linux-kernel - Re: [PATCH v4 10/18] pinctrl: eyeq5: add platform driver

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Date: Wed, 31 Jan 2024 21:55:52 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Théo Lebrun <theo.lebrun@...tlin.com>
Cc: Gregory CLEMENT <gregory.clement@...tlin.com>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>, Rafał Miłecki <rafal@...ecki.pl>, 
	Philipp Zabel <p.zabel@...gutronix.de>, 
	Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>, linux-mips@...r.kernel.org, 
	linux-clk@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
	Tawfik Bayouk <tawfik.bayouk@...ileye.com>, linux-gpio@...r.kernel.org
Subject: Re: [PATCH v4 10/18] pinctrl: eyeq5: add platform driver

Hi Theo,

thanks for your patch!

On Wed, Jan 31, 2024 at 5:27 PM Théo Lebrun <theo.lebrun@...tlin.com> wrote:

> Add the Mobileye EyeQ5 pin controller driver. It might grow to add later
> support of other platforms from Mobileye. It belongs to a syscon region
> called OLB.
>
> Existing pins and their function live statically in the driver code
> rather than in the devicetree, see compatible match data.
>
> Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>

The driver looks very nice and is using all standard features, I'm pretty sure
we can merge this soon.

> +static void eq5p_update_bits(const struct eq5p_pinctrl *pctrl,
> +                            enum eq5p_bank bank, enum eq5p_regs reg,
> +                            u32 mask, u32 val)
> +{
> +       void __iomem *ptr = pctrl->base + eq5p_regs[bank][reg];
> +
> +       writel((readl(ptr) & ~mask) | (val & mask), ptr);
> +}

This is in practice a reimplementation of regmap MMIO.

Can't you just use regmap MMIO to access the banks then...?

Maybe it doesn't add much here. I'm not sure.

> +static bool eq5p_readl_bit(const struct eq5p_pinctrl *pctrl,

eq5p_test_bit() maybe? that describes better what the
function does.

> +                          enum eq5p_bank bank, enum eq5p_regs reg, int bit)
> +{
> +       u32 val = readl(pctrl->base + eq5p_regs[bank][reg]);
> +
> +       return (val & BIT(bit)) != 0;
> +}

Maybe add a check for bit > 31?

> +static int eq5p_pinctrl_get_group_pins(struct pinctrl_dev *pctldev,
> +                                      unsigned int selector,
> +                                      const unsigned int **pins,
> +                                      unsigned int *num_pins)
> +{
> +       *pins = &pctldev->desc->pins[selector].number;
> +       *num_pins = 1;
> +       return 0;
> +}

One pin per group, also known as the "qualcomm trick".

(It's fine.)

> +       mask = 0b11 << offset;

That's pretty nonstandard but it's quite readable so let's keep it!

Yours,
Linus Walleij