[LinuxBIOS] MCP55 LinuxBIOS with USB debug

Lu, Yinghai yinghai.lu at amd.com
Tue Jan 23 18:04:50 CET 2007

If you have smbus hub,


You may need to use

smbus_send_byte(hub_address, hub_channel);


smbus_write_byte(hub_address, hub_channel);


the code is same as CK804's, and the code is verified with Tyan S4881
and 4885.


For PCA9556/PCA9516


static inline void activate_spd_rom(const struct mem_controller *ctrl)


#define SMBUS_HUB 0x18

            unsigned device=(ctrl->channel0[0])>>8;

            smbus_write_byte(SMBUS_HUB, 0x01, device);

            smbus_write_byte(SMBUS_HUB,0x03, 0);







From: linuxbios-bounces at linuxbios.org
[mailto:linuxbios-bounces at linuxbios.org] On Behalf Of bxshi
Sent: Monday, January 22, 2007 11:04 PM
To: yinghailu at gmail.com
Cc: linuxbios at linuxbios.org
Subject: Re: [LinuxBIOS] MCP55 LinuxBIOS with USB debug


Dr. Lu,

In mcp55_smbus.h

static int do_smbus_send_byte(unsigned smbus_io_base, unsigned device,
unsigned char val)


       outb(0, smbus_io_base + SMBHSTCMD);




I wonder why you write 0 to SMBHSTCMD ?  if we are using a smbus_hub , I
think we should write the channel number  we want to enable to this
register. for example , if my memory controller is on channel 2 , we
should write  outb(2,smbus_io_base+SMBHSTCMD). 

So could that be changed to    outb(val,smbus_io_base + SMBHSTCMD) ?




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