linux-kernel - Re: [linux-sunxi] [PATCH 1/7] pinctrl: sunxi: add support for pin controllers without bus gate

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Message-ID: <ef82983f-6f91-46c2-1f67-7d4efc10c905@arm.com>
Date:   Thu, 11 Jan 2018 11:48:40 +0000
From:   Andre Przywara <andre.przywara@....com>
To:     icenowy@...c.io, Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [linux-sunxi] [PATCH 1/7] pinctrl: sunxi: add support for pin
 controllers without bus gate

Hi,

another take to avoid this patch at all, I just remembered this from an
IRC discussion before:

On 06/01/18 04:23, Icenowy Zheng wrote:
> The Allwinner H6 pin controllers (both the main one and the CPUs one)
> have no bus gate clocks.

I don't think this is true. The pin controller *needs* an APB clock,
it's just not gate-able or not exposed or documented.
The "system bus tree" on page 90 in the manual shows that the "GPIO"
block is located on the APB1 bus.
So can't we just reference this apb clock directly? That would be much
cleaner, "more" correct and require less changes: "The best patch is no
patch":

	clocks = <&ccu APB1>, <&osc24M>, <&osc32k>;
	/* or whatever this APB clock is actually called. */
	clock-names = "apb", "hosc", "losc";

Cheers,
Andre.

> 
> Add support for this kind of pin controllers.
> 
> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
> ---
>  drivers/pinctrl/sunxi/pinctrl-sunxi.c | 30 ++++++++++++++++++++----------
>  drivers/pinctrl/sunxi/pinctrl-sunxi.h |  1 +
>  2 files changed, 21 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> index 4b6cb25bc796..68cd505679d9 100644
> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> @@ -1182,7 +1182,12 @@ static int sunxi_pinctrl_setup_debounce(struct sunxi_pinctrl *pctl,
>  	unsigned int hosc_div, losc_div;
>  	struct clk *hosc, *losc;
>  	u8 div, src;
> -	int i, ret;
> +	int i, ret, clk_count;
> +
> +	if (pctl->desc->without_bus_gate)
> +		clk_count = 2;
> +	else
> +		clk_count = 3;
>  
>  	/* Deal with old DTs that didn't have the oscillators */
>  	if (of_count_phandle_with_args(node, "clocks", "#clock-cells") != 3)
> @@ -1360,15 +1365,19 @@ int sunxi_pinctrl_init_with_variant(struct platform_device *pdev,
>  			goto gpiochip_error;
>  	}
>  
> -	clk = devm_clk_get(&pdev->dev, NULL);
> -	if (IS_ERR(clk)) {
> -		ret = PTR_ERR(clk);
> -		goto gpiochip_error;
> -	}
> +	if (!desc->without_bus_gate) {
> +		clk = devm_clk_get(&pdev->dev, NULL);
> +		if (IS_ERR(clk)) {
> +			ret = PTR_ERR(clk);
> +			goto gpiochip_error;
> +		}
>  
> -	ret = clk_prepare_enable(clk);
> -	if (ret)
> -		goto gpiochip_error;
> +		ret = clk_prepare_enable(clk);
> +		if (ret)
> +			goto gpiochip_error;
> +	} else {
> +		clk = NULL;
> +	}
>  
>  	pctl->irq = devm_kcalloc(&pdev->dev,
>  				 pctl->desc->irq_banks,
> @@ -1425,7 +1434,8 @@ int sunxi_pinctrl_init_with_variant(struct platform_device *pdev,
>  	return 0;
>  
>  clk_error:
> -	clk_disable_unprepare(clk);
> +	if (clk)
> +		clk_disable_unprepare(clk);
>  gpiochip_error:
>  	gpiochip_remove(pctl->chip);
>  	return ret;
> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.h b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
> index 11b128f54ed2..ccb6230f0bb5 100644
> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.h
> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
> @@ -113,6 +113,7 @@ struct sunxi_pinctrl_desc {
>  	unsigned			irq_bank_base;
>  	bool				irq_read_needs_mux;
>  	bool				disable_strict_mode;
> +	bool				without_bus_gate;
>  };
>  
>  struct sunxi_pinctrl_function {
>