[Linuxconsole-commit]CVS: ruby/linux/drivers/serial README,NONE,1.1

[James S. <jsi...@us...>]

Update of /cvsroot/linuxconsole/ruby/linux/drivers/serial
In directory usw-pr-cvs1:/tmp/cvs-serv27629

Added Files:
	README 
Log Message:
First docs on the new serial stuff I have been coming up with. Will discuss with Russell King about this.

--- NEW FILE: README ---
	                   The new serial design

After much toying with the various ideas and Russell King's code I have formed 
the start of what to do. The basic idea is simple. To create a serial core where
we can register a device interface to a specific port. This gives use the power
to do things like have a serial console without a tty on port 1, input interface
on port 2, and a tty interface on port 3. Here are the ideas I have come up with
to deal with this. 

1) We need to break up what we setup. The primary this we want to do are: 

   I.   Register and setup hardware ports in a device independent way. The 
        function to do this is 

        int uart_register_port(struct uart_port *port);
 
   II.  The next step is to register the various device interfaces i.e tty, 
	input etc. This function sets up devfs, minor numbers etc. It has
        nothing to do with the hardware. 

        int uart_register_driver(struct uart_driver *uart);
	
   III. The final step is when a device is detected that we map it to a specific
	port. For example if the bus detects a modem then it would only make 
 	sense to map the struct uart_driver that represents the tty interface
 	to the port that the modem wants to use.

	int uart_register_device(struct uart_driver *reg,struct uart_port *port);

2) The structures to represent the hardware and device interfaces. Now with the
   data we want to have data structs that define the hardware state and be able
   to change that state. We also want to make those structs visible to the 
   higher level device interface layers. The second set of data is the device
   layer structs. We don't want them visible to the lower layers. Only the 
   specific device interface would have access to it. At present we have the
   following data structs:

   I.   struct uart_port. This struct represents a serial port. All the data in
	it defines the current hardware state. Both low level and device level
	use this data.

   II.  struct uart_ops. This structure describes all the operations that can be
        done on the physical hardware. It is apart of struct uart_port. 
   	 
   III. struct uart_driver. The data here presents the device interface used to
	represent the hardware. This struct should be interface independent. 
        A void field would be added to this struct which could be cast in the
	higher device level. That data field would depend on the device 
	interface.