drivers/gpio/gpio-reg.c

Source file repositories/reference/linux-study-clean/drivers/gpio/gpio-reg.c

File Facts

System
Linux kernel
Corpus path
drivers/gpio/gpio-reg.c
Extension
.c
Size
4856 bytes
Lines
196
Domain
Driver Families
Bucket
drivers/gpio
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct gpio_reg {
	struct gpio_chip gc;
	spinlock_t lock;
	u32 direction;
	u32 out;
	void __iomem *reg;
	struct irq_domain *irqdomain;
	const int *irqs;
};

#define to_gpio_reg(x) container_of(x, struct gpio_reg, gc)

static int gpio_reg_get_direction(struct gpio_chip *gc, unsigned offset)
{
	struct gpio_reg *r = to_gpio_reg(gc);

	return r->direction & BIT(offset) ? GPIO_LINE_DIRECTION_IN :
					    GPIO_LINE_DIRECTION_OUT;
}

static int gpio_reg_direction_output(struct gpio_chip *gc, unsigned offset,
	int value)
{
	struct gpio_reg *r = to_gpio_reg(gc);

	if (r->direction & BIT(offset))
		return -ENOTSUPP;

	gc->set(gc, offset, value);
	return 0;
}

static int gpio_reg_direction_input(struct gpio_chip *gc, unsigned offset)
{
	struct gpio_reg *r = to_gpio_reg(gc);

	return r->direction & BIT(offset) ? 0 : -ENOTSUPP;
}

static int gpio_reg_set(struct gpio_chip *gc, unsigned int offset, int value)
{
	struct gpio_reg *r = to_gpio_reg(gc);
	unsigned long flags;
	u32 val, mask = BIT(offset);

	spin_lock_irqsave(&r->lock, flags);
	val = r->out;
	if (value)
		val |= mask;
	else
		val &= ~mask;
	r->out = val;
	writel_relaxed(val, r->reg);
	spin_unlock_irqrestore(&r->lock, flags);

	return 0;
}

static int gpio_reg_get(struct gpio_chip *gc, unsigned offset)
{
	struct gpio_reg *r = to_gpio_reg(gc);
	u32 val, mask = BIT(offset);

	if (r->direction & mask) {
		/*
		 * double-read the value, some registers latch after the
		 * first read.
		 */
		readl_relaxed(r->reg);
		val = readl_relaxed(r->reg);
	} else {
		val = r->out;
	}
	return !!(val & mask);
}

static int gpio_reg_set_multiple(struct gpio_chip *gc, unsigned long *mask,
				 unsigned long *bits)
{
	struct gpio_reg *r = to_gpio_reg(gc);
	unsigned long flags;

	spin_lock_irqsave(&r->lock, flags);
	r->out = (r->out & ~*mask) | (*bits & *mask);
	writel_relaxed(r->out, r->reg);
	spin_unlock_irqrestore(&r->lock, flags);

	return 0;
}

Annotation

Implementation Notes