1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Copyright (C) 2002 Russell King
4 *
5 * Commonly used functions by the ARM SCSI-II drivers.
6 */
7
8#include <linux/scatterlist.h>
9
10#define BELT_AND_BRACES
11
12struct arm_cmd_priv {
13 struct scsi_pointer scsi_pointer;
14};
15
16static inline struct scsi_pointer *arm_scsi_pointer(struct scsi_cmnd *cmd)
17{
18 struct arm_cmd_priv *acmd = scsi_cmd_priv(cmd);
19
20 return &acmd->scsi_pointer;
21}
22
23/*
24 * The scatter-gather list handling. This contains all
25 * the yucky stuff that needs to be fixed properly.
26 */
27
28/*
29 * copy_SCp_to_sg() Assumes contiguous allocation at @sg of at-most @max
30 * entries of uninitialized memory. SCp is from scsi-ml and has a valid
31 * (possibly chained) sg-list
32 */
33static inline int copy_SCp_to_sg(struct scatterlist *sg, struct scsi_pointer *SCp, int max)
34{
35 int bufs = SCp->buffers_residual;
36
37 /* FIXME: It should be easy for drivers to loop on copy_SCp_to_sg().
38 * and to remove this BUG_ON. Use min() in-its-place
39 */
40 BUG_ON(bufs + 1 > max);
41
42 sg_set_buf(sg, buf: SCp->ptr, buflen: SCp->this_residual);
43
44 if (bufs) {
45 struct scatterlist *src_sg;
46 unsigned i;
47
48 for_each_sg(sg_next(SCp->buffer), src_sg, bufs, i)
49 *(++sg) = *src_sg;
50 sg_mark_end(sg);
51 }
52
53 return bufs + 1;
54}
55
56static inline int next_SCp(struct scsi_pointer *SCp)
57{
58 int ret = SCp->buffers_residual;
59 if (ret) {
60 SCp->buffer = sg_next(SCp->buffer);
61 SCp->buffers_residual--;
62 SCp->ptr = sg_virt(sg: SCp->buffer);
63 SCp->this_residual = SCp->buffer->length;
64 } else {
65 SCp->ptr = NULL;
66 SCp->this_residual = 0;
67 }
68 return ret;
69}
70
71static inline unsigned char get_next_SCp_byte(struct scsi_pointer *SCp)
72{
73 char c = *SCp->ptr;
74
75 SCp->ptr += 1;
76 SCp->this_residual -= 1;
77
78 return c;
79}
80
81static inline void put_next_SCp_byte(struct scsi_pointer *SCp, unsigned char c)
82{
83 *SCp->ptr = c;
84 SCp->ptr += 1;
85 SCp->this_residual -= 1;
86}
87
88static inline void init_SCp(struct scsi_cmnd *SCpnt)
89{
90 struct scsi_pointer *scsi_pointer = arm_scsi_pointer(cmd: SCpnt);
91
92 memset(scsi_pointer, 0, sizeof(struct scsi_pointer));
93
94 if (scsi_bufflen(cmd: SCpnt)) {
95 unsigned long len = 0;
96
97 scsi_pointer->buffer = scsi_sglist(cmd: SCpnt);
98 scsi_pointer->buffers_residual = scsi_sg_count(cmd: SCpnt) - 1;
99 scsi_pointer->ptr = sg_virt(sg: scsi_pointer->buffer);
100 scsi_pointer->this_residual = scsi_pointer->buffer->length;
101 scsi_pointer->phase = scsi_bufflen(cmd: SCpnt);
102
103#ifdef BELT_AND_BRACES
104 { /*
105 * Calculate correct buffer length. Some commands
106 * come in with the wrong scsi_bufflen.
107 */
108 struct scatterlist *sg;
109 unsigned i, sg_count = scsi_sg_count(cmd: SCpnt);
110
111 scsi_for_each_sg(SCpnt, sg, sg_count, i)
112 len += sg->length;
113
114 if (scsi_bufflen(cmd: SCpnt) != len) {
115 printk(KERN_WARNING
116 "scsi%d.%c: bad request buffer "
117 "length %d, should be %ld\n",
118 SCpnt->device->host->host_no,
119 '0' + SCpnt->device->id,
120 scsi_bufflen(SCpnt), len);
121 /*
122 * FIXME: Totaly naive fixup. We should abort
123 * with error
124 */
125 scsi_pointer->phase =
126 min_t(unsigned long, len,
127 scsi_bufflen(SCpnt));
128 }
129 }
130#endif
131 } else {
132 scsi_pointer->ptr = NULL;
133 scsi_pointer->this_residual = 0;
134 scsi_pointer->phase = 0;
135 }
136}
137

source code of linux/drivers/scsi/arm/arm_scsi.h