what's this linux structure?

[lilzz]

Code: Select all

  #define GPIO_CHIP(_bank) { \
    	.irq_base = IRQ_GPIO_BASE_ ## _bank, \
    	.gpio_chip = { \
    		.label = "Bank " # _bank, \
    		.owner = THIS_MODULE, \
    		.set = gpio_set_value, \
    		.get = gpio_get_value, \
    		.direction_output =gpio_direction_output, \
    		.direction_input = gpio_direction_input, \
    		.base = GPIO_BASE_ ## _bank, \
    		.ngpio =GPIO_NUM_ ## _bank, \
    	}, \
    }

What's this define with .label and .set and others?

Code: Select all

 static void gpio_set_value(struct gpio_chip *chip, unsigned gpio, int value)
    {
    	uint32_t __iomem *reg = CHIP_TO_REG(chip, REG_GPIO_DATA_SET);
    	reg += !value;
    	writel(BIT(gpio), reg);
    }

This function with writel, __iomen, BIT() , where are they referenced from in Linux?

[PeterO]

It would help if you said where you had found this code.
PeterO

[ShiftPlusOne]

The question is a little vague, so I don't know which part you don't understand.

However, all of the important structures and functions are defined in the linux kernel source.
http://lxr.free-electrons.com/source/in ... v=3.12#L52

[joan]

Is it the . in front of the names?

https://gcc.gnu.org/onlinedocs/gcc/Desi ... Inits.html

[Nolaan]

It's just a macro to access GPIO chips consistently, think about it like an API. # is replaced by the argument in the call ie _bank .
## is used for concatenation of arguments. This combination of macro and structure is a clever way to define high level operations to manipulate you GPIO.