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Commit f5710531 authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Jason Cooper
Browse files

clk: mvebu: add suspend/resume for gatable clocks 



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: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-kernel@vger.kernel.org
Acked-by: default avatarGregory 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: default avatarJason Cooper <jason@lakedaemon.net>
parent 4749c02b

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);