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v4.6
  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	spinlock_t lock;
 65	unsigned long *bitmap;
 66	size_t map_size;
 
 
 67
 68	/* function table */
 69	s32 (*reserve_2d)(struct tcm *tcm, u16 height, u16 width, u16 align,
 70			  int16_t offset, uint16_t slot_bytes,
 71			  struct tcm_area *area);
 72	s32 (*reserve_1d)(struct tcm *tcm, u32 slots, struct tcm_area *area);
 73	s32 (*free)(struct tcm *tcm, struct tcm_area *area);
 74	void (*deinit)(struct tcm *tcm);
 75};
 76
 77/*=============================================================================
 78    BASIC TILER CONTAINER MANAGER INTERFACE
 79=============================================================================*/
 80
 81/*
 82 * NOTE:
 83 *
 84 * Since some basic parameter checking is done outside the TCM algorithms,
 85 * TCM implementation do NOT have to check the following:
 86 *
 87 *   area pointer is NULL
 88 *   width and height fits within container
 89 *   number of pages is more than the size of the container
 90 *
 91 */
 92
 93struct tcm *sita_init(u16 width, u16 height);
 94
 95
 96/**
 97 * Deinitialize tiler container manager.
 98 *
 99 * @param tcm	Pointer to container manager.
100 *
101 * @return 0 on success, non-0 error value on error.  The call
102 *	   should free as much memory as possible and meaningful
103 *	   even on failure.  Some error codes: -ENODEV: invalid
104 *	   manager.
105 */
106static inline void tcm_deinit(struct tcm *tcm)
107{
108	if (tcm)
109		tcm->deinit(tcm);
110}
111
112/**
113 * Reserves a 2D area in the container.
114 *
115 * @param tcm		Pointer to container manager.
116 * @param height	Height(in pages) of area to be reserved.
117 * @param width		Width(in pages) of area to be reserved.
118 * @param align		Alignment requirement for top-left corner of area. Not
119 *			all values may be supported by the container manager,
120 *			but it must support 0 (1), 32 and 64.
121 *			0 value is equivalent to 1.
122 * @param offset	Offset requirement, in bytes.  This is the offset
123 *			from a 4KiB aligned virtual address.
124 * @param slot_bytes	Width of slot in bytes
125 * @param area		Pointer to where the reserved area should be stored.
126 *
127 * @return 0 on success.  Non-0 error code on failure.  Also,
128 *	   the tcm field of the area will be set to NULL on
129 *	   failure.  Some error codes: -ENODEV: invalid manager,
130 *	   -EINVAL: invalid area, -ENOMEM: not enough space for
131 *	    allocation.
132 */
133static inline s32 tcm_reserve_2d(struct tcm *tcm, u16 width, u16 height,
134				u16 align, int16_t offset, uint16_t slot_bytes,
135				struct tcm_area *area)
136{
137	/* perform rudimentary error checking */
138	s32 res = tcm  == NULL ? -ENODEV :
139		(area == NULL || width == 0 || height == 0 ||
140		 /* align must be a 2 power */
141		 (align & (align - 1))) ? -EINVAL :
142		(height > tcm->height || width > tcm->width) ? -ENOMEM : 0;
143
144	if (!res) {
145		area->is2d = true;
146		res = tcm->reserve_2d(tcm, height, width, align, offset,
147					slot_bytes, area);
148		area->tcm = res ? NULL : tcm;
149	}
150
151	return res;
152}
153
154/**
155 * Reserves a 1D area in the container.
156 *
157 * @param tcm		Pointer to container manager.
158 * @param slots		Number of (contiguous) slots to reserve.
159 * @param area		Pointer to where the reserved area should be stored.
160 *
161 * @return 0 on success.  Non-0 error code on failure.  Also,
162 *	   the tcm field of the area will be set to NULL on
163 *	   failure.  Some error codes: -ENODEV: invalid manager,
164 *	   -EINVAL: invalid area, -ENOMEM: not enough space for
165 *	    allocation.
166 */
167static inline s32 tcm_reserve_1d(struct tcm *tcm, u32 slots,
168				 struct tcm_area *area)
169{
170	/* perform rudimentary error checking */
171	s32 res = tcm  == NULL ? -ENODEV :
172		(area == NULL || slots == 0) ? -EINVAL :
173		slots > (tcm->width * (u32) tcm->height) ? -ENOMEM : 0;
174
175	if (!res) {
176		area->is2d = false;
177		res = tcm->reserve_1d(tcm, slots, area);
178		area->tcm = res ? NULL : tcm;
179	}
180
181	return res;
182}
183
184/**
185 * Free a previously reserved area from the container.
186 *
187 * @param area	Pointer to area reserved by a prior call to
188 *		tcm_reserve_1d or tcm_reserve_2d call, whether
189 *		it was successful or not. (Note: all fields of
190 *		the structure must match.)
191 *
192 * @return 0 on success.  Non-0 error code on failure.  Also, the tcm
193 *	   field of the area is set to NULL on success to avoid subsequent
194 *	   freeing.  This call will succeed even if supplying
195 *	   the area from a failed reserved call.
196 */
197static inline s32 tcm_free(struct tcm_area *area)
198{
199	s32 res = 0; /* free succeeds by default */
200
201	if (area && area->tcm) {
202		res = area->tcm->free(area->tcm, area);
203		if (res == 0)
204			area->tcm = NULL;
205	}
206
207	return res;
208}
209
210/*=============================================================================
211    HELPER FUNCTION FOR ANY TILER CONTAINER MANAGER
212=============================================================================*/
213
214/**
215 * This method slices off the topmost 2D slice from the parent area, and stores
216 * it in the 'slice' parameter.  The 'parent' parameter will get modified to
217 * contain the remaining portion of the area.  If the whole parent area can
218 * fit in a 2D slice, its tcm pointer is set to NULL to mark that it is no
219 * longer a valid area.
220 *
221 * @param parent	Pointer to a VALID parent area that will get modified
222 * @param slice		Pointer to the slice area that will get modified
223 */
224static inline void tcm_slice(struct tcm_area *parent, struct tcm_area *slice)
225{
226	*slice = *parent;
227
228	/* check if we need to slice */
229	if (slice->tcm && !slice->is2d &&
230		slice->p0.y != slice->p1.y &&
231		(slice->p0.x || (slice->p1.x != slice->tcm->width - 1))) {
232		/* set end point of slice (start always remains) */
233		slice->p1.x = slice->tcm->width - 1;
234		slice->p1.y = (slice->p0.x) ? slice->p0.y : slice->p1.y - 1;
235		/* adjust remaining area */
236		parent->p0.x = 0;
237		parent->p0.y = slice->p1.y + 1;
238	} else {
239		/* mark this as the last slice */
240		parent->tcm = NULL;
241	}
242}
243
244/* Verify if a tcm area is logically valid */
245static inline bool tcm_area_is_valid(struct tcm_area *area)
246{
247	return area && area->tcm &&
248		/* coordinate bounds */
249		area->p1.x < area->tcm->width &&
250		area->p1.y < area->tcm->height &&
251		area->p0.y <= area->p1.y &&
252		/* 1D coordinate relationship + p0.x check */
253		((!area->is2d &&
254		  area->p0.x < area->tcm->width &&
255		  area->p0.x + area->p0.y * area->tcm->width <=
256		  area->p1.x + area->p1.y * area->tcm->width) ||
257		 /* 2D coordinate relationship */
258		 (area->is2d &&
259		  area->p0.x <= area->p1.x));
260}
261
262/* see if a coordinate is within an area */
263static inline bool __tcm_is_in(struct tcm_pt *p, struct tcm_area *a)
264{
265	u16 i;
266
267	if (a->is2d) {
268		return p->x >= a->p0.x && p->x <= a->p1.x &&
269		       p->y >= a->p0.y && p->y <= a->p1.y;
270	} else {
271		i = p->x + p->y * a->tcm->width;
272		return i >= a->p0.x + a->p0.y * a->tcm->width &&
273		       i <= a->p1.x + a->p1.y * a->tcm->width;
274	}
275}
276
277/* calculate area width */
278static inline u16 __tcm_area_width(struct tcm_area *area)
279{
280	return area->p1.x - area->p0.x + 1;
281}
282
283/* calculate area height */
284static inline u16 __tcm_area_height(struct tcm_area *area)
285{
286	return area->p1.y - area->p0.y + 1;
287}
288
289/* calculate number of slots in an area */
290static inline u16 __tcm_sizeof(struct tcm_area *area)
291{
292	return area->is2d ?
293		__tcm_area_width(area) * __tcm_area_height(area) :
294		(area->p1.x - area->p0.x + 1) + (area->p1.y - area->p0.y) *
295							area->tcm->width;
296}
297#define tcm_sizeof(area) __tcm_sizeof(&(area))
298#define tcm_awidth(area) __tcm_area_width(&(area))
299#define tcm_aheight(area) __tcm_area_height(&(area))
300#define tcm_is_in(pt, area) __tcm_is_in(&(pt), &(area))
301
302/* limit a 1D area to the first N pages */
303static inline s32 tcm_1d_limit(struct tcm_area *a, u32 num_pg)
304{
305	if (__tcm_sizeof(a) < num_pg)
306		return -ENOMEM;
307	if (!num_pg)
308		return -EINVAL;
309
310	a->p1.x = (a->p0.x + num_pg - 1) % a->tcm->width;
311	a->p1.y = a->p0.y + ((a->p0.x + num_pg - 1) / a->tcm->width);
312	return 0;
313}
314
315/**
316 * Iterate through 2D slices of a valid area. Behaves
317 * syntactically as a for(;;) statement.
318 *
319 * @param var		Name of a local variable of type 'struct
320 *			tcm_area *' that will get modified to
321 *			contain each slice.
322 * @param area		Pointer to the VALID parent area. This
323 *			structure will not get modified
324 *			throughout the loop.
325 *
326 */
327#define tcm_for_each_slice(var, area, safe) \
328	for (safe = area, \
329	     tcm_slice(&safe, &var); \
330	     var.tcm; tcm_slice(&safe, &var))
331
332#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