riscv: Enable cpu clock if it is present

The cpu clock is probably already enabled if we are executing code (though
we could be executing from a different core). This patch prevents the cpu
clock or its parents from being disabled.

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 2d44d1c..76b0489 100644 (file)
--- a/drivers/cpu/riscv_cpu.c
+++ b/drivers/cpu/riscv_cpu.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ * Copyright (C) 2020, Sean Anderson <seanga2@gmail.com>
  */
 
 #include <clk.h>
@@ -119,6 +120,24 @@ static int riscv_cpu_bind(struct udevice *dev)
        return 0;
 }
 
+static int riscv_cpu_probe(struct udevice *dev)
+{
+       int ret = 0;
+       struct clk clk;
+
+       /* Get a clock if it exists */
+       ret = clk_get_by_index(dev, 0, &clk);
+       if (ret)
+               return 0;
+
+       ret = clk_enable(&clk);
+       clk_free(&clk);
+       if (ret == -ENOSYS || ret == -ENOTSUPP)
+               return 0;
+       else
+               return ret;
+}
+
 static const struct cpu_ops riscv_cpu_ops = {
        .get_desc       = riscv_cpu_get_desc,
        .get_info       = riscv_cpu_get_info,
@@ -135,6 +154,7 @@ U_BOOT_DRIVER(riscv_cpu) = {
        .id = UCLASS_CPU,
        .of_match = riscv_cpu_ids,
        .bind = riscv_cpu_bind,
+       .probe = riscv_cpu_probe,
        .ops = &riscv_cpu_ops,
        .flags = DM_FLAG_PRE_RELOC,
 };