[PATCH 1/6] serial: 8250_dw: add support for clk api

Emilio López
2013-03-16T00:15:11Z

Hello Russell,

El 15/03/13 19:39, Russell King - ARM Linux escribi?:
> On Fri, Mar 15, 2013 at 09:06:23PM +0100, Maxime Ripard wrote:
>> + /* clock got configured through clk api, all done */
>> + if (p->uartclk)
>
> if (IS_ERR(p->uartclk))
>

Isn't IS_ERR for pointers? p->uartclk is an unsigned int

>> + return 0;
>> +
>> + /* try to find out clock frequency from DT as fallback */
>> if (of_property_read_u32(np, "clock-frequency", &val)) {
>> - dev_err(p->dev, "no clock-frequency property set\n");
>> + dev_err(p->dev, "clk or clock-frequency not defined\n");
>> return -EINVAL;
>> }
>> p->uartclk = val;
>> @@ -294,9 +301,21 @@ static int dw8250_probe(struct platform_device *pdev)
>> if (!uart.port.membase)
>> return -ENOMEM;
>>
>> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + data->clk = devm_clk_get(&pdev->dev, NULL);
>> + if (IS_ERR(data->clk))
>> + data->clk = NULL;
>> + else
>> + clk_prepare_enable(data->clk);
>
> if (!IS_ERR(data->clk))
> clk_prepare_enable(data->clk);
>

See below

>> +
>> uart.port.iotype = UPIO_MEM;
>> uart.port.serial_in = dw8250_serial_in;
>> uart.port.serial_out = dw8250_serial_out;
>> + uart.port.private_data = data;
>> + uart.port.uartclk = clk_get_rate(data->clk);
>
> What if data->clk is invalid?
>
> if (!IS_ERR(data->clk)
> uart.port.uartclk = clk_get_rate(data->clk);
>

I'm not sure if it is coincidental or the way it is supposed to be, but
when using the common clock framework, if you pass a NULL to
clk_get_rate, the function explicitly checks for it and returns 0. I
relied on that behaviour when implementing this; see the if..else block
above. Is this not always the case on other clock drivers?

>>
>> dw8250_setup_port(&uart);
>>
>> @@ -312,12 +331,6 @@ static int dw8250_probe(struct platform_device *pdev)
>> return -ENODEV;
>> }
>>
>> - data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> - if (!data)
>> - return -ENOMEM;
>> -
>> - uart.port.private_data = data;
>> -
>> data->line = serial8250_register_8250_port(&uart);
>> if (data->line < 0)
>> return data->line;
>> @@ -333,6 +346,8 @@ static int dw8250_remove(struct platform_device *pdev)
>>
>> serial8250_unregister_port(data->line);
>>
>
> if (!IS_ERR(data->clk)
>

I just double checked and clk_enable/disable, clk_prepare/unprepare also
ignore NULLs passed to them on the CCF.

>> + clk_disable_unprepare(data->clk);
>> +
>> return 0;
>> }
>>
>> --
>> 1.7.10.4

Thanks for the review,

Emilio