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nb/intel/sandybridge: Rewrite get_FRQ 

The code is just clamping the frequency index to a valid range. Do it
with a helper function. Also, add a CPUID check, as Sandy Bridge will
eventually use this code.

Change-Id: I4c7aa5f7615c6edb1ab62fb004abb126df9d284b
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39787
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
This commit is contained in:
Angel Pons 2020-03-23 22:38:08 +01:00 committed by Patrick Georgi
parent 2a0a02f98f
commit a6c8b4becb
2 changed files with 40 additions and 16 deletions
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22
src/commonlib/include/commonlib/clamp.h Normal file
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@ -0,0 +1,22 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef COMMONLIB_CLAMP_H
#define COMMONLIB_CLAMP_H
#include <stdint.h>
/*
* Clamp a value, so that it is between a lower and an upper bound.
*/
static inline u32 clamp_u32(const u32 min, const u32 val, const u32 max)
{
if (val > max)
return max;
if (val < min)
return min;
return val;
}
#endif /* COMMONLIB_CLAMP_H */

34
src/northbridge/intel/sandybridge/raminit_ivy.c
View File

@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0-only */ /* SPDX-License-Identifier: GPL-2.0-only */
/* This file is part of the coreboot project. */ /* This file is part of the coreboot project. */
#include <commonlib/clamp.h>
#include <console/console.h> #include <console/console.h>
#include <console/usb.h> #include <console/usb.h>
#include <delay.h> #include <delay.h>
@ -9,24 +10,25 @@
#include "raminit_common.h" #include "raminit_common.h"
#include "raminit_tables.h" #include "raminit_tables.h"
/* Frequency multiplier */ #define IVB_MIN_DCLK_133_MULT 3
static u32 get_FRQ(u32 tCK, u8 base_freq) #define IVB_MAX_DCLK_133_MULT 10
{ #define IVB_MIN_DCLK_100_MULT 7
const u32 FRQ = 256000 / (tCK * base_freq); #define IVB_MAX_DCLK_100_MULT 12
if (base_freq == 100) { /* Frequency multiplier */
if (FRQ > 12) static u32 get_FRQ(const ramctr_timing *ctrl)
return 12; {
if (FRQ < 7) const u32 FRQ = 256000 / (ctrl->tCK * ctrl->base_freq);
return 7;
} else { if (IS_IVY_CPU(ctrl->cpu)) {
if (FRQ > 10) if (ctrl->base_freq == 100)
return 10; return clamp_u32(IVB_MIN_DCLK_100_MULT, FRQ, IVB_MAX_DCLK_100_MULT);
if (FRQ < 3)
return 3; if (ctrl->base_freq == 133)
return clamp_u32(IVB_MIN_DCLK_133_MULT, FRQ, IVB_MAX_DCLK_133_MULT);
} }
return FRQ; die("Unsupported CPU or base frequency.");
} }
/* Get REFI based on frequency index, tREFI = 7.8usec */ /* Get REFI based on frequency index, tREFI = 7.8usec */
@ -204,7 +206,7 @@ static void find_cas_tck(ramctr_timing *ctrl)
} }
/* Frequency multiplier */ /* Frequency multiplier */
ctrl->FRQ = get_FRQ(ctrl->tCK, ctrl->base_freq); ctrl->FRQ = get_FRQ(ctrl);
printk(BIOS_DEBUG, "Selected DRAM frequency: %u MHz\n", NS2MHZ_DIV256 / ctrl->tCK); printk(BIOS_DEBUG, "Selected DRAM frequency: %u MHz\n", NS2MHZ_DIV256 / ctrl->tCK);
printk(BIOS_DEBUG, "Selected CAS latency : %uT\n", val); printk(BIOS_DEBUG, "Selected CAS latency : %uT\n", val);