drivers/pwm/pwm-bcm-iproc.c

Source file repositories/reference/linux-study-clean/drivers/pwm/pwm-bcm-iproc.c

File Facts

System
Linux kernel
Corpus path
drivers/pwm/pwm-bcm-iproc.c
Extension
.c
Size
6725 bytes
Lines
249
Domain
Driver Families
Bucket
drivers/pwm
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 iproc_pwmc {
	void __iomem *base;
	struct clk *clk;
};

static inline struct iproc_pwmc *to_iproc_pwmc(struct pwm_chip *chip)
{
	return pwmchip_get_drvdata(chip);
}

static void iproc_pwmc_enable(struct iproc_pwmc *ip, unsigned int channel)
{
	u32 value;

	value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
	value |= 1 << IPROC_PWM_CTRL_EN_SHIFT(channel);
	writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);

	/* must be a 400 ns delay between clearing and setting enable bit */
	ndelay(400);
}

static void iproc_pwmc_disable(struct iproc_pwmc *ip, unsigned int channel)
{
	u32 value;

	value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
	value &= ~(1 << IPROC_PWM_CTRL_EN_SHIFT(channel));
	writel(value, ip->base + IPROC_PWM_CTRL_OFFSET);

	/* must be a 400 ns delay between clearing and setting enable bit */
	ndelay(400);
}

static int iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
				struct pwm_state *state)
{
	struct iproc_pwmc *ip = to_iproc_pwmc(chip);
	u64 tmp, multi, rate;
	u32 value, prescale;

	value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);

	if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
		state->enabled = true;
	else
		state->enabled = false;

	if (value & BIT(IPROC_PWM_CTRL_POLARITY_SHIFT(pwm->hwpwm)))
		state->polarity = PWM_POLARITY_NORMAL;
	else
		state->polarity = PWM_POLARITY_INVERSED;

	rate = clk_get_rate(ip->clk);
	if (rate == 0) {
		state->period = 0;
		state->duty_cycle = 0;
		return 0;
	}

	value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
	prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
	prescale &= IPROC_PWM_PRESCALE_MAX;

	multi = NSEC_PER_SEC * (prescale + 1);

	value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm));
	tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
	state->period = div64_u64(tmp, rate);

	value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm));
	tmp = (value & IPROC_PWM_PERIOD_MAX) * multi;
	state->duty_cycle = div64_u64(tmp, rate);

	return 0;
}

static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
			    const struct pwm_state *state)
{
	unsigned long prescale = IPROC_PWM_PRESCALE_MIN;
	struct iproc_pwmc *ip = to_iproc_pwmc(chip);
	u32 value, period, duty;
	u64 rate;

	rate = clk_get_rate(ip->clk);

	/*
	 * Find period count, duty count and prescale to suit duty_cycle and
	 * period. This is done according to formulas described below:

Annotation

Implementation Notes