From 78d705e3be4bfbd2e75157d284096d600ea6eda5 Mon Sep 17 00:00:00 2001
From: Greg Ungerer <gerg@uclinux.org>
Date: Fri, 14 Oct 2011 16:43:15 +1000
Subject: [PATCH] m68k: add ColdFire paging exception handling code

Add code to traps.c to handle MMU exceptions for the ColdFire.
Most of this code is from the 2.6.25 kernel BSP code released by
Freescale.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Matt Waddel <mwaddel@yahoo.com>
Acked-by: Kurt Mahan <kmahan@xmission.com>
---
 arch/m68k/kernel/traps.c | 104 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/arch/m68k/kernel/traps.c b/arch/m68k/kernel/traps.c
index 89362f2bb56..a76452ca964 100644
--- a/arch/m68k/kernel/traps.c
+++ b/arch/m68k/kernel/traps.c
@@ -706,6 +706,88 @@ create_atc_entry:
 #endif /* CPU_M68020_OR_M68030 */
 #endif /* !CONFIG_SUN3 */
 
+#if defined(CONFIG_COLDFIRE) && defined(CONFIG_MMU)
+#include <asm/mcfmmu.h>
+
+/*
+ *	The following table converts the FS encoding of a ColdFire
+ *	exception stack frame into the error_code value needed by
+ *	do_fault.
+*/
+static const unsigned char fs_err_code[] = {
+	0,  /* 0000 */
+	0,  /* 0001 */
+	0,  /* 0010 */
+	0,  /* 0011 */
+	1,  /* 0100 */
+	0,  /* 0101 */
+	0,  /* 0110 */
+	0,  /* 0111 */
+	2,  /* 1000 */
+	3,  /* 1001 */
+	2,  /* 1010 */
+	0,  /* 1011 */
+	1,  /* 1100 */
+	1,  /* 1101 */
+	0,  /* 1110 */
+	0   /* 1111 */
+};
+
+static inline void access_errorcf(unsigned int fs, struct frame *fp)
+{
+	unsigned long mmusr, addr;
+	unsigned int err_code;
+	int need_page_fault;
+
+	mmusr = mmu_read(MMUSR);
+	addr = mmu_read(MMUAR);
+
+	/*
+	 * error_code:
+	 *	bit 0 == 0 means no page found, 1 means protection fault
+	 *	bit 1 == 0 means read, 1 means write
+	 */
+	switch (fs) {
+	case  5:  /* 0101 TLB opword X miss */
+		need_page_fault = cf_tlb_miss(&fp->ptregs, 0, 0, 0);
+		addr = fp->ptregs.pc;
+		break;
+	case  6:  /* 0110 TLB extension word X miss */
+		need_page_fault = cf_tlb_miss(&fp->ptregs, 0, 0, 1);
+		addr = fp->ptregs.pc + sizeof(long);
+		break;
+	case 10:  /* 1010 TLB W miss */
+		need_page_fault = cf_tlb_miss(&fp->ptregs, 1, 1, 0);
+		break;
+	case 14: /* 1110 TLB R miss */
+		need_page_fault = cf_tlb_miss(&fp->ptregs, 0, 1, 0);
+		break;
+	default:
+		/* 0000 Normal  */
+		/* 0001 Reserved */
+		/* 0010 Interrupt during debug service routine */
+		/* 0011 Reserved */
+		/* 0100 X Protection */
+		/* 0111 IFP in emulator mode */
+		/* 1000 W Protection*/
+		/* 1001 Write error*/
+		/* 1011 Reserved*/
+		/* 1100 R Protection*/
+		/* 1101 R Protection*/
+		/* 1111 OEP in emulator mode*/
+		need_page_fault = 1;
+		break;
+	}
+
+	if (need_page_fault) {
+		err_code = fs_err_code[fs];
+		if ((fs == 13) && (mmusr & MMUSR_WF)) /* rd-mod-wr access */
+			err_code |= 2; /* bit1 - write, bit0 - protection */
+		do_page_fault(&fp->ptregs, addr, err_code);
+	}
+}
+#endif /* CONFIG_COLDFIRE CONFIG_MMU */
+
 asmlinkage void buserr_c(struct frame *fp)
 {
 	/* Only set esp0 if coming from user mode */
@@ -716,6 +798,28 @@ asmlinkage void buserr_c(struct frame *fp)
 	printk ("*** Bus Error *** Format is %x\n", fp->ptregs.format);
 #endif
 
+#if defined(CONFIG_COLDFIRE) && defined(CONFIG_MMU)
+	if (CPU_IS_COLDFIRE) {
+		unsigned int fs;
+		fs = (fp->ptregs.vector & 0x3) |
+			((fp->ptregs.vector & 0xc00) >> 8);
+		switch (fs) {
+		case 0x5:
+		case 0x6:
+		case 0x7:
+		case 0x9:
+		case 0xa:
+		case 0xd:
+		case 0xe:
+		case 0xf:
+			access_errorcf(fs, fp);
+			return;
+		default:
+			break;
+		}
+	}
+#endif /* CONFIG_COLDFIRE && CONFIG_MMU */
+
 	switch (fp->ptregs.format) {
 #if defined (CONFIG_M68060)
 	case 4:				/* 68060 access error */