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.
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