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Date: Sat, 8 Jun 2024 18:19:22 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Antoni Pokusinski <apokusinski01@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
apokusinski@...pl
Subject: Re: [PATCH v2] iio: humidity: si7020: add heater support
On Fri, 7 Jun 2024 16:10:30 +0200
Antoni Pokusinski <apokusinski01@...il.com> wrote:
> From: Antoni Pokusinski <apokusinski01@...il.com>
>
> This patch adds support for the integrated on-chip heater that is present
> on all the devices supported by this driver (si7020, si7021, si7013, th6).
> In order to configure the heater, the driver interacts with the following
> device registers:
> * User Register - the 2nd bit of this register is a "Heater Enable bit"
> (0 means that the heater is off, 1 means that it's on).
> * Heater Register - this register is present only on the si70xx devices
> and controls the current flowing through the heater. The 4 lower bits
> of this register can be assigned values from 0x0 to 0xF.
>
> Signed-off-by: Antoni Pokusinski <apokusinski01@...il.com>
>
> --
---
Otherwise this gets picked up in the git log.
Anyhow, I noticed because I was checking b4 picked this one up right.
Excess stuff removed in the description and applied to the togreg
branch of iio.git which is initially pushed out as testing for
0-day to see if it can find anything we missed.
Thanks,
Jonathan
> Changes since v1:
> * macros: remove unnecessary comments
> * macros: add more meaningful names
> * `struct si7020_data`: add comment explaining the mutex
> * `si7020_update_reg()`: change the control flow to more standard
> * use `scoped_guard()` instead of `mutex_lock() <...> mutex_unlock()`
> * `si7020_probe()`: add comment for User Register default value
> * minor format fixes
> --
> Hello, after sending this email I noticed an accidental email mismatch
> between "From:" and the "Signed-off-by:" therefore I send this email
> once again with a corrected signature. Sorry for the confusion.
> ---
> drivers/iio/humidity/si7020.c | 137 +++++++++++++++++++++++++++++++++-
> 1 file changed, 133 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c
> index fb1006649328..1215fab7b1a5 100644
> --- a/drivers/iio/humidity/si7020.c
> +++ b/drivers/iio/humidity/si7020.c
> @@ -23,6 +23,7 @@
> #include <linux/mod_devicetable.h>
> #include <linux/slab.h>
> #include <linux/sysfs.h>
> +#include <linux/stat.h>
>
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> @@ -33,17 +34,38 @@
> #define SI7020CMD_TEMP_HOLD 0xE3
> /* Software Reset */
> #define SI7020CMD_RESET 0xFE
> +#define SI7020CMD_USR_WRITE 0xE6
> +/* "Heater Enabled" bit in the User Register */
> +#define SI7020_USR_HEATER_EN BIT(2)
> +#define SI7020CMD_HEATER_WRITE 0x51
> +/* Heater current configuration bits */
> +#define SI7020_HEATER_VAL GENMASK(3, 0)
> +
> +struct si7020_data {
> + struct i2c_client *client;
> + /* Lock for cached register values */
> + struct mutex lock;
> + u8 user_reg;
> + u8 heater_reg;
> +};
> +
> +static const int si7020_heater_vals[] = { 0, 1, 0xF };
>
> static int si7020_read_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan, int *val,
> int *val2, long mask)
> {
> - struct i2c_client **client = iio_priv(indio_dev);
> + struct si7020_data *data = iio_priv(indio_dev);
> int ret;
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> - ret = i2c_smbus_read_word_swapped(*client,
> + if (chan->type == IIO_CURRENT) {
> + *val = data->heater_reg;
> + return IIO_VAL_INT;
> + }
> +
> + ret = i2c_smbus_read_word_swapped(data->client,
> chan->type == IIO_TEMP ?
> SI7020CMD_TEMP_HOLD :
> SI7020CMD_RH_HOLD);
> @@ -96,17 +118,118 @@ static const struct iio_chan_spec si7020_channels[] = {
> .type = IIO_TEMP,
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
> + },
> + {
> + .type = IIO_CURRENT,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + .info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
> + .extend_name = "heater",
> + }
> +};
> +
> +static int si7020_update_reg(struct si7020_data *data,
> + u8 *reg, u8 cmd, u8 mask, u8 val)
> +{
> + u8 new = (*reg & ~mask) | val;
> + int ret;
> +
> + ret = i2c_smbus_write_byte_data(data->client, cmd, new);
> + if (ret)
> + return ret;
> +
> + *reg = new;
> +
> + return 0;
> +}
> +
> +static int si7020_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct si7020_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + if (chan->type != IIO_CURRENT || val2 != 0 ||
> + val < si7020_heater_vals[0] || val > si7020_heater_vals[2])
> + return -EINVAL;
> +
> + scoped_guard(mutex, &data->lock)
> + ret = si7020_update_reg(data, &data->heater_reg,
> + SI7020CMD_HEATER_WRITE, SI7020_HEATER_VAL, val);
> + return ret;
> + default:
> + return -EINVAL;
> }
> +}
> +
> +static int si7020_read_available(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + const int **vals,
> + int *type, int *length, long mask)
> +{
> + if (mask != IIO_CHAN_INFO_RAW || chan->type != IIO_CURRENT)
> + return -EINVAL;
> +
> + *vals = si7020_heater_vals;
> + *type = IIO_VAL_INT;
> +
> + return IIO_AVAIL_RANGE;
> +}
> +
> +static ssize_t si7020_show_heater_en(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct si7020_data *data = iio_priv(indio_dev);
> +
> + return sysfs_emit(buf, "%d\n", !!(data->user_reg & SI7020_USR_HEATER_EN));
> +}
> +
> +static ssize_t si7020_store_heater_en(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t len)
> +{
> + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> + struct si7020_data *data = iio_priv(indio_dev);
> + int ret;
> + bool val;
> +
> + ret = kstrtobool(buf, &val);
> + if (ret)
> + return ret;
> +
> + scoped_guard(mutex, &data->lock)
> + ret = si7020_update_reg(data, &data->user_reg, SI7020CMD_USR_WRITE,
> + SI7020_USR_HEATER_EN, val ? SI7020_USR_HEATER_EN : 0);
> +
> + return ret < 0 ? ret : len;
> +}
> +
> +static IIO_DEVICE_ATTR(heater_enable, 0644,
> + si7020_show_heater_en, si7020_store_heater_en, 0);
> +
> +static struct attribute *si7020_attributes[] = {
> + &iio_dev_attr_heater_enable.dev_attr.attr,
> + NULL
> +};
> +
> +static const struct attribute_group si7020_attribute_group = {
> + .attrs = si7020_attributes,
> };
>
> static const struct iio_info si7020_info = {
> .read_raw = si7020_read_raw,
> + .write_raw = si7020_write_raw,
> + .read_avail = si7020_read_available,
> + .attrs = &si7020_attribute_group,
> };
>
> static int si7020_probe(struct i2c_client *client)
> {
> struct iio_dev *indio_dev;
> - struct i2c_client **data;
> + struct si7020_data *data;
> int ret;
>
> if (!i2c_check_functionality(client->adapter,
> @@ -126,7 +249,9 @@ static int si7020_probe(struct i2c_client *client)
> return -ENOMEM;
>
> data = iio_priv(indio_dev);
> - *data = client;
> + i2c_set_clientdata(client, indio_dev);
> + data->client = client;
> + mutex_init(&data->lock);
>
> indio_dev->name = dev_name(&client->dev);
> indio_dev->modes = INDIO_DIRECT_MODE;
> @@ -134,6 +259,10 @@ static int si7020_probe(struct i2c_client *client)
> indio_dev->channels = si7020_channels;
> indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
>
> + /* All the "reserved" bits in the User Register are 1s by default */
> + data->user_reg = 0x3A;
> + data->heater_reg = 0x0;
> +
> return devm_iio_device_register(&client->dev, indio_dev);
> }
>
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