Messages in this thread | | | From | Andy Shevchenko <> | Date | Thu, 7 Oct 2021 17:39:18 +0300 | Subject | Re: [PATCH v4] clk: Add write operation for clk_parent debugfs node |
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On Thu, Oct 7, 2021 at 5:09 PM Sam Protsenko <semen.protsenko@linaro.org> 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
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