On 10/19/2015 05:36 PM, Stephen Boyd wrote:
> On 10/20, York Sun wrote:
>> Sorry for top posting. I am on outlook web.
>>
>> We have no problem with device tree. Let's put it aside.
>>
>> When device is not used, the platform data is used to hold the data, filled
>> by a platform device before probing the clock. For my case, the platform
>> device is a PCIe device. It is a multifunction device with I2C controller on
>> it. The pseudo code looks like
>>
>> struct i2c_board_info si5338_info[NUM_SI5338_CHIPS] = {
>> {
>> .type = "si5338",
>> .platform_data = &si5338_pdata[0],
>> },
>> {
>> .type = "si5338",
>> .platform_data = &si5338_pdata[1],
>> },
>> {
>> .type = "si5338",
>> .platform_data = &si5338_pdata[2],
>> },
>> {
>> .type = "si5338",
>> .platform_data = &si5338_pdata[3],
>> },
>> };
>> clk = clk_register_fixed_rate(&pdev->dev, "ref25", NULL, CLK_IS_ROOT,
>> 25000000);
>> for (i = 0; i < NUM_SI5338_CHIPS; i++) {
>> si5338_pdata[i].clk_xtal = clk;
>> adap = i2c_get_adapter(private->i2c_adp->nr + 1 + i);
>> private->i2c_client[i] = i2c_new_probed_device(adap, &si5338_info[i],
>> i2c_si5338_addr, NULL);
>> }
>>
>> You can see, when the fixed-rate clock is registered, the device id of
>> si5338 is unknown yet. (I am using one 25MHz clock to feed multiple si5338,
>> where maybe I should create multiple 25MHz clocks, but that's another
>> discussion.)
>>
>> I hope I have made it clear.
>
> Yes. It would be great if we could modify the i2c framework to
> let us create an i2c device but not call device_register() until a later
> time. So something like this could be done in the platform
> driver:
>
> for (i = 0; i < NUM_SI5338_CHIPS; i++) {
> adap = i2c_get_adapter(private->i2c_adp->nr + 1 + i);
> private->i2c_client[i] = i2c_new_device_unregistered(adap,
> &si5338_info[i], i2c_si5338_addr);
> clkdev_create(clk, NULL, dev_name(private->i2c_client[i]->dev));
> device_register(private->i2c_client[i]->dev);
> }
>
> Then in the si5338 driver we call devm_clk_get(i2c->dev, NULL)
> and we get the xtal clock.
>
Then what do we do before we have this i2c_new_device_unregistered()? Does my
proposal make sense?
York
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