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authorMagnus Damm <damm@opensource.se>2011-06-21 07:55:12 +0000
committerPaul Mundt <lethal@linux-sh.org>2011-06-24 16:27:07 +0900
commit794d78fea51504bad3880d14f354a9847f318f25 (patch)
tree8515152063b174deb5af666f2ade0c4b61fec04f /drivers
parentbccaeafd7c117acee36e90d37c7e05c19be9e7bf (diff)
downloadlinux-794d78fea51504bad3880d14f354a9847f318f25.tar.gz
drivers: sh: late disabling of clocks V2
This V2 patch changes the clock disabling behavior during boot. Two different changes are made: 1) Delay disabling of clocks until late in the boot process. This fixes an existing issue where in-use clocks without software reference are disabled by mistake during boot. One example of this is the handling of the Mackerel serial console output that shares clock with the I2C controller. 2) Write out the "disabled" state to the hardware for clocks that not have been used by the kernel. In other words, make sure so far unused clocks actually get turned off. Signed-off-by: Magnus Damm <damm@opensource.se> Acked-by: Simon Horman <horms@verge.net.au> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/sh/clk/core.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/drivers/sh/clk/core.c b/drivers/sh/clk/core.c
index 7e9c39951ec..ebeaa9e9f06 100644
--- a/drivers/sh/clk/core.c
+++ b/drivers/sh/clk/core.c
@@ -34,6 +34,9 @@ static LIST_HEAD(clock_list);
static DEFINE_SPINLOCK(clock_lock);
static DEFINE_MUTEX(clock_list_sem);
+/* clock disable operations are not passed on to hardware during boot */
+static int allow_disable;
+
void clk_rate_table_build(struct clk *clk,
struct cpufreq_frequency_table *freq_table,
int nr_freqs,
@@ -228,7 +231,7 @@ static void __clk_disable(struct clk *clk)
return;
if (!(--clk->usecount)) {
- if (likely(clk->ops && clk->ops->disable))
+ if (likely(allow_disable && clk->ops && clk->ops->disable))
clk->ops->disable(clk);
if (likely(clk->parent))
__clk_disable(clk->parent);
@@ -747,3 +750,25 @@ err_out:
return err;
}
late_initcall(clk_debugfs_init);
+
+static int __init clk_late_init(void)
+{
+ unsigned long flags;
+ struct clk *clk;
+
+ /* disable all clocks with zero use count */
+ mutex_lock(&clock_list_sem);
+ spin_lock_irqsave(&clock_lock, flags);
+
+ list_for_each_entry(clk, &clock_list, node)
+ if (!clk->usecount && clk->ops && clk->ops->disable)
+ clk->ops->disable(clk);
+
+ /* from now on allow clock disable operations */
+ allow_disable = 1;
+
+ spin_unlock_irqrestore(&clock_lock, flags);
+ mutex_unlock(&clock_list_sem);
+ return 0;
+}
+late_initcall(clk_late_init);