icedrvr

MIPS处理器的bootloader,龙芯就是用的修改过的PMON2

			The SerialICE Driver
			The SerialICE Driver

The SerialICE Driver is downloaded from the host to the SerialICE Controller.
Once the driver has been downloaded, the SerialICE Monitor is able to use it
to communicate with the SerialICE Kernel that is resident on the Target.

For more information of how to select and download an SerialICE Driver please
refer to the section on Getting Started with
SerialICE-1A.  

SerialICE Monitor - SerialICE Kernel Communication

Two tables are used to provide linkage between the SerialICE Monitor and the
SerialICE Kernel.  The driver's table is located at 0x80020000 is used when
the SerialICE Monitor needs to call one of the functions in the driver. These
functions are listed below:

OffsetFunctionDescription

0Entry Point
The entry point of the driver

8DVRIF_VERS
The version number of the driver

12_cputype
The address of an INT that contains the type of the CPU eg. 4001

16_drivername
The address of a string that contains the driver name

20read_target(int type,Ulong addr,int size)
The address of a function that reads a value from the target

24write_target(int type,Ulong addr,Ulong value,int size)
The address of a function that writes a value to the target

28run_target(int mode,int flags,int count)
The address of a function that starts target execution

32setbp_target(int n,int type,Ulong addr)
The address of a function that sets a breakpoint in the target

36clrbp_target(int n)
The address of a function that clears a breakpoint in the target

40flush_target(int type)
The address of a function that flushes the caches in the target

440
Not used

48is_writeable_target(Ulong addr)
The address of a function that returns TRUE if the specified
	address is writeable

The second table is located at 0xbfc00200 and is used when the driver needs
to call functions within the SerialICE Monitor. The functions in this table are
shown below:

OffsetFunctionDescription

0

read(int fd, char *buf, int size)

Read specified number of bytes into buf. Returns number of
bytes read.

4

write(int fd, char *buf, int size)

Write specified number of bytes from buf. Returns number of
bytes written.

8

int open(char *name [,int mode])

Open a device. Returns file descriptor.

12

close(int fd)

Close a file descriptor.

16

ioctl(int fd, int request, arg)

Perform I/O control operation.

20

printf(char *fmtstr, arg...)

Print formatted to stdout.

24addRegRec(RegRec *reg)
The address of a function that adds a register to the current list

28void *malloc(int size)
The address of a function that allocates a block of memory

32cpuInit
The address of a function that ...

36char*getenv(char *name)
The address of a function that returns a pointer to the definition
of the specified environment variable

400
Not used

440
Not used

48stop(int type)
The address of a function that returns control to the Monitor

52int getBpid()
The address of a function that returns the id of the current
breakpoint (if any)

56is_xvwmode() 
The address of a function that returns TRUE if xvwmode is set

60gdbstop(int type)
The address of a function that returns control to the gdb command
mode

64setTrcbp(Ulong addr,int tover)
The address of a function that sets a trace breakpoint

68addCmdRec(CmdRec *cmd)
The address of a function that adds a new command to the current
command list

72Ulong disasm(char *buf,Ulong addr,Ulong instr)
The address of a function that disassembles an instruction

76get_rsa(Ulong *dst,char *src)
The address of a function that performs expression evaluation

80is_gdbmode (read)
The address of a function that returns TRUE if gdbmode is set

84addEnvRec(EnvRec *var)
The address of a function that adds a new environment variable 
to the current list

Once the driver has been loaded, IMON calls the routine whose address
is located at offset 4 (_start) in the table. The routine _start first
clears the bss section and then calls dvrInit(). 

	_start()
	{
	clrbss();
	dvrInit();
	}

dvrInit adds the list of registers and commands that are specific to
this processor. Offsets 8 and 12 contain the address of an int
that contains the processor number (eg. 4001), and the address of a
string that describes the driver (eg. "Driver for LR4001")
respectively.

The driver is divided into a four files: