Re: [PATCH v3 2/2] iio: twl6030-gpadc: TWL6030, TWL6032 GPADC driver

[Grygorii Strashko <grygorii.strashko-l0cyMroinI0@public.gmane.org>]

Hi All,

I have a question regarding this patch and IIO in general
- Does IIO provide sync mechanism with system wide suspend/resume or 
this should be handled by each driver itself?

What if during system suspend iio_read_channel_raw() (or any other 
consumer API) will be called after gpadc driver have been suspended 
already? (I did some investigation and seems it's possible - Am I right?)

If no, could "info_exist_lock" be reused for such purposes?

Regards,
-grygorii


On 07/12/2013 10:56 PM, Lars-Peter Clausen wrote:
>
> A couple of comments inline.
>
> On 07/12/2013 09:18 AM, Oleksandr Kozaruk wrote:
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index ab0767e6..87d699e 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -157,4 +157,12 @@ config VIPERBOARD_ADC
>>         Say yes here to access the ADC part of the Nano River
>>         Technologies Viperboard.
>>
>> +config TWL6030_GPADC
>> +    tristate "TWL6030 GPADC (General Purpose A/D Convertor) Support"
>> +    depends on TWL4030_CORE
>> +    default n
>> +    help
>> +      Say yes here if you want support for the TWL6030 General Purpose
>> +      A/D Convertor.
>> +
>
> Keep it in alphabetical order
>
>>   endmenu
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index 0a825be..8b05633 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -17,3 +17,4 @@ obj-$(CONFIG_MAX1363) += max1363.o
>>   obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>>   obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
>>   obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
>> +obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
>
> Same here.
>
>> diff --git a/drivers/iio/adc/twl6030-gpadc.c
>> b/drivers/iio/adc/twl6030-gpadc.c
>> new file mode 100644
>> index 0000000..6ceb789
>> --- /dev/null
>> +++ b/drivers/iio/adc/twl6030-gpadc.c
>> @@ -0,0 +1,1019 @@
> [...]
>> +static u8 twl6032_channel_to_reg(int channel)
>> +{
>> +    return TWL6032_GPADC_GPCH0_LSB;
>
> There is more than one channel, isn't there?
>
> [...]
>  > +static int twl6030_gpadc_read_raw(struct iio_dev *indio_dev,
>  > +                 const struct iio_chan_spec *chan,
>  > +                 int *val, int *val2, long mask)
>  > +{
>  > +    struct twl6030_gpadc_data *gpadc = iio_priv(indio_dev);
>  > +    int ret = -EINVAL;
>  > +
>  > +    mutex_lock(&gpadc->lock);
>  > +
>  > +    ret = gpadc->pdata->start_conversion(chan->channel);
>  > +    if (ret) {
>  > +        dev_err(gpadc->dev, "failed to start conversion\n");
>  > +        goto err;
>  > +    }
>  > +    /* wait for conversion to complete */
>  > +    wait_for_completion_interruptible_timeout(&gpadc->irq_complete,
>  > +                        msecs_to_jiffies(5000));
>
> wait_for_completion_interruptible_timeout() can return either a negative
> error code if it was interrupted, 0 if it timed out, or a positive value
> if it was successfully completed. You need to handle all three cases.
> Have a look at other existing drivers to see how to do this properly.
>
>  > +
>  > +    switch (mask) {
>  > +    case IIO_CHAN_INFO_RAW:
>  > +        ret = twl6030_gpadc_get_raw(gpadc, chan->channel, val);
>  > +        ret = ret ? -EIO : IIO_VAL_INT;
>  > +        break;
>  > +
>  > +    case IIO_CHAN_INFO_PROCESSED:
>  > +        ret = twl6030_gpadc_get_processed(gpadc, chan->channel, val);
>  > +        ret = ret ? -EIO : IIO_VAL_INT;
>  > +        break;
>  > +
>  > +    default:
>  > +        break;
>  > +    }
>  > +err:
>  > +    mutex_unlock(&gpadc->lock);
>  > +
>  > +    return ret;
>  > +}
>
>> +}
>> +
> [...]
>> +static int twl6030_gpadc_probe(struct platform_device *pdev)
>> +{
>> +    struct device *dev = &pdev->dev;
>> +    struct twl6030_gpadc_data *gpadc;
>> +    const struct twl6030_gpadc_platform_data *pdata;
>> +    const struct of_device_id *match;
>> +    struct iio_dev *indio_dev;
>> +    int irq;
>> +    int ret = 0;
>> +
>> +    match = of_match_device(of_match_ptr(of_twl6030_match_tbl), dev);
>> +    pdata = match ? match->data : dev->platform_data;
>> +
>> +    if (!pdata)
>> +        return -EINVAL;
>> +
>> +    indio_dev = iio_device_alloc(sizeof(struct twl6030_gpadc_data));
>
> sizeof(*gpadc)
>
>> +    if (!indio_dev) {
>> +        dev_err(dev, "failed allocating iio device\n");
>> +        ret = -ENOMEM;
>> +    }
>> +
>> +    gpadc = iio_priv(indio_dev);
>> +
>> +    gpadc->twl6030_cal_tbl = devm_kzalloc(dev,
>> +                    sizeof(struct twl6030_chnl_calib) *
>> +                    pdata->nchannels, GFP_KERNEL);
>> +    if (!gpadc->twl6030_cal_tbl)
>> +        goto err;
>> +
>> +    gpadc->dev = dev;
>> +    gpadc->pdata = pdata;
>> +
>> +    platform_set_drvdata(pdev, indio_dev);
>> +    mutex_init(&gpadc->lock);
>> +    init_completion(&gpadc->irq_complete);
>> +
>> +    ret = pdata->calibrate(gpadc);
>> +    if (ret < 0) {
>> +        dev_err(&pdev->dev, "failed to read calibration registers\n");
>> +        goto err;
>> +    }
>> +
>> +    irq = platform_get_irq(pdev, 0);
>> +    if (irq < 0) {
>> +        dev_err(&pdev->dev, "failed to get irq\n");
>> +        goto err;
>> +    }
>> +
>> +    ret = devm_request_threaded_irq(dev, irq, NULL,
>> +                    twl6030_gpadc_irq_handler,
>> +                    IRQF_ONESHOT, "twl6030_gpadc", gpadc);
>
> You access memory in the interrupt handler which is freed before the
> interrupt handler is freed.
>
>> +    if (ret) {
>> +        dev_dbg(&pdev->dev, "could not request irq\n");
>> +        goto err;
>> +    }
>> +
>> +    ret = twl6030_gpadc_enable_irq(TWL6030_GPADC_RT_SW1_EOC_MASK);
>> +    if (ret < 0) {
>> +        dev_err(&pdev->dev, "failed to enable GPADC interrupt\n");
>> +        goto err;
>> +    }
>> +    ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, TWL6030_GPADCS,
>> +                    TWL6030_REG_TOGGLE1);
>> +    if (ret < 0) {
>> +        dev_err(&pdev->dev, "failed to enable GPADC module\n");
>> +        goto err;
>> +    }
>> +
>> +    indio_dev->name = DRIVER_NAME;
>> +    indio_dev->dev.parent = dev;
>> +    indio_dev->info = &twl6030_gpadc_iio_info;
>> +    indio_dev->modes = INDIO_DIRECT_MODE;
>> +    indio_dev->channels = pdata->iio_channels;
>> +    indio_dev->num_channels = pdata->nchannels;
>> +
>> +    ret = iio_device_register(indio_dev);
>> +    if (ret)
>> +        goto err;
>> +
>> +    return ret;
>> +err:
>> +    iio_device_free(indio_dev);
>> +    return ret;
>> +}
>> +
> [...]
>> +static int twl6030_gpadc_suspend(struct device *pdev)
>> +{
>> +    int ret;
>> +
>> +    ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, TWL6030_GPADCR,
>> +                TWL6030_REG_TOGGLE1);
>> +    if (ret)
>> +        dev_err(pdev, "error reseting GPADC (%d)!\n", ret);
>> +
>> +    return 0;
>> +};
>> +
>> +static int twl6030_gpadc_resume(struct device *pdev)
>> +{
>> +    int ret;
>> +
>> +    ret = twl_i2c_write_u8(TWL6030_MODULE_ID1, TWL6030_GPADCS,
>> +                TWL6030_REG_TOGGLE1);
>> +    if (ret)
>> +        dev_err(pdev, "error setting GPADC (%d)!\n", ret);
>> +
>> +    return 0;
>> +};
>> +
>> +static const struct dev_pm_ops twl6030_gpadc_pm_ops = {
>> +    .suspend = twl6030_gpadc_suspend,
>> +    .resume = twl6030_gpadc_resume,
>> +};
>
> SIMPLE_DEV_PM_OPS?
>
> [...]
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