Initial revision

cpu/ppc4xx/dcr.S

@@ -0,0 +1,198 @@
+/*
+ * (C) Copyright 2001
+ * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+#include <config.h>
+
+#if defined(CONFIG_4xx) && defined(CFG_CMD_SETGETDCR)
+
+#include <ppc4xx.h>
+
+#define _LINUX_CONFIG_H 1       /* avoid reading Linux autoconf.h file  */
+
+#include <ppc_asm.tmpl>
+#include <ppc_defs.h>
+
+#include <asm/cache.h>
+#include <asm/mmu.h>
+
+#define _ASMLANGUAGE
+
+/*****************************************************************************
+ *
+ *  XXX - DANGER
+ *        These routines make use of self modifying code.  DO NOT CALL THEM
+ *	  UNTIL THEY ARE RELOCATED TO RAM.  Additionally, I do not
+ *	  recommend them for use in anything other than an interactive
+ *        debugging environment.  This is mainly due to performance reasons.
+ *
+ ****************************************************************************/
+
+/*
+ * static void _create_MFDCR(unsigned short dcrn)
+ *
+ * Builds a 'mfdcr' instruction for get_dcr
+ * function.
+ */
+		.section ".text"
+		.align 2
+		.type	 _create_MFDCR,@function
+_create_MFDCR:
+		/*
+		 * Build up a 'mfdcr' instruction formatted as follows:
+		 *
+		 *  OPCD |   RT   |    DCRF      |     XO       | CR |
+		 * ---------------|--------------|--------------|----|
+		 * 0   5 | 6   10 | 11        20 | 21        30 | 31 |
+		 *       |        |    DCRN      |              |    |
+		 *   31  |  %r3   | (5..9|0..4)  |      323     |  0 |
+		 *
+		 * Where:
+		 *	OPCD = opcode - 31
+		 *	RT   = destination register - %r3 return register
+		 *	DCRF = DCRN # with upper and lower halves swapped
+		 *	XO   = extended opcode - 323
+		 *	CR   = CR[CR0] NOT undefined - 0
+		 */
+		rlwinm	r0, r3, 27, 27, 31	/* OPCD = 31 */
+		rlwinm	r3, r3, 5, 22, 26
+		or	r3, r3, r0
+		slwi	r3, r3, 10
+		oris	r3, r3, 0x3e30		/* RT = %r3 */
+		ori	r3, r3, 323		/* XO = 323 */
+		slwi	r3, r3, 1		/* CR = 0 */
+
+		mflr	r4
+		stw	r3, 0(r4)		/* Store instr in get_dcr() */
+		dcbst	r0, r4			/* Make sure val is written out */
+		sync				/* Wait for write to complete */
+		icbi	r0, r4			/* Make sure old instr is dumped */
+		isync				/* Wait for icbi to complete */
+
+		blr
+.Lfe1:		.size	 _create_MFDCR,.Lfe1-_create_MFDCR
+/* end _create_MFDCR() */
+
+/*
+ * static void _create_MTDCR(unsigned short dcrn, unsigned long value)
+ *
+ * Builds a 'mtdcr' instruction for set_dcr
+ * function.
+ */
+		.section ".text"
+		.align 2
+		.type	 _create_MTDCR,@function
+_create_MTDCR:
+		/*
+		 * Build up a 'mtdcr' instruction formatted as follows:
+		 *
+		 *  OPCD |   RS   |    DCRF      |     XO       | CR |
+		 * ---------------|--------------|--------------|----|
+		 * 0   5 | 6   10 | 11        20 | 21        30 | 31 |
+		 *       |        |    DCRN      |              |    |
+		 *   31  |  %r3   | (5..9|0..4)  |      451     |  0 |
+		 *
+		 * Where:
+		 *	OPCD = opcode - 31
+		 *	RS   = source register - %r4
+		 *	DCRF = dest. DCRN # with upper and lower halves swapped
+		 *	XO   = extended opcode - 451
+		 *	CR   = CR[CR0] NOT undefined - 0
+		 */
+		rlwinm	r0, r3, 27, 27, 31	/* OPCD = 31 */
+		rlwinm	r3, r3, 5, 22, 26
+		or	r3, r3, r0
+		slwi	r3, r3, 10
+		oris	r3, r3, 0x3e40		/* RS = %r4 */
+		ori	r3, r3, 451		/* XO = 451 */
+		slwi	r3, r3, 1		/* CR = 0 */
+
+		mflr	r5
+		stw	r3, 0(r5)		/* Store instr in set_dcr() */
+		dcbst	r0, r5			/* Make sure val is written out */
+		sync				/* Wait for write to complete */
+		icbi	r0, r5			/* Make sure old instr is dumped */
+		isync				/* Wait for icbi to complete */
+
+		blr
+.Lfe2:		.size	 _create_MTDCR,.Lfe2-_create_MTDCR
+/* end _create_MTDCR() */
+
+
+/*
+ * unsigned long get_dcr(unsigned short dcrn)
+ *
+ * Return a given DCR's value.
+ */
+		/* */
+		/* XXX - This is self modifying code, hence */
+		/* it is in the data section. */
+		/* */
+		.section ".data"
+		.align	2
+		.globl	get_dcr
+		.type	get_dcr,@function
+get_dcr:
+		mflr	r0			/* Get link register */
+		stwu	r1, -32(r1)		/* Save back chain and move SP */
+		stw	r0, +36(r1)		/* Save link register */
+
+		bl	_create_MFDCR		/* Build following instruction */
+		/* XXX - we build this instuction up on the fly. */
+		.long	0			/* Get DCR's value */
+
+		lwz	r0, +36(r1)		/* Get saved link register */
+		mtlr	r0			/* Restore link register */
+		addi	r1, r1, +32		/* Remove frame from stack */
+		blr				/* Return to calling function */
+.Lfe3:		.size	get_dcr,.Lfe3-get_dcr
+/* end get_dcr() */
+
+
+/*
+ * unsigned void set_dcr(unsigned short dcrn, unsigned long value)
+ *
+ * Return a given DCR's value.
+ */
+		/*
+		 * XXX - This is self modifying code, hence
+		 * it is in the data section.
+		 */
+		.section ".data"
+		.align	2
+		.globl	set_dcr
+		.type	set_dcr,@function
+set_dcr:
+		mflr	r0			/* Get link register */
+		stwu	r1, -32(r1)		/* Save back chain and move SP */
+		stw	r0, +36(r1)		/* Save link register */
+
+		bl	_create_MTDCR		/* Build following instruction */
+		/* XXX - we build this instuction up on the fly. */
+		.long	0			/* Set DCR's value */
+
+		lwz	r0, +36(r1)		/* Get saved link register */
+		mtlr	r0			/* Restore link register */
+		addi	r1, r1, +32		/* Remove frame from stack */
+		blr				/* Return to calling function */
+.Lfe4:		.size	set_dcr,.Lfe4-set_dcr
+/* end set_dcr() */
+#endif /* CONFIG_4xx & CFG_CMD_SETGETDCR */