x86: Support jumping from SPL to U-Boot
Add a rough function to handle jumping from 32-bit SPL to 64-bit U-Boot.
This still needs work to clean it up.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/i386/cpu.c b/arch/x86/cpu/i386/cpu.c
index 09a5b91..aabdc94 100644
--- a/arch/x86/cpu/i386/cpu.c
+++ b/arch/x86/cpu/i386/cpu.c
@@ -503,6 +503,70 @@
return -EFAULT;
}
+/*
+ * Jump from SPL to U-Boot
+ *
+ * This function is work-in-progress with many issues to resolve.
+ *
+ * It works by setting up several regions:
+ * ptr - a place to put the code that jumps into 64-bit mode
+ * gdt - a place to put the global descriptor table
+ * pgtable - a place to put the page tables
+ *
+ * The cpu_call64() code is copied from ROM and then manually patched so that
+ * it has the correct GDT address in RAM. U-Boot is copied from ROM into
+ * its pre-relocation address. Then we jump to the cpu_call64() code in RAM,
+ * which changes to 64-bit mode and starts U-Boot.
+ */
+int cpu_jump_to_64bit_uboot(ulong target)
+{
+ typedef void (*func_t)(ulong pgtable, ulong setup_base, ulong target);
+ uint32_t *pgtable;
+ func_t func;
+
+ /* TODO(sjg@chromium.org): Find a better place for this */
+ pgtable = (uint32_t *)0x1000000;
+ if (!pgtable)
+ return -ENOMEM;
+
+ build_pagetable(pgtable);
+
+ /* TODO(sjg@chromium.org): Find a better place for this */
+ char *ptr = (char *)0x3000000;
+ char *gdt = (char *)0x3100000;
+
+ extern char gdt64[];
+
+ memcpy(ptr, cpu_call64, 0x1000);
+ memcpy(gdt, gdt64, 0x100);
+
+ /*
+ * TODO(sjg@chromium.org): This manually inserts the pointers into
+ * the code. Tidy this up to avoid this.
+ */
+ func = (func_t)ptr;
+ ulong ofs = (ulong)cpu_call64 - (ulong)ptr;
+ *(ulong *)(ptr + 7) = (ulong)gdt;
+ *(ulong *)(ptr + 0xc) = (ulong)gdt + 2;
+ *(ulong *)(ptr + 0x13) = (ulong)gdt;
+ *(ulong *)(ptr + 0x117 - 0xd4) -= ofs;
+
+ /*
+ * Copy U-Boot from ROM
+ * TODO(sjg@chromium.org): Figure out a way to get the text base
+ * correctly here, and in the device-tree binman definition.
+ *
+ * Also consider using FIT so we get the correct image length and
+ * parameters.
+ */
+ memcpy((char *)target, (char *)0xfff00000, 0x100000);
+
+ /* Jump to U-Boot */
+ func((ulong)pgtable, 0, (ulong)target);
+
+ return -EFAULT;
+}
+
#ifdef CONFIG_SMP
static int enable_smis(struct udevice *cpu, void *unused)
{