From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Jason Cooper <jason@lakedaemon.net>, Andrew Lunn <andrew@lunn.ch>,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
Gregory Clement <gregory.clement@free-electrons.com>
Cc: linux-arm-kernel@lists.infradead.org,
Tawfik Bayouk <tawfik@marvell.com>,
Nadav Haklai <nadavh@marvell.com>,
Lior Amsalem <alior@marvell.com>,
Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
devicetree@vger.kernel.org,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
Mike Turquette <mturquette@linaro.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH 09/17] clk: mvebu: add suspend/resume for gatable clocks
Date: Fri, 24 Oct 2014 13:59:22 +0200 [thread overview]
Message-ID: <1414151970-6626-10-git-send-email-thomas.petazzoni@free-electrons.com> (raw)
In-Reply-To: <1414151970-6626-1-git-send-email-thomas.petazzoni@free-electrons.com>
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
---
drivers/clk/mvebu/common.c | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/mvebu/common.c b/drivers/clk/mvebu/common.c
index b7fcb46..8799fb8 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 +178,18 @@ struct clk_gating_ctrl {
spinlock_t *lock;
struct clk **gates;
int num_gates;
+ struct syscore_ops syscore_ops;
+ 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 +204,30 @@ 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);
+}
+
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 +245,10 @@ void __init mvebu_clk_gating_setup(struct device_node *np,
/* lock must already be initialized */
ctrl->lock = &ctrl_gating_lock;
+ ctrl->base = base;
+ ctrl->syscore_ops.suspend = mvebu_clk_gating_suspend;
+ ctrl->syscore_ops.resume = mvebu_clk_gating_resume;
+
/* Count, allocate, and register clock gates */
for (n = 0; desc[n].name;)
n++;
@@ -246,6 +270,8 @@ void __init mvebu_clk_gating_setup(struct device_node *np,
of_clk_add_provider(np, clk_gating_get_src, ctrl);
+ register_syscore_ops(&ctrl->syscore_ops);
+
return;
gates_out:
kfree(ctrl);
--
2.0.0
next prev parent reply other threads:[~2014-10-24 12:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1414151970-6626-1-git-send-email-thomas.petazzoni@free-electrons.com>
2014-10-24 11:59 ` [PATCH 03/17] irqchip: irq-armada-370-xp: use proper return value for ->set_affinity() Thomas Petazzoni
2014-11-03 17:20 ` Gregory CLEMENT
2014-11-07 4:09 ` Jason Cooper
2014-10-24 11:59 ` [PATCH 04/17] irqchip: irq-armada-370-xp: suspend/resume support Thomas Petazzoni
2014-11-03 17:38 ` Gregory CLEMENT
2014-11-13 16:32 ` Thomas Petazzoni
2014-10-24 11:59 ` [PATCH 05/17] clocksource: time-armada-370-xp: add " Thomas Petazzoni
2014-11-03 17:45 ` Gregory CLEMENT
2014-10-24 11:59 ` Thomas Petazzoni [this message]
2014-11-04 9:32 ` [PATCH 09/17] clk: mvebu: add suspend/resume for gatable clocks Gregory CLEMENT
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