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, SCp->ptr, 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(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(SCpnt);
91
92	memset(scsi_pointer, 0, sizeof(struct scsi_pointer));
93
94	if (scsi_bufflen(SCpnt)) {
95		unsigned long len = 0;
96
97		scsi_pointer->buffer = scsi_sglist(SCpnt);
98		scsi_pointer->buffers_residual = scsi_sg_count(SCpnt) - 1;
99		scsi_pointer->ptr = sg_virt(scsi_pointer->buffer);
100		scsi_pointer->this_residual = scsi_pointer->buffer->length;
101		scsi_pointer->phase = scsi_bufflen(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(SCpnt);
110
111			scsi_for_each_sg(SCpnt, sg, sg_count, i)
112				len += sg->length;
113
114			if (scsi_bufflen(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