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}