summaryrefslogtreecommitdiffstats
path: root/kernel/drivers/misc/sram.c
blob: eeaaf5fca105d9aeed160fbd13c73ba0bbee539d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
/*
 * Generic on-chip SRAM allocation driver
 *
 * Copyright (C) 2012 Philipp Zabel, Pengutronix
 *
 * 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; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/list.h>
#include <linux/list_sort.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/genalloc.h>

#define SRAM_GRANULARITY	32

struct sram_dev {
	struct gen_pool *pool;
	struct clk *clk;
};

struct sram_reserve {
	struct list_head list;
	u32 start;
	u32 size;
};

static int sram_reserve_cmp(void *priv, struct list_head *a,
					struct list_head *b)
{
	struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
	struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);

	return ra->start - rb->start;
}

static int sram_probe(struct platform_device *pdev)
{
	void __iomem *virt_base;
	struct sram_dev *sram;
	struct resource *res;
	struct device_node *np = pdev->dev.of_node, *child;
	unsigned long size, cur_start, cur_size;
	struct sram_reserve *rblocks, *block;
	struct list_head reserve_list;
	unsigned int nblocks;
	int ret;

	INIT_LIST_HEAD(&reserve_list);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(&pdev->dev, "found no memory resource\n");
		return -EINVAL;
	}

	size = resource_size(res);

	if (!devm_request_mem_region(&pdev->dev,
			res->start, size, pdev->name)) {
		dev_err(&pdev->dev, "could not request region for resource\n");
		return -EBUSY;
	}

	virt_base = devm_ioremap_wc(&pdev->dev, res->start, size);
	if (IS_ERR(virt_base))
		return PTR_ERR(virt_base);

	sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
	if (!sram)
		return -ENOMEM;

	sram->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(sram->clk))
		sram->clk = NULL;
	else
		clk_prepare_enable(sram->clk);

	sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
	if (!sram->pool)
		return -ENOMEM;

	/*
	 * We need an additional block to mark the end of the memory region
	 * after the reserved blocks from the dt are processed.
	 */
	nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
	rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
	if (!rblocks) {
		ret = -ENOMEM;
		goto err_alloc;
	}

	block = &rblocks[0];
	for_each_available_child_of_node(np, child) {
		struct resource child_res;

		ret = of_address_to_resource(child, 0, &child_res);
		if (ret < 0) {
			dev_err(&pdev->dev,
				"could not get address for node %s\n",
				child->full_name);
			goto err_chunks;
		}

		if (child_res.start < res->start || child_res.end > res->end) {
			dev_err(&pdev->dev,
				"reserved block %s outside the sram area\n",
				child->full_name);
			ret = -EINVAL;
			goto err_chunks;
		}

		block->start = child_res.start - res->start;
		block->size = resource_size(&child_res);
		list_add_tail(&block->list, &reserve_list);

		dev_dbg(&pdev->dev, "found reserved block 0x%x-0x%x\n",
			block->start,
			block->start + block->size);

		block++;
	}

	/* the last chunk marks the end of the region */
	rblocks[nblocks - 1].start = size;
	rblocks[nblocks - 1].size = 0;
	list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);

	list_sort(NULL, &reserve_list, sram_reserve_cmp);

	cur_start = 0;

	list_for_each_entry(block, &reserve_list, list) {
		/* can only happen if sections overlap */
		if (block->start < cur_start) {
			dev_err(&pdev->dev,
				"block at 0x%x starts after current offset 0x%lx\n",
				block->start, cur_start);
			ret = -EINVAL;
			goto err_chunks;
		}

		/* current start is in a reserved block, so continue after it */
		if (block->start == cur_start) {
			cur_start = block->start + block->size;
			continue;
		}

		/*
		 * allocate the space between the current starting
		 * address and the following reserved block, or the
		 * end of the region.
		 */
		cur_size = block->start - cur_start;

		dev_dbg(&pdev->dev, "adding chunk 0x%lx-0x%lx\n",
			cur_start, cur_start + cur_size);
		ret = gen_pool_add_virt(sram->pool,
				(unsigned long)virt_base + cur_start,
				res->start + cur_start, cur_size, -1);
		if (ret < 0)
			goto err_chunks;

		/* next allocation after this reserved block */
		cur_start = block->start + block->size;
	}

	kfree(rblocks);

	platform_set_drvdata(pdev, sram);

	dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);

	return 0;

err_chunks:
	kfree(rblocks);
err_alloc:
	if (sram->clk)
		clk_disable_unprepare(sram->clk);
	return ret;
}

static int sram_remove(struct platform_device *pdev)
{
	struct sram_dev *sram = platform_get_drvdata(pdev);

	if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
		dev_dbg(&pdev->dev, "removed while SRAM allocated\n");

	if (sram->clk)
		clk_disable_unprepare(sram->clk);

	return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id sram_dt_ids[] = {
	{ .compatible = "mmio-sram" },
	{}
};
#endif

static struct platform_driver sram_driver = {
	.driver = {
		.name = "sram",
		.of_match_table = of_match_ptr(sram_dt_ids),
	},
	.probe = sram_probe,
	.remove = sram_remove,
};

static int __init sram_init(void)
{
	return platform_driver_register(&sram_driver);
}

postcore_initcall(sram_init);