Useful for testing mux clocks. One can write the index of the parent to
be set into clk_parent node, starting from 0. Example
# cd /sys/kernel/debug/clk/mout_peri_bus
# cat clk_possible_parrents
dout_shared0_div4 dout_shared1_div4
# cat clk_parent
dout_shared0_div4
# echo 1 > clk_parent
# cat clk_parent
dout_shared1_div4
CLOCK_ALLOW_WRITE_DEBUGFS has to be defined in drivers/clk/clk.c in
order to use this feature.
Signed-off-by: Sam Protsenko <[email protected]>
---
Changes in v4:
- Fixed the commit title
Changes in v3:
- Removed unwanted changes added by mistake
Changes in v2:
- Merged write() function into existing 'clk_parent' file
- Removed 'if (val >= core->num_parents)' check
- Removed incorrect usage of IS_ERR_OR_NULL()
drivers/clk/clk.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 52 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 806c55f0991b..f57e33efda9b 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3224,6 +3224,46 @@ static int current_parent_show(struct seq_file *s, void *data)
}
DEFINE_SHOW_ATTRIBUTE(current_parent);
+#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
+static ssize_t current_parent_write(struct file *file, const char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ struct seq_file *s = file->private_data;
+ struct clk_core *core = s->private;
+ struct clk_core *parent;
+ char buf[4] = { 0 };
+ u8 idx;
+ int err;
+
+ if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+ return -EFAULT;
+
+ err = kstrtou8(buf, 0, &idx);
+ if (err)
+ return err;
+
+ parent = clk_core_get_parent_by_index(core, idx);
+ if (!parent)
+ return -ENOENT;
+
+ clk_prepare_lock();
+ err = clk_core_set_parent_nolock(core, parent);
+ clk_prepare_unlock();
+ if (err)
+ return err;
+
+ return count;
+}
+
+static const struct file_operations current_parent_rw_fops = {
+ .open = current_parent_open,
+ .write = current_parent_write,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+#endif
+
static int clk_duty_cycle_show(struct seq_file *s, void *data)
{
struct clk_core *core = s->private;
@@ -3291,9 +3331,20 @@ static void clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
&clk_prepare_enable_fops);
#endif
- if (core->num_parents > 0)
+ if (core->num_parents > 0) {
+#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
+ if (core->num_parents > 1) {
+ debugfs_create_file("clk_parent", 0644, root, core,
+ ¤t_parent_rw_fops);
+ } else {
+ debugfs_create_file("clk_parent", 0444, root, core,
+ ¤t_parent_fops);
+ }
+#else
debugfs_create_file("clk_parent", 0444, root, core,
¤t_parent_fops);
+#endif
+ }
if (core->num_parents > 1)
debugfs_create_file("clk_possible_parents", 0444, root, core,
--
2.30.2
On Thu, Oct 07, 2021 at 08:45:11PM +0300, Sam Protsenko wrote:
> On Thu, 7 Oct 2021 at 17:39, Andy Shevchenko <[email protected]> wrote:
...
> Thanks for the review!
After addressing, feel free to add:
Reviewed-by: Andy Shevchenko <[email protected]>
--
With Best Regards,
Andy Shevchenko
On Thu, Oct 7, 2021 at 5:09 PM Sam Protsenko <[email protected]> wrote:
>
> Useful for testing mux clocks. One can write the index of the parent to
> be set into clk_parent node, starting from 0. Example
>
> # cd /sys/kernel/debug/clk/mout_peri_bus
> # cat clk_possible_parrents
> dout_shared0_div4 dout_shared1_div4
> # cat clk_parent
> dout_shared0_div4
> # echo 1 > clk_parent
> # cat clk_parent
> dout_shared1_div4
>
> CLOCK_ALLOW_WRITE_DEBUGFS has to be defined in drivers/clk/clk.c in
> order to use this feature.
...
> +static ssize_t current_parent_write(struct file *file, const char __user *ubuf,
> + size_t count, loff_t *ppos)
> +{
> + struct seq_file *s = file->private_data;
> + struct clk_core *core = s->private;
> + struct clk_core *parent;
> + char buf[4] = { 0 };
We may use {} (in a more standardized way), but see below.
> + u8 idx;
> + int err;
> + if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
> + return -EFAULT;
> +
> + err = kstrtou8(buf, 0, &idx);
> + if (err)
> + return err;
NIH kstrotu8_from_user().
> + parent = clk_core_get_parent_by_index(core, idx);
> + if (!parent)
> + return -ENOENT;
> +
> + clk_prepare_lock();
> + err = clk_core_set_parent_nolock(core, parent);
> + clk_prepare_unlock();
> + if (err)
> + return err;
> +
> + return count;
> +}
...
> +#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
> + if (core->num_parents > 1) {
> + debugfs_create_file("clk_parent", 0644, root, core,
> + ¤t_parent_rw_fops);
> + } else {
> + debugfs_create_file("clk_parent", 0444, root, core,
> + ¤t_parent_fops);
> + }
> +#else
> debugfs_create_file("clk_parent", 0444, root, core,
> ¤t_parent_fops);
Dup. You can avoid it.
> +#endif
> + }
--
With Best Regards,
Andy Shevchenko
On Thu, 7 Oct 2021 at 17:39, Andy Shevchenko <[email protected]> wrote:
>
> On Thu, Oct 7, 2021 at 5:09 PM Sam Protsenko <[email protected]> wrote:
> >
> > Useful for testing mux clocks. One can write the index of the parent to
> > be set into clk_parent node, starting from 0. Example
> >
> > # cd /sys/kernel/debug/clk/mout_peri_bus
> > # cat clk_possible_parrents
> > dout_shared0_div4 dout_shared1_div4
> > # cat clk_parent
> > dout_shared0_div4
> > # echo 1 > clk_parent
> > # cat clk_parent
> > dout_shared1_div4
> >
> > CLOCK_ALLOW_WRITE_DEBUGFS has to be defined in drivers/clk/clk.c in
> > order to use this feature.
>
> ...
>
> > +static ssize_t current_parent_write(struct file *file, const char __user *ubuf,
> > + size_t count, loff_t *ppos)
> > +{
> > + struct seq_file *s = file->private_data;
> > + struct clk_core *core = s->private;
> > + struct clk_core *parent;
>
> > + char buf[4] = { 0 };
>
> We may use {} (in a more standardized way), but see below.
>
> > + u8 idx;
> > + int err;
>
> > + if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
> > + return -EFAULT;
> > +
> > + err = kstrtou8(buf, 0, &idx);
> > + if (err)
> > + return err;
>
> NIH kstrotu8_from_user().
>
Cool, didn't know about that API existence. Will fix in v5.
> > + parent = clk_core_get_parent_by_index(core, idx);
> > + if (!parent)
> > + return -ENOENT;
> > +
> > + clk_prepare_lock();
> > + err = clk_core_set_parent_nolock(core, parent);
> > + clk_prepare_unlock();
> > + if (err)
> > + return err;
> > +
> > + return count;
> > +}
>
> ...
>
> > +#ifdef CLOCK_ALLOW_WRITE_DEBUGFS
> > + if (core->num_parents > 1) {
> > + debugfs_create_file("clk_parent", 0644, root, core,
> > + ¤t_parent_rw_fops);
>
> > + } else {
> > + debugfs_create_file("clk_parent", 0444, root, core,
> > + ¤t_parent_fops);
> > + }
> > +#else
> > debugfs_create_file("clk_parent", 0444, root, core,
> > ¤t_parent_fops);
>
> Dup. You can avoid it.
>
You're right, will be fixed in v5.
Thanks for the review!
> > +#endif
> > + }
>
> --
> With Best Regards,
> Andy Shevchenko