Re: [PATCH v8 3/9] platform: cznic: turris-omnia-mcu: Add support for MCU connected GPIOs

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Tue, Apr 30, 2024 at 2:51 PM Marek Behún <kabel@kernel.org> 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

...

> -int omnia_cmd_read(const struct i2c_client *client, u8 cmd, void *reply,
> -                  unsigned int len)
> +int omnia_cmd_write_read(const struct i2c_client *client,
> +                        void *cmd, unsigned int cmd_len,
> +                        void *reply, unsigned int reply_len)
>  {
>         struct i2c_msg msgs[2];
> -       int ret;
> +       int ret, num;
>
>         msgs[0].addr = client->addr;
>         msgs[0].flags = 0;
> -       msgs[0].len = 1;
> -       msgs[0].buf = &cmd;
> -       msgs[1].addr = client->addr;
> -       msgs[1].flags = I2C_M_RD;
> -       msgs[1].len = len;
> -       msgs[1].buf = reply;
> -
> -       ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
> +       msgs[0].len = cmd_len;
> +       msgs[0].buf = cmd;
> +       num = 1;
> +
> +       if (reply_len) {
> +               msgs[1].addr = client->addr;
> +               msgs[1].flags = I2C_M_RD;
> +               msgs[1].len = reply_len;
> +               msgs[1].buf = reply;
> +               num++;
> +       }
> +
> +       ret = i2c_transfer(client->adapter, msgs, num);
>         if (ret < 0)
>                 return ret;
> -       if (ret != ARRAY_SIZE(msgs))
> +       if (ret != num)
>                 return -EIO;
>
>         return 0;

Hold on, you are "patching" the code you just brought by the previous
patch?! No, just do from the beginning how it should be at the end.

...

> +#include <linux/devm-helpers.h>

Do you still need this?

...

> +#define FRONT_BUTTON_RELEASE_DELAY     50 /* ms */

Use proper unit suffix instead of a comment like many others do.

_MS here.

...

> +static const char * const omnia_mcu_gpio_templates[64] = {
> +       /* GPIOs with value read from the 16-bit wide status */
> +       [4]  = "gpio%u.MiniPCIe0 Card Detect",
> +       [5]  = "gpio%u.MiniPCIe0 mSATA Indicator",
> +       [6]  = "gpio%u.Front USB3 port over-current",
> +       [7]  = "gpio%u.Rear USB3 port over-current",
> +       [8]  = "gpio%u.Front USB3 port power",
> +       [9]  = "gpio%u.Rear USB3 port power",
> +       [12] = "gpio%u.Front Button",
> +
> +       /* GPIOs with value read from the 32-bit wide extended status */
> +       [16] = "gpio%u.SFP nDET",
> +       [28] = "gpio%u.MiniPCIe0 LED",
> +       [29] = "gpio%u.MiniPCIe1 LED",
> +       [30] = "gpio%u.MiniPCIe2 LED",
> +       [31] = "gpio%u.MiniPCIe0 PAN LED",
> +       [32] = "gpio%u.MiniPCIe1 PAN LED",
> +       [33] = "gpio%u.MiniPCIe2 PAN LED",
> +       [34] = "gpio%u.WAN PHY LED0",
> +       [35] = "gpio%u.WAN PHY LED1",
> +       [36] = "gpio%u.LAN switch p0 LED0",
> +       [37] = "gpio%u.LAN switch p0 LED1",
> +       [38] = "gpio%u.LAN switch p1 LED0",
> +       [39] = "gpio%u.LAN switch p1 LED1",
> +       [40] = "gpio%u.LAN switch p2 LED0",
> +       [41] = "gpio%u.LAN switch p2 LED1",
> +       [42] = "gpio%u.LAN switch p3 LED0",
> +       [43] = "gpio%u.LAN switch p3 LED1",
> +       [44] = "gpio%u.LAN switch p4 LED0",
> +       [45] = "gpio%u.LAN switch p4 LED1",
> +       [46] = "gpio%u.LAN switch p5 LED0",
> +       [47] = "gpio%u.LAN switch p5 LED1",
> +
> +       /* GPIOs with value read from the 16-bit wide extended control status */
> +       [48] = "gpio%u.eMMC nRESET",
> +       [49] = "gpio%u.LAN switch nRESET",
> +       [50] = "gpio%u.WAN PHY nRESET",
> +       [51] = "gpio%u.MiniPCIe0 nPERST",
> +       [52] = "gpio%u.MiniPCIe1 nPERST",
> +       [53] = "gpio%u.MiniPCIe2 nPERST",
> +       [54] = "gpio%u.WAN PHY SFP mux",
> +};

You may reduce the memory footprint of these just by doing "gpio%u."
part(s) outside. Here compiler won't compress this (as in the case of
repetitive string literals),

...

> +static const struct omnia_gpio {
> +       u8 cmd, ctl_cmd;
> +       u32 bit, ctl_bit;
> +       u32 int_bit;
> +       u16 feat, feat_mask;
> +} omnia_gpios[64] = {

It's much better to decouple definition and assignment and put
definition _before_ the macros that fill it.

> +};

...

> +               scoped_guard(mutex, &mcu->lock)
> +                       val = omnia_cmd_read_bit(mcu->client,
> +                                                CMD_GET_EXT_CONTROL_STATUS,
> +                                                EXT_CTL_PHY_SFP_AUTO);
> +
> +               if (val < 0)
> +                       return val;

I would move that under guard  for the sake of better readability
(usual pattern in place). It's anyway a slow path and one branch under
the mutex won't affect anything.

> +               if (val)
> +                       return GPIO_LINE_DIRECTION_IN;
> +
> +               return GPIO_LINE_DIRECTION_OUT;

...

> +       struct omnia_mcu *mcu = gpiochip_get_data(gc);
> +       u32 sts_bits, ext_sts_bits, ext_ctl_bits;
> +       int err, i;

> +       sts_bits = 0;
> +       ext_sts_bits = 0;
> +       ext_ctl_bits = 0;

Why not assign these inside the definition line?

...

> +       for_each_set_bit(i, mask, ARRAY_SIZE(omnia_gpios)) {
> +               if (omnia_gpios[i].cmd == CMD_GET_STATUS_WORD)
> +                       __assign_bit(i, bits, sts_bits & omnia_gpios[i].bit);
> +               else if (omnia_gpios[i].cmd == CMD_GET_EXT_STATUS_DWORD)
> +                       __assign_bit(i, bits, ext_sts_bits &
> +                                             omnia_gpios[i].bit);

One line?

> +               else if (omnia_gpios[i].cmd == CMD_GET_EXT_CONTROL_STATUS)
> +                       __assign_bit(i, bits, ext_ctl_bits &
> +                                             omnia_gpios[i].bit);

Ditto?

> +       }

...

> +       struct omnia_mcu *mcu = gpiochip_get_data(gc);
> +       u16 ext_ctl, ext_ctl_mask;
> +       u8 ctl, ctl_mask;
> +       int i;
> +
> +       ctl = 0;
> +       ctl_mask = 0;
> +       ext_ctl = 0;
> +       ext_ctl_mask = 0;

Assignments in the definition line?

...

> +       for_each_set_bit(i, mask, ARRAY_SIZE(omnia_gpios)) {
> +               if (omnia_gpios[i].ctl_cmd == CMD_GENERAL_CONTROL) {
> +                       ctl_mask |= omnia_gpios[i].ctl_bit;
> +                       if (test_bit(i, bits))
> +                               ctl |= omnia_gpios[i].ctl_bit;
> +               } else if (omnia_gpios[i].ctl_cmd == CMD_EXT_CONTROL) {
> +                       ext_ctl_mask |= omnia_gpios[i].ctl_bit;
> +                       if (test_bit(i, bits))
> +                               ext_ctl |= omnia_gpios[i].ctl_bit;
> +               }
> +       }

...

> +/**
> + * 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.
> + *
> + * 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

an interrupt
a pending
int --> in ?

> + * 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);
> +       }

I will look at this later on,

> +}

> +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);
> +       }
> +}

and into this.

...

> +static size_t omnia_irq_compute_pending_length(u32 rising, u32 falling)
> +{
> +       size_t rlen = 0, flen = 0;
> +
> +       if (rising)
> +               rlen = ((__fls(rising) >> 3) << 1) + 1;
> +
> +       if (falling)
> +               flen = ((__fls(falling) >> 3) << 1) + 2;
> +
> +       return max(rlen, flen);
> +}

I am not sure why you need this, but it can be done easily

x = ((__fls(falling | rising) >> 3) << 1) + 1;
if (falling)
  return x + 1;
return x;

and most likely you can drop minmax.h.

...

> +static const char * const front_button_modes[2] = { "mcu", "cpu" };

2 is not needed.

...

> -#include <linux/i2c.h>

??? That is exactly the point to have things done from the beginning.

> +#include <linux/bitops.h>
> +#include <linux/gpio/driver.h>
>  #include <linux/if_ether.h>
> +#include <linux/mutex.h>
>  #include <linux/types.h>
> +#include <linux/workqueue.h>
>  #include <asm/byteorder.h>

...

> +       err = omnia_cmd_read(client, cmd, &reply, (__fls(bits) >> 3) + 1);

Perhaps a helper for this (__fls(x) >> 3 + (y)) ? It seems it's used
in a few places.


> +       if (err)
> +               return err;

--
With Best Regards,
Andy Shevchenko