Re: [PATCH v2] clk: gpio: Make into a platform driver

[Jyri Sarha <jsarha@ti.com>]

On 02/03/16 23:10, Stephen Boyd wrote:
> clk_get() for DT based clks already returns EPROBE_DEFER when the
> OF clk provider is not present. So having all this code in the
> clk provider to return EPROBE_DEFER when the gpio isn't ready yet
> can be replaced with a platform driver that doesn't add the clk
> provider until the gpio can be requested. Get rid of the
> OF_CLK_DECLARE and convert this to a platform driver instead.
>
> Cc: Jyri Sarha <jsarha@ti.com>
> Cc: Sergej Sawazki <ce3a@gmx.de>
> Cc: Russell King <rmk+kernel@arm.linux.org.uk>
> Cc: Fabio Estevam <fabio.estevam@freescale.com>
> Cc: Jon Nettleton <jon@solid-run.com>
> Cc: Shawn Guo <shawn.guo@linaro.org>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

The gate clock works for Beaglebone-black HDMI audio.

Tested-by: Jyri Sarha <jsarha@ti.com>



> ---
>
> Changes from v1:
>   * Fix build error by removing unused module device table
>
>   drivers/clk/clk-gpio.c | 165 ++++++++++++++++---------------------------------
>   1 file changed, 52 insertions(+), 113 deletions(-)
>
> diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
> index cbbea2985cc9..fb32a7366ef6 100644
> --- a/drivers/clk/clk-gpio.c
> +++ b/drivers/clk/clk-gpio.c
> @@ -20,6 +20,8 @@
>   #include <linux/of_gpio.h>
>   #include <linux/err.h>
>   #include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/of_device.h>
>
>   /**
>    * DOC: basic gpio gated clock which can be enabled and disabled
> @@ -199,134 +201,71 @@ struct clk *clk_register_gpio_mux(struct device *dev, const char *name,
>   }
>   EXPORT_SYMBOL_GPL(clk_register_gpio_mux);
>
> -#ifdef CONFIG_OF
> -/**
> - * clk_register_get() has to be delayed, because -EPROBE_DEFER
> - * can not be handled properly at of_clk_init() call time.
> - */
> -
> -struct clk_gpio_delayed_register_data {
> -	const char *gpio_name;
> -	int num_parents;
> -	const char **parent_names;
> -	struct device_node *node;
> -	struct mutex lock;
> -	struct clk *clk;
> -	struct clk *(*clk_register_get)(const char *name,
> -			const char * const *parent_names, u8 num_parents,
> -			unsigned gpio, bool active_low);
> -};
> -
> -static struct clk *of_clk_gpio_delayed_register_get(
> -		struct of_phandle_args *clkspec, void *_data)
> +static int gpio_clk_driver_probe(struct platform_device *pdev)
>   {
> -	struct clk_gpio_delayed_register_data *data = _data;
> -	struct clk *clk;
> -	int gpio;
> +	struct device_node *node = pdev->dev.of_node;
> +	const char **parent_names, *gpio_name;
> +	int num_parents, gpio;
>   	enum of_gpio_flags of_flags;
> +	struct clk *clk;
> +	bool active_low, is_mux;
> +
> +	num_parents = of_clk_get_parent_count(node);
> +	if (num_parents < 0)
> +		return -EINVAL;
>
> -	mutex_lock(&data->lock);
> +	if (num_parents) {
> +		parent_names = devm_kcalloc(&pdev->dev, num_parents,
> +					    sizeof(char *), GFP_KERNEL);
> +		if (!parent_names)
> +			return -ENOMEM;
>
> -	if (data->clk) {
> -		mutex_unlock(&data->lock);
> -		return data->clk;
> +		of_clk_parent_fill(node, parent_names, num_parents);
> +	} else {
> +		parent_names = NULL;
>   	}
>
> -	gpio = of_get_named_gpio_flags(data->node, data->gpio_name, 0,
> -			&of_flags);
> +	is_mux = of_device_is_compatible(node, "gpio-mux-clock");
> +
> +	gpio_name = is_mux ? "select-gpios" : "enable-gpios";
> +	gpio = of_get_named_gpio_flags(node, gpio_name, 0, &of_flags);
>   	if (gpio < 0) {
> -		mutex_unlock(&data->lock);
>   		if (gpio == -EPROBE_DEFER)
>   			pr_debug("%s: %s: GPIOs not yet available, retry later\n",
> -					data->node->name, __func__);
> +					node->name, __func__);
>   		else
>   			pr_err("%s: %s: Can't get '%s' DT property\n",
> -					data->node->name, __func__,
> -					data->gpio_name);
> -		return ERR_PTR(gpio);
> +					node->name, __func__,
> +					gpio_name);
> +		return gpio;
>   	}
>
> -	clk = data->clk_register_get(data->node->name, data->parent_names,
> -			data->num_parents, gpio, of_flags & OF_GPIO_ACTIVE_LOW);
> -	if (IS_ERR(clk))
> -		goto out;
> -
> -	data->clk = clk;
> -out:
> -	mutex_unlock(&data->lock);
> -
> -	return clk;
> -}
> -
> -static struct clk *of_clk_gpio_gate_delayed_register_get(const char *name,
> -		const char * const *parent_names, u8 num_parents,
> -		unsigned gpio, bool active_low)
> -{
> -	return clk_register_gpio_gate(NULL, name, parent_names ?
> -			parent_names[0] : NULL, gpio, active_low, 0);
> -}
> -
> -static struct clk *of_clk_gpio_mux_delayed_register_get(const char *name,
> -		const char * const *parent_names, u8 num_parents, unsigned gpio,
> -		bool active_low)
> -{
> -	return clk_register_gpio_mux(NULL, name, parent_names, num_parents,
> -			gpio, active_low, 0);
> -}
> -
> -static void __init of_gpio_clk_setup(struct device_node *node,
> -		const char *gpio_name,
> -		struct clk *(*clk_register_get)(const char *name,
> -				const char * const *parent_names,
> -				u8 num_parents,
> -				unsigned gpio, bool active_low))
> -{
> -	struct clk_gpio_delayed_register_data *data;
> -	const char **parent_names;
> -	int i, num_parents;
> -
> -	num_parents = of_clk_get_parent_count(node);
> -	if (num_parents < 0)
> -		return;
> -
> -	data = kzalloc(sizeof(*data), GFP_KERNEL);
> -	if (!data)
> -		return;
> +	active_low = of_flags & OF_GPIO_ACTIVE_LOW;
>
> -	if (num_parents) {
> -		parent_names = kcalloc(num_parents, sizeof(char *), GFP_KERNEL);
> -		if (!parent_names) {
> -			kfree(data);
> -			return;
> -		}
> -
> -		for (i = 0; i < num_parents; i++)
> -			parent_names[i] = of_clk_get_parent_name(node, i);
> -	} else {
> -		parent_names = NULL;
> -	}
> -
> -	data->num_parents = num_parents;
> -	data->parent_names = parent_names;
> -	data->node = node;
> -	data->gpio_name = gpio_name;
> -	data->clk_register_get = clk_register_get;
> -	mutex_init(&data->lock);
> +	if (is_mux)
> +		clk = clk_register_gpio_mux(&pdev->dev, node->name,
> +				parent_names, num_parents, gpio, active_low, 0);
> +	else
> +		clk = clk_register_gpio_gate(&pdev->dev, node->name,
> +				parent_names ?  parent_names[0] : NULL, gpio,
> +				active_low, 0);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
>
> -	of_clk_add_provider(node, of_clk_gpio_delayed_register_get, data);
> +	return of_clk_add_provider(node, of_clk_src_simple_get, clk);
>   }
>
> -static void __init of_gpio_gate_clk_setup(struct device_node *node)
> -{
> -	of_gpio_clk_setup(node, "enable-gpios",
> -		of_clk_gpio_gate_delayed_register_get);
> -}
> -CLK_OF_DECLARE(gpio_gate_clk, "gpio-gate-clock", of_gpio_gate_clk_setup);
> +static const struct of_device_id gpio_clk_match_table[] = {
> +	{ .compatible = "gpio-mux-clock" },
> +	{ .compatible = "gpio-gate-clock" },
> +	{ }
> +};
>
> -void __init of_gpio_mux_clk_setup(struct device_node *node)
> -{
> -	of_gpio_clk_setup(node, "select-gpios",
> -		of_clk_gpio_mux_delayed_register_get);
> -}
> -CLK_OF_DECLARE(gpio_mux_clk, "gpio-mux-clock", of_gpio_mux_clk_setup);
> -#endif
> +static struct platform_driver gpio_clk_driver = {
> +	.probe		= gpio_clk_driver_probe,
> +	.driver		= {
> +		.name	= "gpio-clk",
> +		.of_match_table = gpio_clk_match_table,
> +	},
> +};
> +builtin_platform_driver(gpio_clk_driver);
>