drivers/pwm/pwm-mtk-disp.c

Source file repositories/reference/linux-study-clean/drivers/pwm/pwm-mtk-disp.c

File Facts

System
Linux kernel
Corpus path
drivers/pwm/pwm-mtk-disp.c
Extension
.c
Size
8532 bytes
Lines
318
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 mtk_pwm_data {
	u32 enable_mask;
	unsigned int con0;
	u32 con0_sel;
	unsigned int con1;

	bool has_commit;
	unsigned int commit;
	unsigned int commit_mask;

	unsigned int bls_debug;
	u32 bls_debug_mask;
};

struct mtk_disp_pwm {
	const struct mtk_pwm_data *data;
	struct clk *clk_main;
	struct clk *clk_mm;
	void __iomem *base;
	bool enabled;
};

static inline struct mtk_disp_pwm *to_mtk_disp_pwm(struct pwm_chip *chip)
{
	return pwmchip_get_drvdata(chip);
}

static void mtk_disp_pwm_update_bits(struct mtk_disp_pwm *mdp, u32 offset,
				     u32 mask, u32 data)
{
	void __iomem *address = mdp->base + offset;
	u32 value;

	value = readl(address);
	value &= ~mask;
	value |= data;
	writel(value, address);
}

static int mtk_disp_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
			      const struct pwm_state *state)
{
	struct mtk_disp_pwm *mdp = to_mtk_disp_pwm(chip);
	u32 clk_div, period, high_width, value;
	u64 div, rate;
	int err;

	if (state->polarity != PWM_POLARITY_NORMAL)
		return -EINVAL;

	if (!state->enabled && mdp->enabled) {
		mtk_disp_pwm_update_bits(mdp, DISP_PWM_EN,
					 mdp->data->enable_mask, 0x0);
		clk_disable_unprepare(mdp->clk_mm);
		clk_disable_unprepare(mdp->clk_main);

		mdp->enabled = false;
		return 0;
	}

	if (!mdp->enabled) {
		err = clk_prepare_enable(mdp->clk_main);
		if (err < 0) {
			dev_err(pwmchip_parent(chip), "Can't enable mdp->clk_main: %pe\n",
				ERR_PTR(err));
			return err;
		}

		err = clk_prepare_enable(mdp->clk_mm);
		if (err < 0) {
			dev_err(pwmchip_parent(chip), "Can't enable mdp->clk_mm: %pe\n",
				ERR_PTR(err));
			clk_disable_unprepare(mdp->clk_main);
			return err;
		}
	}

	/*
	 * Find period, high_width and clk_div to suit duty_ns and period_ns.
	 * Calculate proper div value to keep period value in the bound.
	 *
	 * period_ns = 10^9 * (clk_div + 1) * (period + 1) / PWM_CLK_RATE
	 * duty_ns = 10^9 * (clk_div + 1) * high_width / PWM_CLK_RATE
	 *
	 * period = (PWM_CLK_RATE * period_ns) / (10^9 * (clk_div + 1)) - 1
	 * high_width = (PWM_CLK_RATE * duty_ns) / (10^9 * (clk_div + 1))
	 */
	rate = clk_get_rate(mdp->clk_main);
	clk_div = mul_u64_u64_div_u64(state->period, rate, NSEC_PER_SEC) >>
			  PWM_PERIOD_BIT_WIDTH;

Annotation

Implementation Notes