riscv: Try to get cpu frequency from a "clocks" node if it exists

Instead of always using the "clock-frequency" property to determine cpu
frequency, try using a clock in "clocks" if it exists. This patch also
fixes a bug where there could be spurious higher frequencies if sizeof(u32)
!= sizeof(ulong).

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/drivers/cpu/riscv_cpu.c b/drivers/cpu/riscv_cpu.c
index cb04f5638db16b69c9625617456fc7684fe285ab..2d44d1c17b1974d510ede16bbe533edbdae962e2 100644 (file)
--- a/drivers/cpu/riscv_cpu.c
+++ b/drivers/cpu/riscv_cpu.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
  */
 
+#include <clk.h>
 #include <common.h>
 #include <cpu.h>
 #include <dm.h>
@@ -11,6 +12,7 @@
 #include <dm/device-internal.h>
 #include <dm/lists.h>
 #include <linux/bitops.h>
+#include <linux/err.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -29,9 +31,24 @@ 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 ret;
+       struct clk clk;
        const char *mmu;
 
-       dev_read_u32(dev, "clock-frequency", (u32 *)&info->cpu_freq);
+       /* Zero out the frequency, in case sizeof(ulong) != sizeof(u32) */
+       info->cpu_freq = 0;
+
+       /* First try getting the frequency from the assigned clock */
+       ret = clk_get_by_index(dev, 0, &clk);
+       if (!ret) {
+               ret = clk_get_rate(&clk);
+               if (!IS_ERR_VALUE(ret))
+                       info->cpu_freq = ret;
+               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)