drivers/clk/clk-multiplier.c

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

File Facts

System
Linux kernel
Corpus path
drivers/clk/clk-multiplier.c
Extension
.c
Size
3965 bytes
Lines
159
Domain
Driver Families
Bucket
drivers/clk
Inferred role
Driver Families: exported/initcall integration point
Status
integration 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

if (rate == orig_parent_rate * i) {
			/*
			 * This is the best case for us if we have a
			 * perfect match without changing the parent
			 * rate.
			 */
			*best_parent_rate = orig_parent_rate;
			return i;
		}

		parent_rate = clk_hw_round_rate(clk_hw_get_parent(hw),
						rate / i);
		current_rate = parent_rate * i;

		if (__is_best_rate(rate, current_rate, best_rate, flags)) {
			bestmult = i;
			best_rate = current_rate;
			*best_parent_rate = parent_rate;
		}
	}

	return bestmult;
}

static int clk_multiplier_determine_rate(struct clk_hw *hw,
					 struct clk_rate_request *req)
{
	struct clk_multiplier *mult = to_clk_multiplier(hw);
	unsigned long factor = __bestmult(hw, req->rate, &req->best_parent_rate,
					  mult->width, mult->flags);

	req->rate = req->best_parent_rate * factor;

	return 0;
}

static int clk_multiplier_set_rate(struct clk_hw *hw, unsigned long rate,
			       unsigned long parent_rate)
{
	struct clk_multiplier *mult = to_clk_multiplier(hw);
	unsigned long factor = __get_mult(mult, rate, parent_rate);
	unsigned long flags = 0;
	unsigned long val;

	if (mult->lock)
		spin_lock_irqsave(mult->lock, flags);
	else
		__acquire(mult->lock);

	val = clk_mult_readl(mult);
	val &= ~GENMASK(mult->width + mult->shift - 1, mult->shift);
	val |= factor << mult->shift;
	clk_mult_writel(mult, val);

	if (mult->lock)
		spin_unlock_irqrestore(mult->lock, flags);
	else
		__release(mult->lock);

	return 0;
}

const struct clk_ops clk_multiplier_ops = {
	.recalc_rate	= clk_multiplier_recalc_rate,
	.determine_rate = clk_multiplier_determine_rate,
	.set_rate	= clk_multiplier_set_rate,
};
EXPORT_SYMBOL_GPL(clk_multiplier_ops);

Annotation

Implementation Notes