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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2014-11-21 19:00:05 +0300
committerJason Cooper <jason@lakedaemon.net>2014-11-30 19:40:12 +0300
commitf571053152f660769f9f39f150ac984bc4c6ac85 (patch)
treeeb85fc93b3d6fe931c35683524f42a5b07dc46ce /drivers/clk/mvebu/common.c
parent4749c02b8da6d8dbc29218652985bda844017e95 (diff)
downloadlinux-f571053152f660769f9f39f150ac984bc4c6ac85.tar.xz
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>
Diffstat (limited to 'drivers/clk/mvebu/common.c')
-rw-r--r--drivers/clk/mvebu/common.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/drivers/clk/mvebu/common.c b/drivers/clk/mvebu/common.c
index b7fcb469c87a..0d4d1216f2dd 100644
--- a/drivers/clk/mvebu/common.c
+++ b/drivers/clk/mvebu/common.c
@@ -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);