Re: [PATCH v5 03/11] platform: cznic: turris-omnia-mcu: Add support for MCU connected GPIOs

Matti Vaittinen
2024-03-25T09:10:10Z

Hi Marek,

I can't say I did a proper review but browsing through the code without
proper understanding of the platform raised one small question :)

On 3/23/24 18:43, Marek Behún wrote:
> Add support for GPIOs connected to the MCU on the Turris Omnia board.
>
> This includes:
> - front button pin
> - enable pins for USB regulators
> - MiniPCIe / mSATA card presence pins in MiniPCIe port 0
> - LED output pins from WAN ethernet PHY, LAN switch and MiniPCIe ports
> - on board revisions 32+ also various peripheral resets and another
> voltage regulator enable pin
>
> Signed-off-by: Marek Behún <kabel@kernel.org>

...

> +/**
> + * omnia_mask_interleave - Interleaves the bytes from @rising and @falling
> + * @dst: the destination u8 array of interleaved bytes
> + * @rising: rising mask
> + * @falling: falling mask
> + *
> + * Interleaves the little-endian bytes from @rising and @falling words.
This means the 'rising' and 'falling' should always be little-endian?
Should the parameter types reflect this? Or should we see some
cpu_to_le() calls? (Or, is this code just guaranteed to be always
running on a le-machine?).

> + * If @rising = (r0, r1, r2, r3) and @falling = (f0, f1, f2, f3), the result is
> + * @dst = (r0, f0, r1, f1, r2, f2, r3, f3).
> + *
> + * The MCU receives interrupt mask and reports pending interrupt bitmap int this
> + * interleaved format. The rationale behind it is that the low-indexed bits are
> + * more important - in many cases, the user will be interested only in
> + * interrupts with indexes 0 to 7, and so the system can stop reading after
> + * first 2 bytes (r0, f0), to save time on the slow I2C bus.
> + *
> + * Feel free to remove this function and its inverse, omnia_mask_deinterleave,
> + * and use an appropriate bitmap_* function once such a function exists.
> + */
> +static void omnia_mask_interleave(u8 *dst, u32 rising, u32 falling)
> +{
> + for (int i = 0; i < sizeof(u32); ++i) {
> + dst[2 * i] = rising >> (8 * i);
> + dst[2 * i + 1] = falling >> (8 * i);
> + }
> +}
> +
> +/**
> + * omnia_mask_deinterleave - Deinterleaves the bytes into @rising and @falling
> + * @src: the source u8 array containing the interleaved bytes
> + * @rising: pointer where to store the rising mask gathered from @src
> + * @falling: pointer where to store the falling mask gathered from @src
> + *
> + * This is the inverse function to omnia_mask_interleave.
> + */
> +static void omnia_mask_deinterleave(const u8 *src, u32 *rising, u32 *falling)
> +{
> + *rising = *falling = 0;
> +
> + for (int i = 0; i < sizeof(u32); ++i) {
> + *rising |= src[2 * i] << (8 * i);
> + *falling |= src[2 * i + 1] << (8 * i);
> + }

Also here I could expect seeing le_to_cpu() unless I am (again :])
missing something.

> +}

Yours,
-- Matti

--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

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