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[POWERPC] Early serial debug support for PPC44x

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This adds support for early serial debugging via the built in
port on IBM/AMCC PowerPC 44x CPUs.  It uses a bolted TLB entry in
address space 1 for the UART's mapping, allowing robust debugging both
before and after the initialization of the MMU.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
David Gibson
2007-05-08 12:59:31 +10:00
committed by Paul Mackerras
parent f6dfc80554
commit d9b55a0361
9 changed files with 97 additions and 26 deletions
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23
arch/powerpc/kernel/udbg_16550.c
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@@ -191,3 +191,26 @@ void udbg_init_pas_realmode(void)
udbg_getc_poll = NULL;
}
#endif /* CONFIG_PPC_MAPLE */
#ifdef CONFIG_PPC_EARLY_DEBUG_44x
#include <platforms/44x/44x.h>
static void udbg_44x_as1_putc(char c)
{
if (udbg_comport) {
while ((as1_readb(&udbg_comport->lsr) & LSR_THRE) == 0)
/* wait for idle */;
as1_writeb(c, &udbg_comport->thr); eieio();
if (c == '\n')
udbg_44x_as1_putc('\r');
}
}
void __init udbg_init_44x_as1(void)
{
udbg_comport =
(volatile struct NS16550 __iomem *)PPC44x_EARLY_DEBUG_VIRTADDR;
udbg_putc = udbg_44x_as1_putc;
}
#endif /* CONFIG_PPC_EARLY_DEBUG_44x */