+
+/* ADM1177_REG_ALERT_EN */
+#define ADM1177_EN_ADC_OC1	BIT(0)
+#define ADM1177_EN_ADC_OC4	BIT(1)
+#define ADM1177_EN_HS_ALERT	BIT(2)
+#define ADM1177_EN_OFF_ALERT	BIT(3)
+#define ADM1177_CLEAR		BIT(4)
+
+/* ADM1177_REG_CONTROL */
+#define ADM1177_SWOFF		BIT(0)
+
+#define ADM1177_BITS		12
+
+/**
+ * struct adm1177_state - driver instance specific data
+ * @client		pointer to i2c client
+ * @reg			regulator info for the the power supply of the device
+ * @command		internal control register
+ * @r_sense_uohm	current sense resistor value
+ * @alert_threshold_ua	current limit for shutdown
+ * @vrange_high		internal voltage divider
+ */
+struct adm1177_state {
+	struct i2c_client	*client;
+	struct regulator	*reg;
+	u8			command;
+	u32			r_sense_uohm;
+	u32			alert_threshold_ua;
+	bool			vrange_high;
+};
+
+static int adm1177_read(struct adm1177_state *st, u8 num, u8 *data)
+{
+	struct i2c_client *client = st->client;
+	int ret = 0;
+
+	ret = i2c_master_recv(client, data, num);
+	if (ret < 0) {
+		dev_err(&client->dev, "I2C read error\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int adm1177_write_cmd(struct adm1177_state *st, u8 cmd)
+{
+	st->command = cmd;
+	return i2c_smbus_write_byte(st->client, cmd);
+}
+
+static int adm1177_write_reg(struct adm1177_state *st, u8 reg, u8 val)
+{
+	return i2c_smbus_write_byte_data(st->client, reg, val);
+}
+
+static int adm1177_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val,
+			   int *val2,
+			   long mask)
+{
+	struct adm1177_state *st = iio_priv(indio_dev);
+	u8 data[3];
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		adm1177_read(st, 3, data);
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			*val = (data[0] << 4) | (data[2] >> 4);
+			return IIO_VAL_INT;
+		case IIO_CURRENT:
+			*val = (data[1] << 4) | (data[2] & 0xF);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			if (st->command & ADM1177_CMD_VRANGE)
+				*val = 6650;
+			else
+				*val = 26350;
+
+			*val2 = ADM1177_BITS;
+			return IIO_VAL_FRACTIONAL_LOG2;
+		case IIO_CURRENT:
+			*val = 105840 / st->r_sense_uohm;
+
+			*val2 = ADM1177_BITS;
+			return IIO_VAL_FRACTIONAL_LOG2;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_chan_spec adm1177_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.indexed = 1,
+		.channel = 0,
+	},
+	{
+		.type = IIO_CURRENT,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.indexed = 1,
+		.channel = 0,
+	},
+};
+
+static const struct iio_info adm1177_info = {
+	.read_raw = &adm1177_read_raw,
+};
+static void adm1177_remove(void *data)
+{
+	struct adm1177_state *st = data;
+
+	if (st->reg)
+		regulator_disable(st->reg);
+}
+
+static int adm1177_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	int ret;
+	struct device_node *np;
+	struct adm1177_state *st;
+	struct iio_dev *indio_dev;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	st->client = client;
+
+	np = client->dev.of_node;
+
+	st->reg = devm_regulator_get_optional(&client->dev, "vref");
+	if (IS_ERR(st->reg)) {
+		if (PTR_ERR(st->reg) == EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		st->reg = NULL;
+	} else {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			return ret;
+		ret = devm_add_action_or_reset(&client->dev, adm1177_remove,
+					       st);
+		if (ret)
+			return ret;
+	}
+
+	of_property_read_u32(np, "adi,r-sense-micro-ohms", &st->r_sense_uohm);
+	of_property_read_u32(np, "adi,shutdown-threshold-microamp",
+			     &st->alert_threshold_ua);
+	st->vrange_high = of_property_read_bool(np,
+				"adi,vrange-high-enable");
+	if (st->alert_threshold_ua) {
+		unsigned int val;
+
+		val = (st->alert_threshold_ua * st->r_sense_uohm * 0xFF);
+		val /= 105840000U;
+		if (val > 0xFF) {
+			dev_err(&client->dev,
+				"Requested shutdown current %d uA above limit\n",
+				st->alert_threshold_ua);
+
+			val = 0xFF;
+		}
+		adm1177_write_reg(st, ADM1177_REG_ALERT_TH, val);
+	}
+
+	adm1177_write_cmd(st, ADM1177_CMD_V_CONT |
+			      ADM1177_CMD_I_CONT |
+			      (st->vrange_high ? 0 : ADM1177_CMD_VRANGE));
+
+	indio_dev->name = id->name;
+	indio_dev->channels = adm1177_channels;
+	indio_dev->num_channels = ARRAY_SIZE(adm1177_channels);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &adm1177_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id adm1177_ids[] = {
+	{ "adm1177", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, adm1177_ids);
+
+static const struct of_device_id adm1177_dt_ids[] = {
+	{ .compatible = "adi,adm1177" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, adm1177_dt_ids);
+
+static struct i2c_driver adm1177_driver = {
+	.driver = {
+		.name = "adm1177",
+		.of_match_table = adm1177_dt_ids,
+	},
+	.probe = adm1177_probe,
+	.id_table = adm1177_ids,
+};
+module_i2c_driver(adm1177_driver);
+
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Analog Devices ADM1177 ADC driver");
+MODULE_LICENSE("GPL v2");
-- 
2.17.1