target/linux/bcm27xx/patches-5.15/950-0534-gpio-bcm-virt-Fix-the-get-method.patch

   1 From 6e6d30ab723843fea8d9df368b35e89327f33c11 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Tue, 19 Oct 2021 11:23:43 +0100
   4 Subject: [PATCH] gpio: bcm-virt: Fix the get() method
   5
   6 The get() method does not understand the on-the-wire encoding of the
   7 remote GPIO states, thinking they are simple on/off bits when they are
   8 really pairs of 16-bit counts. Rewrite the get() handler to return the
   9 value last written, which will eventually match the actual GPIO state
  10 if there are no other changes.
  11
  12 See: https://github.com/raspberrypi/linux/issues/4638
  13
  14 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  15 ---
  16  drivers/gpio/gpio-bcm-virt.c | 2 +-
  17  1 file changed, 1 insertion(+), 1 deletion(-)
  18
  19 --- a/drivers/gpio/gpio-bcm-virt.c
  20 +++ b/drivers/gpio/gpio-bcm-virt.c
  21 @@ -49,7 +49,7 @@ static int brcmvirt_gpio_get(struct gpio
  22         unsigned v;
  23         gpio = container_of(gc, struct brcmvirt_gpio, gc);
  24         v = readl(gpio->ts_base + off);
  25 -       return (v >> off) & 1;
  26 +       return (s16)((v >> 16) - v) > 0;
  27  }
  28
  29  static void brcmvirt_gpio_set(struct gpio_chip *gc, unsigned off, int val)