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 #include <ppc_asm.tmpl>
16 #include <asm/cache.h>
21 /*****************************************************************************
24 * These routines make use of self modifying code. DO NOT CALL THEM
25 * UNTIL THEY ARE RELOCATED TO RAM. Additionally, I do not
26 * recommend them for use in anything other than an interactive
27 * debugging environment. This is mainly due to performance reasons.
29 ****************************************************************************/
32 * static void _create_MFDCR(unsigned short dcrn)
34 * Builds a 'mfdcr' instruction for get_dcr
39 .type _create_MFDCR,@function
42 * Build up a 'mfdcr' instruction formatted as follows:
44 * OPCD | RT | DCRF | XO | CR |
45 * ---------------|--------------|--------------|----|
46 * 0 5 | 6 10 | 11 20 | 21 30 | 31 |
48 * 31 | %r3 | (5..9|0..4) | 323 | 0 |
52 * RT = destination register - %r3 return register
53 * DCRF = DCRN # with upper and lower halves swapped
54 * XO = extended opcode - 323
55 * CR = CR[CR0] NOT undefined - 0
57 rlwinm r0, r3, 27, 27, 31 /* OPCD = 31 */
58 rlwinm r3, r3, 5, 22, 26
61 oris r3, r3, 0x3e30 /* RT = %r3 */
62 ori r3, r3, 323 /* XO = 323 */
63 slwi r3, r3, 1 /* CR = 0 */
66 stw r3, 0(r4) /* Store instr in get_dcr() */
67 dcbst r0, r4 /* Make sure val is written out */
68 sync /* Wait for write to complete */
69 icbi r0, r4 /* Make sure old instr is dumped */
70 isync /* Wait for icbi to complete */
73 .Lfe1: .size _create_MFDCR,.Lfe1-_create_MFDCR
74 /* end _create_MFDCR() */
77 * static void _create_MTDCR(unsigned short dcrn, unsigned long value)
79 * Builds a 'mtdcr' instruction for set_dcr
84 .type _create_MTDCR,@function
87 * Build up a 'mtdcr' instruction formatted as follows:
89 * OPCD | RS | DCRF | XO | CR |
90 * ---------------|--------------|--------------|----|
91 * 0 5 | 6 10 | 11 20 | 21 30 | 31 |
93 * 31 | %r3 | (5..9|0..4) | 451 | 0 |
97 * RS = source register - %r4
98 * DCRF = dest. DCRN # with upper and lower halves swapped
99 * XO = extended opcode - 451
100 * CR = CR[CR0] NOT undefined - 0
102 rlwinm r0, r3, 27, 27, 31 /* OPCD = 31 */
103 rlwinm r3, r3, 5, 22, 26
106 oris r3, r3, 0x3e40 /* RS = %r4 */
107 ori r3, r3, 451 /* XO = 451 */
108 slwi r3, r3, 1 /* CR = 0 */
111 stw r3, 0(r5) /* Store instr in set_dcr() */
112 dcbst r0, r5 /* Make sure val is written out */
113 sync /* Wait for write to complete */
114 icbi r0, r5 /* Make sure old instr is dumped */
115 isync /* Wait for icbi to complete */
118 .Lfe2: .size _create_MTDCR,.Lfe2-_create_MTDCR
119 /* end _create_MTDCR() */
123 * unsigned long get_dcr(unsigned short dcrn)
125 * Return a given DCR's value.
128 /* XXX - This is self modifying code, hence */
129 /* it is in the data section. */
134 .type get_dcr,@function
136 mflr r0 /* Get link register */
137 stwu r1, -32(r1) /* Save back chain and move SP */
138 stw r0, +36(r1) /* Save link register */
140 bl _create_MFDCR /* Build following instruction */
141 /* XXX - we build this instuction up on the fly. */
142 .long 0 /* Get DCR's value */
144 lwz r0, +36(r1) /* Get saved link register */
145 mtlr r0 /* Restore link register */
146 addi r1, r1, +32 /* Remove frame from stack */
147 blr /* Return to calling function */
148 .Lfe3: .size get_dcr,.Lfe3-get_dcr
153 * unsigned void set_dcr(unsigned short dcrn, unsigned long value)
155 * Return a given DCR's value.
158 * XXX - This is self modifying code, hence
159 * it is in the data section.
164 .type set_dcr,@function
166 mflr r0 /* Get link register */
167 stwu r1, -32(r1) /* Save back chain and move SP */
168 stw r0, +36(r1) /* Save link register */
170 bl _create_MTDCR /* Build following instruction */
171 /* XXX - we build this instuction up on the fly. */
172 .long 0 /* Set DCR's value */
174 lwz r0, +36(r1) /* Get saved link register */
175 mtlr r0 /* Restore link register */
176 addi r1, r1, +32 /* Remove frame from stack */
177 blr /* Return to calling function */
178 .Lfe4: .size set_dcr,.Lfe4-set_dcr