[PATCH 3/9] TILER-DMM: Sample TCM implementation: Simple TILER Allocator (SiTA)

[David Sin]

From: Ravi Ramachandra <r.ramachandra@xxxxxx>

This patch implements a simple TILER Container Manager (TCM).

Signed-off-by: Ravi Ramachandra <r.ramachandra@xxxxxx>
Signed-off-by: Lajos Molnar <molnar@xxxxxx>
Signed-off-by: David Sin <davidsin@xxxxxx>
---
 drivers/misc/tiler/tcm/Makefile    |    1 +
 drivers/misc/tiler/tcm/_tcm-sita.h |   61 +++++
 drivers/misc/tiler/tcm/tcm-sita.c  |  422 ++++++++++++++++++++++++++++++++++++
 drivers/misc/tiler/tcm/tcm-sita.h  |   28 +++
 4 files changed, 512 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/tiler/tcm/Makefile
 create mode 100644 drivers/misc/tiler/tcm/_tcm-sita.h
 create mode 100644 drivers/misc/tiler/tcm/tcm-sita.c
 create mode 100644 drivers/misc/tiler/tcm/tcm-sita.h

diff --git a/drivers/misc/tiler/tcm/Makefile b/drivers/misc/tiler/tcm/Makefile
new file mode 100644
index 0000000..8434607
--- /dev/null
+++ b/drivers/misc/tiler/tcm/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_TI_TILER) += tcm-sita.o
diff --git a/drivers/misc/tiler/tcm/_tcm-sita.h b/drivers/misc/tiler/tcm/_tcm-sita.h
new file mode 100644
index 0000000..6e4d292
--- /dev/null
+++ b/drivers/misc/tiler/tcm/_tcm-sita.h
@@ -0,0 +1,61 @@
+/*
+ * SImple Tiler Allocator (SiTA) private structures.
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _TCM_SITA_H
+#define _TCM_SITA_H
+
+#include "../tcm.h"
+
+/* length between two coordinates */
+#define LEN(a, b) ((a) > (b) ? (a) - (b) + 1 : (b) - (a) + 1)
+
+enum criteria {
+	CR_MAX_NEIGHS		= 0x01,
+	CR_FIRST_FOUND		= 0x10,
+	CR_BIAS_HORIZONTAL	= 0x20,
+	CR_BIAS_VERTICAL	= 0x40,
+	CR_DIAGONAL_BALANCE	= 0x80
+};
+
+/* nearness to the beginning of the search field from 0 to 1000 */
+struct nearness_factor {
+	s32 x;
+	s32 y;
+};
+
+/*
+ * Statistics on immediately neighboring slots. Edge is the number of
+ * border segments that are also border segments of the scan field.  Busy
+ * refers to the number of neighbors that are occupied.
+ */
+struct neighbor_stats {
+	u16 edge;
+	u16 busy;
+};
+
+/* structure to keep the score of a potential allocation */
+struct score {
+	struct nearness_factor	f;
+	struct neighbor_stats	n;
+	struct tcm_area		a;
+	u16    neighs;		/* number of busy neighbors */
+};
+
+struct sita_pvt {
+	struct mutex mtx;
+	struct tcm_area ***map;	/* pointers to the parent area for each slot */
+};
+
+#endif
diff --git a/drivers/misc/tiler/tcm/tcm-sita.c b/drivers/misc/tiler/tcm/tcm-sita.c
new file mode 100644
index 0000000..a7ceac4
--- /dev/null
+++ b/drivers/misc/tiler/tcm/tcm-sita.c
@@ -0,0 +1,422 @@
+/*
+ * SImple Tiler Allocator (SiTA): 2D and 1D allocation(reservation) algorithm
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/slab.h>
+
+#include "_tcm-sita.h"
+#include "tcm-sita.h"
+
+#define TCM_ALG_NAME "tcm_sita"
+#include "tcm-utils.h"
+
+#define ALIGN_DOWN(value, align) ((value) & ~((align) - 1))
+
+/* Individual selection criteria for different scan areas */
+static s32 CR_L2R_T2B = CR_BIAS_HORIZONTAL;
+
+/*
+ * TCM API - Sita Implementation
+ */
+static s32 sita_reserve_2d(struct tcm *tcm, u16 h, u16 w, u8 align,
+			   struct tcm_area *area);
+static s32 sita_free(struct tcm *tcm, struct tcm_area *area);
+static void sita_deinit(struct tcm *tcm);
+
+/*
+ * Main Scanner functions
+ */
+static s32 scan_areas_and_find_fit(struct tcm *tcm, u16 w, u16 h, u16 align,
+				   struct tcm_area *area);
+
+static s32 scan_l2r_t2b(struct tcm *tcm, u16 w, u16 h, u16 align,
+			struct tcm_area *field, struct tcm_area *area);
+
+/*
+ * Support Infrastructure Methods
+ */
+static s32 is_area_free(struct tcm_area ***map, u16 x0, u16 y0, u16 w, u16 h);
+
+static s32 update_candidate(struct tcm *tcm, u16 x0, u16 y0, u16 w, u16 h,
+			    struct tcm_area *field, s32 criteria,
+			    struct score *best);
+
+static void get_nearness_factor(struct tcm_area *field,
+				struct tcm_area *candidate,
+				struct nearness_factor *nf);
+
+static void get_neighbor_stats(struct tcm *tcm, struct tcm_area *area,
+			       struct neighbor_stats *stat);
+
+static void fill_area(struct tcm *tcm,
+				struct tcm_area *area, struct tcm_area *parent);
+
+/*
+ * Utility Methods
+ */
+struct tcm *sita_init(u16 width, u16 height, void *attr)
+{
+	struct tcm *tcm;
+	struct sita_pvt *pvt;
+	struct tcm_area area = {NULL};
+	s32 i;
+
+	if (width == 0 || height == 0)
+		return NULL;
+
+	tcm = kzalloc(sizeof(*tcm), GFP_KERNEL);
+	pvt = kzalloc(sizeof(*pvt), GFP_KERNEL);
+	if (!tcm || !pvt)
+		goto error;
+
+	/* Updating the pointers to SiTA implementation APIs */
+	tcm->height = height;
+	tcm->width = width;
+	tcm->reserve_2d = sita_reserve_2d;
+	tcm->free = sita_free;
+	tcm->deinit = sita_deinit;
+	tcm->pvt = (void *)pvt;
+
+	mutex_init(&(pvt->mtx));
+
+	/* Creating tam map */
+	pvt->map = kzalloc(sizeof(*pvt->map) * tcm->width, GFP_KERNEL);
+	if (!pvt->map)
+		goto error;
+
+	for (i = 0; i < tcm->width; i++) {
+		pvt->map[i] =
+			kzalloc(sizeof(**pvt->map) * tcm->height,
+								GFP_KERNEL);
+		if (pvt->map[i] == NULL) {
+			while (i--)
+				kfree(pvt->map[i]);
+			kfree(pvt->map);
+			goto error;
+		}
+	}
+
+	mutex_lock(&(pvt->mtx));
+	assign(&area, 0, 0, width - 1, height - 1);
+	fill_area(tcm, &area, NULL);
+	mutex_unlock(&(pvt->mtx));
+	return tcm;
+
+error:
+	kfree(tcm);
+	kfree(pvt);
+	return NULL;
+}
+
+static void sita_deinit(struct tcm *tcm)
+{
+	struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
+	struct tcm_area area = {NULL};
+	s32 i;
+
+	area.p1.x = tcm->width - 1;
+	area.p1.y = tcm->height - 1;
+
+	mutex_lock(&(pvt->mtx));
+	fill_area(tcm, &area, NULL);
+	mutex_unlock(&(pvt->mtx));
+
+	mutex_destroy(&(pvt->mtx));
+
+	for (i = 0; i < tcm->height; i++)
+		kfree(pvt->map[i]);
+	kfree(pvt->map);
+	kfree(pvt);
+}
+
+/*
+ * Reserve a 2D area in the container
+ */
+static s32 sita_reserve_2d(struct tcm *tcm, u16 h, u16 w, u8 align,
+			   struct tcm_area *area)
+{
+	s32 ret;
+	struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
+
+	/* not supporting more than 64 as alignment */
+	if (align > 64)
+		return -EINVAL;
+
+	/* we prefer 1, 32 and 64 as alignment */
+	align = align <= 1 ? 1 : align <= 32 ? 32 : 64;
+
+	mutex_lock(&(pvt->mtx));
+	ret = scan_areas_and_find_fit(tcm, w, h, align, area);
+	if (!ret)
+		/* update map */
+		fill_area(tcm, area, area);
+
+	mutex_unlock(&(pvt->mtx));
+	return ret;
+}
+
+/*
+ * Unreserve a previously allocated 2D or 1D area
+ */
+static s32 sita_free(struct tcm *tcm, struct tcm_area *area)
+{
+	struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
+
+	mutex_lock(&(pvt->mtx));
+
+	/* Clear the contents of the associated tiles in the map */
+	fill_area(tcm, area, NULL);
+
+	mutex_unlock(&(pvt->mtx));
+
+	return 0;
+}
+
+/*
+ * Note: In general the cordinates in the scan field area relevant to the can
+ * sweep directions. The scan origin (e.g. top-left corner) will always be
+ * the p0 member of the field.  Therfore, for a scan from top-left p0.x <= p1.x
+ * and p0.y <= p1.y; whereas, for a scan from bottom-right p1.x <= p0.x and p1.y
+ * <= p0.y
+ */
+
+/*
+ * Raster scan horizontally left to right from top to bottom to find a place for
+ * a 2D area of given size inside a scan field.
+ */
+static s32 scan_l2r_t2b(struct tcm *tcm, u16 w, u16 h, u16 align,
+			struct tcm_area *field, struct tcm_area *area)
+{
+	s32 x, y;
+	s16 start_x, end_x, start_y, end_y;
+	struct tcm_area ***map = ((struct sita_pvt *)tcm->pvt)->map;
+	struct score best = {{0}, {0}, {NULL}, 0};
+
+	PA(2, "scan_l2r_t2b:", field);
+
+	start_x = field->p0.x;
+	end_x = field->p1.x;
+	start_y = field->p0.y;
+	end_y = field->p1.y;
+
+	/* check scan area co-ordinates */
+	if (field->p1.x < field->p0.x ||
+	    field->p1.y < field->p0.y)
+		return -EINVAL;
+
+	/* check if allocation would fit in scan area */
+	if (w > LEN(end_x, start_x) || h > LEN(end_y, start_y))
+		return -ENOSPC;
+
+	start_x = ALIGN(start_x, align);
+
+	/* check if allocation would still fit in scan area */
+	if (w > LEN(end_x, start_x))
+		return -ENOSPC;
+
+	/* adjust end_x and end_y, as allocation would not fit beyond */
+	end_x = end_x - w + 1; /* + 1 to be inclusive */
+	end_y = end_y - h + 1;
+
+	P2("ali=%d x=%d..%d y=%d..%d", align, start_x, end_x, start_y, end_y);
+
+	/* scan field top-to-bottom, left-to-right */
+	for (y = start_y; y <= end_y; y++) {
+		for (x = start_x; x <= end_x; x += align) {
+			if (is_area_free(map, x, y, w, h)) {
+				P3("found shoulder: %d,%d", x, y);
+
+				/* update best candidate */
+				if (update_candidate(tcm, x, y, w, h, field,
+							CR_L2R_T2B, &best))
+					goto done;
+				break;
+			} else if (map[x][y]) {
+				/* step over 2D areas */
+				x = ALIGN_DOWN(map[x][y]->p1.x, align);
+				P3("moving to: %d,%d", x, y);
+			}
+		}
+	}
+
+	if (!best.a.tcm)
+		return -ENOSPC;
+done:
+	assign(area, best.a.p0.x, best.a.p0.y, best.a.p1.x, best.a.p1.y);
+	return 0;
+}
+
+/*
+ * Find a place for a 2D area of given size inside a scan field based on its
+ * alignment needs.
+ */
+static s32 scan_areas_and_find_fit(struct tcm *tcm, u16 w, u16 h, u16 align,
+				   struct tcm_area *area)
+{
+	struct tcm_area field = {NULL};
+
+	/* scan whole container left to right, top to bottom */
+	assign(&field, 0, 0, tcm->width - 1, tcm->height - 1);
+	return scan_l2r_t2b(tcm, w, h, align, &field, area);
+}
+
+/* check if an entire area is free */
+static s32 is_area_free(struct tcm_area ***map, u16 x0, u16 y0, u16 w, u16 h)
+{
+	u16 x = 0, y = 0;
+	for (y = y0; y < y0 + h; y++) {
+		for (x = x0; x < x0 + w; x++) {
+			if (map[x][y])
+				return false;
+		}
+	}
+	return true;
+}
+
+/* fills an area with a parent tcm_area */
+static void fill_area(struct tcm *tcm, struct tcm_area *area,
+			struct tcm_area *parent)
+{
+	s32 x, y;
+	struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
+
+	PA(2, "fill 2d area", area);
+	for (x = area->p0.x; x <= area->p1.x; ++x)
+		for (y = area->p0.y; y <= area->p1.y; ++y)
+			pvt->map[x][y] = parent;
+}
+
+/*
+ * Compares a candidate area to the current best area, and if it is a better
+ * fit, it updates the best to this one. Return 1 (true) if the candidate area
+ * is known to be the final best, so no more searching should be performed
+ */
+static s32 update_candidate(struct tcm *tcm, u16 x0, u16 y0, u16 w, u16 h,
+			    struct tcm_area *field, s32 criteria,
+			    struct score *best)
+{
+	struct score me;	/* score for area */
+
+	/*
+	 * If first found is enabled then we stop looking
+	 * NOTE: For horizontal bias we always give the first found, because our
+	 * scan is horizontal-raster-based and the first candidate will always
+	 * have the horizontal bias.
+	 */
+	bool first = criteria & (CR_FIRST_FOUND | CR_BIAS_HORIZONTAL);
+
+	assign(&me.a, x0, y0, x0 + w - 1, y0 + h - 1);
+
+	/* calculate score for current candidate */
+	if (!first) {
+		get_neighbor_stats(tcm, &me.a, &me.n);
+		me.neighs = me.n.edge + me.n.busy;
+		get_nearness_factor(field, &me.a, &me.f);
+	}
+
+	/* the 1st candidate is always the best */
+	if (!best->a.tcm)
+		goto better;
+
+	/* see if this are is better than the best so far */
+
+	/* neighbor check */
+	if ((criteria & CR_MAX_NEIGHS) &&
+		me.neighs > best->neighs)
+		goto better;
+
+	/* vertical bias check */
+	if ((criteria & CR_BIAS_VERTICAL) &&
+	/*
+	 * NOTE: not checking if lengths are same, because that does not
+	 * find new shoulders on the same row after a fit
+	 */
+		LEN(me.a.p0.y, field->p0.y) >
+		LEN(best->a.p0.y, field->p0.y))
+		goto better;
+
+	/* diagonal balance check */
+	if ((criteria & CR_DIAGONAL_BALANCE) &&
+		best->neighs <= me.neighs &&
+		(best->neighs < me.neighs ||
+		 /* this implies that neighs and occupied match */
+		 best->n.busy < me.n.busy ||
+		 (best->n.busy == me.n.busy &&
+		  /* check the nearness factor */
+		  best->f.x + best->f.y > me.f.x + me.f.y)))
+		goto better;
+
+	/* not better, keep going */
+	return 0;
+
+better:
+	/* save current area as best */
+	memcpy(best, &me, sizeof(me));
+	best->a.tcm = tcm;
+	return first;
+}
+
+/*
+ * Calculate the nearness factor of an area in a search field.  The nearness
+ * factor is smaller if the area is closer to the search origin.
+ */
+static void get_nearness_factor(struct tcm_area *field, struct tcm_area *area,
+				struct nearness_factor *nf)
+{
+	/*
+	 * Using signed math as field coordinates may be reversed if
+	 * search direction is right-to-left or bottom-to-top.
+	 */
+	nf->x = (s32)(area->p0.x - field->p0.x) * 1000 /
+		(field->p1.x - field->p0.x);
+	nf->y = (s32)(area->p0.y - field->p0.y) * 1000 /
+		(field->p1.y - field->p0.y);
+}
+
+/* get neighbor statistics */
+static void get_neighbor_stats(struct tcm *tcm, struct tcm_area *area,
+			 struct neighbor_stats *stat)
+{
+	s16 x = 0, y = 0;
+	struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
+
+	/* Clearing any exisiting values */
+	memset(stat, 0, sizeof(*stat));
+
+	/* process top & bottom edges */
+	for (x = area->p0.x; x <= area->p1.x; x++) {
+		if (area->p0.y == 0)
+			stat->edge++;
+		else if (pvt->map[x][area->p0.y - 1])
+			stat->busy++;
+
+		if (area->p1.y == tcm->height - 1)
+			stat->edge++;
+		else if (pvt->map[x][area->p1.y + 1])
+			stat->busy++;
+	}
+
+	/* process left & right edges */
+	for (y = area->p0.y; y <= area->p1.y; ++y) {
+		if (area->p0.x == 0)
+			stat->edge++;
+		else if (pvt->map[area->p0.x - 1][y])
+			stat->busy++;
+
+		if (area->p1.x == tcm->width - 1)
+			stat->edge++;
+		else if (pvt->map[area->p1.x + 1][y])
+			stat->busy++;
+	}
+}
diff --git a/drivers/misc/tiler/tcm/tcm-sita.h b/drivers/misc/tiler/tcm/tcm-sita.h
new file mode 100644
index 0000000..a435bce
--- /dev/null
+++ b/drivers/misc/tiler/tcm/tcm-sita.h
@@ -0,0 +1,28 @@
+/*
+ * SImple Tiler Allocator (SiTA) interface.
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef TCM_SITA_H
+#define TCM_SITA_H
+
+#include "../tcm.h"
+
+/*
+ * Create a SiTA tiler container manager.
+ */
+struct tcm *sita_init(u16 width, u16 height, void *attr);
+
+TCM_INIT(sita_init, void);
+
+#endif
-- 
1.7.0.4

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