字符设备驱动（1）代码分析---之gpio_to_irq

2025-01-07 来源：cnblogs

/**************************************************************

gpio_to_irq(S5PV210_GPH2(0))

**************************************************************/

4 #define gpio_to_irq __gpio_to_irq

6 int __gpio_to_irq(unsigned gpio)

7 {

8 struct gpio_chip *chip;

9 chip = gpio_to_chip(S5PV210_GPH2(0));

static inline struct gpio_chip *gpio_to_chip(unsigned gpio)

{

return gpio_desc[S5PV210_GPH2(0)].chip;

//参考gpio-s5pv210.c中

//samsung_gpiolib_add_4bit_chips(s5pv210_gpio_4bit, nr_chips)函数

//gpio_desc[id].chip = chip;

}

10 return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;

11 //s5pv210_gpio_4bit

12 }

int samsung_gpiolib_to_irq(struct gpio_chip *chip, unsigned int offset)

{

//获得gpio_chip结构体所在的父结构体s3c_gpio_chip的指针

struct s3c_gpio_chip *s3c_chip = container_of(chip,struct s3c_gpio_chip, chip);

//获取虚拟映射机制中定义的终端号

return s3c_chip->irq_base + offset;

#define IRQ_EINT(x) ((x) < 16 ? ((x) + S5P_EINT_BASE1)

: ((x) - 16 + S5P_EINT_BASE2))

#define S5P_EINT_BASE2 (IRQ_VIC_END + 1)

#define IRQ_VIC_END S5P_IRQ_VIC3(31)

#define S5P_IRQ_VIC3(x) (S5P_VIC3_BASE + (x))

#define S5P_VIC3_BASE S5P_IRQ(96)

#define S5P_IRQ(x) ((x) + S5P_IRQ_OFFSET)

#define S5P_IRQ_OFFSET (32)

#define S5P_EINT_BASE1 (S5P_IRQ_VIC0(0))

#define S5P_IRQ_VIC0(x) (S5P_VIC0_BASE + (x))

#define S5P_VIC0_BASE S5P_IRQ(0)

}

static struct s3c_gpio_chip s5pv210_gpio_4bit[] = {

{

.chip = {

.base = S5PV210_GPA0(0),

.ngpio = S5PV210_GPIO_A0_NR,

.label = 'GPA0',

...............

{

.base = (S5P_VA_GPIO + 0xC40),

.config = &gpio_cfg_noint,

.irq_base = IRQ_EINT(16),

.chip = {

.base = S5PV210_GPH2(0),

.ngpio = S5PV210_GPIO_H2_NR,

.label = 'GPH2',

.to_irq = samsung_gpiolib_to_irq,

{

.base = (S5P_VA_GPIO + 0xC60),

.config = &gpio_cfg_noint,

.irq_base = IRQ_EINT(24),

.chip = {

.base = S5PV210_GPH3(0),

.ngpio = S5PV210_GPIO_H3_NR,

.label = 'GPH3',

.to_irq = samsung_gpiolib_to_irq,

};

1 static __init int s5pv210_gpiolib_init(void)

2 {

3 struct s3c_gpio_chip *chip = s5pv210_gpio_4bit;

4 int nr_chips = ARRAY_SIZE(s5pv210_gpio_4bit);

for (i = 0; i < nr_chips; i++, chip++) {

if (chip->config == NULL) {

chip->config = &gpio_cfg;

chip->group = gpioint_group++;

}

if (chip->base == NULL)

chip->base = S5PV210_BANK_BASE(i);

}

6 samsung_gpiolib_add_4bit_chips(s5pv210_gpio_4bit, nr_chips);

void __init samsung_gpiolib_add_4bit_chips(struct s3c_gpio_chip *chip,

int nr_chips)

{

for (; nr_chips > 0; nr_chips--, chip++)

{

samsung_gpiolib_add_4bit(chip);

void __init samsung_gpiolib_add_4bit(struct s3c_gpio_chip *chip)

{

chip->chip.direction_input = samsung_gpiolib_4bit_input;

chip->chip.direction_output = samsung_gpiolib_4bit_output;

chip->pm = __gpio_pm(&s3c_gpio_pm_4bit);

}

s3c_gpiolib_add(chip);

__init void s3c_gpiolib_add(struct s3c_gpio_chip *chip)

{

　　　　　　　　　　//将s3c_gpio_chip 结构体变量s5pv210_gpio_4bit数组中的每一个数组变量 '.chip'传递给gpio_chip结构体指针gc

　　　　　　　　　　struct gpio_chip *gc = &chip->chip;

　　　　　　　　　//gc = {

// .base = S5PV210_GPH2(0),

// .ngpio = S5PV210_GPIO_H2_NR,

// .label = 'GPH2',

// .to_irq = samsung_gpiolib_to_irq,

// },

int ret;

spin_lock_init(&chip->lock);

　　　　　　　　　　//给gc结构体指针其他结构体成员赋值

if (!gc->direction_input)

gc->direction_input = s3c_gpiolib_input;

if (!gc->direction_output)

gc->direction_output = s3c_gpiolib_output;

if (!gc->set)

gc->set = s3c_gpiolib_set;

if (!gc->get)

gc->get = s3c_gpiolib_get;

#ifdef CONFIG_PM

if (chip->pm != NULL) {

if (!chip->pm->save || !chip->pm->resume)

printk(KERN_ERR 'gpio: %s has missing PM functionsn',

gc->label);

} else

printk(KERN_ERR 'gpio: %s has no PM functionn', gc->label);

#endif

// gpiochip_add() prints own failure message on error.

ret = gpiochip_add(gc);

int gpiochip_add(struct gpio_chip *chip){

unsigned long flags; int status = 0; unsigned id;

int base = chip->base; //base = S5PV210_GPH2(0)

　　//查看获得的gpio_chip结构体指针基址和范围是否在有效范围之内

if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))

&& base >= 0) {

status = -EINVAL;

goto fail;

}

spin_lock_irqsave(&gpio_lock, flags);

if (base < 0) {

base = gpiochip_find_base(chip->ngpio);

if (base < 0) {

status = base;

goto unlock;

}

chip->base = base;

}

//these GPIO numbers must not be managed by another gpio_chip

//遍历某个GPIO端口组的所有IO，如：S5PV210_GPH2端口组的8个IO口S5PV210_GPH2(0)~(7)

　　for (id = base; id < base + chip->ngpio; id++)

　　{

　　//正常状态gpio_desc[base].chip未被初始化，所以各个成员为NULL

　　　　if (gpio_desc[id].chip != NULL) {

status = -EBUSY;

break;

}

if (status == 0) {

for (id = base; id < base + chip->ngpio; id++) {

gpio_desc[id].chip = chip;

//至此完成gpio_desc[S5PV210_GPH2(0)].chip的赋值，作为返回值在gpio_to_chip()中返回

// REVISIT: most hardware initializes GPIOs as

* inputs (often with pullups enabled) so power

* usage is minimized. Linux code should set the

* gpio direction first thing; but until it does,

* we may expose the wrong direction in sysfs.

gpio_desc[id].flags = !chip->direction_input

? (1 << FLAG_IS_OUT)

: 0;

}

of_gpiochip_add(chip);

unlock:

spin_unlock_irqrestore(&gpio_lock, flags);

if (status)

goto fail;

status = gpiochip_export(chip);

if (status)

goto fail;

return 0;

fail:

//failures here can mean systems won't boot...

pr_err('gpiochip_add: gpios %d..%d (%s) failed to registern',

chip->base, chip->base + chip->ngpio - 1,

chip->label ? : 'generic');

return status;

}

if (ret >= 0)

s3c_gpiolib_track(chip)

}

7 s5p_register_gpioint_bank(IRQ_GPIOINT, 0, S5P_GPIOINT_GROUP_MAXNR);

9 return 0;

10 }

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字符设备驱动代码分析 gpio_to_irq

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