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authorAaron Durbin <adurbin@chromium.org>2013-04-10 14:59:21 -0500
committerAlexandru Gagniuc <mr.nuke.me@gmail.com>2013-11-24 16:03:18 +0100
commitf24262d01822bd8634e44b5aab19dafe7e04ae72 (patch)
tree2cef436c007ecbef9508e61c8196b535c7228942 /src
parent7c351316429f8b991df7ea233a5528f4efb3b8e0 (diff)
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>
Diffstat (limited to 'src')
-rw-r--r--src/cpu/intel/haswell/haswell.h19
-rw-r--r--src/cpu/intel/haswell/haswell_init.c60
2 files changed, 79 insertions, 0 deletions
diff --git a/src/cpu/intel/haswell/haswell.h b/src/cpu/intel/haswell/haswell.h
index ab1cef470c..96f94ebd0a 100644
--- a/src/cpu/intel/haswell/haswell.h
+++ b/src/cpu/intel/haswell/haswell.h
@@ -100,6 +100,25 @@
#define PSS_LATENCY_TRANSITION 10
#define PSS_LATENCY_BUSMASTER 10
+/* PCODE MMIO communications live in the MCHBAR. */
+#define BIOS_MAILBOX_INTERFACE 0x5da4
+#define MAILBOX_RUN_BUSY (1 << 31)
+#define MAILBOX_BIOS_CMD_READ_PCS 1
+#define MAILBOX_BIOS_CMD_WRITE_PCS 2
+#define MAILBOX_BIOS_CMD_READ_CALIBRATION 0x509
+#define MAILBOX_BIOS_CMD_FSM_MEASURE_INTVL 0x909
+/* Errors are returned back in bits 7:0. */
+#define MAILBOX_BIOS_ERROR_NONE 0
+#define MAILBOX_BIOS_ERROR_INVALID_COMMAND 1
+#define MAILBOX_BIOS_ERROR_TIMEOUT 2
+#define MAILBOX_BIOS_ERROR_ILLEGAL_DATA 3
+#define MAILBOX_BIOS_ERROR_RESERVED 4
+#define MAILBOX_BIOS_ERROR_ILLEGAL_VR_ID 5
+#define MAILBOX_BIOS_ERROR_VR_INTERFACE_LOCKED 6
+#define MAILBOX_BIOS_ERROR_VR_ERROR 7
+/* Data is passed through bits 31:0 of the data register. */
+#define BIOS_MAILBOX_DATA 0x5da0
+
/* Region of SMM space is reserved for multipurpose use. It falls below
* the IED region and above the SMM handler. */
#define RESERVED_SMM_SIZE CONFIG_SMM_RESERVED_SIZE
diff --git a/src/cpu/intel/haswell/haswell_init.c b/src/cpu/intel/haswell/haswell_init.c
index 5b53afedf5..0b7a8985cf 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 @@ static int is_ult(void)
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 @@ static void bsp_init_before_ap_bringup(struct bus *cpu_bus)
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);
}