Hello.

I tried to use GPIO28 and GPIO29 as I2C.
So, I used SET_GPIO_ALT(28, 0) and SET_GPIO_ALT(29, 0) after INP_GPIO(28) and INP_GPIO(29), respectively.
But, my code, which worked fine with I2C-1, doesn't work with that command.
GPIO28, GPIO29 pins are not woking in I2C mode.
I looked through the bcm2385 library and it looks all the parts related to GPIO setting is the same.

Any idea?

define them like this and we will not forget to call INP_GPIO:

define OUT_GPIO(g) INP_GPIO(g); _(gpio.addr + ((g)/10)) |= (1<<(((g)%10)_3))

define SET_GPIO_ALT(g,a) INP_GPIO(g); _(gpio.addr + (((g)/10))) |= (((a)<=3?(a) + 4:(a)==4?3:2)<<(((g)%10)_3))

Hi there!

I tend to forget things... so why not wrap the INP_GPIO macro inside the OUT_GPIO and SET_GPIO_ALT ones? Like so:

#define OUT_GPIO(g)       do { \
  INP_GPIO(g); \
  *(gpio.addr + ((g)/10)) |=  (1<<(((g)%10)*3)); \
} while(0)

#define SET_GPIO_ALT(g,a) do { \
  INP_GPIO(g); \
  *(gpio.addr + (((g)/10))) |= (((a)<=3?(a) + 4:(a)==4?3:2)<<(((g)%10)*3)); \
} while(0)

Also helps to get cleaner code. Tested on my rpi and works great ;)

define GPIO_READ(g) *(gpio.addr + 13) &= (1<<(g))

should be

define GPIO_READ(g) (*(gpio.addr + 13) &= (1<<(g)))

otherwise, consider the following code:
if (GPIO_READ(echo) != 0) {
}

the operator "&=" has very low prority, even lower than "!=".