Commit f4151b9b authored by Stefan Roese's avatar Stefan Roese Committed by Josh Boyer
Browse files

[POWERPC] 4xx: Fix TLB 0 problem with CONFIG_SERIAL_TEXT_DEBUG 



Right now TLB entry 0 ist used as UART0 mapping for the early debug
output (via CONFIG_SERIAL_TEXT_DEBUG). This causes problems when many
TLB's get used upon Linux bootup (e.g. while PCIe scanning behind
bridges and/or switches on 440SPe platforms). This will overwrite the
TLB 0 entry and further debug output's may crash/hang the system.

This patch moves the early debug UART0 TLB entry from 0 to 62 as done
in arch/powerpc. This way it is in the "pinned" area and will not get
overwritten. Also the arch/ppc/mm/44x_mmu.c code is now synced with the
newer code from arch/powerpc.

Signed-off-by: default avatarStefan Roese <sr@denx.de>
Signed-off-by: default avatarJosh Boyer <jwboyer@linux.vnet.ibm.com>
parent 4922566f

arch/ppc/kernel/head_44x.S

+1 −1
Original line number Diff line number Diff line
@@ -195,7 +195,7 @@ skpinv: addi r4,r4,1 /* Increment */ 
	li	r5,0

	ori	r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_I | PPC44x_TLB_G)



        li      r0,0                    /* TLB slot 0 */

	li	r0,62			/* TLB slot 62 */



	tlbwe	r3,r0,PPC44x_TLB_PAGEID	/* Load the pageid fields */

	tlbwe	r4,r0,PPC44x_TLB_XLAT	/* Load the translation fields */

arch/ppc/mm/44x_mmu.c

+16 −35
Original line number Diff line number Diff line
@@ -60,38 +60,28 @@ extern char etext[], _stext[]; 
 * Just needed it declared someplace.

 */

unsigned int tlb_44x_index = 0;

unsigned int tlb_44x_hwater = 62;

unsigned int tlb_44x_hwater = PPC4XX_TLB_SIZE - 1 - PPC44x_EARLY_TLBS;

int icache_44x_need_flush;



/*

 * "Pins" a 256MB TLB entry in AS0 for kernel lowmem

 */

static void __init

ppc44x_pin_tlb(int slot, unsigned int virt, unsigned int phys)

static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)

{

	unsigned long attrib = 0;



	__asm__ __volatile__("\

	clrrwi	%2,%2,10\n\

	ori	%2,%2,%4\n\

	clrrwi	%1,%1,10\n\

	li	%0,0\n\

	ori	%0,%0,%5\n\

	tlbwe	%2,%3,%6\n\

	tlbwe	%1,%3,%7\n\

	tlbwe	%0,%3,%8"

	__asm__ __volatile__(

		"tlbwe	%2,%3,%4\n"

		"tlbwe	%1,%3,%5\n"

		"tlbwe	%0,%3,%6\n"

	:

	: "r" (attrib), "r" (phys), "r" (virt), "r" (slot),

	  "i" (PPC44x_TLB_VALID | PPC44x_TLB_256M),

	  "i" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),

	: "r" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),

	  "r" (phys),

	  "r" (virt | PPC44x_TLB_VALID | PPC44x_TLB_256M),

	  "r" (tlb_44x_hwater--), /* slot for this TLB entry */

	  "i" (PPC44x_TLB_PAGEID),

	  "i" (PPC44x_TLB_XLAT),

	  "i" (PPC44x_TLB_ATTRIB));

}



/*

 * MMU_init_hw does the chip-specific initialization of the MMU hardware.

 */

void __init MMU_init_hw(void)

{

	flush_instruction_cache();
@@ -99,22 +89,13 @@ void __init MMU_init_hw(void) 


unsigned long __init mmu_mapin_ram(void)

{

	unsigned int pinned_tlbs = 1;

	int i;

	unsigned long addr;



	/* Determine number of entries necessary to cover lowmem */

	pinned_tlbs = (unsigned int)

		(_ALIGN(total_lowmem, PPC_PIN_SIZE) >> PPC44x_PIN_SHIFT);



	/* Write upper watermark to save location */

	tlb_44x_hwater = PPC44x_LOW_SLOT - pinned_tlbs;



	/* If necessary, set additional pinned TLBs */

	if (pinned_tlbs > 1)

		for (i = (PPC44x_LOW_SLOT-(pinned_tlbs-1)); i < PPC44x_LOW_SLOT; i++) {

			unsigned int phys_addr = (PPC44x_LOW_SLOT-i) * PPC_PIN_SIZE;

			ppc44x_pin_tlb(i, phys_addr+PAGE_OFFSET, phys_addr);

		}

	/* Pin in enough TLBs to cover any lowmem not covered by the

	 * initial 256M mapping established in head_44x.S */

	for (addr = PPC_PIN_SIZE; addr < total_lowmem;

	     addr += PPC_PIN_SIZE)

		ppc44x_pin_tlb(addr + PAGE_OFFSET, addr);



	return total_lowmem;

}

include/asm-ppc/mmu.h

+6 −0
Original line number Diff line number Diff line
@@ -383,6 +383,12 @@ typedef struct _P601_BAT { 
#define BOOKE_PAGESZ_256GB	14

#define BOOKE_PAGESZ_1TB	15



#ifndef CONFIG_SERIAL_TEXT_DEBUG

#define PPC44x_EARLY_TLBS	1

#else

#define PPC44x_EARLY_TLBS	2

#endif



/*

 * Freescale Book-E MMU support

 */