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Date: Mon, 10 Sep 2012 11:07:45 +0200
From: Lars-Peter Clausen <lars@...afoo.de>
To: "Kim, Milo" <Milo.Kim@...com>
CC: Jonathan Cameron <jic23@...nel.org>,
Jonathan Cameron <jic23@....ac.uk>,
"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] iio: adc: add new lp8788 adc driver
On 09/10/2012 10:02 AM, Kim, Milo wrote:
> TI LP8788 PMU provides regulators, battery charger, ADC,
> RTC, backlight driver and current sinks.
>
> This patch enables the LP8788 ADC functions.
>
> The LP8788 ADC has 13 ADC input selection and supports 12-bit resolution.
> Internal operation of getting ADC is access to registers of LP8788.
> The LP8788 ADC uses exported functions for accessing these registers.
> (exported by LP8788 MFD device driver)
>
> This driver supports IIO_CHAN_INFO_RAW and SCALE.
> The scale is micro unit.
> So the IIO consumer can get the result as following.
>
> result = ADC raw value * (scale_int + scale_part / 1000000)
>
> (The IIO map for the IIO consumer)
>
> The ADC input can be selective in the platform side.
> Even though this platform data is not defined,
> the default IIO map is created for supporting the power supply driver.
> The battery voltage and temperature are used inside this driver.
>
Hi,
One issue and a couple of nitpicks inline.
> Signed-off-by: Milo(Woogyom) Kim <milo.kim@...com>
> ---
> drivers/iio/adc/Kconfig | 6 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/lp8788_adc.c | 270 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 277 insertions(+)
[...]
> diff --git a/drivers/iio/adc/lp8788_adc.c b/drivers/iio/adc/lp8788_adc.c
> new file mode 100644
> index 0000000..6079f9e
> --- /dev/null
> +++ b/drivers/iio/adc/lp8788_adc.c
> @@ -0,0 +1,270 @@
[...]
> +
> +static const int lp8788_scale[LPADC_MAX] = {
> + [LPADC_VBATT_5P5] = 1343,
> + [LPADC_VIN_CHG] = 3052,
> + [LPADC_IBATT] = 610,
> + [LPADC_IC_TEMP] = 610,
> + [LPADC_VBATT_6P0] = 1465,
> + [LPADC_VBATT_5P0] = 1221,
> + [LPADC_ADC1] = 610,
> + [LPADC_ADC2] = 610,
> + [LPADC_VDD] = 1025,
> + [LPADC_VCOIN] = 757,
> + [LPADC_VDD_LDO] = 610,
> + [LPADC_ADC3] = 610,
> + [LPADC_ADC4] = 610,
> +};
> +
[...]
> +static int lp8788_adc_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct lp8788_adc *adc = iio_priv(indio_dev);
> + enum lp8788_adc_id id = chan->channel;
> + int ret;
> +
> + mutex_lock(&adc->lock);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = lp8788_get_adc_result(adc, id, val) ? -EIO : IIO_VAL_INT;
> + break;
> + case IIO_CHAN_INFO_SCALE:
> + *val = (lp8788_scale[id] / 1000) * 1000;
> + *val2 = (lp8788_scale[id] % 1000) * 1000000;
This looks suspicious. E.g. if the entry in your table has the value "1234"
you'd end up with a scale factor of 1000.234000000. Which looks wrong for
two reasons, given that you return INT_PLUS_MICRO val2 should never exceed 6
decimal digits and secondly val is multiplied by a factor of thousand.
Can you tell us in what unit the values in lp8788_scale are, that would make
review easier.
> + ret = IIO_VAL_INT_PLUS_MICRO;
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> +
> + mutex_unlock(&adc->lock);
> +
> + return ret;
> +}
> +
> +static const struct iio_info lp8788_adc_info = {
> + .read_raw = &lp8788_adc_read_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +#define LP8788_CHAN(_id, _type) { \
> + .type = _type, \
> + .indexed = 1, \
> + .channel = LPADC_##_id, \
> + .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT | \
> + IIO_CHAN_INFO_SCALE_SEPARATE_BIT, \
> + .address = LP8788_ADC_RAW, \
> + .scan_type = IIO_ST('u', 12, 16, 0), \
> + .scan_index = 1, \
> + .datasheet_name = "LP8788_"#_id, \
I'd drop the "LP8788_" prefix.
> +}
> +
[...]
> +static int lp8788_iio_map_register(struct iio_dev *indio_dev,
> + struct lp8788_platform_data *pdata,
> + struct lp8788_adc *adc)
> +{
> + struct iio_map *map;
> + int ret;
> +
> + map = !pdata || !pdata->adc_pdata ?
This could use a pair of parenthesis.
> + lp8788_default_iio_maps : pdata->adc_pdata;
> +
> + ret = iio_map_array_register(indio_dev, map);
> + if (ret) {
> + dev_err(adc->lp->dev, "iio map err: %d\n", ret);
> + return ret;
> + }
> +
> + adc->map = map;
> + return 0;
> +}
> +
[...]
> +static int __devexit lp8788_adc_remove(struct platform_device *pdev)
> +{
> + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
extra space.
> + struct lp8788_adc *adc = iio_priv(indio_dev);
> +
> + iio_device_unregister(indio_dev);
> + lp8788_iio_map_unregister(indio_dev, adc);
> + iio_device_free(indio_dev);
> +
> + return 0;
> +}
--
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