drivers/clk/imx/clk-cpu.c

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

File Facts

System
Linux kernel
Corpus path
drivers/clk/imx/clk-cpu.c
Extension
.c
Size
2210 bytes
Lines
111
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

struct clk_cpu {
	struct clk_hw	hw;
	struct clk	*div;
	struct clk	*mux;
	struct clk	*pll;
	struct clk	*step;
};

static inline struct clk_cpu *to_clk_cpu(struct clk_hw *hw)
{
	return container_of(hw, struct clk_cpu, hw);
}

static unsigned long clk_cpu_recalc_rate(struct clk_hw *hw,
					 unsigned long parent_rate)
{
	struct clk_cpu *cpu = to_clk_cpu(hw);

	return clk_get_rate(cpu->div);
}

static int clk_cpu_determine_rate(struct clk_hw *hw,
				  struct clk_rate_request *req)
{
	struct clk_cpu *cpu = to_clk_cpu(hw);

	req->rate = clk_round_rate(cpu->pll, req->rate);

	return 0;
}

static int clk_cpu_set_rate(struct clk_hw *hw, unsigned long rate,
			    unsigned long parent_rate)
{
	struct clk_cpu *cpu = to_clk_cpu(hw);
	int ret;

	/* switch to PLL bypass clock */
	ret = clk_set_parent(cpu->mux, cpu->step);
	if (ret)
		return ret;

	/* reprogram PLL */
	ret = clk_set_rate(cpu->pll, rate);
	if (ret) {
		clk_set_parent(cpu->mux, cpu->pll);
		return ret;
	}
	/* switch back to PLL clock */
	clk_set_parent(cpu->mux, cpu->pll);

	/* Ensure the divider is what we expect */
	clk_set_rate(cpu->div, rate);

	return 0;
}

static const struct clk_ops clk_cpu_ops = {
	.recalc_rate	= clk_cpu_recalc_rate,
	.determine_rate = clk_cpu_determine_rate,
	.set_rate	= clk_cpu_set_rate,
};

struct clk_hw *imx_clk_hw_cpu(const char *name, const char *parent_name,
		struct clk *div, struct clk *mux, struct clk *pll,
		struct clk *step)
{
	struct clk_cpu *cpu;
	struct clk_hw *hw;
	struct clk_init_data init;
	int ret;

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

	cpu->div = div;
	cpu->mux = mux;
	cpu->pll = pll;
	cpu->step = step;

	init.name = name;
	init.ops = &clk_cpu_ops;
	init.flags = CLK_IS_CRITICAL;
	init.parent_names = &parent_name;
	init.num_parents = 1;

	cpu->hw.init = &init;
	hw = &cpu->hw;

Annotation

Implementation Notes