possible serial driver fixup for au1x00 in 2.6?

Basically, au1x00_uart.c is doing the same thing as 8250.c.

If I want
to add extra serial port support by 8250.c. There could be some problem. Any idea?

Quoted 1 line · rolf liu

Basically, au1x00_uart.c is doing the same thing as 8250.c.

Basically.

Quoted 3 lines

If I want
to add extra serial port support by 8250.c. There could be some problem. Any idea?

Don't know, haven't tried it. In general, the au1x00 serial driver needs to be rewritten.

Pete

Pete,
To try if 8250.c can work under db1550/linux 2.6.12, I turn off the au1x00_uart.c config and just compiled in the 8250 support. When I boot the kernel, nothing comes up through the console, which should be provided by 8250 support, by 8250_early.c?

Quoted 6 lines · rolf liu

Pete,
To try if 8250.c can work under db1550/linux 2.6.12, I turn off the au1x00_uart.c config and just compiled in the 8250 support. When I boot the kernel, nothing comes up through the console, which should be provided by 8250 support, by 8250_early.c?

You can't just enable the serial.c (8250). The UARTs for the Au1x00 are memory mapped, but are accessed thru the functions au_readx and au_writex. If you take a look at the au1x00_uart.c you can see that the functions for serial register access contains access to the au1x00 registers thru au_readl and au_writel. The serial.c does some more things, that does not belong to 8250 (and successors), but to the way how the chips are attached to the bus. I see the need to write a more modular structure:

One 8250.c that does only the serial chip stuff and one module per chip-access-method (serial_io.c, serial_pci.c, serial_mm.c, serial_au1x00.c, ...). These modules must know how to access the registers, but not what they mean. 8250.c does not know how to access the registers, but what to do with it.

Thats teamwork.

That could be adopted to more chips that have a registers to access. I think about the i8255 3-port io chip or the i8254-CTC and there are many more.

There must be a callback for interrupts like it exists for the parallel port stuff.

Could look like that:
struct register_access_s
{
void (*delete_resource) (struct register_access_s *);
...
int (*writel) (struct register_access_s *bus, long reg, u32 value); int (*writew) (struct register_access_s *bus, long reg, u16 value); int (*writeb) (struct register_access_s *bus, long reg, u8 value);
...
int (*readl) (struct register_access_s *bus, long reg, u32 *value); int (*readw) (struct register_access_s *bus, long reg, u16 *value); int (*readb) (struct register_access_s *bus, long reg, u8 *value);
...
void *private;
};

struct register_access_s *create_au1x00_register_access (u32 au1x00_register_address, size_t size, u32 irq);
struct register_access_s *create_io_register_access (u16 io_address, size_t size, u32 irq);
struct register_access_s *create_mm_register_access (void *vaddress, size_t size, u32 irq);

struct register_access_s *au1x00_uart0_regs = create_au1x00_register_access (UART0_ADDR, 8, AU1000_UART0_INT); struct register_access_s *uart0_regs = create_io_register_access (0x3E0, 8, 4);

register_8250 (au1x00_uart0_regs, ...);
register_8250 (uart0_regs, ...);

au1x00_uart0_regs->delete_resource (au1x00_uart0_regs);
...
uart3_regs->delete_resource (uart3_regs);

May be a chip can have more than one interrupts and does not have even one.

Michael

Pete,
To try if 8250.c can work under db1550/linux 2.6.12, I turn off the au1x00_uart.c config and just compiled in the 8250 support. When I boot the kernel, nothing comes up through the console, which should be provided by 8250 support, by 8250_early.c?

Any idea?

Quoted 15 lines · rolf liu

Quoted 1 line

Basically, au1x00_uart.c is doing the same thing as 8250.c.

Basically.

Quoted 3 lines

If I want
to add extra serial port support by 8250.c. There could be some problem. Any idea?

Don't know, haven't tried it. In general, the au1x00 serial driver needs to be rewritten.

Pete

Quoted 7 lines · rolf liu

Pete,
To try if 8250.c can work under db1550/linux 2.6.12, I turn off the au1x00_uart.c config and just compiled in the 8250 support. When I boot the kernel, nothing comes up through the console, which should be provided by 8250 support, by 8250_early.c?

Any idea?

Yes. The 8250.c won't work with the au1x uart. I know I said in a previous email that the 8250 "basically" does the same thing as the au1x uart driver, but if the 8250 worked with the Au1x SoCs, why would we even have the au1x serial driver in place?

Pete

Quoted 18 lines · Pete Popov

Quoted 15 lines · rolf liu

Quoted 1 line

Basically, au1x00_uart.c is doing the same thing as 8250.c.

Basically.

Quoted 3 lines

If I want
to add extra serial port support by 8250.c. There could be some problem. Any idea?

Don't know, haven't tried it. In general, the au1x00 serial driver needs to be rewritten.

Pete

I just give 8250.c a dirty hack, letting it just manage the additional serial ports. So there are two serial driver in the system at the same time :( Sound funny.