Date:   Sat, 11 Jan 2020 08:33:03 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Beniamin Bia <beniamin.bia@...log.com>
Cc:     linux-hwmon@...r.kernel.org, Michael.Hennerich@...log.com,
        linux-kernel@...r.kernel.org, jdelvare@...e.com,
        mark.rutland@....com, lgirdwood@...il.com, broonie@...nel.org,
        devicetree@...r.kernel.org, biabeniamin@...look.com
Subject: Re: [PATCH v3 1/3] hwmon: adm1177: Add ADM1177 Hot Swap Controller
 and Digital Power Monitor driver

On Tue, Jan 07, 2020 at 12:59:27PM +0200, Beniamin Bia wrote:
> 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: Beniamin Bia <beniamin.bia@...log.com>

Applied to hwmon-next.

Thanks,
Guenter

> ---
> Changes in v3:
> -alert_threshold_ua clamped to maximum
> 
>  Documentation/hwmon/adm1177.rst |  36 ++++
>  drivers/hwmon/Kconfig           |  10 ++
>  drivers/hwmon/Makefile          |   1 +
>  drivers/hwmon/adm1177.c         | 288 ++++++++++++++++++++++++++++++++
>  4 files changed, 335 insertions(+)
>  create mode 100644 Documentation/hwmon/adm1177.rst
>  create mode 100644 drivers/hwmon/adm1177.c
> 
> diff --git a/Documentation/hwmon/adm1177.rst b/Documentation/hwmon/adm1177.rst
> new file mode 100644
> index 000000000000..c81e0b4abd28
> --- /dev/null
> +++ b/Documentation/hwmon/adm1177.rst
> @@ -0,0 +1,36 @@
> +Kernel driver adm1177
> +=====================
> +
> +Supported chips:
> +  * Analog Devices ADM1177
> +    Prefix: 'adm1177'
> +    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADM1177.pdf
> +
> +Author: Beniamin Bia <beniamin.bia@...log.com>
> +
> +
> +Description
> +-----------
> +
> +This driver supports hardware monitoring for Analog Devices ADM1177
> +Hot-Swap Controller and Digital Power Monitors with Soft Start Pin.
> +
> +
> +Usage Notes
> +-----------
> +
> +This driver does not auto-detect devices. You will have to instantiate the
> +devices explicitly. Please see Documentation/i2c/instantiating-devices for
> +details.
> +
> +
> +Sysfs entries
> +-------------
> +
> +The following attributes are supported. Current maxim attribute
> +is read-write, all other attributes are read-only.
> +
> +in0_input		Measured voltage in microvolts.
> +
> +curr1_input		Measured current in microamperes.
> +curr1_max_alarm		Overcurrent alarm in microamperes.
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 5308c59d7001..3db8f5752675 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -164,6 +164,16 @@ config SENSORS_ADM1031
>  	  This driver can also be built as a module. If so, the module
>  	  will be called adm1031.
>  
> +config SENSORS_ADM1177
> +	tristate "Analog Devices ADM1177 and compatibles"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for Analog Devices ADM1177
> +	  sensor chips.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called adm1177.
> +
>  config SENSORS_ADM9240
>  	tristate "Analog Devices ADM9240 and compatibles"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 40c036ea45e6..27d04eab1be4 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -34,6 +34,7 @@ obj-$(CONFIG_SENSORS_ADM1025)	+= adm1025.o
>  obj-$(CONFIG_SENSORS_ADM1026)	+= adm1026.o
>  obj-$(CONFIG_SENSORS_ADM1029)	+= adm1029.o
>  obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
> +obj-$(CONFIG_SENSORS_ADM1177)	+= adm1177.o
>  obj-$(CONFIG_SENSORS_ADM9240)	+= adm9240.o
>  obj-$(CONFIG_SENSORS_ADS7828)	+= ads7828.o
>  obj-$(CONFIG_SENSORS_ADS7871)	+= ads7871.o
> diff --git a/drivers/hwmon/adm1177.c b/drivers/hwmon/adm1177.c
> new file mode 100644
> index 000000000000..1f2ff7a29306
> --- /dev/null
> +++ b/drivers/hwmon/adm1177.c
> @@ -0,0 +1,288 @@
> +// 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/bits.h>
> +#include <linux/device.h>
> +#include <linux/hwmon.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +
> +/*  Command Byte Operations */
> +#define ADM1177_CMD_V_CONT	BIT(0)
> +#define ADM1177_CMD_I_CONT	BIT(2)
> +#define ADM1177_CMD_VRANGE	BIT(4)
> +
> +/* Extended Register */
> +#define ADM1177_REG_ALERT_TH	2
> +
> +#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
> + * @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;
> +	u32			r_sense_uohm;
> +	u32			alert_threshold_ua;
> +	bool			vrange_high;
> +};
> +
> +static int adm1177_read_raw(struct adm1177_state *st, u8 num, u8 *data)
> +{
> +	return i2c_master_recv(st->client, data, num);
> +}
> +
> +static int adm1177_write_cmd(struct adm1177_state *st, u8 cmd)
> +{
> +	return i2c_smbus_write_byte(st->client, cmd);
> +}
> +
> +static int adm1177_write_alert_thr(struct adm1177_state *st,
> +				   u32 alert_threshold_ua)
> +{
> +	u64 val;
> +	int ret;
> +
> +	val = 0xFFULL * alert_threshold_ua * st->r_sense_uohm;
> +	val = div_u64(val, 105840000U);
> +	val = div_u64(val, 1000U);
> +	if (val > 0xFF)
> +		val = 0xFF;
> +
> +	ret = i2c_smbus_write_byte_data(st->client, ADM1177_REG_ALERT_TH,
> +					val);
> +	if (!ret)
> +		return ret;
> +
> +	st->alert_threshold_ua = alert_threshold_ua;
> +	return 0;
> +}
> +
> +static int adm1177_read(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long *val)
> +{
> +	struct adm1177_state *st = dev_get_drvdata(dev);
> +	u8 data[3];
> +	long dummy;
> +	int ret;
> +
> +	switch (type) {
> +	case hwmon_curr:
> +		switch (attr) {
> +		case hwmon_curr_input:
> +			ret = adm1177_read_raw(st, 3, data);
> +			if (ret < 0)
> +				return ret;
> +			dummy = (data[1] << 4) | (data[2] & 0xF);
> +			/*
> +			 * convert to milliamperes
> +			 * ((105.84mV / 4096) x raw) / senseResistor(ohm)
> +			 */
> +			*val = div_u64((105840000ull * dummy),
> +				       4096 * st->r_sense_uohm);
> +			return 0;
> +		case hwmon_curr_max_alarm:
> +			*val = st->alert_threshold_ua;
> +			return 0;
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +	case hwmon_in:
> +		ret = adm1177_read_raw(st, 3, data);
> +		if (ret < 0)
> +			return ret;
> +		dummy = (data[0] << 4) | (data[2] >> 4);
> +		/*
> +		 * convert to millivolts based on resistor devision
> +		 * (V_fullscale / 4096) * raw
> +		 */
> +		if (st->vrange_high)
> +			dummy *= 26350;
> +		else
> +			dummy *= 6650;
> +
> +		*val = DIV_ROUND_CLOSEST(dummy, 4096);
> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int adm1177_write(struct device *dev, enum hwmon_sensor_types type,
> +			 u32 attr, int channel, long val)
> +{
> +	struct adm1177_state *st = dev_get_drvdata(dev);
> +
> +	switch (type) {
> +	case hwmon_curr:
> +		switch (attr) {
> +		case hwmon_curr_max_alarm:
> +			adm1177_write_alert_thr(st, val);
> +			return 0;
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static umode_t adm1177_is_visible(const void *data,
> +				  enum hwmon_sensor_types type,
> +				  u32 attr, int channel)
> +{
> +	const struct adm1177_state *st = data;
> +
> +	switch (type) {
> +	case hwmon_in:
> +		switch (attr) {
> +		case hwmon_in_input:
> +			return 0444;
> +		}
> +		break;
> +	case hwmon_curr:
> +		switch (attr) {
> +		case hwmon_curr_input:
> +			if (st->r_sense_uohm)
> +				return 0444;
> +			return 0;
> +		case hwmon_curr_max_alarm:
> +			if (st->r_sense_uohm)
> +				return 0644;
> +			return 0;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +	return 0;
> +}
> +
> +static const struct hwmon_channel_info *adm1177_info[] = {
> +	HWMON_CHANNEL_INFO(curr,
> +			   HWMON_C_INPUT | HWMON_C_MAX_ALARM),
> +	HWMON_CHANNEL_INFO(in,
> +			   HWMON_I_INPUT),
> +	NULL
> +};
> +
> +static const struct hwmon_ops adm1177_hwmon_ops = {
> +	.is_visible = adm1177_is_visible,
> +	.read = adm1177_read,
> +	.write = adm1177_write,
> +};
> +
> +static const struct hwmon_chip_info adm1177_chip_info = {
> +	.ops = &adm1177_hwmon_ops,
> +	.info = adm1177_info,
> +};
> +
> +static void adm1177_remove(void *data)
> +{
> +	struct adm1177_state *st = data;
> +
> +	regulator_disable(st->reg);
> +}
> +
> +static int adm1177_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct device *hwmon_dev;
> +	struct adm1177_state *st;
> +	u32 alert_threshold_ua;
> +	int ret;
> +
> +	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
> +	if (!st)
> +		return -ENOMEM;
> +
> +	st->client = client;
> +
> +	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;
> +	}
> +
> +	if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
> +				     &st->r_sense_uohm))
> +		st->r_sense_uohm = 0;
> +	if (device_property_read_u32(dev, "adi,shutdown-threshold-microamp",
> +				     &alert_threshold_ua)) {
> +		if (st->r_sense_uohm)
> +			/*
> +			 * set maximum default value from datasheet based on
> +			 * shunt-resistor
> +			 */
> +			alert_threshold_ua = div_u64(105840000000,
> +						     st->r_sense_uohm);
> +		else
> +			alert_threshold_ua = 0;
> +	}
> +	st->vrange_high = device_property_read_bool(dev,
> +						    "adi,vrange-high-enable");
> +	if (alert_threshold_ua && st->r_sense_uohm)
> +		adm1177_write_alert_thr(st, alert_threshold_ua);
> +
> +	ret = adm1177_write_cmd(st, ADM1177_CMD_V_CONT |
> +				    ADM1177_CMD_I_CONT |
> +				    (st->vrange_high ? 0 : ADM1177_CMD_VRANGE));
> +	if (ret)
> +		return ret;
> +
> +	hwmon_dev =
> +		devm_hwmon_device_register_with_info(dev, client->name, st,
> +						     &adm1177_chip_info, NULL);
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static const struct i2c_device_id adm1177_id[] = {
> +	{"adm1177", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, adm1177_id);
> +
> +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 = {
> +	.class = I2C_CLASS_HWMON,
> +	.driver = {
> +		.name = "adm1177",
> +		.of_match_table = adm1177_dt_ids,
> +	},
> +	.probe = adm1177_probe,
> +	.id_table = adm1177_id,
> +};
> +module_i2c_driver(adm1177_driver);
> +
> +MODULE_AUTHOR("Beniamin Bia <beniamin.bia@...log.com>");
> +MODULE_AUTHOR("Michael Hennerich <michael.hennerich@...log.com>");
> +MODULE_DESCRIPTION("Analog Devices ADM1177 ADC driver");
> +MODULE_LICENSE("GPL v2");

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