clk: mvebu: add suspend/resume for gatable clocks (f5710531) · Commits · 戴 / test

This commit adds suspend/resume support for the gatable clock driver used on Marvell EBU platforms. When getting out of suspend, the Marvell EBU platforms go through the bootloader, which re-enables all gatable clocks. However, upon resume, the clock framework will not disable again all gatable clocks that are not used. Therefore, if the clock driver does not save/restore the state of the gatable clocks, all gatable clocks that are not claimed by any device driver will remain enabled after a resume. This is why this driver saves and restores the state of those clocks. Since clocks aren't real devices, we don't have the normal ->suspend() and ->resume() of the device model, and have to use the ->suspend() and ->resume() hooks of the syscore_ops mechanism. This mechanism has the unfortunate idea of not providing a way of passing private data, which requires us to change the driver to make the assumption that there is only once instance of the gatable clock control structure. Signed-off-by:

Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: Mike Turquette <mturquette@linaro.org> Cc: linux-kernel@vger.kernel.org Acked-by:

Gregory CLEMENT <gregory.clement@free-electrons.com> Link: https://lkml.kernel.org/r/1416585613-2113-9-git-send-email-thomas.petazzoni@free-electrons.com Signed-off-by:

Jason Cooper <jason@lakedaemon.net>

drivers/clk/mvebu/common.c

+30 −2

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@
		#include <linux/io.h>
		#include <linux/of.h>
		#include <linux/of_address.h>
		#include <linux/syscore_ops.h>

		#include "common.h"

		@@ -177,14 +178,17 @@ struct clk_gating_ctrl {
		spinlock_t *lock;
		struct clk **gates;
		int num_gates;
		void __iomem *base;
		u32 saved_reg;
		};

		#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)

		static struct clk_gating_ctrl *ctrl;

		static struct clk *clk_gating_get_src(
		struct of_phandle_args clkspec, void data)
		{
		struct clk_gating_ctrl ctrl = (struct clk_gating_ctrl )data;
		int n;

		if (clkspec->args_count < 1)
		@@ -199,15 +203,35 @@ static struct clk *clk_gating_get_src(
		return ERR_PTR(-ENODEV);
		}

		static int mvebu_clk_gating_suspend(void)
		{
		ctrl->saved_reg = readl(ctrl->base);
		return 0;
		}

		static void mvebu_clk_gating_resume(void)
		{
		writel(ctrl->saved_reg, ctrl->base);
		}

		static struct syscore_ops clk_gate_syscore_ops = {
		.suspend = mvebu_clk_gating_suspend,
		.resume = mvebu_clk_gating_resume,
		};

		void __init mvebu_clk_gating_setup(struct device_node *np,
		const struct clk_gating_soc_desc *desc)
		{
		struct clk_gating_ctrl *ctrl;
		struct clk *clk;
		void __iomem *base;
		const char *default_parent = NULL;
		int n;

		if (ctrl) {
		pr_err("mvebu-clk-gating: cannot instantiate more than one gatable clock device\n");
		return;
		}

		base = of_iomap(np, 0);
		if (WARN_ON(!base))
		return;
		@@ -225,6 +249,8 @@ void __init mvebu_clk_gating_setup(struct device_node *np,
		/* lock must already be initialized */
		ctrl->lock = &ctrl_gating_lock;

		ctrl->base = base;

		/* Count, allocate, and register clock gates */
		for (n = 0; desc[n].name;)
		n++;
		@@ -246,6 +272,8 @@ void __init mvebu_clk_gating_setup(struct device_node *np,

		of_clk_add_provider(np, clk_gating_get_src, ctrl);

		register_syscore_ops(&clk_gate_syscore_ops);

		return;
		gates_out:
		kfree(ctrl);

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