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Message-ID: <dea56d34-bab1-4bca-9daf-5a48b4e0507e@roeck-us.net>
Date: Mon, 18 Dec 2023 09:37:56 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Abdel Alkuor <alkuor@...il.com>, Jean Delvare <jdelvare@...e.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, Jonathan Corbet <corbet@....net>
Cc: linux-hwmon@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 2/2] hwmon: (lm75) Add AMS AS6200 temperature sensor
On 12/17/23 20:52, Abdel Alkuor wrote:
> as6200 is a temperature sensor with 0.0625°C resolution and a
> range between -40°C to 125°C.
>
> By default, the driver configures as6200 as following:
> - Converstion rate: 8 Hz
> - Conversion mode: continuous
> - Consecutive fault counts: 4 samples
> - Alert state: high polarity
> - Alert mode: comparator mode
>
> Interrupt is supported for the alert pin.
>
> Datasheet: https://ams.com/documents/20143/36005/AS6200_DS000449_4-00.pdf
> Signed-off-by: Abdel Alkuor <alkuor@...il.com>
> ---
> Changes in v2:
> - Incorporate as6200 into lm75 driver
>
> Documentation/hwmon/lm75.rst | 10 +++
> drivers/hwmon/lm75.c | 132 +++++++++++++++++++++++++++++------
> 2 files changed, 122 insertions(+), 20 deletions(-)
>
> diff --git a/Documentation/hwmon/lm75.rst b/Documentation/hwmon/lm75.rst
> index 8d0ab4ad5fb5..6adab608dd05 100644
> --- a/Documentation/hwmon/lm75.rst
> +++ b/Documentation/hwmon/lm75.rst
> @@ -133,6 +133,16 @@ Supported chips:
>
> https://www.nxp.com/docs/en/data-sheet/PCT2075.pdf
>
> + * AMS OSRAM AS6200
> +
> + Prefix: 'as6200'
> +
> + Addresses scanned: none
> +
> + Datasheet: Publicly available at the AMS website
> +
> + https://ams.com/documents/20143/36005/AS6200_DS000449_4-00.pdf
> +
> Author: Frodo Looijaard <frodol@....nl>
>
> Description
> diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
> index 5b2ea05c951e..2d153f6729e0 100644
> --- a/drivers/hwmon/lm75.c
> +++ b/drivers/hwmon/lm75.c
> @@ -7,6 +7,7 @@
>
> #include <linux/module.h>
> #include <linux/init.h>
> +#include <linux/interrupt.h>
> #include <linux/slab.h>
> #include <linux/jiffies.h>
> #include <linux/i2c.h>
> @@ -25,6 +26,7 @@
>
> enum lm75_type { /* keep sorted in alphabetical order */
> adt75,
> + as6200,
> at30ts74,
> ds1775,
> ds75,
> @@ -55,6 +57,7 @@ enum lm75_type { /* keep sorted in alphabetical order */
>
> /**
> * struct lm75_params - lm75 configuration parameters.
> + * @config_reg_16bits Configure register size is 2 bytes.
@config_reg_16bits:
> * @set_mask: Bits to set in configuration register when configuring
> * the chip.
> * @clr_mask: Bits to clear in configuration register when configuring
> @@ -75,17 +78,20 @@ enum lm75_type { /* keep sorted in alphabetical order */
> * @sample_times: All the possible sample times to be set. Mandatory if
> * num_sample_times is larger than 1. If set, number of
> * entries must match num_sample_times.
> + * @alarm Alarm is supported.
@alarm:
> */
>
> struct lm75_params {
> - u8 set_mask;
> - u8 clr_mask;
> + bool config_reg_16bits;
> + u16 set_mask;
> + u16 clr_mask;
> u8 default_resolution;
> u8 resolution_limits;
> const u8 *resolutions;
> unsigned int default_sample_time;
> u8 num_sample_times;
> const unsigned int *sample_times;
> + bool alarm;
> };
>
> /* Addresses scanned */
> @@ -104,8 +110,8 @@ struct lm75_data {
> struct i2c_client *client;
> struct regmap *regmap;
> struct regulator *vs;
> - u8 orig_conf;
> - u8 current_conf;
> + u16 orig_conf;
> + u16 current_conf;
> u8 resolution; /* In bits, 9 to 16 */
> unsigned int sample_time; /* In ms */
> enum lm75_type kind;
> @@ -128,6 +134,15 @@ static const struct lm75_params device_params[] = {
> .default_resolution = 12,
> .default_sample_time = MSEC_PER_SEC / 10,
> },
> + [as6200] = {
> + .config_reg_16bits = true,
> + .set_mask = 0x94C0, /* 8 sample/s, 4 CF, positive polarity */
> + .default_resolution = 12,
> + .default_sample_time = 125,
> + .num_sample_times = 4,
> + .sample_times = (unsigned int []){ 125, 250, 1000, 4000 },
> + .alarm = true,
> + },
> [at30ts74] = {
> .set_mask = 3 << 5, /* 12-bit mode*/
> .default_resolution = 12,
> @@ -317,20 +332,23 @@ static inline long lm75_reg_to_mc(s16 temp, u8 resolution)
> return ((temp >> (16 - resolution)) * 1000) >> (resolution - 8);
> }
>
> -static int lm75_write_config(struct lm75_data *data, u8 set_mask,
> - u8 clr_mask)
> +static int lm75_write_config(struct lm75_data *data, u16 set_mask,
> + u16 clr_mask)
> {
> - u8 value;
> + unsigned int value;
>
> - clr_mask |= LM75_SHUTDOWN;
> + clr_mask |= LM75_SHUTDOWN << (8 * data->params->config_reg_16bits);
> value = data->current_conf & ~clr_mask;
> value |= set_mask;
>
> if (data->current_conf != value) {
> s32 err;
> -
> - err = i2c_smbus_write_byte_data(data->client, LM75_REG_CONF,
> - value);
> + if (data->params->config_reg_16bits)
> + err = regmap_write(data->regmap, LM75_REG_CONF, value);
> + else
> + err = i2c_smbus_write_byte_data(data->client,
> + LM75_REG_CONF,
> + value);
> if (err)
> return err;
> data->current_conf = value;
> @@ -338,6 +356,33 @@ static int lm75_write_config(struct lm75_data *data, u8 set_mask,
> return 0;
> }
>
> +static int lm75_read_config(struct lm75_data *data, u16 *config)
> +{
> + int ret;
> + unsigned int status;
> +
> + if (data->params->config_reg_16bits) {
> + ret = regmap_read(data->regmap, LM75_REG_CONF, &status);
> + } else {
> + ret = i2c_smbus_read_byte_data(data->client, LM75_REG_CONF);
> + status = ret;
> + }
> +
> + if (ret < 0)
> + return ret;
> +
> + *config = status;
> + return 0;
> +}
> +
> +static irqreturn_t lm75_alarm_handler(int irq, void *private)
> +{
> + struct device *hwmon_dev = private;
> +
> + hwmon_notify_event(hwmon_dev, hwmon_temp, hwmon_temp_alarm, 0);
> + return IRQ_HANDLED;
> +}
> +
> static int lm75_read(struct device *dev, enum hwmon_sensor_types type,
> u32 attr, int channel, long *val)
> {
> @@ -366,6 +411,9 @@ static int lm75_read(struct device *dev, enum hwmon_sensor_types type,
> case hwmon_temp_max_hyst:
> reg = LM75_REG_HYST;
> break;
> + case hwmon_temp_alarm:
> + reg = LM75_REG_CONF;
> + break;
> default:
> return -EINVAL;
> }
> @@ -373,7 +421,17 @@ static int lm75_read(struct device *dev, enum hwmon_sensor_types type,
> if (err < 0)
> return err;
>
> - *val = lm75_reg_to_mc(regval, data->resolution);
> + if (attr == hwmon_temp_alarm) {
> + switch (data->kind) {
> + case as6200:
> + *val = (regval >> 5) & 0x1;
> + break;
> + default:
> + return -EINVAL;
> + }
> + } else {
> + *val = lm75_reg_to_mc(regval, data->resolution);
> + }
> break;
> default:
> return -EINVAL;
> @@ -436,6 +494,7 @@ static int lm75_update_interval(struct device *dev, long val)
> data->resolution = data->params->resolutions[index];
> break;
> case tmp112:
> + case as6200:
> err = regmap_read(data->regmap, LM75_REG_CONF, ®);
> if (err < 0)
> return err;
> @@ -503,6 +562,9 @@ static umode_t lm75_is_visible(const void *data, enum hwmon_sensor_types type,
> case hwmon_temp_max:
> case hwmon_temp_max_hyst:
> return 0644;
> + case hwmon_temp_alarm:
> + if (config_data->params->alarm)
> + return 0444;
Missing
break;
> }
> break;
> default:
> @@ -515,7 +577,8 @@ static const struct hwmon_channel_info * const lm75_info[] = {
> HWMON_CHANNEL_INFO(chip,
> HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL),
> HWMON_CHANNEL_INFO(temp,
> - HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST),
> + HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST |
> + HWMON_T_ALARM),
> NULL
> };
>
> @@ -574,7 +637,7 @@ static int lm75_probe(struct i2c_client *client)
> struct device *dev = &client->dev;
> struct device *hwmon_dev;
> struct lm75_data *data;
> - int status, err;
> + int err;
> enum lm75_type kind;
>
> if (client->dev.of_node)
> @@ -623,13 +686,13 @@ static int lm75_probe(struct i2c_client *client)
> return err;
>
> /* Cache original configuration */
> - status = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
> - if (status < 0) {
> - dev_dbg(dev, "Can't read config? %d\n", status);
> - return status;
> + err = lm75_read_config(data, &data->current_conf);
> + if (err) {
> + dev_dbg(dev, "Can't read config? %d\n", err);
> + return err;
> }
I don't think splitting the return value from the error code adds any value,
even more so since it needs to be dereferenced below anyway. Please just keep
the original semantics here, and have lm75_read_config() return the combined
error code and status.
> - data->orig_conf = status;
> - data->current_conf = status;
> +
> + data->orig_conf = data->current_conf;
>
> err = lm75_write_config(data, data->params->set_mask,
> data->params->clr_mask);
> @@ -646,6 +709,30 @@ static int lm75_probe(struct i2c_client *client)
> if (IS_ERR(hwmon_dev))
> return PTR_ERR(hwmon_dev);
>
> + if (client->irq) {
> + if (data->params->alarm) {
> + err = devm_request_threaded_irq(dev,
> + client->irq,
> + NULL,
> + &lm75_alarm_handler,
> + IRQF_ONESHOT,
> + client->name,
> + hwmon_dev);
> + if (err)
> + return err;
> + } else {
> + /*
> + * Currently, alarm is only supported for chips with
> + * alarm bit.
> + * In the future, if alarm is needed for chips with
> + * no alarm bit, current temp needs to be compared
> + * against the max and max hyst values to set/clear
> + * the alarm state.
Please don't make such suggestions. If userspace wants to compare attributes
if there is no alarm attribute, it is free to do it. We should not even try
to do it in the kernel.
> + */
> + dev_warn(dev, "alarm interrupt is not supported\n");
I think this should be an error: There should be no interrupt configured on a
chip not supporting it.
> + }
> + }
> +
> dev_info(dev, "%s: sensor '%s'\n", dev_name(hwmon_dev), client->name);
>
> return 0;
> @@ -654,6 +741,7 @@ static int lm75_probe(struct i2c_client *client)
> static const struct i2c_device_id lm75_ids[] = {
> { "adt75", adt75, },
> { "at30ts74", at30ts74, },
> + { "as6200", as6200, },
Alphabetic order, please
> { "ds1775", ds1775, },
> { "ds75", ds75, },
> { "ds7505", ds7505, },
> @@ -689,6 +777,10 @@ static const struct of_device_id __maybe_unused lm75_of_match[] = {
> .compatible = "adi,adt75",
> .data = (void *)adt75
> },
> + {
> + .compatible = "ams,as6200",
> + .data = (void *)as6200
> + },
> {
> .compatible = "atmel,at30ts74",
> .data = (void *)at30ts74
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