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v5.4
  1/*
 
 
  2 * TILER container manager specification and support functions for TI
  3 * TILER driver.
  4 *
  5 * Author: Lajos Molnar <molnar@ti.com>
  6 *
  7 * All rights reserved.
  8 *
  9 * Redistribution and use in source and binary forms, with or without
 10 * modification, are permitted provided that the following conditions
 11 * are met:
 12 *
 13 * * Redistributions of source code must retain the above copyright
 14 *   notice, this list of conditions and the following disclaimer.
 15 *
 16 * * Redistributions in binary form must reproduce the above copyright
 17 *   notice, this list of conditions and the following disclaimer in the
 18 *   documentation and/or other materials provided with the distribution.
 19 *
 20 * * Neither the name of Texas Instruments Incorporated nor the names of
 21 *   its contributors may be used to endorse or promote products derived
 22 *   from this software without specific prior written permission.
 23 *
 24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 26 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 27 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 28 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 29 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 30 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 31 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 32 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 33 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 34 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 35 */
 36
 37#ifndef TCM_H
 38#define TCM_H
 39
 40struct tcm;
 41
 42/* point */
 43struct tcm_pt {
 44	u16 x;
 45	u16 y;
 46};
 47
 48/* 1d or 2d area */
 49struct tcm_area {
 50	bool is2d;		/* whether area is 1d or 2d */
 51	struct tcm    *tcm;	/* parent */
 52	struct tcm_pt  p0;
 53	struct tcm_pt  p1;
 54};
 55
 56struct tcm {
 57	u16 width, height;	/* container dimensions */
 58	int lut_id;		/* Lookup table identifier */
 59
 60	unsigned int y_offset;	/* offset to use for y coordinates */
 61
 62	spinlock_t lock;
 63	unsigned long *bitmap;
 64	size_t map_size;
 
 
 65
 66	/* function table */
 67	s32 (*reserve_2d)(struct tcm *tcm, u16 height, u16 width, u16 align,
 68			  s16 offset, u16 slot_bytes,
 69			  struct tcm_area *area);
 70	s32 (*reserve_1d)(struct tcm *tcm, u32 slots, struct tcm_area *area);
 71	s32 (*free)(struct tcm *tcm, struct tcm_area *area);
 72	void (*deinit)(struct tcm *tcm);
 73};
 74
 75/*=============================================================================
 76    BASIC TILER CONTAINER MANAGER INTERFACE
 77=============================================================================*/
 78
 79/*
 80 * NOTE:
 81 *
 82 * Since some basic parameter checking is done outside the TCM algorithms,
 83 * TCM implementation do NOT have to check the following:
 84 *
 85 *   area pointer is NULL
 86 *   width and height fits within container
 87 *   number of pages is more than the size of the container
 88 *
 89 */
 90
 91struct tcm *sita_init(u16 width, u16 height);
 92
 93
 94/**
 95 * Deinitialize tiler container manager.
 96 *
 97 * @param tcm	Pointer to container manager.
 98 *
 99 * @return 0 on success, non-0 error value on error.  The call
100 *	   should free as much memory as possible and meaningful
101 *	   even on failure.  Some error codes: -ENODEV: invalid
102 *	   manager.
103 */
104static inline void tcm_deinit(struct tcm *tcm)
105{
106	if (tcm)
107		tcm->deinit(tcm);
108}
109
110/**
111 * Reserves a 2D area in the container.
112 *
113 * @param tcm		Pointer to container manager.
114 * @param height	Height(in pages) of area to be reserved.
115 * @param width		Width(in pages) of area to be reserved.
116 * @param align		Alignment requirement for top-left corner of area. Not
117 *			all values may be supported by the container manager,
118 *			but it must support 0 (1), 32 and 64.
119 *			0 value is equivalent to 1.
120 * @param offset	Offset requirement, in bytes.  This is the offset
121 *			from a 4KiB aligned virtual address.
122 * @param slot_bytes	Width of slot in bytes
123 * @param area		Pointer to where the reserved area should be stored.
124 *
125 * @return 0 on success.  Non-0 error code on failure.  Also,
126 *	   the tcm field of the area will be set to NULL on
127 *	   failure.  Some error codes: -ENODEV: invalid manager,
128 *	   -EINVAL: invalid area, -ENOMEM: not enough space for
129 *	    allocation.
130 */
131static inline s32 tcm_reserve_2d(struct tcm *tcm, u16 width, u16 height,
132				u16 align, s16 offset, u16 slot_bytes,
133				struct tcm_area *area)
134{
135	/* perform rudimentary error checking */
136	s32 res = tcm  == NULL ? -ENODEV :
137		(area == NULL || width == 0 || height == 0 ||
138		 /* align must be a 2 power */
139		 (align & (align - 1))) ? -EINVAL :
140		(height > tcm->height || width > tcm->width) ? -ENOMEM : 0;
141
142	if (!res) {
143		area->is2d = true;
144		res = tcm->reserve_2d(tcm, height, width, align, offset,
145					slot_bytes, area);
146		area->tcm = res ? NULL : tcm;
147	}
148
149	return res;
150}
151
152/**
153 * Reserves a 1D area in the container.
154 *
155 * @param tcm		Pointer to container manager.
156 * @param slots		Number of (contiguous) slots to reserve.
157 * @param area		Pointer to where the reserved area should be stored.
158 *
159 * @return 0 on success.  Non-0 error code on failure.  Also,
160 *	   the tcm field of the area will be set to NULL on
161 *	   failure.  Some error codes: -ENODEV: invalid manager,
162 *	   -EINVAL: invalid area, -ENOMEM: not enough space for
163 *	    allocation.
164 */
165static inline s32 tcm_reserve_1d(struct tcm *tcm, u32 slots,
166				 struct tcm_area *area)
167{
168	/* perform rudimentary error checking */
169	s32 res = tcm  == NULL ? -ENODEV :
170		(area == NULL || slots == 0) ? -EINVAL :
171		slots > (tcm->width * (u32) tcm->height) ? -ENOMEM : 0;
172
173	if (!res) {
174		area->is2d = false;
175		res = tcm->reserve_1d(tcm, slots, area);
176		area->tcm = res ? NULL : tcm;
177	}
178
179	return res;
180}
181
182/**
183 * Free a previously reserved area from the container.
184 *
185 * @param area	Pointer to area reserved by a prior call to
186 *		tcm_reserve_1d or tcm_reserve_2d call, whether
187 *		it was successful or not. (Note: all fields of
188 *		the structure must match.)
189 *
190 * @return 0 on success.  Non-0 error code on failure.  Also, the tcm
191 *	   field of the area is set to NULL on success to avoid subsequent
192 *	   freeing.  This call will succeed even if supplying
193 *	   the area from a failed reserved call.
194 */
195static inline s32 tcm_free(struct tcm_area *area)
196{
197	s32 res = 0; /* free succeeds by default */
198
199	if (area && area->tcm) {
200		res = area->tcm->free(area->tcm, area);
201		if (res == 0)
202			area->tcm = NULL;
203	}
204
205	return res;
206}
207
208/*=============================================================================
209    HELPER FUNCTION FOR ANY TILER CONTAINER MANAGER
210=============================================================================*/
211
212/**
213 * This method slices off the topmost 2D slice from the parent area, and stores
214 * it in the 'slice' parameter.  The 'parent' parameter will get modified to
215 * contain the remaining portion of the area.  If the whole parent area can
216 * fit in a 2D slice, its tcm pointer is set to NULL to mark that it is no
217 * longer a valid area.
218 *
219 * @param parent	Pointer to a VALID parent area that will get modified
220 * @param slice		Pointer to the slice area that will get modified
221 */
222static inline void tcm_slice(struct tcm_area *parent, struct tcm_area *slice)
223{
224	*slice = *parent;
225
226	/* check if we need to slice */
227	if (slice->tcm && !slice->is2d &&
228		slice->p0.y != slice->p1.y &&
229		(slice->p0.x || (slice->p1.x != slice->tcm->width - 1))) {
230		/* set end point of slice (start always remains) */
231		slice->p1.x = slice->tcm->width - 1;
232		slice->p1.y = (slice->p0.x) ? slice->p0.y : slice->p1.y - 1;
233		/* adjust remaining area */
234		parent->p0.x = 0;
235		parent->p0.y = slice->p1.y + 1;
236	} else {
237		/* mark this as the last slice */
238		parent->tcm = NULL;
239	}
240}
241
242/* Verify if a tcm area is logically valid */
243static inline bool tcm_area_is_valid(struct tcm_area *area)
244{
245	return area && area->tcm &&
246		/* coordinate bounds */
247		area->p1.x < area->tcm->width &&
248		area->p1.y < area->tcm->height &&
249		area->p0.y <= area->p1.y &&
250		/* 1D coordinate relationship + p0.x check */
251		((!area->is2d &&
252		  area->p0.x < area->tcm->width &&
253		  area->p0.x + area->p0.y * area->tcm->width <=
254		  area->p1.x + area->p1.y * area->tcm->width) ||
255		 /* 2D coordinate relationship */
256		 (area->is2d &&
257		  area->p0.x <= area->p1.x));
258}
259
260/* see if a coordinate is within an area */
261static inline bool __tcm_is_in(struct tcm_pt *p, struct tcm_area *a)
262{
263	u16 i;
264
265	if (a->is2d) {
266		return p->x >= a->p0.x && p->x <= a->p1.x &&
267		       p->y >= a->p0.y && p->y <= a->p1.y;
268	} else {
269		i = p->x + p->y * a->tcm->width;
270		return i >= a->p0.x + a->p0.y * a->tcm->width &&
271		       i <= a->p1.x + a->p1.y * a->tcm->width;
272	}
273}
274
275/* calculate area width */
276static inline u16 __tcm_area_width(struct tcm_area *area)
277{
278	return area->p1.x - area->p0.x + 1;
279}
280
281/* calculate area height */
282static inline u16 __tcm_area_height(struct tcm_area *area)
283{
284	return area->p1.y - area->p0.y + 1;
285}
286
287/* calculate number of slots in an area */
288static inline u16 __tcm_sizeof(struct tcm_area *area)
289{
290	return area->is2d ?
291		__tcm_area_width(area) * __tcm_area_height(area) :
292		(area->p1.x - area->p0.x + 1) + (area->p1.y - area->p0.y) *
293							area->tcm->width;
294}
295#define tcm_sizeof(area) __tcm_sizeof(&(area))
296#define tcm_awidth(area) __tcm_area_width(&(area))
297#define tcm_aheight(area) __tcm_area_height(&(area))
298#define tcm_is_in(pt, area) __tcm_is_in(&(pt), &(area))
299
300/* limit a 1D area to the first N pages */
301static inline s32 tcm_1d_limit(struct tcm_area *a, u32 num_pg)
302{
303	if (__tcm_sizeof(a) < num_pg)
304		return -ENOMEM;
305	if (!num_pg)
306		return -EINVAL;
307
308	a->p1.x = (a->p0.x + num_pg - 1) % a->tcm->width;
309	a->p1.y = a->p0.y + ((a->p0.x + num_pg - 1) / a->tcm->width);
310	return 0;
311}
312
313/**
314 * Iterate through 2D slices of a valid area. Behaves
315 * syntactically as a for(;;) statement.
316 *
317 * @param var		Name of a local variable of type 'struct
318 *			tcm_area *' that will get modified to
319 *			contain each slice.
320 * @param area		Pointer to the VALID parent area. This
321 *			structure will not get modified
322 *			throughout the loop.
323 *
324 */
325#define tcm_for_each_slice(var, area, safe) \
326	for (safe = area, \
327	     tcm_slice(&safe, &var); \
328	     var.tcm; tcm_slice(&safe, &var))
329
330#endif
v3.15
  1/*
  2 * tcm.h
  3 *
  4 * TILER container manager specification and support functions for TI
  5 * TILER driver.
  6 *
  7 * Author: Lajos Molnar <molnar@ti.com>
  8 *
  9 * All rights reserved.
 10 *
 11 * Redistribution and use in source and binary forms, with or without
 12 * modification, are permitted provided that the following conditions
 13 * are met:
 14 *
 15 * * Redistributions of source code must retain the above copyright
 16 *   notice, this list of conditions and the following disclaimer.
 17 *
 18 * * Redistributions in binary form must reproduce the above copyright
 19 *   notice, this list of conditions and the following disclaimer in the
 20 *   documentation and/or other materials provided with the distribution.
 21 *
 22 * * Neither the name of Texas Instruments Incorporated nor the names of
 23 *   its contributors may be used to endorse or promote products derived
 24 *   from this software without specific prior written permission.
 25 *
 26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 27 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 28 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 30 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 31 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 32 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 33 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 34 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 35 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 36 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 37 */
 38
 39#ifndef TCM_H
 40#define TCM_H
 41
 42struct tcm;
 43
 44/* point */
 45struct tcm_pt {
 46	u16 x;
 47	u16 y;
 48};
 49
 50/* 1d or 2d area */
 51struct tcm_area {
 52	bool is2d;		/* whether area is 1d or 2d */
 53	struct tcm    *tcm;	/* parent */
 54	struct tcm_pt  p0;
 55	struct tcm_pt  p1;
 56};
 57
 58struct tcm {
 59	u16 width, height;	/* container dimensions */
 60	int lut_id;		/* Lookup table identifier */
 61
 62	unsigned int y_offset;	/* offset to use for y coordinates */
 63
 64	/* 'pvt' structure shall contain any tcm details (attr) along with
 65	linked list of allocated areas and mutex for mutually exclusive access
 66	to the list.  It may also contain copies of width and height to notice
 67	any changes to the publicly available width and height fields. */
 68	void *pvt;
 69
 70	/* function table */
 71	s32 (*reserve_2d)(struct tcm *tcm, u16 height, u16 width, u8 align,
 
 72			  struct tcm_area *area);
 73	s32 (*reserve_1d)(struct tcm *tcm, u32 slots, struct tcm_area *area);
 74	s32 (*free)      (struct tcm *tcm, struct tcm_area *area);
 75	void (*deinit)   (struct tcm *tcm);
 76};
 77
 78/*=============================================================================
 79    BASIC TILER CONTAINER MANAGER INTERFACE
 80=============================================================================*/
 81
 82/*
 83 * NOTE:
 84 *
 85 * Since some basic parameter checking is done outside the TCM algorithms,
 86 * TCM implementation do NOT have to check the following:
 87 *
 88 *   area pointer is NULL
 89 *   width and height fits within container
 90 *   number of pages is more than the size of the container
 91 *
 92 */
 93
 94struct tcm *sita_init(u16 width, u16 height, struct tcm_pt *attr);
 95
 96
 97/**
 98 * Deinitialize tiler container manager.
 99 *
100 * @param tcm	Pointer to container manager.
101 *
102 * @return 0 on success, non-0 error value on error.  The call
103 *	   should free as much memory as possible and meaningful
104 *	   even on failure.  Some error codes: -ENODEV: invalid
105 *	   manager.
106 */
107static inline void tcm_deinit(struct tcm *tcm)
108{
109	if (tcm)
110		tcm->deinit(tcm);
111}
112
113/**
114 * Reserves a 2D area in the container.
115 *
116 * @param tcm		Pointer to container manager.
117 * @param height	Height(in pages) of area to be reserved.
118 * @param width		Width(in pages) of area to be reserved.
119 * @param align		Alignment requirement for top-left corner of area. Not
120 *			all values may be supported by the container manager,
121 *			but it must support 0 (1), 32 and 64.
122 *			0 value is equivalent to 1.
 
 
 
123 * @param area		Pointer to where the reserved area should be stored.
124 *
125 * @return 0 on success.  Non-0 error code on failure.  Also,
126 *	   the tcm field of the area will be set to NULL on
127 *	   failure.  Some error codes: -ENODEV: invalid manager,
128 *	   -EINVAL: invalid area, -ENOMEM: not enough space for
129 *	    allocation.
130 */
131static inline s32 tcm_reserve_2d(struct tcm *tcm, u16 width, u16 height,
132				 u16 align, struct tcm_area *area)
 
133{
134	/* perform rudimentary error checking */
135	s32 res = tcm  == NULL ? -ENODEV :
136		(area == NULL || width == 0 || height == 0 ||
137		 /* align must be a 2 power */
138		 (align & (align - 1))) ? -EINVAL :
139		(height > tcm->height || width > tcm->width) ? -ENOMEM : 0;
140
141	if (!res) {
142		area->is2d = true;
143		res = tcm->reserve_2d(tcm, height, width, align, area);
 
144		area->tcm = res ? NULL : tcm;
145	}
146
147	return res;
148}
149
150/**
151 * Reserves a 1D area in the container.
152 *
153 * @param tcm		Pointer to container manager.
154 * @param slots		Number of (contiguous) slots to reserve.
155 * @param area		Pointer to where the reserved area should be stored.
156 *
157 * @return 0 on success.  Non-0 error code on failure.  Also,
158 *	   the tcm field of the area will be set to NULL on
159 *	   failure.  Some error codes: -ENODEV: invalid manager,
160 *	   -EINVAL: invalid area, -ENOMEM: not enough space for
161 *	    allocation.
162 */
163static inline s32 tcm_reserve_1d(struct tcm *tcm, u32 slots,
164				 struct tcm_area *area)
165{
166	/* perform rudimentary error checking */
167	s32 res = tcm  == NULL ? -ENODEV :
168		(area == NULL || slots == 0) ? -EINVAL :
169		slots > (tcm->width * (u32) tcm->height) ? -ENOMEM : 0;
170
171	if (!res) {
172		area->is2d = false;
173		res = tcm->reserve_1d(tcm, slots, area);
174		area->tcm = res ? NULL : tcm;
175	}
176
177	return res;
178}
179
180/**
181 * Free a previously reserved area from the container.
182 *
183 * @param area	Pointer to area reserved by a prior call to
184 *		tcm_reserve_1d or tcm_reserve_2d call, whether
185 *		it was successful or not. (Note: all fields of
186 *		the structure must match.)
187 *
188 * @return 0 on success.  Non-0 error code on failure.  Also, the tcm
189 *	   field of the area is set to NULL on success to avoid subsequent
190 *	   freeing.  This call will succeed even if supplying
191 *	   the area from a failed reserved call.
192 */
193static inline s32 tcm_free(struct tcm_area *area)
194{
195	s32 res = 0; /* free succeeds by default */
196
197	if (area && area->tcm) {
198		res = area->tcm->free(area->tcm, area);
199		if (res == 0)
200			area->tcm = NULL;
201	}
202
203	return res;
204}
205
206/*=============================================================================
207    HELPER FUNCTION FOR ANY TILER CONTAINER MANAGER
208=============================================================================*/
209
210/**
211 * This method slices off the topmost 2D slice from the parent area, and stores
212 * it in the 'slice' parameter.  The 'parent' parameter will get modified to
213 * contain the remaining portion of the area.  If the whole parent area can
214 * fit in a 2D slice, its tcm pointer is set to NULL to mark that it is no
215 * longer a valid area.
216 *
217 * @param parent	Pointer to a VALID parent area that will get modified
218 * @param slice		Pointer to the slice area that will get modified
219 */
220static inline void tcm_slice(struct tcm_area *parent, struct tcm_area *slice)
221{
222	*slice = *parent;
223
224	/* check if we need to slice */
225	if (slice->tcm && !slice->is2d &&
226		slice->p0.y != slice->p1.y &&
227		(slice->p0.x || (slice->p1.x != slice->tcm->width - 1))) {
228		/* set end point of slice (start always remains) */
229		slice->p1.x = slice->tcm->width - 1;
230		slice->p1.y = (slice->p0.x) ? slice->p0.y : slice->p1.y - 1;
231		/* adjust remaining area */
232		parent->p0.x = 0;
233		parent->p0.y = slice->p1.y + 1;
234	} else {
235		/* mark this as the last slice */
236		parent->tcm = NULL;
237	}
238}
239
240/* Verify if a tcm area is logically valid */
241static inline bool tcm_area_is_valid(struct tcm_area *area)
242{
243	return area && area->tcm &&
244		/* coordinate bounds */
245		area->p1.x < area->tcm->width &&
246		area->p1.y < area->tcm->height &&
247		area->p0.y <= area->p1.y &&
248		/* 1D coordinate relationship + p0.x check */
249		((!area->is2d &&
250		  area->p0.x < area->tcm->width &&
251		  area->p0.x + area->p0.y * area->tcm->width <=
252		  area->p1.x + area->p1.y * area->tcm->width) ||
253		 /* 2D coordinate relationship */
254		 (area->is2d &&
255		  area->p0.x <= area->p1.x));
256}
257
258/* see if a coordinate is within an area */
259static inline bool __tcm_is_in(struct tcm_pt *p, struct tcm_area *a)
260{
261	u16 i;
262
263	if (a->is2d) {
264		return p->x >= a->p0.x && p->x <= a->p1.x &&
265		       p->y >= a->p0.y && p->y <= a->p1.y;
266	} else {
267		i = p->x + p->y * a->tcm->width;
268		return i >= a->p0.x + a->p0.y * a->tcm->width &&
269		       i <= a->p1.x + a->p1.y * a->tcm->width;
270	}
271}
272
273/* calculate area width */
274static inline u16 __tcm_area_width(struct tcm_area *area)
275{
276	return area->p1.x - area->p0.x + 1;
277}
278
279/* calculate area height */
280static inline u16 __tcm_area_height(struct tcm_area *area)
281{
282	return area->p1.y - area->p0.y + 1;
283}
284
285/* calculate number of slots in an area */
286static inline u16 __tcm_sizeof(struct tcm_area *area)
287{
288	return area->is2d ?
289		__tcm_area_width(area) * __tcm_area_height(area) :
290		(area->p1.x - area->p0.x + 1) + (area->p1.y - area->p0.y) *
291							area->tcm->width;
292}
293#define tcm_sizeof(area) __tcm_sizeof(&(area))
294#define tcm_awidth(area) __tcm_area_width(&(area))
295#define tcm_aheight(area) __tcm_area_height(&(area))
296#define tcm_is_in(pt, area) __tcm_is_in(&(pt), &(area))
297
298/* limit a 1D area to the first N pages */
299static inline s32 tcm_1d_limit(struct tcm_area *a, u32 num_pg)
300{
301	if (__tcm_sizeof(a) < num_pg)
302		return -ENOMEM;
303	if (!num_pg)
304		return -EINVAL;
305
306	a->p1.x = (a->p0.x + num_pg - 1) % a->tcm->width;
307	a->p1.y = a->p0.y + ((a->p0.x + num_pg - 1) / a->tcm->width);
308	return 0;
309}
310
311/**
312 * Iterate through 2D slices of a valid area. Behaves
313 * syntactically as a for(;;) statement.
314 *
315 * @param var		Name of a local variable of type 'struct
316 *			tcm_area *' that will get modified to
317 *			contain each slice.
318 * @param area		Pointer to the VALID parent area. This
319 *			structure will not get modified
320 *			throughout the loop.
321 *
322 */
323#define tcm_for_each_slice(var, area, safe) \
324	for (safe = area, \
325	     tcm_slice(&safe, &var); \
326	     var.tcm; tcm_slice(&safe, &var))
327
328#endif