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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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34
arch/powerpc/kernel/head_44x.S
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@@ -172,36 +172,28 @@ skpinv: addi r4,r4,1 /* Increment */
isync
4:
#ifdef CONFIG_SERIAL_TEXT_DEBUG
/*
* Add temporary UART mapping for early debug.
* We can map UART registers wherever we want as long as they don't
* interfere with other system mappings (e.g. with pinned entries).
* For an example of how we handle this - see ocotea.h. --ebs
*/
#ifdef CONFIG_PPC_EARLY_DEBUG_44x
/* Add UART mapping for early debug. */
/* pageid fields */
lis r3,UART0_IO_BASE@h
ori r3,r3,PPC44x_TLB_VALID | PPC44x_TLB_4K
lis r3,PPC44x_EARLY_DEBUG_VIRTADDR@h
ori r3,r3,PPC44x_TLB_VALID|PPC44x_TLB_TS|PPC44x_TLB_64K
/* xlat fields */
lis r4,UART0_PHYS_IO_BASE@h /* RPN depends on SoC */
#ifndef CONFIG_440EP
ori r4,r4,0x0001 /* ERPN is 1 for second 4GB page */
#endif
lis r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW@h
ori r4,r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSHIGH
/* attrib fields */
li r5,0
ori r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_I | PPC44x_TLB_G)
li r5,(PPC44x_TLB_SW|PPC44x_TLB_SR|PPC44x_TLB_I|PPC44x_TLB_G)
li r0,62 /* TLB slot 0 */
li r0,0 /* TLB slot 0 */
tlbwe r3,r0,PPC44x_TLB_PAGEID /* Load the pageid fields */
tlbwe r4,r0,PPC44x_TLB_XLAT /* Load the translation fields */
tlbwe r5,r0,PPC44x_TLB_ATTRIB /* Load the attrib/access fields */
tlbwe r3,r0,PPC44x_TLB_PAGEID
tlbwe r4,r0,PPC44x_TLB_XLAT
tlbwe r5,r0,PPC44x_TLB_ATTRIB
/* Force context change */
isync
#endif /* CONFIG_SERIAL_TEXT_DEBUG */
#endif /* CONFIG_PPC_EARLY_DEBUG_44x */
/* Establish the interrupt vector offsets */
SET_IVOR(0, CriticalInput);

1
arch/powerpc/kernel/of_platform.c
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@@ -29,7 +29,6 @@
#include <asm/ppc-pci.h>
#include <asm/atomic.h>
/*
* The list of OF IDs below is used for matching bus types in the
* system whose devices are to be exposed as of_platform_devices.

3
arch/powerpc/kernel/udbg.c
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@@ -51,6 +51,9 @@ void __init udbg_early_init(void)
udbg_init_pas_realmode();
#elif defined(CONFIG_BOOTX_TEXT)
udbg_init_btext();
#elif defined(CONFIG_PPC_EARLY_DEBUG_44x)
/* PPC44x debug */
udbg_init_44x_as1();
#endif
}

23
arch/powerpc/kernel/udbg_16550.c
View File

@@ -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 */