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Commit d9b55a03 authored by David Gibson's avatar David Gibson Committed by Paul Mackerras
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[POWERPC] Early serial debug support for PPC44x 



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: default avatarDavid Gibson <dwg@au1.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent f6dfc805

arch/powerpc/Kconfig.debug

+18 −4
Original line number Diff line number Diff line
@@ -139,10 +139,6 @@ config BOOTX_TEXT 
	  Say Y here to see progress messages from the boot firmware in text

	  mode. Requires either BootX or Open Firmware.



config SERIAL_TEXT_DEBUG

	bool "Support for early boot texts over serial port"

	depends on 4xx



config PPC_EARLY_DEBUG

	bool "Early debugging (dangerous)"
@@ -207,6 +203,24 @@ config PPC_EARLY_DEBUG_BEAT 
	help

	  Select this to enable early debugging for Celleb with Beat.



config PPC_EARLY_DEBUG_44x

	bool "Early serial debugging for IBM/AMCC 44x CPUs"

	depends on 44x

	select PPC_UDBG_16550

	help

	  Select this to enable early debugging for IBM 44x chips via the

	  inbuilt serial port.



endchoice



config PPC_EARLY_DEBUG_44x_PHYSLOW

	hex "Low 32 bits of early debug UART physical address"

	depends PPC_EARLY_DEBUG_44x

	default "0x40000200"



config PPC_EARLY_DEBUG_44x_PHYSHIGH

	hex "EPRN of early debug UART physical address"

	depends PPC_EARLY_DEBUG_44x

	default "0x1"



endmenu

arch/powerpc/kernel/head_44x.S

+13 −21
Original line number Diff line number Diff line
@@ -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);

arch/powerpc/kernel/of_platform.c

+0 −1
Original line number Diff line number Diff line
@@ -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.

arch/powerpc/kernel/udbg.c

+3 −0
Original line number Diff line number Diff line
@@ -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

}

arch/powerpc/kernel/udbg_16550.c

+23 −0
Original line number Diff line number Diff line
@@ -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 */