Commit a331659e authored by Sam Protsenko's avatar Sam Protsenko Committed by Stephen Boyd
Browse files

clk: Add write operation for clk_parent debugfs node 



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_parents
      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: default avatarSam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: default avatarFabio Estevam <festevam@gmail.com>
Acked-by: default avatarMichael Turquette <mturquette@baylibre.com>
Link: https://lore.kernel.org/r/20211013172042.10884-1-semen.protsenko@linaro.org


[sboyd@kernel.org: Collapse ifdefs]
Signed-off-by: default avatarStephen Boyd <sboyd@kernel.org>
parent fa55b7dc

drivers/clk/clk.c

+41 −1
Original line number Diff line number Diff line
@@ -3217,6 +3217,42 @@ 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;

	u8 idx;

	int err;



	err = kstrtou8_from_user(ubuf, count, 0, &idx);

	if (err < 0)

		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;
@@ -3282,8 +3318,12 @@ static void clk_debug_create_one(struct clk_core *core, struct dentry *pdentry) 
#ifdef CLOCK_ALLOW_WRITE_DEBUGFS

	debugfs_create_file("clk_prepare_enable", 0644, root, core,

			    &clk_prepare_enable_fops);

#endif



	if (core->num_parents > 1)

		debugfs_create_file("clk_parent", 0644, root, core,

				    &current_parent_rw_fops);

	else

#endif

	if (core->num_parents > 0)

		debugfs_create_file("clk_parent", 0444, root, core,

				    &current_parent_fops);