smbus_spd.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <device/pci_def.h>
#include <device/device.h>
#include <stddef.h>
#include <OEM.h>                /* SMBUS0_BASE_ADDRESS */
 
/* warning: Porting.h includes an open #pragma pack(1) */
#include <vendorcode/amd/include/Porting.h>
#include <AGESA.h>
#include "chip.h"
#include "smbus_spd.h"
 
#include <northbridge/amd/agesa/dimmSpd.h>
 
/* uncomment for source level debug - GDB gets really confused otherwise. */
//#pragma optimize ("", off)
 
/**
 *      Read a single SPD byte.  If the first byte is being read, set up the
 *      address and offset. Following bytes auto increment.
 */
static UINT8 readSmbusByte(UINT16 iobase, UINT8 address, char *buffer,
                                                   int offset, int initial_offset)
{
        unsigned int status = -1;
        UINT64 time_limit;
 
        /* clear status register */
        __outbyte(iobase + SMBUS_STATUS_REG, 0x1E);
 
        if (offset == initial_offset) {
                /* Clear slave status, set offset, set slave address and start reading */
                __outbyte(iobase + SMBUS_SLAVE_STATUS_REG, 0x3E);
                __outbyte(iobase + SMBUS_CONTROL_REG, offset);
                __outbyte(iobase + SMBUS_HOST_CMD_REG, address | READ_BIT);
                __outbyte(iobase + SMBUS_COMMAND_REG, SMBUS_READ_BYTE_COMMAND);
        } else {
                /* Issue read command - auto increments to next byte */
                __outbyte(iobase + SMBUS_COMMAND_REG, SMBUS_READ_COMMAND);
        }
        /* time limit to avoid hanging for unexpected error status */
        time_limit = __rdtsc() + MAX_READ_TSC_COUNT;
        while (__rdtsc() <= time_limit) {
                status = __inbyte(iobase + SMBUS_STATUS_REG);
                if ((status & SMBUS_INTERRUPT_MASK) == 0)
                        continue;       /* SMBusInterrupt not set, keep waiting */
                if ((status & HOSTBUSY_MASK) != 0)
                        continue;       /* HostBusy set, keep waiting */
                break;
        }
 
        if (status != STATUS__COMPLETED_SUCCESSFULLY)
                return AGESA_ERROR;
 
        buffer[0] = __inbyte(iobase + SMBUS_DATA0_REG);
        return AGESA_SUCCESS;
}
 
static void writePmReg(UINT8 reg, UINT8 data)
{
        __outbyte(PMIO_INDEX_REG, reg);
        __outbyte(PMIO_DATA_REG, data);
}
 
static void setupFch(UINT16 ioBase)
{
        /* set up SMBUS - Set to SMBUS 0 & set base address */
        /* For SB800 & Hudson1 to SB900 & Hudson 2/3 */
        writePmReg(SMBUS_BAR_HIGH_BYTE, ioBase >> 8);
        writePmReg(SMBUS_BAR_LOW_BYTE, (ioBase & 0xe0) | 1);
 
        /* set SMBus clock to 400 KHz */
        __outbyte(ioBase + SMBUS_CLOCK_REG, SMBUS_FREQUENCY_CONST / 400000);
}
 
/**
 *      Read one or more SPD bytes from a DIMM.
 *      Start with offset zero and read sequentially.
 *      Reads 128 bytes in 7-8 ms at 400 KHz.
 */
static UINT8 readspd(UINT16 iobase, UINT8 SmbusSlaveAddress, char *buffer,
                                         UINT16 count)
{
        UINT16 index;
        UINT8 status;
        UINT8 initial_offset = 0;
 
        setupFch(iobase);
 
        for (index = initial_offset; index < count; index++) {
                status = readSmbusByte(iobase, SmbusSlaveAddress, &buffer[index], index,
                                initial_offset);
                if (status != AGESA_SUCCESS)
                        return status;
        }
 
        return status;
}
 
int smbus_readSpd(int spdAddress, char *buf, size_t len)
{
        int ioBase = SMBUS0_BASE_ADDRESS;
        setupFch (ioBase);
        return readspd (ioBase, spdAddress, buf, len);
}