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Message-ID: <20240720175439.54b73f2c@jic23-huawei>
Date: Sat, 20 Jul 2024 17:54:39 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Joshua Felmeden <jfelmeden@...goodpenguin.co.uk>
Cc: Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
<conor+dt@...nel.org>, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] iio: humidity: Add support for ENS210
On Fri, 19 Jul 2024 13:50:54 +0100
Joshua Felmeden <jfelmeden@...goodpenguin.co.uk> wrote:
> Add support for ENS210/ENS210A/ENS211/ENS212/ENS213A/ENS215.
>
> The ENS21x is a family of temperature and relative humidity sensors with
> accuracies tailored to the needs of specific applications.
>
> Signed-off-by: Joshua Felmeden <jfelmeden@...goodpenguin.co.uk>
Hi Joshua
Looking pretty good, but a few more minor comments.
Jonathan
> +
> +/**
> + * struct ens210_data - Humidity/Temperature sensor device structure
> + * @client: i2c client
> + * @lock: lock protecting the i2c conversion
> + * @res_index: index to selected sensor resolution
> + */
> +struct ens210_data {
> + struct i2c_client *client;
> + const struct ens210_chip_info *chip_info;
> + struct mutex lock;
Docs rather different to content. Make sure to run kernel-doc script
over the files and fix warnings.
> +};
> +
> +/* calculate 17-bit crc7 */
> +static u8 ens210_crc7(u32 val)
> +{
> + __be32 val_be = (cpu_to_be32(val & 0x1ffff) >> 0x8);
drop excess outer brackets.
> +
> + return crc7_be(0xde, (u8 *)&val_be, 3) >> 1;
> +}
> +
> +static int ens210_get_measurement(struct iio_dev *indio_dev, bool temp, int *val)
> +{
> + u32 regval;
> + u8 regval_le[3];
> + int ret;
> + struct ens210_data *data = iio_priv(indio_dev);
> +
> + /* assert read */
> + ret = i2c_smbus_write_byte_data(data->client, ENS210_REG_SENS_START,
> + temp ? ENS210_SENS_START_T_START :
> + ENS210_SENS_START_H_START);
> + if (ret)
> + return ret;
> +
> + /* wait for conversion to be ready */
> + msleep(data->chip_info->conv_time_msec);
> +
> + ret = i2c_smbus_read_byte_data(data->client,
> + ENS210_REG_SENS_STAT);
> + if (ret < 0)
> + return ret;
> +
> + /* perform read */
> + ret = i2c_smbus_read_i2c_block_data(
> + data->client, temp ? ENS210_REG_T_VAL : ENS210_REG_H_VAL, 3,
> + (u8 *)®val_le);
> + if (ret < 0) {
> + dev_err(&data->client->dev, "failed to read register");
> + return -EIO;
> + } else if (ret != 3) {
> + dev_err(&indio_dev->dev, "expected 3 bytes, received %d\n", ret);
Use the i2c dev for all error messages.
The indio_dev->dev one is only available in some paths and not generally
as useful.
Add a local
struct device *dev = &data->client->dev;
in places where you use it lots of times.
> + return -EIO;
> + }
> +
> + regval = get_unaligned_le24(regval_le);
> + if (ens210_crc7(regval) != ((regval >> 17) & 0x7f)) {
> + /* crc fail */
> + dev_err(&indio_dev->dev, "ens invalid crc\n");
> + return -EIO;
> + }
> +
> + *val = regval & 0xffff;
I wondered what the 17th bit is and it seems to be a valid flag.
Should we be checking that before returning the data?
> + return IIO_VAL_INT;
> +}
> +
> +static int ens210_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *channel, int *val,
> + int *val2, long mask)
> +{
> + struct ens210_data *data = iio_priv(indio_dev);
> + int ret = -EINVAL;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + scoped_guard(mutex, &data->lock) {
> + ret = ens210_get_measurement(
> + indio_dev, channel->type == IIO_TEMP, val);
Odd line wrapping. I'd just use a slightly long line and format as
> ret = ens210_get_measurement(indio_dev,
channel->type == IIO_TEMP,
val);
> + if (ret)
> + return ret;
> + return IIO_VAL_INT;
> + }
> + return ret;
unreachable();
The compiler may fail to figure out we can't get here so we tell it.
The drop the return ret;
> + case IIO_CHAN_INFO_SCALE:
> + if (channel->type == IIO_TEMP) {
> + *val = 15;
> + *val2 = 625000;
> + } else {
> + *val = 1;
> + *val2 = 953125;
> + }
> + return IIO_VAL_INT_PLUS_MICRO;
> + case IIO_CHAN_INFO_OFFSET:
> + if (channel->type == IIO_TEMP) {
> + *val = -17481;
> + *val2 = 600000;
> + ret = IIO_VAL_INT_PLUS_MICRO;
> + break;
> + }
> + *val = 0;
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> + return ret;
Unreachable code I think, so drop it.
> +}
> +
> +static int ens210_probe(struct i2c_client *client)
> +{
> + const struct i2c_device_id *id = i2c_client_get_device_id(client);
Don't think this is used any more.
> + struct ens210_data *data;
> + struct iio_dev *indio_dev;
> + uint16_t part_id;
> + int ret;
> +
> + if (!i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> + I2C_FUNC_SMBUS_WRITE_BYTE |
> + I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> + dev_err_probe(&client->dev, -EOPNOTSUPP,
> + "adapter does not support some i2c transactions\n");
> + return -EOPNOTSUPP;
return dev_err_probe()
don't worry about the slightly long line.
> + }
> +
> + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + data = iio_priv(indio_dev);
> + i2c_set_clientdata(client, indio_dev);
Used? If not drop it.
> + data->client = client;
> + mutex_init(&data->lock);
> + data->chip_info = i2c_get_match_data(client);
> +
> + ret = devm_regulator_get_enable(&client->dev, "vdd");
> + if (ret)
> + return ret;
> +
> + /* reset device */
> + ret = i2c_smbus_write_byte_data(client, ENS210_REG_SYS_CTRL,
> + ENS210_SYS_CTRL_SYS_RESET);
> + if (ret)
> + return ret;
> +
> + /* wait for device to become active */
> + usleep_range(4000, 5000);
> +
> + /* disable low power mode */
> + ret = i2c_smbus_write_byte_data(client, ENS210_REG_SYS_CTRL, 0x00);
> + if (ret)
> + return ret;
> +
> + /* wait for device to finish */
> + usleep_range(4000, 5000);
> +
> + /* get part_id */
> + part_id = i2c_smbus_read_word_data(client, ENS210_REG_PART_ID);
> +
> + if (part_id != data->chip_info->part_id) {
> + dev_info(&client->dev,
> + "Part ID does not match (0x%04x != 0x%04lx)\n", part_id,
%04x as per the build bot warning.
> + data->chip_info->part_id);
> + }
> +
> + /* reenable low power */
> + ret = i2c_smbus_write_byte_data(client, ENS210_REG_SYS_CTRL,
> + ENS210_SYS_CTRL_LOW_POWER_ENABLE);
> + if (ret)
> + return ret;
> +
> + indio_dev->name = data->chip_info->name;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = ens210_channels;
> + indio_dev->num_channels = ARRAY_SIZE(ens210_channels);
> + indio_dev->info = &ens210_info;
> +
> + return devm_iio_device_register(&client->dev, indio_dev);
> +}
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