linux-kernel - Re: [PATCH v1 10/11] cpufreq: tegra20: Wrap cpufreq into platform driver

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Date:   Fri, 18 May 2018 11:07:55 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Peter Geis <pgwipeout@...il.com>
Subject: Re: [PATCH v1 10/11] cpufreq: tegra20: Wrap cpufreq into platform
 driver

On Thu, May 17, 2018 at 09:00:55PM +0300, Dmitry Osipenko wrote:
> Currently tegra20-cpufreq kernel module isn't getting autoloaded because
> there is no device associated with the module, this is one of two patches
> that resolves the module autoloading. This patch adds a module alias that
> will associate the tegra20-cpufreq kernel module with the platform device,
> other patch will instantiate the actual platform device. And now it makes
> sense to wrap cpufreq driver into a platform driver for consistency.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/cpufreq/tegra20-cpufreq.c | 116 +++++++++++++++++++-----------
>  1 file changed, 73 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
> index c0a7b5a78aa6..f9d02a28df9e 100644
> --- a/drivers/cpufreq/tegra20-cpufreq.c
> +++ b/drivers/cpufreq/tegra20-cpufreq.c
> @@ -19,7 +19,7 @@
>  #include <linux/clk.h>
>  #include <linux/cpufreq.h>
>  #include <linux/module.h>
> -#include <linux/of.h>
> +#include <linux/platform_device.h>
>  
>  static struct cpufreq_frequency_table freq_table[] = {
>  	{ .frequency = 216000 },
> @@ -33,15 +33,19 @@ static struct cpufreq_frequency_table freq_table[] = {
>  	{ .frequency = CPUFREQ_TABLE_END },
>  };
>  
> -static struct clk *cpu_clk;
> -static struct clk *pll_x_clk;
> -static struct clk *pll_p_clk;
> -static bool pll_x_prepared;
> +struct tegra20_cpufreq_data {

Nit: I'm not a big fan of _data suffixes because they are completely
redundant. Any data structure by definition hosts data, so I'd just drop
that.

[...]
> @@ -152,55 +161,76 @@ static struct cpufreq_driver tegra_cpufreq_driver = {
>  	.suspend		= cpufreq_generic_suspend,
>  };
>  
> -static int __init tegra_cpufreq_init(void)
> +static int tegra20_cpufreq_probe(struct platform_device *pdev)
>  {
> +	struct tegra20_cpufreq_data *data;
>  	int err;
>  
> -	if (!of_machine_is_compatible("nvidia,tegra20"))
> -		return -ENODEV;
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
>  
> -	cpu_clk = clk_get_sys(NULL, "cclk");
> -	if (IS_ERR(cpu_clk))
> -		return PTR_ERR(cpu_clk);
> +	data->cpu_clk = clk_get_sys(NULL, "cclk");
> +	if (IS_ERR(data->cpu_clk))
> +		return PTR_ERR(data->cpu_clk);
>  
> -	pll_x_clk = clk_get_sys(NULL, "pll_x");
> -	if (IS_ERR(pll_x_clk)) {
> -		err = PTR_ERR(pll_x_clk);
> +	data->pll_x_clk = clk_get_sys(NULL, "pll_x");
> +	if (IS_ERR(data->pll_x_clk)) {
> +		err = PTR_ERR(data->pll_x_clk);
>  		goto put_cpu;
>  	}
>  
> -	pll_p_clk = clk_get_sys(NULL, "pll_p");
> -	if (IS_ERR(pll_p_clk)) {
> -		err = PTR_ERR(pll_p_clk);
> +	data->pll_p_clk = clk_get_sys(NULL, "pll_p");
> +	if (IS_ERR(data->pll_p_clk)) {
> +		err = PTR_ERR(data->pll_p_clk);
>  		goto put_pll_x;
>  	}
>  
> +	data->dev = &pdev->dev;
> +
> +	tegra_cpufreq_driver.driver_data = data;

Couldn't this be embedded into struct tegra20_cpufreq_data? Moving
everything but this into a per-device data structure seems half-baked.

Thierry

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