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* tcm-sita.c
*
* SImple Tiler Allocator (SiTA): 2D and 1D allocation(reservation) algorithm
*
* Authors: Ravi Ramachandra <r.ramachandra@ti.com>,
* Lajos Molnar <molnar@ti.com>
*
* Copyright (C) 2009-2010 Texas Instruments, Inc.
*
* This package is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*/
#include <linux/slab.h>
#include <linux/spinlock.h>
#include "tcm-sita.h"
#define ALIGN_DOWN(value, align) ((value) & ~((align) - 1))
/* Individual selection criteria for different scan areas */
static s32 CR_L2R_T2B = CR_BIAS_HORIZONTAL;
static s32 CR_R2L_T2B = CR_DIAGONAL_BALANCE;
/*********************************************
* 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_reserve_1d(struct tcm *tcm, u32 slots, 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);
static s32 scan_r2l_t2b(struct tcm *tcm, u16 w, u16 h, u16 align,
struct tcm_area *field, struct tcm_area *area);
static s32 scan_r2l_b2t_one_dim(struct tcm *tcm, u32 num_slots,
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, struct tcm_pt *attr)
{
struct tcm *tcm;
struct sita_pvt *pvt;
struct tcm_area area = {0};
s32 i;
if (width == 0 || height == 0)
return NULL;
tcm = kmalloc(sizeof(*tcm), GFP_KERNEL);
pvt = kmalloc(sizeof(*pvt), GFP_KERNEL);
if (!tcm || !pvt)
goto error;
memset(tcm, 0, sizeof(*tcm));
memset(pvt, 0, sizeof(*pvt));
/* Updating the pointers to SiTA implementation APIs */
tcm->height = height;
tcm->width = width;
tcm->reserve_2d = sita_reserve_2d;
tcm->reserve_1d = sita_reserve_1d;
tcm->free = sita_free;
tcm->deinit = sita_deinit;
tcm->pvt = (void *)pvt;
spin_lock_init(&(pvt->lock));
/* Creating tam map */
pvt->map = kmalloc(sizeof(*pvt->map) * tcm->width, GFP_KERNEL);
if (!pvt->map)
goto error;
for (i = 0; i < tcm->width; i++) {
pvt->map[i] =
kmalloc(sizeof(**pvt->map) * tcm->height,
GFP_KERNEL);
if (pvt->map[i] == NULL) {
while (i--)
kfree(pvt->map[i]);
kfree(pvt->map);
goto error;
}
}
if (attr && attr->x <= tcm->width && attr->y <= tcm->height) {
pvt->div_pt.x = attr->x;
pvt->div_pt.y = attr->y;
} else {
/* Defaulting to 3:1 ratio on width for 2D area split */
/* Defaulting to 3:1 ratio on height for 2D and 1D split */
pvt->div_pt.x = (tcm->width * 3) / 4;
pvt->div_pt.y = (tcm->height * 3) / 4;
}
spin_lock(&(pvt->lock));
assign(&area, 0, 0, width - 1, height - 1);
fill_area(tcm, &area, NULL);
spin_unlock(&(pvt->lock));
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 = {0};
s32 i;
area.p1.x = tcm->width - 1;
area.p1.y = tcm->height - 1;
spin_lock(&(pvt->lock));
fill_area(tcm, &area, NULL);
spin_unlock(&(pvt->lock));
for (i = 0; i < tcm->height; i++)
kfree(pvt->map[i]);
kfree(pvt->map);
kfree(pvt);
}
/**
* Reserve a 1D area in the container
*
* @param num_slots size of 1D area
* @param area pointer to the area that will be populated with the
* reserved area
*
* @return 0 on success, non-0 error value on failure.
*/
static s32 sita_reserve_1d(struct tcm *tcm, u32 num_slots,
struct tcm_area *area)
{
s32 ret;
struct tcm_area field = {0};
struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
spin_lock(&(pvt->lock));
/* Scanning entire container */
assign(&field, tcm->width - 1, tcm->height - 1, 0, 0);
ret = scan_r2l_b2t_one_dim(tcm, num_slots, &field, area);
if (!ret)
/* update map */
fill_area(tcm, area, area);
spin_unlock(&(pvt->lock));
return ret;
}
/**
* Reserve a 2D area in the container
*
* @param w width
* @param h height
* @param area pointer to the area that will be populated with the reserved
* area
*
* @return 0 on success, non-0 error value on failure.
*/
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;
spin_lock(&(pvt->lock));
ret = scan_areas_and_find_fit(tcm, w, h, align, area);
if (!ret)
/* update map */
fill_area(tcm, area, area);
spin_unlock(&(pvt->lock));
return ret;
}
/**
* Unreserve a previously allocated 2D or 1D area
* @param area area to be freed
* @return 0 - success
*/
static s32 sita_free(struct tcm *tcm, struct tcm_area *area)
{
struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
spin_lock(&(pvt->lock));
/* check that this is in fact an existing area */
WARN_ON(pvt->map[area->p0.x][area->p0.y] != area ||
pvt->map[area->p1.x][area->p1.y] != area);
/* Clear the contents of the associated tiles in the map */
fill_area(tcm, area, NULL);
spin_unlock(&(pvt->lock));
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 right to left from top to bottom to find a place for
* a 2D area of given size inside a scan field.
*
* @param w width of desired area
* @param h height of desired area
* @param align desired area alignment
* @param area pointer to the area that will be set to the best position
* @param field area to scan (inclusive)
*
* @return 0 on success, non-0 error value on failure.
*/
static s32 scan_r2l_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, found_x = -1;
struct tcm_area ***map = ((struct sita_pvt *)tcm->pvt)->map;
struct score best = {{0}, {0}, {0}, 0};
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->p0.x < field->p1.x ||
field->p1.y < field->p0.y)
return -EINVAL;
/* check if allocation would fit in scan area */
if (w > LEN(start_x, end_x) || h > LEN(end_y, start_y))
return -ENOSPC;
/* adjust start_x and end_y, as allocation would not fit beyond */
start_x = ALIGN_DOWN(start_x - w + 1, align); /* - 1 to be inclusive */
end_y = end_y - h + 1;
/* check if allocation would still fit in scan area */
if (start_x < end_x)
return -ENOSPC;
/* scan field top-to-bottom, right-to-left */
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)) {
found_x = x;
/* update best candidate */
if (update_candidate(tcm, x, y, w, h, field,
CR_R2L_T2B, &best))
goto done;
/* change upper x bound */
end_x = x + 1;
break;
} else if (map[x][y] && map[x][y]->is2d) {
/* step over 2D areas */
x = ALIGN(map[x][y]->p0.x - w + 1, align);
}
}
/* break if you find a free area shouldering the scan field */
if (found_x == start_x)
break;
}
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;
}
/**
* 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.
*
* @param w width of desired area
* @param h height of desired area
* @param align desired area alignment
* @param area pointer to the area that will be set to the best position
* @param field area to scan (inclusive)
*
* @return 0 on success, non-0 error value on failure.
*/
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, found_x = -1;
struct tcm_area ***map = ((struct sita_pvt *)tcm->pvt)->map;
struct score best = {{0}, {0}, {0}, 0};
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;
/* 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)) {
found_x = x;
/* update best candidate */
if (update_candidate(tcm, x, y, w, h, field,
CR_L2R_T2B, &best))
goto done;
/* change upper x bound */
end_x = x - 1;
break;
} else if (map[x][y] && map[x][y]->is2d) {
/* step over 2D areas */
x = ALIGN_DOWN(map[x][y]->p1.x, align);
}
}
/* break if you find a free area shouldering the scan field */
if (found_x == start_x)
break;
}
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;
}
/**
* Raster scan horizontally right to left from bottom to top to find a place
* for a 1D area of given size inside a scan field.
*
* @param num_slots size of desired area
* @param align desired area alignment
* @param area pointer to the area that will be set to the best
* position
* @param field area to scan (inclusive)
*
* @return 0 on success, non-0 error value on failure.
*/
static s32 scan_r2l_b2t_one_dim(struct tcm *tcm, u32 num_slots,
struct tcm_area *field, struct tcm_area *area)
{
s32 found = 0;
s16 x, y;
struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
struct tcm_area *p;
/* check scan area co-ordinates */
if (field->p0.y < field->p1.y)
return -EINVAL;
/**
* Currently we only support full width 1D scan field, which makes sense
* since 1D slot-ordering spans the full container width.
*/
if (tcm->width != field->p0.x - field->p1.x + 1)
return -EINVAL;
/* check if allocation would fit in scan area */
if (num_slots > tcm->width * LEN(field->p0.y, field->p1.y))
return -ENOSPC;
x = field->p0.x;
y = field->p0.y;
/* find num_slots consecutive free slots to the left */
while (found < num_slots) {
if (y < 0)
return -ENOSPC;
/* remember bottom-right corner */
if (found == 0) {
area->p1.x = x;
area->p1.y = y;
}
/* skip busy regions */
p = pvt->map[x][y];
if (p) {
/* move to left of 2D areas, top left of 1D */
x = p->p0.x;
if (!p->is2d)
y = p->p0.y;
/* start over */
found = 0;
} else {
/* count consecutive free slots */
found++;
if (found == num_slots)
break;
}
/* move to the left */
if (x == 0)
y--;
x = (x ? : tcm->width) - 1;
}
/* set top-left corner */
area->p0.x = x;
area->p0.y = y;
return 0;
}
/**
* Find a place for a 2D area of given size inside a scan field based on its
* alignment needs.
*
* @param w width of desired area
* @param h height of desired area
* @param align desired area alignment
* @param area pointer to the area that will be set to the best position
*
* @return 0 on success, non-0 error value on failure.
*/
static s32 scan_areas_and_find_fit(struct tcm *tcm, u16 w, u16 h, u16 align,
struct tcm_area *area)
{
s32 ret = 0;
struct tcm_area field = {0};
u16 boundary_x, boundary_y;
struct sita_pvt *pvt = (struct sita_pvt *)tcm->pvt;
if (align > 1) {
/* prefer top-left corner */
boundary_x = pvt->div_pt.x - 1;
boundary_y = pvt->div_pt.y - 1;
/* expand width and height if needed */
if (w > pvt->div_pt.x)
boundary_x = tcm->width - 1;
if (h > pvt->div_pt.y)
boundary_y = tcm->height - 1;
assign(&field, 0, 0, boundary_x, boundary_y);
ret = scan_l2r_t2b(tcm, w, h, align, &field, area);
/* scan whole container if failed, but do not scan 2x */
if (ret != 0 && (boundary_x != tcm->width - 1 ||
boundary_y != tcm->height - 1)) {
/* scan the entire container if nothing found */
assign(&field, 0, 0, tcm->width - 1, tcm->height - 1);
ret = scan_l2r_t2b(tcm, w, h, align, &field, area);
}
} else if (align == 1) {
/* prefer top-right corner */
boundary_x = pvt->div_pt.x;
boundary_y = pvt->div_pt.y - 1;
/* expand width and height if needed */
if (w > (tcm->width - pvt->div_pt.x))
boundary_x = 0;
if (h > pvt->div_pt.y)
boundary_y = tcm->height - 1;
assign(&field, tcm->width - 1, 0, boundary_x, boundary_y);
ret = scan_r2l_t2b(tcm, w, h, align, &field, area);
/* scan whole container if failed, but do not scan 2x */
if (ret != 0 && (boundary_x != 0 ||
boundary_y != tcm->height - 1)) {
/* scan the entire container if nothing found */
assign(&field, tcm->width - 1, 0, 0, tcm->height - 1);
ret = scan_r2l_t2b(tcm, w, h, align, &field,
area);
}
}
return ret;
}
/* 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;
struct tcm_area a, a_;
/* set area's tcm; otherwise, enumerator considers it invalid */
area->tcm = tcm;
tcm_for_each_slice(a, *area, a_) {
for (x = a.p0.x; x <= a.p1.x; ++x)
for (y = a.p0.y; y <= a.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.
*
* @param x0, y0, w, h top, left, width, height of candidate area
* @param field scan field
* @param criteria scan criteria
* @param best best candidate and its scores
*
* @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 */
/*
* 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_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;
BUG_ON(first);
/* 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++;
}
}
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