Stefan Reinauer (stefan.reinauer@coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/4136
-gerrit
commit 0f327c9f3b566470d6d7d2ce80c9da65472303d5 Author: Aaron Durbin adurbin@chromium.org Date: Wed Apr 10 14:59:21 2013 -0500
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 --- src/cpu/intel/haswell/haswell.h | 19 ++++++++++++ src/cpu/intel/haswell/haswell_init.c | 60 ++++++++++++++++++++++++++++++++++++ 2 files changed, 79 insertions(+)
diff --git a/src/cpu/intel/haswell/haswell.h b/src/cpu/intel/haswell/haswell.h index ab1cef4..96f94eb 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 5b53afe..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 @@ 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); }