Print cpu frequency at boot time. In case we have pre-defined cpu frequency value in device tree try to set it. Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx> --- arch/arc/kernel/setup.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c index 877cec8..b5fcc5d 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -464,12 +464,61 @@ void __init setup_arch(char **cmdline_p) arc_unwind_init(); } +static int __init set_cpu_freq(int cpu_id) +{ + struct device_node *cpunode; + u32 cpu_freq_required; + struct clk *clk; + int ret; + + cpunode = of_get_cpu_node(cpu_id, NULL); + if (cpunode == NULL) { + pr_err("Can't find CPU %d node.\n", cpu_id); + return -ENOENT; + } + + clk = of_clk_get(cpunode, 0); + if (IS_ERR(clk)) { + pr_err("CPU %d missing clk.\n", cpu_id); + return PTR_ERR(clk); + } + + ret = clk_prepare_enable(clk); + if (ret) { + pr_err("Couldn't enable CPU %d clk.\n", cpu_id); + return ret; + } + + /* + * In case we have pre-defined cpu frequency value in device tree + * try to set it. Otherwise just print current cpu frequency. + */ + if (of_property_read_u32(cpunode, "cpu-freq", &cpu_freq_required)) { + pr_info("CPU %d has no cpu-freq param. Frequency is %lu Hz.\n", + cpu_id, clk_get_rate(clk)); + return 0; + } + + if (clk_set_rate(clk, cpu_freq_required)) + pr_err("CPU %d frequency set failed. Probably fixed-clock is used for cpu.\n", + cpu_id); + + pr_info("CPU %d frequency is %lu Hz.\n", cpu_id, clk_get_rate(clk)); + + return 0; +} + /* * Called from start_kernel() - boot CPU only */ void __init time_init(void) { of_clk_init(NULL); + /* + * As for now we have common clock for all cpu cores, so set + * frequency only for master cpu. + */ + set_cpu_freq(0); timer_probe(); } -- 2.9.3 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html