AMG88xx has an on-board thermistor which is used for more accurate processing of its temperature readings from the 8x8 thermopile array
Cc: [email protected] Signed-off-by: Matt Ranostay <[email protected]> --- drivers/media/i2c/Kconfig | 1 + drivers/media/i2c/video-i2c.c | 81 +++++++++++++++++++++++++++++++++++ 2 files changed, 82 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 Changes from v3: * add 'imply HWMON' to avoid build race conditions diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig index 341452fe98df..799a0278b690 100644 --- a/drivers/media/i2c/Kconfig +++ b/drivers/media/i2c/Kconfig @@ -1002,6 +1002,7 @@ config VIDEO_I2C tristate "I2C transport video support" depends on VIDEO_V4L2 && I2C select VIDEOBUF2_VMALLOC + imply HWMON ---help--- Enable the I2C transport video support which supports the following: 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 -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
