Re: [PATCH V5] iio: acpi: Add ACPI0008 ALS driver

[Jonathan Cameron <jic23@kernel.org>]

On 09/05/13 20:15, Lars-Peter Clausen wrote:
> On 07/21/2013 01:58 AM, Marek Vasut wrote:
>> From: Martin Liska <marxin.liska@gmail.com>
>>
>> Add basic implementation of the ACPI0008 Ambient Light Sensor driver.
>> This driver currently supports only the ALI property, yet is ready to
>> be easily extended to handle ALC, ALT, ALP ones as well.
>>
>> Signed-off-by: Martin Liska <marxin.liska@gmail.com>
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Cc: Jonathan Cameron <jic23@kernel.org>
>> Cc: Zhang Rui <rui.zhang@intel.com>
>> ---
>>   drivers/staging/iio/light/Kconfig    |   10 ++
>>   drivers/staging/iio/light/Makefile   |    1 +
>>   drivers/staging/iio/light/acpi-als.c |  326 ++++++++++++++++++++++++++++++++++
> 
> New IIO drivers should go to drivers/iio not drivers/staging/iio
> 
>>   3 files changed, 337 insertions(+)
>>   create mode 100644 drivers/staging/iio/light/acpi-als.c
>>
>> V2: Fix the channel mask, so it's really reading RAW data.
>> V3: Put scan timestamp into the buffer only when enabled,
>>      Set the light sensor ID to 0 instead of 1
>> V4: Select IIO_TRIGGERED_BUFFER as we need it here
>> V5: Use irq_work to trigger the buffer
>>      Use module_acpi_driver()
>>
>> diff --git a/drivers/staging/iio/light/Kconfig b/drivers/staging/iio/light/Kconfig
>> index ca8d6e6..0238a7f 100644
>> --- a/drivers/staging/iio/light/Kconfig
>> +++ b/drivers/staging/iio/light/Kconfig
>> @@ -3,6 +3,16 @@
>>   #
>>   menu "Light sensors"
>>
>> +config ACPI_ALS
>> +    tristate "ACPI Ambient Light Sensor"
>> +    depends on ACPI
>> +    select IIO_TRIGGERED_BUFFER
>> +    help
>> +     Support for the ACPI0008 Ambient Light Sensor.
>> +
>> +     This driver can also be built as a module.  If so, the module
>> +     will be called acpi-als.
>> +
>>   config SENSORS_ISL29018
>>       tristate "ISL 29018 light and proximity sensor"
>>       depends on I2C
>> diff --git a/drivers/staging/iio/light/Makefile b/drivers/staging/iio/light/Makefile
>> index 9960fdf..a3f68bc 100644
>> --- a/drivers/staging/iio/light/Makefile
>> +++ b/drivers/staging/iio/light/Makefile
>> @@ -2,6 +2,7 @@
>>   # Makefile for industrial I/O Light sensors
>>   #
>>
>> +obj-$(CONFIG_ACPI_ALS)    += acpi-als.o
>>   obj-$(CONFIG_SENSORS_ISL29018)    += isl29018.o
>>   obj-$(CONFIG_SENSORS_ISL29028)    += isl29028.o
>>   obj-$(CONFIG_TSL2583)    += tsl2583.o
>> diff --git a/drivers/staging/iio/light/acpi-als.c b/drivers/staging/iio/light/acpi-als.c
>> new file mode 100644
>> index 0000000..f63427c
>> --- /dev/null
>> +++ b/drivers/staging/iio/light/acpi-als.c
>> @@ -0,0 +1,326 @@
> [...]
>> +static void acpi_als_notify(struct acpi_device *device, u32 event)
>> +{
>> +    struct iio_dev *iio = acpi_driver_data(device);
>> +    struct acpi_als *als = iio_priv(iio);
>> +    s64 time_ns = iio_get_time_ns();
>> +
>> +    mutex_lock(&als->lock);
> 
> Hm, so you lock the mutex here and unlock the mutex acpi_als_trigger_handler. This really needs some explanation. You
> also need to implement validate_trigger and validate_device callbacks to make sure that this trigger is only used with
> this device and vice versa.

It may need some annotation as well to avoid various checks picking this up.

> 
>> +
>> +    if (iio_buffer_enabled(iio)) {
>> +        als->evt_time = time_ns;
>> +        als->evt_event = event;
>> +        irq_work_queue(&als->work);
>> +    }
>> +}
>> +
>> +static int acpi_als_read_raw(struct iio_dev *iio,
>> +            struct iio_chan_spec const *chan, int *val,
>> +            int *val2, long mask)
>> +{
>> +    struct acpi_als *als = iio_priv(iio);
>> +
>> +    if (mask != IIO_CHAN_INFO_RAW)
>> +        return -EINVAL;
>> +
>> +    /* we support only illumination (_ALI) so far. */
>> +    if (chan->type != IIO_LIGHT)
>> +        return -EINVAL;
> 
> Since you only registered a IIO_LIGHT channel with a RAW property this function will never be called with anything else,
> so strictly speaking the checks above are unnecessary.
> 
>> +
>> +    *val = als_read_value(als, ACPI_ALS_ILLUMINANCE);
>> +    return IIO_VAL_INT;
>> +}
> [..]
>> +static int acpi_als_add(struct acpi_device *device)
>> +{
>> +    struct acpi_als *als;
>> +    struct iio_dev *iio;
>> +    struct device *dev = &device->dev;
>> +    int ret;
>> +
>> +    /*
>> +     * The event buffer contains timestamp and all the data from
>> +     * the ACPI0008 block. There are multiple, but so far we only
>> +     * support _ALI (illuminance). Yes, we're ready for more!
>> +     */
>> +    uint16_t *evt_buffer;
>> +    const unsigned int evt_sources = 1;
>> +    const unsigned int evt_buffer_size = sizeof(int64_t) +
>> +                (sizeof(uint16_t) * evt_sources);
>> +
>> +    evt_buffer = devm_kzalloc(dev, evt_buffer_size, GFP_KERNEL);
>> +    if (!evt_buffer)
>> +        return -ENOMEM;
>> +
>> +    iio = iio_device_alloc(sizeof(*als));
> 
> devm_...
Also for the trigger allocation.
> 
> [...]
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