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SMBus Access
4. SMBus Access
The base address of SMBus must be known before access. The relevant bus and device
information are as following.
#define IO_SC
#define IO_DA
#define PCIBASEADDRESS 0x80000000
#define PCI_BUS_NUM 0
#define PCI_DEV_NUM 31
#define PCI_FUN_NUM
4.1
Get SMBus Base Address
int SMBUS_BASE;
int DATA_ADDR = PCIBASEADDRESS + (PCI_BUS_NUM<<16) +
Outportl (DATA_ADDR + 0x20, IO_SC);
SMBUS_BASE = Inportl (IO_DA) & 0xfffffff0;
4.2
SMBus_ReadByte (char DEVID, char OFFSET)
Read the value of OFFSET from SMBus device DEVID.
Outportb (LOWORD (SMBUS_BASE), 0xFE);
Outportb (LOWORD (SMBUS_BASE) + 0x04, DEVID + 1); // out Base + 04, (DEVID + 1)
Outportb (LOWORD (SMBUS_BASE) + 0x03, OFFSET);
Outportb (LOWORD (SMBUS_BASE) + 0x02, 0x48);
mdelay (20);
while ((Inportl (SMBUS_BASE) & 0x01) != 0);
SMB_DATA = Inportb (LOWORD (SMBUS_BASE) + 0x05);
4.3
SMBus_WriteByte (char DEVID, char OFFSET, char DATA)
Write DATA to OFFSET on SMBus device DEVID.
Outportb (LOWORD (SMBUS_BASE), 0xFE);
Outportb (LOWORD (SMBUS_BASE) + 0x04, DEVID);
Outportb (LOWORD (SMBUS_BASE) + 0x03, OFFSET);
Outportb (LOWORD (SMBUS_BASE) + 0x05, DATA);
Outportb (LOWORD (SMBUS_BASE) + 0x02, 0x48);
mdelay (20);
0xCF8
0xCFC
4
(PCI_DEV_NUM<<11) +
(PCI_FUN_NUM<<8);
// out Base + 03, OFFSET
// out Base + 02, 48H
// delay 20ms to let data ready
// wait SMBus ready
// input Base + 05
// out Base + 04, (DEVID)
// out Base + 03, OFFSET
// out Base + 05, DATA
// out Base + 02, 48H
// wait 20ms
MS-98H7
A-7
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