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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: 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>
This commit is contained in:
Thomas Petazzoni 2014-11-21 17:00:05 +01:00 committed by Jason Cooper
parent 4749c02b8d
commit f571053152
1 changed files with 30 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/clk/mvebu/common.c
View File

@ -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);