For test and debug purposes, it's often necessary 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_DEBUGS.
Signed-off-by: Mike Tipton <[email protected]>
---
drivers/clk/clk.c | 38 ++++++++++++++++++++++++++++++++++----
1 file changed, 34 insertions(+), 4 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 236923b25543..3640bbc56870 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3034,13 +3034,14 @@ static int clk_dump_show(struct seq_file *s, void *data)
}
DEFINE_SHOW_ATTRIBUTE(clk_dump);
-#undef CLOCK_ALLOW_WRITE_DEBUGFS
-#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
/*
- * This can be dangerous, therefore don't provide any real compile time
- * configuration option for this feature.
+ * These features can be dangerous, therefore don't provide any real compile
+ * time configuration option for them.
* People who want to use this will need to modify the source code directly.
*/
+#undef CLOCK_ALLOW_WRITE_DEBUGFS
+#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
+
static int clk_rate_set(void *data, u64 val)
{
struct clk_core *core = data;
@@ -3054,6 +3055,31 @@ 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
@@ -3231,6 +3257,10 @@ 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,
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
On 6/29/2020 5:30 PM, Mike Tipton wrote:
> For test and debug purposes, it's often necessary 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_DEBUGS.
>
> Signed-off-by: Mike Tipton <[email protected]>
> ---
> drivers/clk/clk.c | 38 ++++++++++++++++++++++++++++++++++----
> 1 file changed, 34 insertions(+), 4 deletions(-)
>
Friendly reminder.
Thanks,
Mike
Quoting Mike Tipton (2020-06-29 17:30:24)
> For test and debug purposes, it's often necessary 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_DEBUGS.
DEBUGFS
>
> Signed-off-by: Mike Tipton <[email protected]>
> ---
> drivers/clk/clk.c | 38 ++++++++++++++++++++++++++++++++++----
> 1 file changed, 34 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 236923b25543..3640bbc56870 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3034,13 +3034,14 @@ static int clk_dump_show(struct seq_file *s, void *data)
> }
> DEFINE_SHOW_ATTRIBUTE(clk_dump);
>
> -#undef CLOCK_ALLOW_WRITE_DEBUGFS
> -#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
This didn't need to change.
> /*
> - * This can be dangerous, therefore don't provide any real compile time
> - * configuration option for this feature.
> + * These features can be dangerous, therefore don't provide any real compile
> + * time configuration option for them.
> * People who want to use this will need to modify the source code directly.
> */
> +#undef CLOCK_ALLOW_WRITE_DEBUGFS
> +#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
So I put it back and dropped your rewording.
> +
> static int clk_rate_set(void *data, u64 val)
> {
> struct clk_core *core = data;
> @@ -3054,6 +3055,31 @@ 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
> @@ -3231,6 +3257,10 @@ 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
This is ugly but I guess we can't do much.
> + debugfs_create_file("clk_prepare_enable", 0644, root, core,
> + &clk_prepare_enable_fops);
> +#endif
>
Applied to clk-next.