x86: qemu: fix cpu device in smp boot

Currently, when booting with more that one CPU enabled, U-Boot scans
'cpu' node in device tree and calculates CPU number. This does not scale
well as changing CPU number also requires modifying .dts and re-compiling
U-Boot.

This patch uses fw_cfg interface provided by QEMU to detect online CPU
number at runtime, and dynamically adds 'cpu' device to U-Boot's driver
model.

Signed-off-by: Miao Yan <yanmiaobest@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/arch/x86/cpu/mp_init.c b/arch/x86/cpu/mp_init.c
index 2a3ce488a90132ed1b7f0795a51c076f617743de..7917350bff267acd988d68065b35269e00e84729 100644 (file)
--- a/arch/x86/cpu/mp_init.c
+++ b/arch/x86/cpu/mp_init.c
@@ -20,8 +20,11 @@
 #include <asm/mtrr.h>
 #include <asm/processor.h>
 #include <asm/sipi.h>
+#include <asm/fw_cfg.h>
 #include <dm/device-internal.h>
 #include <dm/uclass-internal.h>
+#include <dm/lists.h>
+#include <dm/root.h>
 #include <linux/linkage.h>
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -441,6 +444,69 @@ static int init_bsp(struct udevice **devp)
        return 0;
 }
 
+#ifdef CONFIG_QEMU
+static int qemu_cpu_fixup(void)
+{
+       int ret;
+       int cpu_num;
+       int cpu_online;
+       struct udevice *dev, *pdev;
+       struct cpu_platdata *plat;
+       char *cpu;
+
+       /* first we need to find '/cpus' */
+       for (device_find_first_child(dm_root(), &pdev);
+            pdev;
+            device_find_next_child(&pdev)) {
+               if (!strcmp(pdev->name, "cpus"))
+                       break;
+       }
+       if (!pdev) {
+               printf("unable to find cpus device\n");
+               return -ENODEV;
+       }
+
+       /* calculate cpus that are already bound */
+       cpu_num = 0;
+       for (uclass_find_first_device(UCLASS_CPU, &dev);
+            dev;
+            uclass_find_next_device(&dev)) {
+               cpu_num++;
+       }
+
+       /* get actual cpu number */
+       cpu_online = qemu_fwcfg_online_cpus();
+       if (cpu_online < 0) {
+               printf("unable to get online cpu number: %d\n", cpu_online);
+               return cpu_online;
+       }
+
+       /* bind addtional cpus */
+       dev = NULL;
+       for (; cpu_num < cpu_online; cpu_num++) {
+               /*
+                * allocate device name here as device_bind_driver() does
+                * not copy device name, 8 bytes are enough for
+                * sizeof("cpu@") + 3 digits cpu number + '\0'
+                */
+               cpu = malloc(8);
+               if (!cpu) {
+                       printf("unable to allocate device name\n");
+                       return -ENOMEM;
+               }
+               sprintf(cpu, "cpu@%d", cpu_num);
+               ret = device_bind_driver(pdev, "cpu_qemu", cpu, &dev);
+               if (ret) {
+                       printf("binding cpu@%d failed: %d\n", cpu_num, ret);
+                       return ret;
+               }
+               plat = dev_get_parent_platdata(dev);
+               plat->cpu_id = cpu_num;
+       }
+       return 0;
+}
+#endif
+
 int mp_init(struct mp_params *p)
 {
        int num_aps;
@@ -454,6 +520,12 @@ int mp_init(struct mp_params *p)
        if (ret)
                return ret;
 
+#ifdef CONFIG_QEMU
+       ret = qemu_cpu_fixup();
+       if (ret)
+               return ret;
+#endif
+
        ret = init_bsp(&cpu);
        if (ret) {
                debug("Cannot init boot CPU: err=%d\n", ret);

diff --git a/arch/x86/cpu/qemu/cpu.c b/arch/x86/cpu/qemu/cpu.c
index a4bf53dacefecaf3a07c435efcb6f90d01a76a7f..a1b70c6bde7381a003fb7ab391e10b7f46ca1f93 100644 (file)
--- a/arch/x86/cpu/qemu/cpu.c
+++ b/arch/x86/cpu/qemu/cpu.c
@@ -13,16 +13,6 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-int cpu_qemu_bind(struct udevice *dev)
-{
-       struct cpu_platdata *plat = dev_get_parent_platdata(dev);
-
-       plat->cpu_id = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
-                                     "intel,apic-id", -1);
-
-       return 0;
-}
-
 int cpu_qemu_get_desc(struct udevice *dev, char *buf, int size)
 {
        if (size < CPU_MAX_NAME_LEN)
@@ -52,6 +42,5 @@ U_BOOT_DRIVER(cpu_qemu_drv) = {
        .name           = "cpu_qemu",
        .id             = UCLASS_CPU,
        .of_match       = cpu_qemu_ids,
-       .bind           = cpu_qemu_bind,
        .ops            = &cpu_qemu_ops,
 };