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clk: Add support for enabling/disabling clocks from debugfs

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For test and debug purposes, it's simple enough to enable or disable
clocks from shell. Add a new debugfs file 'clk_prepare_enable' that
calls clk_prepare_enable() when writing "1" and clk_disable_unprepare()
when writing "0".

This can have security implications, so only support it when the code
has been modified to #define CLOCK_ALLOW_WRITE_DEBUGFS.

Signed-off-by: Mike Tipton <mdtipton@codeaurora.org>
Link: https://lore.kernel.org/r/20200630003024.6282-1-mdtipton@codeaurora.org
[sboyd@kernel.org: Reword commit text and remove comment update]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
This commit is contained in:
Mike Tipton 2020-06-29 17:30:24 -07:00 committed by Stephen Boyd
parent b3a9e3b962
commit 03111b1088
1 changed files with 29 additions and 0 deletions
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29
drivers/clk/clk.c
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@ -3039,6 +3039,31 @@ static int clk_rate_set(void *data, u64 val)
}
#define clk_rate_mode 0644
static int clk_prepare_enable_set(void *data, u64 val)
{
struct clk_core *core = data;
int ret = 0;
if (val)
ret = clk_prepare_enable(core->hw->clk);
else
clk_disable_unprepare(core->hw->clk);
return ret;
}
static int clk_prepare_enable_get(void *data, u64 *val)
{
struct clk_core *core = data;
*val = core->enable_count && core->prepare_count;
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(clk_prepare_enable_fops, clk_prepare_enable_get,
clk_prepare_enable_set, "%llu\n");
#else
#define clk_rate_set NULL
#define clk_rate_mode 0444
@ -3216,6 +3241,10 @@ static void clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
debugfs_create_u32("clk_notifier_count", 0444, root, &core->notifier_count);
debugfs_create_file("clk_duty_cycle", 0444, root, core,
&clk_duty_cycle_fops);
#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
debugfs_create_file("clk_prepare_enable", 0644, root, core,
&clk_prepare_enable_fops);
#endif
if (core->num_parents > 0)
debugfs_create_file("clk_parent", 0444, root, core,