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/* SPDX-License-Identifier: GPL-2.0-only */
/* This file is part of the coreboot project. */
#include <console/console.h>
#include <device/mmio.h>
#include "raminit.h"
#include "i945.h"
/**
* sample the strobes signal
*/
static u32 sample_strobes(int channel_offset, struct sys_info *sysinfo)
{
u32 reg32, addr;
int i;
MCHBAR32(C0DRC1 + channel_offset) |= (1 << 6);
MCHBAR32(C0DRC1 + channel_offset) &= ~(1 << 6);
addr = 0;
if (channel_offset != 0) { /* must be dual channel */
if (sysinfo->interleaved == 1)
addr |= (1 << 6);
else
addr = ((u32)MCHBAR8(C0DRB3)) << 25;
}
for (i = 0; i < 28; i++) {
read32((void *)addr);
read32((void *)(addr + 0x80));
}
reg32 = MCHBAR32(RCVENMT);
if (channel_offset == 0)
reg32 = reg32 << 2;
/**
* [19] = 1: all bits are high
* [18] = 1: all bits are low
* [19:18] = 00: bits are mixed high, low
*/
return reg32;
}
/**
* This function sets receive enable coarse and medium timing parameters
*/
static void set_receive_enable(int channel_offset, u8 medium, u8 coarse)
{
u32 reg32;
printk(BIOS_SPEW, " %s() medium=0x%x, coarse=0x%x\n", __func__, medium, coarse);
reg32 = MCHBAR32(C0DRT1 + channel_offset);
reg32 &= 0xf0ffffff;
reg32 |= ((u32)coarse & 0x0f) << 24;
MCHBAR32(C0DRT1 + channel_offset) = reg32;
/* This should never happen: */
if (coarse > 0x0f)
printk(BIOS_DEBUG, "%s: coarse overflow: 0x%02x.\n", __func__, coarse);
/* medium control
*
* 00 - 1/4 clock
* 01 - 1/2 clock
* 10 - 3/4 clock
* 11 - 1 clock
*/
reg32 = MCHBAR32(RCVENMT);
if (!channel_offset) {
/* Channel 0 */
reg32 &= ~(3 << 2);
reg32 |= medium << 2;
} else {
/* Channel 1 */
reg32 &= ~(3 << 0);
reg32 |= medium;
}
MCHBAR32(RCVENMT) = reg32;
}
static int normalize(int channel_offset, u8 *mediumcoarse, u8 *fine)
{
printk(BIOS_SPEW, " %s()\n", __func__);
if (*fine < 0x80)
return 0;
*fine -= 0x80;
*mediumcoarse += 1;
if (*mediumcoarse >= 0x40) {
printk(BIOS_DEBUG, "Normalize Error\n");
return -1;
}
set_receive_enable(channel_offset, *mediumcoarse & 3, *mediumcoarse >> 2);
MCHBAR8(C0WL0REOST + channel_offset) = *fine;
return 0;
}
static int find_preamble(int channel_offset, u8 *mediumcoarse,
struct sys_info *sysinfo)
{
/* find start of the data phase */
u32 reg32;
printk(BIOS_SPEW, " %s()\n", __func__);
do {
if (*mediumcoarse < 4) {
printk(BIOS_DEBUG, "No Preamble found.\n");
return -1;
}
*mediumcoarse -= 4;
set_receive_enable(channel_offset, *mediumcoarse & 3, *mediumcoarse >> 2);
reg32 = sample_strobes(channel_offset, sysinfo);
} while (reg32 & (1 << 19));
if (!(reg32 & (1 << 18))) {
printk(BIOS_DEBUG, "No Preamble found (neither high nor low).\n");
return -1;
}
return 0;
}
/**
* add a quarter clock to the current receive enable settings
*/
static int add_quarter_clock(int channel_offset, u8 *mediumcoarse, u8 *fine)
{
printk(BIOS_SPEW, " %s() mediumcoarse=%02x fine=%02x\n", __func__,
*mediumcoarse, *fine);
if (*fine >= 0x80) {
*fine -= 0x80;
*mediumcoarse += 2;
if (*mediumcoarse >= 0x40) {
printk(BIOS_DEBUG, "clocks at max.\n");
return -1;
}
set_receive_enable(channel_offset, *mediumcoarse & 3, *mediumcoarse >> 2);
} else {
*fine += 0x80;
}
MCHBAR8(C0WL0REOST + channel_offset) = *fine;
return 0;
}
static int find_strobes_low(int channel_offset, u8 *mediumcoarse, u8 *fine,
struct sys_info *sysinfo)
{
u32 rcvenmt;
printk(BIOS_SPEW, " %s()\n", __func__);
for (;;) {
MCHBAR8(C0WL0REOST + channel_offset) = *fine;
set_receive_enable(channel_offset, *mediumcoarse & 3, *mediumcoarse >> 2);
rcvenmt = sample_strobes(channel_offset, sysinfo);
if (((rcvenmt & (1 << 18)) != 0))
return 0;
*fine -= 0x80;
if (*fine == 0)
continue;
*mediumcoarse -= 2;
if (*mediumcoarse < 0xfe)
continue;
break;
}
printk(BIOS_DEBUG, "Could not find low strobe\n");
return 0;
}
static int find_strobes_edge(int channel_offset, u8 *mediumcoarse, u8 *fine,
struct sys_info *sysinfo)
{
int counter;
u32 rcvenmt;
printk(BIOS_SPEW, " %s()\n", __func__);
counter = 8;
set_receive_enable(channel_offset, *mediumcoarse & 3, *mediumcoarse >> 2);
for (;;) {
MCHBAR8(C0WL0REOST + channel_offset) = *fine;
rcvenmt = sample_strobes(channel_offset, sysinfo);
if ((rcvenmt & (1 << 19)) == 0) {
counter = 8;
} else {
counter--;
if (!counter)
break;
}
*fine = *fine + 1;
if (*fine < 0xf8) {
if (*fine & (1 << 3)) {
*fine &= ~(1 << 3);
*fine += 0x10;
}
continue;
}
*fine = 0;
*mediumcoarse += 2;
if (*mediumcoarse <= 0x40) {
set_receive_enable(channel_offset, *mediumcoarse & 3,
*mediumcoarse >> 2);
continue;
}
printk(BIOS_DEBUG, "Could not find rising edge.\n");
return -1;
}
*fine -= 7;
if (*fine >= 0xf9) {
*mediumcoarse -= 2;
set_receive_enable(channel_offset, *mediumcoarse & 3, *mediumcoarse >> 2);
}
*fine &= ~(1 << 3);
MCHBAR8(C0WL0REOST + channel_offset) = *fine;
return 0;
}
/**
* Here we use a trick. The RCVEN channel 0 registers are all at an
* offset of 0x80 to the channel 0 registers. We don't want to waste
* a lot of if ()s so let's just pass 0 or 0x80 for the channel offset.
*/
static int receive_enable_autoconfig(int channel_offset, struct sys_info *sysinfo)
{
u8 mediumcoarse;
u8 fine;
printk(BIOS_SPEW, "%s() for channel %d\n", __func__, channel_offset ? 1 : 0);
/* Set initial values */
mediumcoarse = (sysinfo->cas << 2) | 3;
fine = 0;
if (find_strobes_low(channel_offset, &mediumcoarse, &fine, sysinfo))
return -1;
if (find_strobes_edge(channel_offset, &mediumcoarse, &fine, sysinfo))
return -1;
if (add_quarter_clock(channel_offset, &mediumcoarse, &fine))
return -1;
if (find_preamble(channel_offset, &mediumcoarse, sysinfo))
return -1;
if (add_quarter_clock(channel_offset, &mediumcoarse, &fine))
return -1;
if (normalize(channel_offset, &mediumcoarse, &fine))
return -1;
/* This is a debug check to see if the rcven code is fully working.
* It can be removed when the output message is not printed anymore
*/
if (MCHBAR8(C0WL0REOST + channel_offset) == 0)
printk(BIOS_DEBUG, "Weird. No C%sWL0REOST\n", channel_offset?"1":"0");
return 0;
}
void receive_enable_adjust(struct sys_info *sysinfo)
{
/* Is channel 0 populated? */
if (sysinfo->dimm[0] != SYSINFO_DIMM_NOT_POPULATED
|| sysinfo->dimm[1] != SYSINFO_DIMM_NOT_POPULATED)
if (receive_enable_autoconfig(0, sysinfo))
return;
/* Is channel 1 populated? */
if (sysinfo->dimm[2] != SYSINFO_DIMM_NOT_POPULATED
|| sysinfo->dimm[3] != SYSINFO_DIMM_NOT_POPULATED)
if (receive_enable_autoconfig(0x80, sysinfo))
return;
}
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