Messages in this thread Patch in this message | | | From | Sam Protsenko <> | Subject | [PATCH v5] clk: Add write operation for clk_parent debugfs node | Date | Thu, 7 Oct 2021 21:21:58 +0300 |
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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: Sam Protsenko <semen.protsenko@linaro.org> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> --- Changes in v5: - Used kstrtou8_from_user() API - Got rid of code duplication - Fixed typo in commit message - Added R-b tag by Andy Shevchenko
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 | 50 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 47 insertions(+), 3 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 806c55f0991b..6154d5bc2b45 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -3224,6 +3224,42 @@ 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; @@ -3291,9 +3327,17 @@ static void clk_debug_create_one(struct clk_core *core, struct dentry *pdentry) &clk_prepare_enable_fops); #endif - if (core->num_parents > 0) - debugfs_create_file("clk_parent", 0444, root, core, - ¤t_parent_fops); +#ifdef CLOCK_ALLOW_WRITE_DEBUGFS + if (core->num_parents > 1) + debugfs_create_file("clk_parent", 0644, root, core, + ¤t_parent_rw_fops); + else +#endif + { + if (core->num_parents > 0) + debugfs_create_file("clk_parent", 0444, root, core, + ¤t_parent_fops); + } if (core->num_parents > 1) debugfs_create_file("clk_possible_parents", 0444, root, core, -- 2.30.2
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