linux-kernel - Re: [PATCH 1/6] serial: 8250_dw: add support for clocks property when using DeviceTree

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Date:	Fri, 15 Mar 2013 20:48:09 +0100
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
CC:	linux-arm-kernel@...ts.infradead.org, kevin@...winnertech.com,
	sunny@...winnertech.com, shuge@...winnertech.com,
	Emilio López 
	<emilio@...pez.com.ar>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.cz>, linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] serial: 8250_dw: add support for clocks property
 when using DeviceTree

Hi Heikki

Le 15/03/2013 13:56, Heikki Krogerus a écrit :
>> @@ -137,8 +140,15 @@ static int dw8250_probe_of(struct uart_port *p)
>>  		p->regshift = val;
>>  
>>  	if (of_property_read_u32(np, "clock-frequency", &val)) {
>> -		dev_err(p->dev, "no clock-frequency property set\n");
>> -		return -EINVAL;
>> +		/* Get clk rate through clk driver if present */
>> +		data->clk = clk_get(p->dev, NULL);
>> +		if (IS_ERR(data->clk)) {
>> +			dev_err(p->dev, "clk or clock-frequency not defined\n");
>> +			return -EINVAL;
>> +		}
>> +
>> +		clk_prepare_enable(data->clk);
>> +		val = clk_get_rate(data->clk);
> 
> Don't get the clk here..
> 
>>  	}
>>  	p->uartclk = val;
>>  
>> @@ -300,6 +310,12 @@ static int dw8250_probe(struct platform_device *pdev)
> 
> Get it here so it is then handled for also others besides DT users.
> And prefer devm_clk_get(). Something like this:
> 
>         ...
>         uart.port.membase = ioremap(regs->start, resource_size(regs));
>         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);
> +       clk_prepare_enable(data->clk);
> +
>         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);
> 
>   	dw8250_setup_port(&uart);
>         ... 
> 
> Then in dw8250_probe_of() you need to use the "clock-frequency"
> property only when p->uartclk is 0.

Thanks for your feedback.
Emilio made a new version of this patch, I'll send it soon.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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