Re: [U-Boot] [PATCH v6 6/8] x86: qemu: fix cpu device in smp boot

[Bin Meng]

On Thu, Jan 7, 2016 at 5:32 PM, Miao Yan  wrote:
> 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 
> Reviewed-by: Simon Glass 
> Reviewed-by: Bin Meng 
> Tested-by: Bin Meng 
> ---

applied to u-boot-x86/next, thanks!
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[U-Boot] [PATCH v6 6/8] x86: qemu: fix cpu device in smp boot

[Miao Yan]

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 
Reviewed-by: Simon Glass 
Reviewed-by: Bin Meng 
Tested-by: Bin Meng 
---
Changes in v6:
  - remove cpu_qemu_bind

 arch/x86/cpu/mp_init.c  | 72 +
 arch/x86/cpu/qemu/cpu.c | 11 
 2 files changed, 72 insertions(+), 11 deletions(-)

diff --git a/arch/x86/cpu/mp_init.c b/arch/x86/cpu/mp_init.c
index 2a3ce48..7917350 100644
--- a/arch/x86/cpu/mp_init.c
+++ b/arch/x86/cpu/mp_init.c
@@ -20,8 +20,11 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
+#include 
+#include 
 #include 
 
 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;
+device_find_next_child()) {
+   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;
+uclass_find_next_device()) {
+   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, );
+   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();
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 a4bf53d..a1b70c6 100644
--- 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= _qemu_ops,
 };
-- 
1.9.1

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