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Message-ID: <Zx1chYp4FRyG8fKM@surfacebook.localdomain>
Date: Sun, 27 Oct 2024 00:17:57 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Neil Armstrong <neil.armstrong@...aro.org>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Jonathan Cameron <jic23@...nel.org>,
Lars-Peter Clausen <lars@...afoo.de>, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v2 3/3] iio: magnetometer: add Allegro MicroSystems
ALS31300 3-D Linear Hall Effect driver
Mon, Oct 21, 2024 at 02:38:55PM +0200, Neil Armstrong kirjoitti:
> The Allegro MicroSystems ALS31300 is a 3-D Linear Hall Effect Sensor
> mainly used for 3D head-on motion sensing applications.
>
> The device is configured over I2C, and as part of the Sensor data the
> temperature core is also provided.
>
> While the device provides an IRQ gpio, it depends on a configuration
> programmed into the internal EEPROM, thus only the default mode is
> supported and buffered input via trigger is also supported to allow
> streaming values with the same sensing timestamp.
>
> The device can be configured with different sensitivities in factory,
> but the sensitivity value used to calculate value into the Gauss
> unit is not available from registers, thus the sensitivity is provided
> by the compatible/device-id string which is based on the part number
> as described in the datasheet page 2.
...
Some headers are missing...
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
+ pm.h
> +#include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
+ types.h
...
> +#define ALS31300_DATA_X_GET(b) \
> + sign_extend32(FIELD_GET(ALS31300_VOL_MSB_X_AXIS, b[0]) << 4 | \
> + FIELD_GET(ALS31300_VOL_LSB_X_AXIS, b[1]), 11)
> +#define ALS31300_DATA_Y_GET(b) \
> + sign_extend32(FIELD_GET(ALS31300_VOL_MSB_Y_AXIS, b[0]) << 4 | \
> + FIELD_GET(ALS31300_VOL_LSB_Y_AXIS, b[1]), 11)
> +#define ALS31300_DATA_Z_GET(b) \
> + sign_extend32(FIELD_GET(ALS31300_VOL_MSB_Z_AXIS, b[0]) << 4 | \
> + FIELD_GET(ALS31300_VOL_LSB_Z_AXIS, b[1]), 11)
> +#define ALS31300_TEMPERATURE_GET(b) \
> + (FIELD_GET(ALS31300_VOL_MSB_TEMPERATURE, b[0]) << 6 | \
> + FIELD_GET(ALS31300_VOL_LSB_TEMPERATURE, b[1]))
These and in the code seems like you make a home grown endianes conversion.
I suppose all of them have to be __beXX with the respective masks that cover
all the bits.
> +static int als31300_get_measure(struct als31300_data *data,
> + u16 *t, s16 *x, s16 *y, s16 *z)
> +{
> + unsigned int count = 0;
> + u32 buf[2];
Shouldn't this be __be64 buf?
> + int ret;
> +
> + guard(mutex)(&data->mutex);
> +
> + ret = pm_runtime_resume_and_get(data->dev);
> + if (ret)
> + return ret;
> + /* Max update rate is 2KHz, wait up to 1ms */
> + while (count < 50) {
> + /* Read Data */
> + ret = regmap_bulk_read(data->map, ALS31300_VOL_MSB, buf, 2);
At bare minimum ARRAY_SIZE(), but see above, I think it should use the respective type.
> + if (ret) {
> + dev_err(data->dev, "read data failed, error %d\n", ret);
> + goto out;
> + }
> +
> + /* Check if data is valid, happens right after getting out of sleep mode */
> + if (FIELD_GET(ALS31300_VOL_MSB_NEW_DATA, buf[0]))
> + break;
> +
> + usleep_range(10, 20);
> + ++count;
> + }
> +
> + if (count >= 50) {
> + ret = -ETIMEDOUT;
> + goto out;
> + }
This one of the longest variant of implementing
do {
...
} while (!FIELD_GET(...) && --count)
But you also may consider something from iopoll.h (I don't remember if we have
regmap_read_poll_timeout() for bulk transfers.
> + *t = ALS31300_TEMPERATURE_GET(buf);
> + *x = ALS31300_DATA_X_GET(buf);
> + *y = ALS31300_DATA_Y_GET(buf);
> + *z = ALS31300_DATA_Z_GET(buf);
> +
> +out:
> + pm_runtime_mark_last_busy(data->dev);
> + pm_runtime_put_autosuspend(data->dev);
Last discussion with Rafael on the topic of the above puts a question mark to
all these cases when runtime PM idle callback has not been implemented.
Shouldn't this be simply
pm_runtime_put(data->dev);
?
> + return ret;
> +}
...
> + case IIO_CHAN_INFO_SCALE:
> + switch (chan->type) {
> + case IIO_TEMP:
> + /*
> + * Fractional part of:
> + * 1000 * 302 * (value - 1708)
> + * temp = ----------------------------
> + * 4096
> + * to convert temperature in millicelcius
> + */
> + *val = 1000 * 302;
MILLI from units.h ?
> + *val2 = 4096;
> + return IIO_VAL_FRACTIONAL;
> + case IIO_MAGN:
> + /*
> + * Devices are configured in factory
> + * with different sensitivities:
> + * - 500 GAUSS <-> 4 LSB/Gauss
> + * - 1000 GAUSS <-> 2 LSB/Gauss
> + * - 2000 GAUSS <-> 1 LSB/Gauss
> + * with translates by a division of the returned
> + * value to get Gauss value.
> + * The sensisitivity cannot be read at runtime
> + * so the value depends on the model compatible
> + * or device id.
> + */
> + *val = 1;
> + *val2 = data->variant_info->sensitivity;
> + return IIO_VAL_FRACTIONAL;
> + default:
> + return -EINVAL;
> + }
...
> + struct {
> + u16 temperature;
> + s16 channels[3];
> + aligned_s64 timestamp;
> + } __packed scan;
Why __packed?
...
> +static int als31300_set_operating_mode(struct als31300_data *data,
> + unsigned int val)
> +{
> + int ret;
> +
> + ret = regmap_update_bits(data->map, ALS31300_VOL_MODE,
> + ALS31300_VOL_MODE_SLEEP, val);
> + if (ret) {
> + dev_err(data->dev, "failed to set operating mode (%pe)\n", ERR_PTR(ret));
> + return ret;
> + }
> +
> + /* The time it takes to exit sleep mode is equivalent to Power-On Delay Time */
> + if (val == ALS31300_VOL_MODE_ACTIVE_MODE)
> + usleep_range(600, 650);
> +
> + return ret;
return 0;
> +}
...
> +static int als31300_probe(struct i2c_client *i2c)
> +{
> + struct device *dev = &i2c->dev;
> + struct als31300_data *data;
> + struct iio_dev *indio_dev;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + data = iio_priv(indio_dev);
> + data->dev = dev;
> + i2c_set_clientdata(i2c, indio_dev);
> + mutex_init(&data->mutex);
Why not devm_mutex_init()? How does this being cleaned up?
> + data->variant_info = i2c_get_match_data(i2c);
> + if (!data->variant_info)
> + return -EINVAL;
> +
> + data->map = devm_regmap_init_i2c(i2c, &als31300_regmap_config);
> + if (IS_ERR(data->map))
> + return dev_err_probe(dev, PTR_ERR(data->map),
> + "failed to allocate register map\n");
> +
> + ret = devm_regulator_get_enable(dev, "vcc");
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to enable regulator\n");
> +
> + ret = als31300_set_operating_mode(data, ALS31300_VOL_MODE_ACTIVE_MODE);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to power on device\n");
> +
> + ret = devm_add_action_or_reset(dev, als31300_power_down, data);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to add powerdown action\n");
> +
> + indio_dev->info = &als31300_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->name = i2c->name;
> + indio_dev->channels = als31300_channels;
> + indio_dev->num_channels = ARRAY_SIZE(als31300_channels);
> + indio_dev->available_scan_masks = als31300_scan_masks;
> +
> + ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
> + iio_pollfunc_store_time,
> + als31300_trigger_handler,
> + &als31300_setup_ops);
> + if (ret < 0) {
> + dev_err(dev, "iio triggered buffer setup failed\n");
> + return ret;
Why not return dev_err_probe(...);
> + }
> +
> + ret = pm_runtime_set_active(dev);
> + if (ret < 0)
> + return ret;
> +
> + ret = devm_pm_runtime_enable(dev);
> + if (ret)
> + return ret;
> +
> + pm_runtime_get_noresume(dev);
> + pm_runtime_set_autosuspend_delay(dev, 200);
> + pm_runtime_use_autosuspend(dev);
> +
> + pm_runtime_mark_last_busy(dev);
> + pm_runtime_put_autosuspend(dev);
> +
> + ret = devm_iio_device_register(dev, indio_dev);
> + if (ret)
> + return dev_err_probe(dev, ret, "device register failed\n");
> +
> + return 0;
> +}
--
With Best Regards,
Andy Shevchenko
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