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 
12 struct arm_cmd_priv {
13 	struct scsi_pointer scsi_pointer;
14 };
15 
arm_scsi_pointer(struct scsi_cmnd * cmd)16 static 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  */
copy_SCp_to_sg(struct scatterlist * sg,struct scsi_pointer * SCp,int max)33 static 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 
next_SCp(struct scsi_pointer * SCp)56 static 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 
get_next_SCp_byte(struct scsi_pointer * SCp)71 static 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 
put_next_SCp_byte(struct scsi_pointer * SCp,unsigned char c)81 static 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 
init_SCp(struct scsi_cmnd * SCpnt)88 static 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