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