On 3/28/25 3:28 AM, Nuno Sá wrote:
> On Fri, 2025-03-21 at 21:28 +0100, Angelo Dureghello wrote:
>> From: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
>>
>> The ad3552r can be feeded from the HDL controller by an internally
>> generated 16bit ramp, useful for debug pourposes. Add debugfs a file
>> to enable or disable it.
>>
>> Signed-off-by: Angelo Dureghello <adureghello@xxxxxxxxxxxx>
>> ---
...
>> +static ssize_t ad3552r_hs_write_data_source(struct file *f,
>> + const char __user *userbuf,
>> + size_t count, loff_t *ppos)
>> +{
>> + struct ad3552r_hs_state *st = file_inode(f)->i_private;
>> + char buf[64];
>> + int ret;
>> +
>> + ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, userbuf,
>> + count);
>> + if (ret < 0)
>> + return ret;
>> +
>> + buf[count] = 0;
>> +
>> + if (count == 10 && !strncmp(buf, "iio-buffer", 10)) {
>> + ret = ad3552r_hs_set_data_source(st, IIO_BACKEND_EXTERNAL);
>> + if (ret)
>> + return ret;
>> + } else if (count == 22 && !strncmp(buf, "backend-ramp-generator", 22)) {
>> + ret = ad3552r_hs_set_data_source(st,
>> + IIO_BACKEND_INTERNAL_RAMP_16BIT);
>> + if (ret)
>> + return ret;
>> + } else {
>> + return -EINVAL;
>> + }
>
> Are we expected to add more data types in the future? If not, this could be simply an
> enable/disable ramp generator thing... It would be much simpler.
Angelo actually had implemented it that way originally. :-)
I suggested to change it to a string because the HDL project for this family
of DACs actually has 3 possibilities for the data source:
* Selectable input source: DMA/ADC/TEST_RAMP;
And there are other potential sources from the generic AXI DAC like
0x00: internal tone (DDS) that seems somewhat likely to be seen in the future.
>
> Anyways, you could define a static array and use match_string()?
>
> Lastly, for insterfaces like this, it's always helpful to have an _available kind of
> attribute.
>
> - Nuno Sá
>
>
>
>>
>> static const struct of_device_id ad3552r_hs_of_id[] = {
>>
>
>
