haswell: calibrate 24MHz clock against BCLK
On haswell ULT systems there is a 24MHz clock that continuously runs
when deep package c-states are entered. The 100MHz BCLK is shut down
in the lower c-states. When the package wakes back up a conversion
formula needs to be applied. The 24MHz calibration is done using the
internal PCODE unit.
Change-Id: I6be7702fb1de1429273724536f5af9125b98da64
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/48292
Tested-by: Stefan Reinauer <reinauer@google.com>
Commit-Queue: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/4136
Tested-by: build bot (Jenkins)
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
diff --git a/src/cpu/intel/haswell/haswell_init.c b/src/cpu/intel/haswell/haswell_init.c
index 5b53afed..0b7a898 100644
--- a/src/cpu/intel/haswell/haswell_init.c
+++ b/src/cpu/intel/haswell/haswell_init.c
@@ -34,6 +34,7 @@
#include <cpu/intel/turbo.h>
#include <cpu/x86/cache.h>
#include <cpu/x86/name.h>
+#include <delay.h>
#include <pc80/mc146818rtc.h>
#include <northbridge/intel/haswell/haswell.h>
#include <southbridge/intel/lynxpoint/pch.h>
@@ -217,6 +218,62 @@
return ult;
}
+/* The core 100MHz BLCK is disabled in deeper c-states. One needs to calibrate
+ * the 100MHz BCLCK against the 24MHz BLCK to restore the clocks properly
+ * when a core is woken up. */
+static int pcode_ready(void)
+{
+ int wait_count;
+ const int delay_step = 10;
+
+ wait_count = 0;
+ do {
+ if (!(MCHBAR32(BIOS_MAILBOX_INTERFACE) & MAILBOX_RUN_BUSY))
+ return 0;
+ wait_count += delay_step;
+ udelay(delay_step);
+ } while (wait_count < 1000);
+
+ return -1;
+}
+
+static void calibrate_24mhz_bclk(void)
+{
+ int err_code;
+
+ if (pcode_ready() < 0) {
+ printk(BIOS_ERR, "PCODE: mailbox timeout on wait ready.\n");
+ return;
+ }
+
+ /* A non-zero value initiates the PCODE calibration. */
+ MCHBAR32(BIOS_MAILBOX_DATA) = ~0;
+ MCHBAR32(BIOS_MAILBOX_INTERFACE) =
+ MAILBOX_RUN_BUSY | MAILBOX_BIOS_CMD_FSM_MEASURE_INTVL;
+
+ if (pcode_ready() < 0) {
+ printk(BIOS_ERR, "PCODE: mailbox timeout on completion.\n");
+ return;
+ }
+
+ err_code = MCHBAR32(BIOS_MAILBOX_INTERFACE) & 0xff;
+
+ printk(BIOS_DEBUG, "PCODE: 24MHz BLCK calibration response: %d\n",
+ err_code);
+
+ /* Read the calibrated value. */
+ MCHBAR32(BIOS_MAILBOX_INTERFACE) =
+ MAILBOX_RUN_BUSY | MAILBOX_BIOS_CMD_READ_CALIBRATION;
+
+ if (pcode_ready() < 0) {
+ printk(BIOS_ERR, "PCODE: mailbox timeout on read.\n");
+ return;
+ }
+
+ printk(BIOS_DEBUG, "PCODE: 24MHz BLCK calibration value: 0x%08x\n",
+ MCHBAR32(BIOS_MAILBOX_DATA));
+}
+
int cpu_config_tdp_levels(void)
{
msr_t platform_info;
@@ -517,6 +574,9 @@
x86_setup_var_mtrrs(cpuid_eax(0x80000008) & 0xff, 2);
x86_mtrr_check();
+ if (is_ult())
+ calibrate_24mhz_bclk();
+
/* Call through the cpu driver's initialization. */
cpu_initialize(0);
}