x86: Display basic CPU information on boot
Display the type of CPU (x86 or x86_64) when starting up.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
index 7a4de29..8c1eacc 100644
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -275,3 +275,67 @@
:
: "eax");
}
+
+static bool has_cpuid(void)
+{
+ unsigned long flag;
+
+ asm volatile("pushf\n" \
+ "pop %%eax\n"
+ "mov %%eax, %%ecx\n" /* ecx = flags */
+ "xor %1, %%eax\n"
+ "push %%eax\n"
+ "popf\n" /* flags ^= $2 */
+ "pushf\n"
+ "pop %%eax\n" /* eax = flags */
+ "push %%ecx\n"
+ "popf\n" /* flags = ecx */
+ "xor %%ecx, %%eax\n"
+ "mov %%eax, %0"
+ : "=r" (flag)
+ : "i" (1 << 21)
+ : "eax", "ecx", "memory");
+
+ return flag != 0;
+}
+
+static bool can_detect_long_mode(void)
+{
+ unsigned long flag;
+
+ asm volatile("mov $0x80000000, %%eax\n"
+ "cpuid\n"
+ "mov %%eax, %0"
+ : "=r" (flag)
+ :
+ : "eax", "ebx", "ecx", "edx", "memory");
+
+ return flag > 0x80000000UL;
+}
+
+static bool has_long_mode(void)
+{
+ unsigned long flag;
+
+ asm volatile("mov $0x80000001, %%eax\n"
+ "cpuid\n"
+ "mov %%edx, %0"
+ : "=r" (flag)
+ :
+ : "eax", "ebx", "ecx", "edx", "memory");
+
+ return flag & (1 << 29) ? true : false;
+}
+
+int cpu_has_64bit(void)
+{
+ return has_cpuid() && can_detect_long_mode() &&
+ has_long_mode();
+}
+
+int print_cpuinfo(void)
+{
+ printf("CPU: %s\n", cpu_has_64bit() ? "x86_64" : "x86");
+
+ return 0;
+}