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 <s...@chromium.org>
---
Changes in v5: None
Changes in v4:
- Update commit message to indicate that CPU-identity bug is fixed
Changes in v3: None
Changes in v2: None
drivers/timer/Kconfig | 9 +++++++++
drivers/timer/tsc_timer.c | 7 +++++--
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 41f9755133..96cc49273f 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -188,6 +188,15 @@ config X86_TSC_READ_BASE
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 a11a82f21a..ffa2ac74c3 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -49,8 +49,7 @@ static unsigned long native_calibrate_tsc(void)
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:
@@ -406,6 +405,10 @@ static void tsc_timer_ensure_setup(bool early)
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;
--
2.24.0.432.g9d3f5f5b63-goog
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