[PATCH 0/3] ARC: get frequency via clock driver instead of reading device tree

[PATCH 0/3] ARC: get frequency via clock driver instead of reading device tree

[Vlad Zakharov]

This patch series replaces reading device tree with getting CPU
clock frequency via clock driver in show_cpuinfo function.

In order to achieve this we also add cpu nodes to device tree which
describes SMP system and add "clocks" properties to all ARC cpu nodes. 

Vlad Zakharov (3):
  ARC: [dts] add input clocks for cpu nodes
  ARC: [dts] add cpu nodes to ARCHS SMP device tree
  arc: get rate from clk driver instead of reading device tree

 arch/arc/boot/dts/skeleton.dtsi        |  1 +
 arch/arc/boot/dts/skeleton_hs.dtsi     |  1 +
 arch/arc/boot/dts/skeleton_hs_idu.dtsi | 21 ++++++++++++++++++++-
 arch/arc/kernel/setup.c                | 17 +++++++++++++----
 4 files changed, 35 insertions(+), 5 deletions(-)

-- 
2.7.4

[PATCH 1/3] ARC: [dts] add input clocks for cpu nodes

[Vlad Zakharov]

ARC CPU cores are driven by core_clk so we add corresponding "clocks"
property to ARC cpu nodes.

Signed-off-by: Vlad Zakharov <vzakhar@synopsys.com>
---
 arch/arc/boot/dts/skeleton.dtsi        | 1 +
 arch/arc/boot/dts/skeleton_hs.dtsi     | 1 +
 arch/arc/boot/dts/skeleton_hs_idu.dtsi | 1 +
 3 files changed, 3 insertions(+)

diff --git a/arch/arc/boot/dts/skeleton.dtsi b/arch/arc/boot/dts/skeleton.dtsi
index 65808fe..2891cb2 100644
--- a/arch/arc/boot/dts/skeleton.dtsi
+++ b/arch/arc/boot/dts/skeleton.dtsi
@@ -26,6 +26,7 @@
 			device_type = "cpu";
 			compatible = "snps,arc770d";
 			reg = <0>;
+			clocks = <&core_clk>;
 		};
 	};
 
diff --git a/arch/arc/boot/dts/skeleton_hs.dtsi b/arch/arc/boot/dts/skeleton_hs.dtsi
index 2dfe803..5e944d3 100644
--- a/arch/arc/boot/dts/skeleton_hs.dtsi
+++ b/arch/arc/boot/dts/skeleton_hs.dtsi
@@ -21,6 +21,7 @@
 			device_type = "cpu";
 			compatible = "snps,archs38";
 			reg = <0>;
+			clocks = <&core_clk>;
 		};
 	};
 
diff --git a/arch/arc/boot/dts/skeleton_hs_idu.dtsi b/arch/arc/boot/dts/skeleton_hs_idu.dtsi
index 4c11079..662c5e0 100644
--- a/arch/arc/boot/dts/skeleton_hs_idu.dtsi
+++ b/arch/arc/boot/dts/skeleton_hs_idu.dtsi
@@ -21,6 +21,7 @@
 			device_type = "cpu";
 			compatible = "snps,archs38xN";
 			reg = <0>;
+			clocks = <&core_clk>;
 		};
 	};
 
-- 
2.7.4

[PATCH 2/3] ARC: [dts] add cpu nodes to ARCHS SMP device tree

[Vlad Zakharov]

Trying to get clock for CPU cores on SMP systems I found that I was only
able to get clock for core[0]. That was because only one cpu@0 node was
represented in ARC HS device tree and it was impossible to get clock for
"non-existing" cores.

So as ARC HS may have up to 4 cores we update device tree to match
maximum possible cores quantity.

Signed-off-by: Vlad Zakharov <vzakhar@synopsys.com>
---
 arch/arc/boot/dts/skeleton_hs_idu.dtsi | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arc/boot/dts/skeleton_hs_idu.dtsi b/arch/arc/boot/dts/skeleton_hs_idu.dtsi
index 662c5e0..54b277d 100644
--- a/arch/arc/boot/dts/skeleton_hs_idu.dtsi
+++ b/arch/arc/boot/dts/skeleton_hs_idu.dtsi
@@ -19,10 +19,28 @@
 
 		cpu@0 {
 			device_type = "cpu";
-			compatible = "snps,archs38xN";
+			compatible = "snps,archs38";
 			reg = <0>;
 			clocks = <&core_clk>;
 		};
+		cpu@1 {
+			device_type = "cpu";
+			compatible = "snps,archs38";
+			reg = <1>;
+			clocks = <&core_clk>;
+		};
+		cpu@2 {
+			device_type = "cpu";
+			compatible = "snps,archs38";
+			reg = <2>;
+			clocks = <&core_clk>;
+		};
+		cpu@3 {
+			device_type = "cpu";
+			compatible = "snps,archs38";
+			reg = <3>;
+			clocks = <&core_clk>;
+		};
 	};
 
 	/* TIMER0 with interrupt for clockevent */
-- 
2.7.4

[PATCH 3/3] arc: get rate from clk driver instead of reading device tree

[Vlad Zakharov]

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.

Signed-off-by: Vlad Zakharov <vzakhar@synopsys.com>
---
 arch/arc/kernel/setup.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index 3093fa8..fa62404 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>
@@ -488,8 +489,9 @@ 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");
-	u32 freq = 0;
+	struct device *cpu_dev = get_cpu_device(cpu_id);
+	struct clk *cpu_clk;
+	unsigned long freq = 0;
 
 	if (!cpu_online(cpu_id)) {
 		seq_printf(m, "processor [%d]\t: Offline\n", cpu_id);
@@ -502,9 +504,15 @@ 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);
+	cpu_clk = clk_get(cpu_dev, NULL);
+	if (IS_ERR(cpu_clk)) {
+		seq_printf(m, "CPU speed \t: Cannot get clock for processor [%d]\n",
+			   cpu_id);
+	} else {
+		freq = clk_get_rate(cpu_clk);
+	}
 	if (freq)
-		seq_printf(m, "CPU speed\t: %u.%02u Mhz\n",
+		seq_printf(m, "CPU speed\t: %lu.%02lu Mhz\n",
 			   freq / 1000000, (freq / 10000) % 100);
 
 	seq_printf(m, "Bogo MIPS\t: %lu.%02lu\n",
-- 
2.7.4

Re: [PATCH 0/3] ARC: get frequency via clock driver instead of reading device tree

[Vineet Gupta]

On 03/03/2017 03:29 AM, Vlad Zakharov wrote:
> This patch series replaces reading device tree with getting CPU
> clock frequency via clock driver in show_cpuinfo function.
> 
> In order to achieve this we also add cpu nodes to device tree which
> describes SMP system and add "clocks" properties to all ARC cpu nodes. 

Series seems sane to me - will give it a spin next week before adding for 4.11

Thx,
-Vieet


> Vlad Zakharov (3):
>   ARC: [dts] add input clocks for cpu nodes
>   ARC: [dts] add cpu nodes to ARCHS SMP device tree
>   arc: get rate from clk driver instead of reading device tree
> 
>  arch/arc/boot/dts/skeleton.dtsi        |  1 +
>  arch/arc/boot/dts/skeleton_hs.dtsi     |  1 +
>  arch/arc/boot/dts/skeleton_hs_idu.dtsi | 21 ++++++++++++++++++++-
>  arch/arc/kernel/setup.c                | 17 +++++++++++++----
>  4 files changed, 35 insertions(+), 5 deletions(-)
>