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iio: magnetometer: ak8975: Add gpio reset support

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According to AK09911 datasheet, if reset gpio is provided then
deassert reset on ak8975_power_on() and assert reset on ak8975_power_off().

Without reset's deassertion during ak8975_power_on(), driver's probe fails
on ak8975_who_i_am() while checking for device identity for AK09911 chip.

AK09911 has an active low reset gpio to handle register's reset.
AK09911 datasheet says that, if not used, reset pin should be connected
to VID. This patch emulates this situation.

Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Jonathan Albrieux 2020-05-28 17:01:05 +02:00 committed by Jonathan Cameron
parent c2ea1d0cad
commit 9604ed758d
1 changed files with 18 additions and 0 deletions
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18
drivers/iio/magnetometer/ak8975.c
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@ -358,6 +358,7 @@ struct ak8975_data {
u8 asa[3]; u8 asa[3];
long raw_to_gauss[3]; long raw_to_gauss[3];
struct gpio_desc *eoc_gpiod; struct gpio_desc *eoc_gpiod;
struct gpio_desc *reset_gpiod;
int eoc_irq; int eoc_irq;
wait_queue_head_t data_ready_queue; wait_queue_head_t data_ready_queue;
unsigned long flags; unsigned long flags;
@ -384,6 +385,9 @@ static int ak8975_power_on(const struct ak8975_data *data)
"Failed to enable specified Vid supply\n"); "Failed to enable specified Vid supply\n");
return ret; return ret;
} }
gpiod_set_value_cansleep(data->reset_gpiod, 0);
/* /*
* According to the datasheet the power supply rise time is 200us * According to the datasheet the power supply rise time is 200us
* and the minimum wait time before mode setting is 100us, in * and the minimum wait time before mode setting is 100us, in
@ -396,6 +400,8 @@ static int ak8975_power_on(const struct ak8975_data *data)
/* Disable attached power regulator if any. */ /* Disable attached power regulator if any. */
static void ak8975_power_off(const struct ak8975_data *data) static void ak8975_power_off(const struct ak8975_data *data)
{ {
gpiod_set_value_cansleep(data->reset_gpiod, 1);
regulator_disable(data->vid); regulator_disable(data->vid);
regulator_disable(data->vdd); regulator_disable(data->vdd);
} }
@ -839,6 +845,7 @@ static int ak8975_probe(struct i2c_client *client,
struct ak8975_data *data; struct ak8975_data *data;
struct iio_dev *indio_dev; struct iio_dev *indio_dev;
struct gpio_desc *eoc_gpiod; struct gpio_desc *eoc_gpiod;
struct gpio_desc *reset_gpiod;
const void *match; const void *match;
unsigned int i; unsigned int i;
int err; int err;
@ -856,6 +863,16 @@ static int ak8975_probe(struct i2c_client *client,
if (eoc_gpiod) if (eoc_gpiod)
gpiod_set_consumer_name(eoc_gpiod, "ak_8975"); gpiod_set_consumer_name(eoc_gpiod, "ak_8975");
/*
* According to AK09911 datasheet, if reset GPIO is provided then
* deassert reset on ak8975_power_on() and assert reset on
* ak8975_power_off().
*/
reset_gpiod = devm_gpiod_get_optional(&client->dev,
"reset", GPIOD_OUT_HIGH);
if (IS_ERR(reset_gpiod))
return PTR_ERR(reset_gpiod);
/* Register with IIO */ /* Register with IIO */
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (indio_dev == NULL) if (indio_dev == NULL)
@ -866,6 +883,7 @@ static int ak8975_probe(struct i2c_client *client,
data->client = client; data->client = client;
data->eoc_gpiod = eoc_gpiod; data->eoc_gpiod = eoc_gpiod;
data->reset_gpiod = reset_gpiod;
data->eoc_irq = 0; data->eoc_irq = 0;
err = iio_read_mount_matrix(&client->dev, "mount-matrix", &data->orientation); err = iio_read_mount_matrix(&client->dev, "mount-matrix", &data->orientation);