Re: [Xenomai-help] Omap3630, rtserial, xeno_16550A: crash on insmod

[Manfred <manfred@domain.hid>]

(In reply to Wolfgangs Respond)

Thank you for the explanations.
So I managed to recompile the kernel module with a lot of "printk"

commands. And I could track the problem to the following:
it fails in:[1]
int __init rt_16550_init(void)

When calling these lines:
rt_16550_reg_out(mode, base, IER, 0);
DEBUGPRINT("after reg_out IER \n");
rt_16550_reg_in(mode, base, IIR);
DEBUGPRINT("after reg_in IIR \n");

So it seems to fail the first time when it tries to call:
rt_16550_reg_in(mode, base, IIR);
where
mode=1
rt_16550_reg_in is defined in:
16550A_io.h:161:
static RT_16550_IO_INLINE u8
rt_16550_reg_in(io_mode_t io_mode, unsigned long base, int off)
{
	switch (io_mode) {
	case MODE_PIO:
		return inb(base + off);
	default: /* MODE_MMIO */
		return readb((void *)base + off);
	}
}

--> where is MODE_PIO defined?: is it 1 or 0?
(could not find it in any .c or .h file)

So anyway, it either fails in inb(base+off)
or (more probably:) in read(void*)base+off

-->
Is this consistent with your assumption that we need a regshift?
If yes, which function calls need to be fixed?
-->
I tried to look in 8250.c [2]:
regshift seems to be mostly used when using map_8250_in_reg and
map_8250_out_reg:
offset = map_8250_in_reg(p, offset) << p->regshift;
offset = map_8250_in_reg(p, offset) << p->regshift;
but also elsewhere:
2498 static unsigned int serial8250_port_size(struct uart_8250_port *pt)
2499 {
2500         if (pt->port.iotype == UPIO_AU)
2501                 return 0x1000;
2502 #ifdef CONFIG_ARCH_OMAP
2503         if (is_omap_port(pt))
2504                 return 0x16 << pt->port.regshift;
2505 #endif
2506         return 8 << pt->port.regshift;
2507 }
or:
2600 static void serial8250_release_rsa_resource(struct uart_8250_port *up)
2601 {
2602         unsigned long offset = UART_RSA_BASE << up->port.regshift;
2603         unsigned int size = 8 << up->port.regshift;
2604
2605         switch (up->port.iotype) {
2606         case UPIO_HUB6:
2607         case UPIO_PORT:
2608                 release_region(up->port.iobase + offset, size);
2609                 break;
2610         }
2611 }

-->
So can I just change the function in 16550A.c like this?:
rt_16550_reg_in(io_mode_t io_mode, unsigned long base, int off, int
regshift)
{
  	switch (io_mode) {
	case MODE_PIO:
		return inb(base + off);
	default: /* MODE_MMIO */
  		/* ADD REGSHIFT for MMIO Mode: */
  		unsigned long paddr=((void*)base+off)<< regshift;
  		return readb((void *)base + off);
	}
}

Thanks for the help.
Please note, this is really my first try on kernel modules and drivers,
So sorry, in case I got it all wrong.

--Manfred


[1]:
http://git.xenomai.org/?p=xenomai-2.6.git;a=blob;f=
ksrc/drivers/serial/16550A.c;h=8c8c86438874f03e4df17e6a2a1c02b9788f57b0;
hb=8f6feff876029244dabc1257cdf13209fbd64fb5
[2]:
http://www.sakoman.com/cgi-bin/gitweb.cgi?p=linux-omap-2.6.git;
a=blob_plain;f=drivers/tty/serial/8250.c;
hb=a6679de82eaa9128566dd5eea291afeb615764ea

 > On 1/13/12 8:37 AM, Wolfgang Grandegger wrote:
 >
 > The regshift is not yet supported. Therefore you need to adapt the
 > 16550A driver, preferably by using a module parameter.
 >
 >> The details of the addresses in omap3630/dm37x can be found here:
 >> http://www.ti.com/litv/pdf/sprugn4n
 >> Chapter 19: UART
 >> page 2950: UART Register Addresses.
 >
 > I looked to the Linux source code:
 >
 > http://lxr.linux.no/#linux+v3.2.1/arch/arm/mach-omap2/serial.c
 >
 > Therein I found the regshift=2. Adding some printk's would tell you
 > quickly what you need to get the serial uart running.
 >
 > Wolfgang.