Re: [PATCH 2/2] iio: ak8975: Implement data ready interrupt handling

[Jonathan Cameron <jic23@kernel.org>]

On 04/16/2013 03:37 PM, Jacek Anaszewski wrote:
> Implement "data ready" interrupt handling in addition to the
> two existing read modes - DRDY GPIO polling and ST1 register
> DRDY bit polling.
> 
> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Andrew Chew <achew@nvidia.com>

Allowing either the gpio or the interrupt is a little ususual, but
I suppose does avoid having to change existing users to gain interrupt
support (if their gpio subsystem happens to support interrupts).

As there is no rush for this cycle, I'll take this once you have made
 the requested changes to the other patch as long as no one else
has raised any issues.

Jonathan
> ---
>  drivers/iio/magnetometer/ak8975.c |   91 ++++++++++++++++++++++++++++++++++++-
>  1 files changed, 89 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
> index eb17eca..d379c4c 100644
> --- a/drivers/iio/magnetometer/ak8975.c
> +++ b/drivers/iio/magnetometer/ak8975.c
> @@ -24,10 +24,11 @@
>  #include <linux/kernel.h>
>  #include <linux/slab.h>
>  #include <linux/i2c.h>
> +#include <linux/interrupt.h>
>  #include <linux/err.h>
>  #include <linux/mutex.h>
>  #include <linux/delay.h>
> -
> +#include <linux/bitops.h>
>  #include <linux/gpio.h>
>  #include <linux/of_gpio.h>
>  
> @@ -83,6 +84,7 @@
>   */
>  #define AK8975_MAX_CONVERSION_TIMEOUT	500
>  #define AK8975_CONVERSION_DONE_POLL_TIME 10
> +#define AK8975_DATA_READY_TIMEOUT	((100*HZ)/1000)
>  
>  /*
>   * Per-instance context data for the device.
> @@ -95,6 +97,9 @@ struct ak8975_data {
>  	long			raw_to_gauss[3];
>  	u8			reg_cache[AK8975_MAX_REGS];
>  	int			eoc_gpio;
> +	int			eoc_irq;
> +	wait_queue_head_t	data_ready_queue;
> +	unsigned long		flags;
>  };
>  
>  static const int ak8975_index_to_reg[] = {
> @@ -124,6 +129,51 @@ static int ak8975_write_data(struct i2c_client *client,
>  }
>  
>  /*
> + * Handle data ready irq
> + */
> +static irqreturn_t ak8975_irq_handler(int irq, void *data)
> +{
> +	struct ak8975_data *ak8975 = data;
> +
> +	set_bit(0, &ak8975->flags);
> +	wake_up(&ak8975->data_ready_queue);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/*
> + * Install data ready interrupt handler
> + */
> +static int ak8975_setup_irq(struct ak8975_data *data)
> +{
> +	struct i2c_client *client = data->client;
> +	int rc;
> +	int irq;
> +
> +	if (client->irq)
> +		irq = client->irq;
> +	else
> +		irq = gpio_to_irq(data->eoc_gpio);
> +
> +	rc = request_irq(irq, ak8975_irq_handler,
> +			 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
> +			 dev_name(&client->dev), data);
> +	if (rc < 0) {
> +		dev_err(&client->dev,
> +			"irq %d request failed, (gpio %d): %d\n",
> +			irq, data->eoc_gpio, rc);
> +		return rc;
> +	}
> +
> +	init_waitqueue_head(&data->data_ready_queue);
> +	clear_bit(0, &data->flags);
> +	data->eoc_irq = irq;
> +
> +	return rc;
> +}
> +
> +
> +/*
>   * Perform some start-of-day setup, including reading the asa calibration
>   * values and caching them.
>   */
> @@ -171,6 +221,16 @@ static int ak8975_setup(struct i2c_client *client)
>  				AK8975_REG_CNTL_MODE_POWER_DOWN,
>  				AK8975_REG_CNTL_MODE_MASK,
>  				AK8975_REG_CNTL_MODE_SHIFT);
> +
> +	if (data->eoc_gpio > 0 || client->irq) {
> +		ret = ak8975_setup_irq(data);
> +		if (ret < 0) {
> +			dev_err(&client->dev,
> +				"Error setting data ready interrupt\n");
> +			return ret;
> +		}
> +	}
> +
>  	if (ret < 0) {
>  		dev_err(&client->dev, "Error in setting power-down mode\n");
>  		return ret;
> @@ -267,9 +327,23 @@ static int wait_conversion_complete_polled(struct ak8975_data *data)
>  		dev_err(&client->dev, "Conversion timeout happened\n");
>  		return -EINVAL;
>  	}
> +
>  	return read_status;
>  }
>  
> +/* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
> +static int wait_conversion_complete_interrupt(struct ak8975_data *data)
> +{
> +	int ret;
> +
> +	ret = wait_event_timeout(data->data_ready_queue,
> +				 test_bit(0, &data->flags),
> +				 AK8975_DATA_READY_TIMEOUT);
> +	clear_bit(0, &data->flags);
> +
> +	return ret > 0 ? 0 : -ETIME;
> +}
> +
>  /*
>   * Emits the raw flux value for the x, y, or z axis.
>   */
> @@ -295,13 +369,16 @@ static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
>  	}
>  
>  	/* Wait for the conversion to complete. */
> -	if (gpio_is_valid(data->eoc_gpio))
> +	if (data->eoc_irq)
> +		ret = wait_conversion_complete_interrupt(data);
> +	else if (gpio_is_valid(data->eoc_gpio))
>  		ret = wait_conversion_complete_gpio(data);
>  	else
>  		ret = wait_conversion_complete_polled(data);
>  	if (ret < 0)
>  		goto exit;
>  
> +	/* This will be executed only for non-interrupt based waiting case */
>  	if (ret & AK8975_REG_ST1_DRDY_MASK) {
>  		ret = i2c_smbus_read_byte_data(client, AK8975_REG_ST2);
>  		if (ret < 0) {
> @@ -412,6 +489,11 @@ static int ak8975_probe(struct i2c_client *client,
>  	}
>  	data = iio_priv(indio_dev);
>  	i2c_set_clientdata(client, indio_dev);
> +
> +	data->client = client;
> +	data->eoc_gpio = eoc_gpio;
> +	data->eoc_irq = 0;
> +
>  	/* Perform some basic start-of-day setup of the device. */
>  	err = ak8975_setup(client);
>  	if (err < 0) {
> @@ -436,6 +518,8 @@ static int ak8975_probe(struct i2c_client *client,
>  
>  exit_free_iio:
>  	iio_device_free(indio_dev);
> +	if (data->eoc_irq)
> +		free_irq(data->eoc_irq, NULL);
>  exit_gpio:
>  	if (gpio_is_valid(eoc_gpio))
>  		gpio_free(eoc_gpio);
> @@ -450,6 +534,9 @@ static int ak8975_remove(struct i2c_client *client)
>  
>  	iio_device_unregister(indio_dev);
>  
> +	if (data->eoc_irq)
> +		free_irq(data->eoc_irq, NULL);
> +
>  	if (gpio_is_valid(data->eoc_gpio))
>  		gpio_free(data->eoc_gpio);
>  
>