cpu: Add a RISC-V CPU driver

This adds a driver for RISC-V CPU. Note the driver will bind
a RISC-V timer driver if "timebase-frequency" property is
present in the device tree.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
Reviewed-by: Anup Patel <anup@brainfault.org>

diff --git a/drivers/cpu/Kconfig b/drivers/cpu/Kconfig
index d405200..3d5729f 100644 (file)
--- a/drivers/cpu/Kconfig
+++ b/drivers/cpu/Kconfig
@@ -13,3 +13,9 @@ config CPU_MPC83XX
        select CLK_MPC83XX
        help
          Support CPU cores for SoCs of the MPC83xx series.
+
+config CPU_RISCV
+       bool "Enable RISC-V CPU driver"
+       depends on CPU && RISCV
+       help
+         Support CPU cores for RISC-V architecture.

diff --git a/drivers/cpu/Makefile b/drivers/cpu/Makefile
index 858b037..be0300c 100644 (file)
--- a/drivers/cpu/Makefile
+++ b/drivers/cpu/Makefile
@@ -8,4 +8,5 @@ obj-$(CONFIG_CPU) += cpu-uclass.o
 
 obj-$(CONFIG_ARCH_BMIPS) += bmips_cpu.o
 obj-$(CONFIG_CPU_MPC83XX) += mpc83xx_cpu.o
+obj-$(CONFIG_CPU_RISCV) += riscv_cpu.o
 obj-$(CONFIG_SANDBOX) += cpu_sandbox.o

diff --git a/drivers/cpu/riscv_cpu.c b/drivers/cpu/riscv_cpu.c
new file mode 100644 (file)
index 0000000..5e15df5
--- /dev/null
+++ b/drivers/cpu/riscv_cpu.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ */
+
+#include <common.h>
+#include <cpu.h>
+#include <dm.h>
+#include <errno.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+
+static int riscv_cpu_get_desc(struct udevice *dev, char *buf, int size)
+{
+       const char *isa;
+
+       isa = dev_read_string(dev, "riscv,isa");
+       if (size < (strlen(isa) + 1))
+               return -ENOSPC;
+
+       strcpy(buf, isa);
+
+       return 0;
+}
+
+static int riscv_cpu_get_info(struct udevice *dev, struct cpu_info *info)
+{
+       const char *mmu;
+
+       dev_read_u32(dev, "clock-frequency", (u32 *)&info->cpu_freq);
+
+       mmu = dev_read_string(dev, "mmu-type");
+       if (!mmu)
+               info->features |= BIT(CPU_FEAT_MMU);
+
+       return 0;
+}
+
+static int riscv_cpu_get_count(struct udevice *dev)
+{
+       ofnode node;
+       int num = 0;
+
+       ofnode_for_each_subnode(node, dev_ofnode(dev->parent)) {
+               const char *device_type;
+
+               device_type = ofnode_read_string(node, "device_type");
+               if (!device_type)
+                       continue;
+               if (strcmp(device_type, "cpu") == 0)
+                       num++;
+       }
+
+       return num;
+}
+
+static int riscv_cpu_bind(struct udevice *dev)
+{
+       struct cpu_platdata *plat = dev_get_parent_platdata(dev);
+       struct driver *drv;
+       int ret;
+
+       /* save the hart id */
+       plat->cpu_id = dev_read_addr(dev);
+
+       /* first examine the property in current cpu node */
+       ret = dev_read_u32(dev, "timebase-frequency", &plat->timebase_freq);
+       /* if not found, then look at the parent /cpus node */
+       if (ret)
+               dev_read_u32(dev->parent, "timebase-frequency",
+                            &plat->timebase_freq);
+
+       /*
+        * Bind riscv-timer driver on hart 0
+        *
+        * We only instantiate one timer device which is enough for U-Boot.
+        * Pass the "timebase-frequency" value as the driver data for the
+        * timer device.
+        *
+        * Return value is not checked since it's possible that the timer
+        * driver is not included.
+        */
+       if (!plat->cpu_id && plat->timebase_freq) {
+               drv = lists_driver_lookup_name("riscv_timer");
+               if (!drv) {
+                       debug("Cannot find the timer driver, not included?\n");
+                       return 0;
+               }
+
+               device_bind_with_driver_data(dev, drv, "riscv_timer",
+                                            plat->timebase_freq, ofnode_null(),
+                                            NULL);
+       }
+
+       return 0;
+}
+
+static const struct cpu_ops riscv_cpu_ops = {
+       .get_desc       = riscv_cpu_get_desc,
+       .get_info       = riscv_cpu_get_info,
+       .get_count      = riscv_cpu_get_count,
+};
+
+static const struct udevice_id riscv_cpu_ids[] = {
+       { .compatible = "riscv" },
+       { }
+};
+
+U_BOOT_DRIVER(riscv_cpu) = {
+       .name = "riscv_cpu",
+       .id = UCLASS_CPU,
+       .of_match = riscv_cpu_ids,
+       .bind = riscv_cpu_bind,
+       .ops = &riscv_cpu_ops,
+       .flags = DM_FLAG_PRE_RELOC,
+};