On 02/22/2017 02:36 AM, Vlad Zakharov wrote:
> We were reading clock rate directly from device tree "clock-frequency"
> property of corresponding clock node in show_cpuinfo function.
>
> Such approach is correct only in case cpu is always clocked by
> "fixed-clock". If we use clock driver that allows rate to be changed
> this won't work as rate may change during the time or even
> "clock-frequency" property may not be presented at all.
>
> So this commit replaces reading device tree with getting rate from clock
> driver. This approach is much more flexible and will work for both fixed
> and mutable clocks.
So except the clk_put() comment - this looks much better to me.
And while we are at it - one of my wish list has been to print the core clk in
early boot - i.e. in setup_processor()->arc_cpu_mumbojumbo() call path which is
different from the other case u fixed. Any ideas how to do that - clk framework
will not have init by then - so we need to read out from FDT or some such !
>
> Signed-off-by: Vlad Zakharov <vzakhar at synopsys.com>
> ---
> arch/arc/kernel/setup.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
> index 3093fa8..49b0804 100644
> --- a/arch/arc/kernel/setup.c
> +++ b/arch/arc/kernel/setup.c
> @@ -10,6 +10,7 @@
> #include <linux/fs.h>
> #include <linux/delay.h>
> #include <linux/root_dev.h>
> +#include <linux/clk.h>
> #include <linux/clk-provider.h>
> #include <linux/clocksource.h>
> #include <linux/console.h>
> @@ -488,7 +489,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
> {
> char *str;
> int cpu_id = ptr_to_cpu(v);
> - struct device_node *core_clk = of_find_node_by_name(NULL, "core_clk");
> + struct device *cpu_dev = get_cpu_device(cpu_id);
> + struct clk *cpu_clk = clk_get(cpu_dev, "core_clk");
> u32 freq = 0;
>
> if (!cpu_online(cpu_id)) {
> @@ -502,7 +504,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
>
> seq_printf(m, arc_cpu_mumbojumbo(cpu_id, str, PAGE_SIZE));
>
> - of_property_read_u32(core_clk, "clock-frequency", &freq);
> + freq = clk_get_rate(cpu_clk);
> if (freq)
> seq_printf(m, "CPU speed\t: %u.%02u Mhz\n",
> freq / 1000000, (freq / 10000) % 100);
>
