Hi Jonathan,
On 12/10/2024 16:50, Jonathan Cameron wrote:
On Mon, 07 Oct 2024 15:14:40 +0200
Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
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.
Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Hi Neil.
Pretty clean driver. Just a few minor comments inline.
Thanks,
Jonathan
diff --git a/drivers/iio/magnetometer/als31300.c b/drivers/iio/magnetometer/als31300.c
new file mode 100644
index 000000000000..123e6a63b516
--- /dev/null
+++ b/drivers/iio/magnetometer/als31300.c
@@ -0,0 +1,459 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for the Allegro MicroSystems ALS31300 3-D Linear Hall Effect Sensor
+ *
+ * Copyright (c) 2024 Linaro Limited
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+/*
+ * The Allegro MicroSystems ALS31300 has an EEPROM space to configure how
+ * the device works and how the interrupt line behaves,
behaves.
+ * we only support the default setup with external trigger
Only the default setup with external trigger is supported.
etc.
Ack, I'll rephrase that part
+ *
+ * Since by default the interrupt line is disable, we don't
+ * support GPIO interrupt events for now.
+ *
+ * It should be possible to adapt the driver to the current
+ * device setup, but we leave it as a future exercise.
+ */
+
+#define ALS31300_EEPROM_CONFIG 0x02
+#define ALS31300_EEPROM_INTERRUPT 0x03
+#define ALS31300_EEPROM_CUSTOMER_1 0x0d
+#define ALS31300_EEPROM_CUSTOMER_2 0x0e
+#define ALS31300_EEPROM_CUSTOMER_3 0x0f
+#define ALS31300_VOLATILE_MODE 0x27
Is spelling out volatile needed? Maybe VOL or just V or skip
it completely as it makes for some long lines?
Yep, there's no formal naming on the datasheet for those so I'll
reduce to _VOL
+#define ALS31300_VOLATILE_MODE_LPDCM GENMASK(6, 4)
+#define ALS31300_VOLATILE_MODE_SLEEP GENMASK(1, 0)
+#define ALS31300_VOLATILE_MSB 0x28
+#define ALS31300_VOLATILE_MSB_TEMPERATURE GENMASK(5, 0)
+#define ALS31300_VOLATILE_MSB_INTERRUPT BIT(6)
+#define ALS31300_VOLATILE_MSB_NEW_DATA BIT(7)
+#define ALS31300_VOLATILE_MSB_Z_AXIS GENMASK(15, 8)
+#define ALS31300_VOLATILE_MSB_Y_AXIS GENMASK(23, 16)
+#define ALS31300_VOLATILE_MSB_X_AXIS GENMASK(31, 24)
+#define ALS31300_VOLATILE_LSB 0x29
+#define ALS31300_VOLATILE_LSB_TEMPERATURE GENMASK(5, 0)
+#define ALS31300_VOLATILE_LSB_HALL_STATUS GENMASK(7, 7)
+#define ALS31300_VOLATILE_LSB_Z_AXIS GENMASK(11, 8)
+#define ALS31300_VOLATILE_LSB_Y_AXIS GENMASK(15, 12)
+#define ALS31300_VOLATILE_LSB_X_AXIS GENMASK(19, 16)
+#define ALS31300_VOLATILE_LSB_INTERRUPT_WRITE BIT(20)
+#define ALS31300_CUSTOMER_ACCESS 0x35
+
+#define ALS31300_LPDCM_INACTIVE_0_5_MS 0
+#define ALS31300_LPDCM_INACTIVE_1_0_MS 1
+#define ALS31300_LPDCM_INACTIVE_5_0_MS 2
+#define ALS31300_LPDCM_INACTIVE_10_0_MS 3
+#define ALS31300_LPDCM_INACTIVE_50_0_MS 4
+#define ALS31300_LPDCM_INACTIVE_100_0_MS 5
+#define ALS31300_LPDCM_INACTIVE_500_0_MS 6
+#define ALS31300_LPDCM_INACTIVE_1000_0_MS 7
I'd move these up to next to the field def above.
Can play games with indent to make it clear they are the contents of
that field.
#define ALS31300_VOLATILE_MODE_LPDCM GENMASK(6, 4)
#define ALS31300_LPDCM_INACTIVE_0_5_MS 0
etc
If it's accepted, then I'll do it!
+
+#define ALS31300_VOLATILE_MODE_ACTIVE_MODE 0
+#define ALS31300_VOLATILE_MODE_SLEEP_MODE 1
+#define ALS31300_VOLATILE_MODE_LPDCM_MODE 2
+
+#define ALS31300_DATA_X_GET(__buf) \
Why __buf? I'd just use b
Right
+ ((int)(s8)FIELD_GET(ALS31300_VOLATILE_MSB_X_AXIS, __buf[0]) << 4 | \
+ FIELD_GET(ALS31300_VOLATILE_LSB_X_AXIS, __buf[1]))
+#define ALS31300_DATA_Y_GET(__buf) \
+ ((int)(s8)FIELD_GET(ALS31300_VOLATILE_MSB_Y_AXIS, __buf[0]) << 4 | \
+ FIELD_GET(ALS31300_VOLATILE_LSB_Y_AXIS, __buf[1]))
+#define ALS31300_DATA_Z_GET(__buf) \
+ ((int)(s8)FIELD_GET(ALS31300_VOLATILE_MSB_Z_AXIS, __buf[0]) << 4 | \
+ FIELD_GET(ALS31300_VOLATILE_LSB_Z_AXIS, __buf[1]))
Nice way to make these more readable is sign_extend32() rather than the casts.
So
sign_extend32(FIELD_GET(ALS31300_VOLATILE_MSB_X_AXIS, b[0]) << 4 |
FIELD_GET(ALS31300_VOLATILE_LSB_X_AXIS, b[1]),
11);
Thanks for the suggestion, it's indeed better
+#define ALS31300_TEMPERATURE_GET(__buf) \
+ ((u32)(u8)FIELD_GET(ALS31300_VOLATILE_MSB_TEMPERATURE, __buf[0]) << 6 | \
+ FIELD_GET(ALS31300_VOLATILE_LSB_TEMPERATURE, __buf[1]))
What does the u8 cast change?
It was to align with the s8 defines, but it won't be needed with sign_extend32
+
+struct als31300_data {
+ struct device *dev;
+ /* protects power on/off the device and access HW */
+ struct mutex mutex;
+ unsigned long sensitivity;
+ struct regmap *map;
+ struct {
+ u16 temperature;
+ s16 channels[3];
+ s64 timestamp __aligned(8);
aligned_s64 timestamp
It's new so for now only in the togreg branch of iio.git.
Ack, I'll use it and rebase on your togreg branch
+ } scan;
+};
+
+/* The whole measure is split into 2x32bit registers, we need to read them both at once */
+static int als31300_get_measure(struct als31300_data *data, s16 *t, s16 *x,
+ s16 *y, s16 *z)
+{
+ unsigned int count = 0;
+ u32 buf[2];
+ int ret;
+
+ mutex_lock(&data->mutex);
guard(mutex)(&data->mutex) and drop the unlock handling.
It's a small simplification but still nice to have here.
Ok, it'll be my first time, hope I'll get it right
+ ret = pm_runtime_resume_and_get(data->dev);
+ if (ret)
+ goto unlock;
+
+ /* Max update rate it 2KHz, wait up to 1ms */
+ while (count < 50) {
+ /* Read Data */
+ ret = regmap_bulk_read(data->map, ALS31300_VOLATILE_MSB, buf, 2);
+ 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_VOLATILE_MSB_NEW_DATA, buf[0]))
+ break;
+
+ usleep_range(10, 20);
+ ++count;
+ }
+
+ if (count >= 50) {
+ ret = -ETIMEDOUT;
+ goto out;
+ }
+
+ *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);
+
+unlock:
+ mutex_unlock(&data->mutex);
+
+ return ret;
+}
+
+static int als31300_read_raw(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan, int *val,
+ int *val2, long mask)
+{
+ struct als31300_data *data = iio_priv(indio_dev);
+ s16 t, x, y, z;
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_PROCESSED:
+ case IIO_CHAN_INFO_RAW:
+ ret = als31300_get_measure(data, &t, &x, &y, &z);
+ if (ret)
+ return ret;
blank line here would perhaps make this a tiny bit easier to read.
Ack
+ switch (chan->address) {
+ case TEMPERATURE:
+ *val = t;
+ return IIO_VAL_INT;
+ case AXIS_X:
+ *val = x;
+ return IIO_VAL_INT;
+ case AXIS_Y:
+ *val = y;
+ return IIO_VAL_INT;
+ case AXIS_Z:
+ *val = z;
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+ case IIO_CHAN_INFO_SCALE:
+ switch (chan->type) {
+ case IIO_TEMP:
+ /*
+ * Fractional part of:
+ * 302(value - 1708)
+ * temp = ------------------
+ * 4096
+ * to convert temperature in Celcius
Units in IIO ABI (because we copied hwmon) are millidegrees celcius.
Bad decision a long time back, but we are stuck with it.
See Documentation/ABI/testing/sysfs-bus-iio
I was wondering, now I have my answer :-)
+ */
+ *val = 302;
+ *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->sensitivity;
+ return IIO_VAL_FRACTIONAL;
+ default:
+ return -EINVAL;
+ }
+ case IIO_CHAN_INFO_OFFSET:
+ switch (chan->type) {
+ case IIO_TEMP:
+ *val = -1708;
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static irqreturn_t als31300_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct als31300_data *data = iio_priv(indio_dev);
+ s16 x, y, z;
+ u16 t;
+ int ret;
+
+ ret = als31300_get_measure(data, &t, &x, &y, &z);
+ if (ret)
+ goto trigger_out;
+
+ data->scan.temperature = t;
+ data->scan.channels[0] = x;
+ data->scan.channels[1] = y;
+ data->scan.channels[2] = z;
This is pretty small. I'd just put scan on the stack in this function.
Ack
+ iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
+ iio_get_time_ns(indio_dev));
pf->timestamp given you are providing a non threaded interrupt handler
to fill that in.
Ok
+
+trigger_out:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+static const struct iio_chan_spec als31300_channels[] = {
+ {
+ .type = IIO_TEMP,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+ BIT(IIO_CHAN_INFO_SCALE) |
+ BIT(IIO_CHAN_INFO_OFFSET),
+ .address = TEMPERATURE,
+ .scan_index = TEMPERATURE,
+ .scan_type = {
+ .sign = 'u',
+ .realbits = 16,
+ .storagebits = 16,
+ .endianness = IIO_CPU,
+ },
+ },
+ ALS31300_AXIS_CHANNEL(X, AXIS_X),
+ ALS31300_AXIS_CHANNEL(Y, AXIS_Y),
+ ALS31300_AXIS_CHANNEL(Z, AXIS_Z),
+ IIO_CHAN_SOFT_TIMESTAMP(6),
Why 6?
Technically it's not wrong ABI, just odd to leave a gap between the channels
and the timestamp. Probably wants to be 4
Seems it's a bad copy-paste and not knowing what 6 was meaning, thx for the clarification
+};
+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);
+
+ data->sensitivity = (unsigned long)of_device_get_match_data(dev);
After changing the data to pointers to structures below use
i2c_get_match_data() That will try various types of firmware and fall
back to the id tables if appropriate.
Yep I have a change that does that already, I figured that out after sending v1...
+
+ 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");
...
+
+static DEFINE_RUNTIME_DEV_PM_OPS(als31300_pm_ops,
+ als31300_runtime_suspend, als31300_runtime_resume,
+ NULL);
+
+static const struct i2c_device_id als31300_id[] = {
+ { "als31300-500" },
This needs data as well because you can probe via the sysfs interface instead
of DT which will use these ids.
+ { "als31300-1000" },
+ { "als31300-2000" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, als31300_id);
+
+static const struct of_device_id als31300_of_match[] = {
+ { .compatible = "allegromicro,als31300-500", .data = (void *)4 },
+ { .compatible = "allegromicro,als31300-1000", .data = (void *)2 },
+ { .compatible = "allegromicro,als31300-2000", .data = (void *)1 },
Use pointers to structures and also use them above. Even if those structures
have just one value in them for now.
Just have something like
struct als31300_variant_info {
u8 sensitivity;
};
static const struct als31300_variant_info al31300_variant_500 = {
.sensitivity = 4;
};
etc.
Yep I'll switch to that
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, als31300_of_match);
+
+static struct i2c_driver als31300_driver = {
+ .driver = {
+ .name = "als31300",
+ .of_match_table = als31300_of_match,
+ .pm = pm_ptr(&als31300_pm_ops),
+ },
+ .probe = als31300_probe,
+ .id_table = als31300_id,
+};
+module_i2c_driver(als31300_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ALS31300 3-D Linear Hall Effect Driver");
+MODULE_AUTHOR("Neil Armstrong <neil.armstrong@xxxxxxxxxx>");
Thanks,
Neil
