drivers/clk/at91/clk-plldiv.c

Source file repositories/reference/linux-study-clean/drivers/clk/at91/clk-plldiv.c

File Facts

System
Linux kernel
Corpus path
drivers/clk/at91/clk-plldiv.c
Extension
.c
Size
2376 bytes
Lines
116
Domain
Driver Families
Bucket
drivers/clk
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 clk_plldiv {
	struct clk_hw hw;
	struct regmap *regmap;
};

static unsigned long clk_plldiv_recalc_rate(struct clk_hw *hw,
					    unsigned long parent_rate)
{
	struct clk_plldiv *plldiv = to_clk_plldiv(hw);
	unsigned int mckr;

	regmap_read(plldiv->regmap, AT91_PMC_MCKR, &mckr);

	if (mckr & AT91_PMC_PLLADIV2)
		return parent_rate / 2;

	return parent_rate;
}

static int clk_plldiv_determine_rate(struct clk_hw *hw,
				     struct clk_rate_request *req)
{
	unsigned long div;

	if (req->rate > req->best_parent_rate) {
		req->rate = req->best_parent_rate;

		return 0;
	}

	div = req->best_parent_rate / 2;
	if (req->rate < div) {
		req->rate = div;

		return 0;
	}

	if (req->rate - div < req->best_parent_rate - req->rate) {
		req->rate = div;

		return 0;
	}

	req->rate = req->best_parent_rate;

	return 0;
}

static int clk_plldiv_set_rate(struct clk_hw *hw, unsigned long rate,
			       unsigned long parent_rate)
{
	struct clk_plldiv *plldiv = to_clk_plldiv(hw);

	if ((parent_rate != rate) && (parent_rate / 2 != rate))
		return -EINVAL;

	regmap_update_bits(plldiv->regmap, AT91_PMC_MCKR, AT91_PMC_PLLADIV2,
			   parent_rate != rate ? AT91_PMC_PLLADIV2 : 0);

	return 0;
}

static const struct clk_ops plldiv_ops = {
	.recalc_rate = clk_plldiv_recalc_rate,
	.determine_rate = clk_plldiv_determine_rate,
	.set_rate = clk_plldiv_set_rate,
};

struct clk_hw * __init
at91_clk_register_plldiv(struct regmap *regmap, const char *name,
			 const char *parent_name)
{
	struct clk_plldiv *plldiv;
	struct clk_hw *hw;
	struct clk_init_data init;
	int ret;

	plldiv = kzalloc_obj(*plldiv);
	if (!plldiv)
		return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &plldiv_ops;
	init.parent_names = parent_name ? &parent_name : NULL;
	init.num_parents = parent_name ? 1 : 0;
	init.flags = CLK_SET_RATE_GATE;

	plldiv->hw.init = &init;
	plldiv->regmap = regmap;

Annotation

Implementation Notes