3 * Erik Theisen, Wave 7 Optics, etheisen@mindspring.com
5 * SPDX-License-Identifier: GPL-2.0+
9 #if defined(CONFIG_4xx) && defined(CONFIG_CMD_SETGETDCR)
11 #include <asm/ppc4xx.h>
13 #define _LINUX_CONFIG_H 1 /* avoid reading Linux autoconf.h file */
15 #include <ppc_asm.tmpl>
18 #include <asm/cache.h>
23 /*****************************************************************************
26 * These routines make use of self modifying code. DO NOT CALL THEM
27 * UNTIL THEY ARE RELOCATED TO RAM. Additionally, I do not
28 * recommend them for use in anything other than an interactive
29 * debugging environment. This is mainly due to performance reasons.
31 ****************************************************************************/
34 * static void _create_MFDCR(unsigned short dcrn)
36 * Builds a 'mfdcr' instruction for get_dcr
41 .type _create_MFDCR,@function
44 * Build up a 'mfdcr' instruction formatted as follows:
46 * OPCD | RT | DCRF | XO | CR |
47 * ---------------|--------------|--------------|----|
48 * 0 5 | 6 10 | 11 20 | 21 30 | 31 |
50 * 31 | %r3 | (5..9|0..4) | 323 | 0 |
54 * RT = destination register - %r3 return register
55 * DCRF = DCRN # with upper and lower halves swapped
56 * XO = extended opcode - 323
57 * CR = CR[CR0] NOT undefined - 0
59 rlwinm r0, r3, 27, 27, 31 /* OPCD = 31 */
60 rlwinm r3, r3, 5, 22, 26
63 oris r3, r3, 0x3e30 /* RT = %r3 */
64 ori r3, r3, 323 /* XO = 323 */
65 slwi r3, r3, 1 /* CR = 0 */
68 stw r3, 0(r4) /* Store instr in get_dcr() */
69 dcbst r0, r4 /* Make sure val is written out */
70 sync /* Wait for write to complete */
71 icbi r0, r4 /* Make sure old instr is dumped */
72 isync /* Wait for icbi to complete */
75 .Lfe1: .size _create_MFDCR,.Lfe1-_create_MFDCR
76 /* end _create_MFDCR() */
79 * static void _create_MTDCR(unsigned short dcrn, unsigned long value)
81 * Builds a 'mtdcr' instruction for set_dcr
86 .type _create_MTDCR,@function
89 * Build up a 'mtdcr' instruction formatted as follows:
91 * OPCD | RS | DCRF | XO | CR |
92 * ---------------|--------------|--------------|----|
93 * 0 5 | 6 10 | 11 20 | 21 30 | 31 |
95 * 31 | %r3 | (5..9|0..4) | 451 | 0 |
99 * RS = source register - %r4
100 * DCRF = dest. DCRN # with upper and lower halves swapped
101 * XO = extended opcode - 451
102 * CR = CR[CR0] NOT undefined - 0
104 rlwinm r0, r3, 27, 27, 31 /* OPCD = 31 */
105 rlwinm r3, r3, 5, 22, 26
108 oris r3, r3, 0x3e40 /* RS = %r4 */
109 ori r3, r3, 451 /* XO = 451 */
110 slwi r3, r3, 1 /* CR = 0 */
113 stw r3, 0(r5) /* Store instr in set_dcr() */
114 dcbst r0, r5 /* Make sure val is written out */
115 sync /* Wait for write to complete */
116 icbi r0, r5 /* Make sure old instr is dumped */
117 isync /* Wait for icbi to complete */
120 .Lfe2: .size _create_MTDCR,.Lfe2-_create_MTDCR
121 /* end _create_MTDCR() */
125 * unsigned long get_dcr(unsigned short dcrn)
127 * Return a given DCR's value.
130 /* XXX - This is self modifying code, hence */
131 /* it is in the data section. */
136 .type get_dcr,@function
138 mflr r0 /* Get link register */
139 stwu r1, -32(r1) /* Save back chain and move SP */
140 stw r0, +36(r1) /* Save link register */
142 bl _create_MFDCR /* Build following instruction */
143 /* XXX - we build this instuction up on the fly. */
144 .long 0 /* Get DCR's value */
146 lwz r0, +36(r1) /* Get saved link register */
147 mtlr r0 /* Restore link register */
148 addi r1, r1, +32 /* Remove frame from stack */
149 blr /* Return to calling function */
150 .Lfe3: .size get_dcr,.Lfe3-get_dcr
155 * unsigned void set_dcr(unsigned short dcrn, unsigned long value)
157 * Return a given DCR's value.
160 * XXX - This is self modifying code, hence
161 * it is in the data section.
166 .type set_dcr,@function
168 mflr r0 /* Get link register */
169 stwu r1, -32(r1) /* Save back chain and move SP */
170 stw r0, +36(r1) /* Save link register */
172 bl _create_MTDCR /* Build following instruction */
173 /* XXX - we build this instuction up on the fly. */
174 .long 0 /* Set DCR's value */
176 lwz r0, +36(r1) /* Get saved link register */
177 mtlr r0 /* Restore link register */
178 addi r1, r1, +32 /* Remove frame from stack */
179 blr /* Return to calling function */
180 .Lfe4: .size set_dcr,.Lfe4-set_dcr