Re: [v2] Input: pwm-beeper: support customized freq for SND_BELL

[Heiko Schocher <hs@denx.de>]

Hello David,

Am 27.02.2017 um 19:11 schrieb David Lechner:
> On 02/20/2017 02:37 AM, Heiko Schocher wrote:
>> From: Guan Ben <ben.guan@cn.bosch.com>
>>
>> extend the pwm-beeper driver to support customized frequency
>> for SND_BELL from device tree.
>>
>> Signed-off-by: Guan Ben <ben.guan@cn.bosch.com>
>> Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
>> [hs@denx.de: adapted to 4.10-rc7]
>> Signed-off-by: Heiko Schocher <hs@denx.de>
>> ---
>>
>> Changes in v2:
>> - add comment from Rob Herring:
>>   rename property name "bell-frequency" to "beeper-hz"
>
> Is there a separate patch for the devicetree bindings documentation?

No, it is in this patch ... In the meantime I got an
Acked-by from Rob Herring ...

>> - add comment from Dmitry Torokhov:
>>   use device_property_read_u32() instead of of_property_read_u32()
>> - rebased against c470abd4fde40ea6a0846a2beab642a578c0b8cd
>>   Linux 4.10
>>
>>  .../devicetree/bindings/input/pwm-beeper.txt       |  3 ++
>>  drivers/input/misc/pwm-beeper.c                    | 36 ++++++++++++++++------
>>  2 files changed, 30 insertions(+), 9 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/input/pwm-beeper.txt
>> b/Documentation/devicetree/bindings/input/pwm-beeper.txt
>> index be332ae..4e4e128 100644
>> --- a/Documentation/devicetree/bindings/input/pwm-beeper.txt
>> +++ b/Documentation/devicetree/bindings/input/pwm-beeper.txt
>> @@ -5,3 +5,6 @@ Registers a PWM device as beeper.
>>  Required properties:
>>  - compatible: should be "pwm-beeper"
>>  - pwms: phandle to the physical PWM device
>> +
>> +optional properties:
>> +- beeper-hz:  bell frequency in Hz
>> diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
>> index 5f9655d..5ea6fda 100644
>> --- a/drivers/input/misc/pwm-beeper.c
>> +++ b/drivers/input/misc/pwm-beeper.c
>> @@ -27,6 +27,7 @@ struct pwm_beeper {
>>      struct pwm_device *pwm;
>>      struct work_struct work;
>>      unsigned long period;
>> +    unsigned int bell_frequency;
>>  };
>>
>>  #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
>> @@ -58,20 +59,17 @@ static int pwm_beeper_event(struct input_dev *input,
>>      if (type != EV_SND || value < 0)
>>          return -EINVAL;
>>
>> -    switch (code) {
>> -    case SND_BELL:
>> -        value = value ? 1000 : 0;
>
> This would be much simpler if you just changed the single line above:
>
>          value = value ? beeper->bell_frequency : 0;

Ok, I readded the switch statement, and changed this line.

>> -        break;
>> -    case SND_TONE:
>> -        break;
>> -    default:
>> +    if (code != SND_BELL && code != SND_TONE)
>>          return -EINVAL;
>> -    }
>>
>>      if (value == 0)
>>          beeper->period = 0;
>> -    else
>> +    else {
>> +        if (code == SND_BELL)
>> +            value = beeper->bell_frequency;
>> +
>>          beeper->period = HZ_TO_NANOSECONDS(value);
>> +    }
>>
>>      schedule_work(&beeper->work);
>>
>> @@ -93,6 +91,25 @@ static void pwm_beeper_close(struct input_dev *input)
>>      pwm_beeper_stop(beeper);
>>  }
>>
>> +static void pwm_beeper_init_bell_frequency(struct device *dev,
>> +                       struct pwm_beeper *beeper)
>> +{
>> +    struct device_node *node;
>> +    unsigned int bell_frequency = 1000;
>> +    int err;
>> +
>> +    if (IS_ENABLED(CONFIG_OF)) {
>
> I don't think the check for CONFIG_OF is needed when using device_property_read_u32().

Yes, removed.

>
>> +        node = dev->of_node;
>
> node variable is never used

Removed.

>
>> +        err = device_property_read_u32(dev, "beeper-hz",
>> +                           &bell_frequency);
>
> Does the device_property_read_u32() function guarantee that bell_frequency is not modified when err
> < 0 ?

Yes. This function "ends" in of_property_read_variable_u32_array()
which first searches the property (If not found returns) and if all
checks are fine, fills the "*out_values" with the values from the
property...

>> +        if (err < 0)
>> +            dev_dbg(dev, "Failed to read beeper-hz, using default: %u Hz\n",
>
> "Failed" sounds like an error, but this is a perfectly normal thing to happen. Maybe better to say
> "'beeper-hz' not specified, using default: %u Hz\n".

Changed.

>
>> +                bell_frequency);
>> +    }
>> +
>> +    beeper->bell_frequency = bell_frequency;
>> +}
>> +
>>  static int pwm_beeper_probe(struct platform_device *pdev)
>>  {
>>      unsigned long pwm_id = (unsigned long)dev_get_platdata(&pdev->dev);
>> @@ -122,6 +139,7 @@ static int pwm_beeper_probe(struct platform_device *pdev)
>>      pwm_apply_args(beeper->pwm);
>>
>>      INIT_WORK(&beeper->work, pwm_beeper_work);
>> +    pwm_beeper_init_bell_frequency(&pdev->dev, beeper);
>
> This function is so simple, it could just be done inline here.

Indeed ... changed.

Thanks!

bye,
Heiko
>
>>
>>      beeper->input = input_allocate_device();
>>      if (!beeper->input) {
>>
>

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany