x86: slimbootloader: Set TSC information for tsc_timer

Slim Bootloader already calibrated TSC and provides it to U-Boot.
Therefore, U-Boot does not have to re-calibrate TSC.
Configuring tsc_base and clock_rate makes x86 tsc_timer driver bypass
TSC calibration and use the provided TSC frequency.
- Get TSC frequency from performance info hob
- Set tsc_base and clock_rate for tsc_timer driver

Signed-off-by: Aiden Park <aiden.park@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/arch/x86/cpu/slimbootloader/slimbootloader.c b/arch/x86/cpu/slimbootloader/slimbootloader.c
index 9f3a61ec61..e6b174ca88 100644
--- a/arch/x86/cpu/slimbootloader/slimbootloader.c
+++ b/arch/x86/cpu/slimbootloader/slimbootloader.c
@@ -4,9 +4,46 @@
  */
 
 #include <common.h>
+#include <asm/arch/slimbootloader.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/**
+ * This sets tsc_base and clock_rate for early_timer and tsc_timer.
+ * The performance info guid hob has all performance timestamp data, but
+ * the only tsc frequency info is used for the timer driver for now.
+ *
+ * Slim Bootloader already calibrated TSC and provides it to U-Boot.
+ * Therefore, U-Boot does not have to re-calibrate TSC.
+ * Configuring tsc_base and clock_rate here makes x86 tsc_timer driver
+ * bypass TSC calibration and use the provided TSC frequency.
+ */
+static void tsc_init(void)
+{
+	struct sbl_performance_info *data;
+	const efi_guid_t guid = SBL_PERFORMANCE_INFO_GUID;
+
+	if (!gd->arch.hob_list)
+		panic("hob list not found!");
+
+	gd->arch.tsc_base = rdtsc();
+	debug("tsc_base=0x%llx\n", gd->arch.tsc_base);
+
+	data = hob_get_guid_hob_data(gd->arch.hob_list, NULL, &guid);
+	if (!data) {
+		debug("performance info hob not found\n");
+		return;
+	}
+
+	/* frequency is in KHz, so to Hz */
+	gd->arch.clock_rate = data->frequency * 1000;
+	debug("freq=0x%lx\n", gd->arch.clock_rate);
+}
 
 int arch_cpu_init(void)
 {
+	tsc_init();
+
 	return x86_cpu_init_f();
 }