On Wed, Jun 27, 2018 at 11:12:43AM -0700, Matt Ranostay wrote:
> AMG88xx has an on-board thermistor which is used for more accurate
> processing of its temperature readings from the 8x8 thermopile array
>
> Cc: linux-hwmon@xxxxxxxxxxxxxxx
> Signed-off-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx>
Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> drivers/media/i2c/video-i2c.c | 81 +++++++++++++++++++++++++++++++++++
> 1 file changed, 81 insertions(+)
>
> Changes from v1:
> * remove unneeded include statement
> * removed evil &NULL dereference if hwmon isn't enabled
> * return PTR_ERR instead of boolean IS_ERR from amg88xx_hwmon_init()
> * use error code returned from hwmon_init() to display dev_warn
>
> Changes from v2:
> * change #ifdef check to use cleaner IS_ENABLED(CONFIG_HWMON)
> * document why the temperature value isn't sign extended more concisely
>
> diff --git a/drivers/media/i2c/video-i2c.c b/drivers/media/i2c/video-i2c.c
> index 0b347cc19aa5..7dc9338502e5 100644
> --- a/drivers/media/i2c/video-i2c.c
> +++ b/drivers/media/i2c/video-i2c.c
> @@ -10,6 +10,7 @@
>
> #include <linux/delay.h>
> #include <linux/freezer.h>
> +#include <linux/hwmon.h>
> #include <linux/kthread.h>
> #include <linux/i2c.h>
> #include <linux/list.h>
> @@ -77,6 +78,9 @@ struct video_i2c_chip {
>
> /* xfer function */
> int (*xfer)(struct video_i2c_data *data, char *buf);
> +
> + /* hwmon init function */
> + int (*hwmon_init)(struct video_i2c_data *data);
> };
>
> static int amg88xx_xfer(struct video_i2c_data *data, char *buf)
> @@ -101,6 +105,74 @@ static int amg88xx_xfer(struct video_i2c_data *data, char *buf)
> return (ret == 2) ? 0 : -EIO;
> }
>
> +#if IS_ENABLED(CONFIG_HWMON)
> +
> +static const u32 amg88xx_temp_config[] = {
> + HWMON_T_INPUT,
> + 0
> +};
> +
> +static const struct hwmon_channel_info amg88xx_temp = {
> + .type = hwmon_temp,
> + .config = amg88xx_temp_config,
> +};
> +
> +static const struct hwmon_channel_info *amg88xx_info[] = {
> + &amg88xx_temp,
> + NULL
> +};
> +
> +static umode_t amg88xx_is_visible(const void *drvdata,
> + enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + return 0444;
> +}
> +
> +static int amg88xx_read(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long *val)
> +{
> + struct video_i2c_data *data = dev_get_drvdata(dev);
> + struct i2c_client *client = data->client;
> + int tmp = i2c_smbus_read_word_data(client, 0x0e);
> +
> + if (tmp < 0)
> + return tmp;
> +
> + /*
> + * Check for sign bit, this isn't a two's complement value but an
> + * absolute temperature that needs to be inverted in the case of being
> + * negative.
> + */
> + if (tmp & BIT(11))
> + tmp = -(tmp & 0x7ff);
> +
> + *val = (tmp * 625) / 10;
> +
> + return 0;
> +}
> +
> +static const struct hwmon_ops amg88xx_hwmon_ops = {
> + .is_visible = amg88xx_is_visible,
> + .read = amg88xx_read,
> +};
> +
> +static const struct hwmon_chip_info amg88xx_chip_info = {
> + .ops = &amg88xx_hwmon_ops,
> + .info = amg88xx_info,
> +};
> +
> +static int amg88xx_hwmon_init(struct video_i2c_data *data)
> +{
> + void *hwmon = devm_hwmon_device_register_with_info(&data->client->dev,
> + "amg88xx", data, &amg88xx_chip_info, NULL);
> +
> + return PTR_ERR(hwmon);
> +}
> +#else
> +#define amg88xx_hwmon_init NULL
> +#endif
> +
> #define AMG88XX 0
>
> static const struct video_i2c_chip video_i2c_chip[] = {
> @@ -111,6 +183,7 @@ static const struct video_i2c_chip video_i2c_chip[] = {
> .buffer_size = 128,
> .bpp = 16,
> .xfer = &amg88xx_xfer,
> + .hwmon_init = amg88xx_hwmon_init,
> },
> };
>
> @@ -505,6 +578,14 @@ static int video_i2c_probe(struct i2c_client *client,
> video_set_drvdata(&data->vdev, data);
> i2c_set_clientdata(client, data);
>
> + if (data->chip->hwmon_init) {
> + ret = data->chip->hwmon_init(data);
> + if (ret < 0) {
> + dev_warn(&client->dev,
> + "failed to register hwmon device\n");
> + }
> + }
> +
> ret = video_register_device(&data->vdev, VFL_TYPE_GRABBER, -1);
> if (ret < 0)
> goto error_unregister_device;
> --
> 2.17.1
>
> --
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