x86: timer: Reduce timer code size in TPL on Intel CPUs
Most of the timer-calibration methods are not needed on recent Intel CPUs
and just increase code size. Add an option to use the known-good way to
get the clock frequency in TPL. Size reduction is about 700 bytes.
Note that version 1 of this commit caused bootstage to crash since the CPU
was not identified. This is corrected by changes previously applied to
make sure that the CPU is identified before spl_init() is called, such as
39146a2e0b x86: Move CPU init to before spl_init()
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 41f9755..96cc492 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -188,6 +188,15 @@
The only exception is when U-Boot is used as a secondary bootloader,
where this option should be enabled.
+config TPL_X86_TSC_TIMER_NATIVE
+ bool "x86 TSC timer uses native calibration"
+ depends on TPL && X86_TSC_TIMER
+ help
+ Selects native timer calibration for TPL and don't include the other
+ methods in the code. This helps to reduce code size in TPL and works
+ on fairly modern Intel chips. Code-size reductions is about 700
+ bytes.
+
config MTK_TIMER
bool "MediaTek timer support"
depends on TIMER
diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 813817f..43cb2d8 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -50,8 +50,7 @@
return 0;
crystal_freq = tsc_info.ecx / 1000;
-
- if (!crystal_freq) {
+ if (!CONFIG_IS_ENABLED(X86_TSC_TIMER_NATIVE) && !crystal_freq) {
switch (gd->arch.x86_model) {
case INTEL_FAM6_SKYLAKE_MOBILE:
case INTEL_FAM6_SKYLAKE_DESKTOP:
@@ -407,6 +406,10 @@
if (fast_calibrate)
goto done;
+ /* Reduce code size by dropping other methods */
+ if (CONFIG_IS_ENABLED(X86_TSC_TIMER_NATIVE))
+ panic("no timer");
+
fast_calibrate = cpu_mhz_from_cpuid();
if (fast_calibrate)
goto done;