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Subject[PATCH 1/5] ARC: set and print cpu frequency at boot time
Date
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@synopsys.com>
---
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
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