Re: [PATCH 2/6] Clocklib: debugfs support

Andrew Morton
2008-04-07T22:59:42Z

On Thu, 3 Apr 2008 17:23:37 +0400
Dmitry Baryshkov <dbaryshkov@gmail.com> wrote:

> Provide /sys/kernel/debug/clock to ease debugging.
>

Plese fully document the proposed kernel->userspace interface in the
changelog so that we can review it design.

> diff --git a/include/linux/clklib.h b/include/linux/clklib.h
> index 3d0ffaf..77514cc 100644
> --- a/include/linux/clklib.h
> +++ b/include/linux/clklib.h
> @@ -19,6 +19,7 @@ struct seq_file;
> * @get_rate: obtain the current clock rate of a specified clock
> * @set_rate: set the clock rate for a specified clock
> * @round_rate: adjust a reate to the exact rate a clock can provide
> + * @format: output any additional information for a clock
> *
> * This structure specifies clock operations that are used to configure
> * specific clock.
> @@ -30,6 +31,7 @@ struct clk_ops {
> unsigned long (*get_rate) (struct clk *clk);
> int (*set_rate) (struct clk *, unsigned long);
> long (*round_rate) (struct clk *, unsigned long);
> + int (*format) (struct clk *, struct seq_file *);

It's conventional to leave no space between the ) and the ( here. Using a
tab is quite unconventional.

> };
>
> /**
> diff --git a/kernel/clklib.c b/kernel/clklib.c
> index 012f845..8d872e1 100644
> --- a/kernel/clklib.c
> +++ b/kernel/clklib.c
> @@ -324,3 +324,77 @@ out:
> return rc;
> }
> EXPORT_SYMBOL(clk_alloc_function);
> +
> +#ifdef CONFIG_DEBUG_FS
> +
> +#include <linux/debugfs.h>
> +#include <linux/seq_file.h>
> +
> +#define NAME_FIELD_LEN 20
> +
> +static void dump_clocks(struct seq_file *s, struct clk *parent, int nest)
> +{
> + struct clk *clk;
> + int i;
> +
> + list_for_each_entry(clk, &clocks, node) {
> + if (clk->parent == parent) {
> + for (i = 0; i < nest; i++) {
> + seq_putc(s, ' ');
> + seq_putc(s, ' ');
> + }
> + seq_puts(s, clk->name);
> +
> + i = 2 * nest + strlen(clk->name);
> + if (i >= NAME_FIELD_LEN)
> + i = NAME_FIELD_LEN - 1;
> + for (; i < NAME_FIELD_LEN; i++) {
> + seq_putc(s, ' ');
> + }
> + seq_printf(s, "%c use=%d rate=%10lu Hz",
> + clk->ops && clk->ops->set_parent ? '*' : ' ',
> + clk->users,
> + __clk_get_rate(clk));
> + if (clk->ops && clk->ops->format)
> + clk->ops->format(clk, s);
> + seq_putc(s, '\n');
> +
> + dump_clocks(s, clk, nest + 1);
> + }
> + }
> +}

hm, this would break the one-value-per-file rule, except that applies to
sysfs, but this interface is implemented via debug fs, but it is proposed
that it appear under /sys. Tricky.