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Message-ID: <4D9C6D1F.30007@cam.ac.uk>
Date: Wed, 06 Apr 2011 14:39:43 +0100
From: Jonathan Cameron <jic23@....ac.uk>
To: Alan Cox <alan@...ux.jf.intel.com>
CC: linux-kernel@...r.kernel.org, greg@...ah.com,
"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>
Subject: Re: [PATCH] oaktrail AK8975 support via IIO
On 04/06/11 13:31, Alan Cox wrote:
> Actually this is generic 'I have no GPIO' support for the AK8975, instead
> we have to go bus polling.
>
> Huang Liang produced an initial patch which worked by removing the support
> for GPIO pins. This patch instead makes GPIO support optional and Huang then
> fixed some bugs in it.
cc'd linux-iio
> Signed-off-by: Alan Cox <alan@...ux.intel.com>
> ---
>
> drivers/staging/iio/magnetometer/ak8975.c | 120 ++++++++++++++++++++---------
> 1 files changed, 83 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/staging/iio/magnetometer/ak8975.c b/drivers/staging/iio/magnetometer/ak8975.c
> index 420f206..d71904a 100644
> --- a/drivers/staging/iio/magnetometer/ak8975.c
> +++ b/drivers/staging/iio/magnetometer/ak8975.c
> @@ -206,7 +206,7 @@ static int ak8975_setup(struct i2c_client *client)
> }
>
> /* Precalculate scale factor for each axis and
> - store in the device data. */
> + store in the device data. */
> data->raw_to_gauss[0] = ((data->asa[0] + 128) * 30) >> 8;
> data->raw_to_gauss[1] = ((data->asa[1] + 128) * 30) >> 8;
> data->raw_to_gauss[2] = ((data->asa[2] + 128) * 30) >> 8;
> @@ -316,6 +316,59 @@ static ssize_t show_scale(struct device *dev, struct device_attribute *devattr,
> return sprintf(buf, "%ld\n", data->raw_to_gauss[this_attr->address]);
> }
>
> +static int wait_conversion_complete_gpio(struct ak8975_data *data)
> +{
> + struct i2c_client *client = data->client;
> + u8 read_status;
> + u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
> + int ret;
> +
> + /* Wait for the conversion to complete. */
> + while (timeout_ms) {
> + msleep(AK8975_CONVERSION_DONE_POLL_TIME);
> + if (gpio_get_value(data->eoc_gpio))
> + break;
> + timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
> + }
> + if (!timeout_ms) {
> + dev_err(&client->dev, "Conversion timeout happened\n");
> + return -EINVAL;
> + }
> +
> + ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
> + if (ret < 0) {
> + dev_err(&client->dev, "Error in reading ST1\n");
> + return ret;
> + }
> + return read_status;
> +}
> +
> +static int wait_conversion_complete_polled(struct ak8975_data *data)
> +{
> + struct i2c_client *client = data->client;
> + u8 read_status;
> + u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
> + int ret;
> +
> + /* Wait for the conversion to complete. */
> + while (timeout_ms) {
> + msleep(AK8975_CONVERSION_DONE_POLL_TIME);
> + ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
> + if (ret < 0) {
> + dev_err(&client->dev, "Error in reading ST1\n");
> + return ret;
> + }
> + if (read_status)
> + break;
> + timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
> + }
> + if (!timeout_ms) {
> + dev_err(&client->dev, "Conversion timeout happened\n");
> + return -EINVAL;
> + }
> + return read_status;
> +}
> +
> /*
> * Emits the raw flux value for the x, y, or z axis.
> */
> @@ -326,7 +379,6 @@ static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,
> struct ak8975_data *data = indio_dev->dev_data;
> struct i2c_client *client = data->client;
> struct iio_dev_attr *this_attr = to_iio_dev_attr(devattr);
> - u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
> u16 meas_reg;
> s16 raw;
> u8 read_status;
> @@ -352,23 +404,14 @@ static ssize_t show_raw(struct device *dev, struct device_attribute *devattr,
> }
>
> /* Wait for the conversion to complete. */
> - while (timeout_ms) {
> - msleep(AK8975_CONVERSION_DONE_POLL_TIME);
> - if (gpio_get_value(data->eoc_gpio))
> - break;
> - timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
> - }
> - if (!timeout_ms) {
> - dev_err(&client->dev, "Conversion timeout happened\n");
> - ret = -EINVAL;
> + if (data->eoc_gpio)
> + ret = wait_conversion_complete_gpio(data);
> + else
> + ret = wait_conversion_complete_polled(data);
> + if (ret < 0)
> goto exit;
> - }
>
> - ret = ak8975_read_data(client, AK8975_REG_ST1, 1, &read_status);
> - if (ret < 0) {
> - dev_err(&client->dev, "Error in reading ST1\n");
> - goto exit;
> - }
> + read_status = ret;
>
> if (read_status & AK8975_REG_ST1_DRDY_MASK) {
> ret = ak8975_read_data(client, AK8975_REG_ST2, 1, &read_status);
> @@ -454,25 +497,26 @@ static int ak8975_probe(struct i2c_client *client,
> data->eoc_irq = client->irq;
> data->eoc_gpio = irq_to_gpio(client->irq);
>
> - if (!data->eoc_gpio) {
> - dev_err(&client->dev, "failed, no valid GPIO\n");
> - err = -EINVAL;
> - goto exit_free;
> - }
> -
> - err = gpio_request(data->eoc_gpio, "ak_8975");
> - if (err < 0) {
> - dev_err(&client->dev, "failed to request GPIO %d, error %d\n",
> - data->eoc_gpio, err);
> - goto exit_free;
> - }
> + /* We may not have a GPIO based IRQ to scan, that is fine, we will
> + poll if so */
> + if (data->eoc_gpio > 0) {
> + err = gpio_request(data->eoc_gpio, "ak_8975");
> + if (err < 0) {
> + dev_err(&client->dev,
> + "failed to request GPIO %d, error %d\n",
> + data->eoc_gpio, err);
> + goto exit_free;
> + }
>
> - err = gpio_direction_input(data->eoc_gpio);
> - if (err < 0) {
> - dev_err(&client->dev, "Failed to configure input direction for"
> - " GPIO %d, error %d\n", data->eoc_gpio, err);
> - goto exit_gpio;
> - }
> + err = gpio_direction_input(data->eoc_gpio);
> + if (err < 0) {
> + dev_err(&client->dev,
> + "Failed to configure input direction for GPIO %d, error %d\n",
> + data->eoc_gpio, err);
> + goto exit_gpio;
> + }
> + } else
> + data->eoc_gpio = 0; /* No GPIO available */
>
> /* Perform some basic start-of-day setup of the device. */
> err = ak8975_setup(client);
> @@ -503,7 +547,8 @@ static int ak8975_probe(struct i2c_client *client,
> exit_free_iio:
> iio_free_device(data->indio_dev);
> exit_gpio:
> - gpio_free(data->eoc_gpio);
> + if (data->eoc_gpio)
> + gpio_free(data->eoc_gpio);
> exit_free:
> kfree(data);
> exit:
> @@ -517,7 +562,8 @@ static int ak8975_remove(struct i2c_client *client)
> iio_device_unregister(data->indio_dev);
> iio_free_device(data->indio_dev);
>
> - gpio_free(data->eoc_gpio);
> + if (data->eoc_gpio)
> + gpio_free(data->eoc_gpio);
>
> kfree(data);
>
>
--
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