[PATCH] riscv: Try to get cpu frequency from device tree

[Sean Anderson]

Instead of always using the "clock-frequency" property to determine cpu
frequency, try using a clock in "clocks" if it exists.

Signed-off-by Sean Anderson <seanga2 at gmail.com>
---
This patch depends on <https://patchwork.ozlabs.org/patch/1223933/>.

 drivers/cpu/riscv_cpu.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/cpu/riscv_cpu.c b/drivers/cpu/riscv_cpu.c
index 1e32bb5678..280c9de376 100644
--- a/drivers/cpu/riscv_cpu.c
+++ b/drivers/cpu/riscv_cpu.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2018, Bin Meng <bmeng.cn at gmail.com>
  */
 
+#include <clk.h>
 #include <common.h>
 #include <cpu.h>
 #include <dm.h>
@@ -27,11 +28,24 @@ static int riscv_cpu_get_desc(struct udevice *dev, char *buf, int size)
 
 static int riscv_cpu_get_info(struct udevice *dev, struct cpu_info *info)
 {
+	int err;
+	struct clk clk;
 	const char *mmu;
 
 	/* Zero out the frequency, in case sizeof(ulong) != sizeof(u32) */
 	info->cpu_freq = 0;
-	dev_read_u32(dev, "clock-frequency", (u32 *)&info->cpu_freq);
+
+	/* First try getting the frequency from the assigned clock */
+	err = clk_get_by_index(dev, 0, &clk);
+	if (!err) {
+		err = clk_get_rate(&clk);
+		if (!IS_ERR_VALUE(err))
+			info->cpu_freq = err;
+		clk_free(&clk);
+	}
+
+	if (!info->cpu_freq)
+		dev_read_u32(dev, "clock-frequency", (u32 *)&info->cpu_freq);
 
 	mmu = dev_read_string(dev, "mmu-type");
 	if (!mmu)
-- 
2.24.1