drivers/misc/sram.c

   1 /*
   2  * Generic on-chip SRAM allocation driver
   3  *
   4  * Copyright (C) 2012 Philipp Zabel, Pengutronix
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  18  * MA 02110-1301, USA.
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/init.h>
  23 #include <linux/clk.h>
  24 #include <linux/err.h>
  25 #include <linux/io.h>
  26 #include <linux/of.h>
  27 #include <linux/of_address.h>
  28 #include <linux/list.h>
  29 #include <linux/list_sort.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/slab.h>
  32 #include <linux/spinlock.h>
  33 #include <linux/genalloc.h>
  34
  35 #define SRAM_GRANULARITY        4096
  36
  37 struct sram_dev {
  38         struct gen_pool *pool;
  39         struct clk *clk;
  40 };
  41
  42 struct sram_reserve {
  43         struct list_head list;
  44         u32 start;
  45         u32 size;
  46 };
  47
  48 static int sram_reserve_cmp(void *priv, struct list_head *a,
  49                                         struct list_head *b)
  50 {
  51         struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
  52         struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);
  53
  54         return ra->start - rb->start;
  55 }
  56
  57 static int sram_probe(struct platform_device *pdev)
  58 {
  59         void __iomem *virt_base;
  60         struct sram_dev *sram;
  61         struct resource *res;
  62         struct device_node *np = pdev->dev.of_node, *child;
  63         unsigned long size, cur_start, cur_size;
  64         struct sram_reserve *rblocks, *block;
  65         struct list_head reserve_list;
  66         unsigned int nblocks;
  67         int ret;
  68
  69         INIT_LIST_HEAD(&reserve_list);
  70
  71         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  72         virt_base = devm_ioremap_resource(&pdev->dev, res);
  73         if (IS_ERR(virt_base))
  74                 return PTR_ERR(virt_base);
  75
  76         size = resource_size(res);
  77
  78         sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
  79         if (!sram)
  80                 return -ENOMEM;
  81
  82         sram->clk = devm_clk_get(&pdev->dev, NULL);
  83         if (IS_ERR(sram->clk))
  84                 sram->clk = NULL;
  85         else
  86                 clk_prepare_enable(sram->clk);
  87
  88         sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
  89         if (!sram->pool)
  90                 return -ENOMEM;
  91
  92         /*
  93          * We need an additional block to mark the end of the memory region
  94          * after the reserved blocks from the dt are processed.
  95          */
  96         nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
  97         rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
  98         if (!rblocks) {
  99                 ret = -ENOMEM;
 100                 goto err_alloc;
 101         }
 102
 103         block = &rblocks[0];
 104         for_each_available_child_of_node(np, child) {
 105                 struct resource child_res;
 106
 107                 ret = of_address_to_resource(child, 0, &child_res);
 108                 if (ret < 0) {
 109                         dev_err(&pdev->dev,
 110                                 "could not get address for node %s\n",
 111                                 child->full_name);
 112                         goto err_chunks;
 113                 }
 114
 115                 if (child_res.start < res->start || child_res.end > res->end) {
 116                         dev_err(&pdev->dev,
 117                                 "reserved block %s outside the sram area\n",
 118                                 child->full_name);
 119                         ret = -EINVAL;
 120                         goto err_chunks;
 121                 }
 122
 123                 block->start = child_res.start - res->start;
 124                 block->size = resource_size(&child_res);
 125                 list_add_tail(&block->list, &reserve_list);
 126
 127                 dev_dbg(&pdev->dev, "found reserved block 0x%x-0x%x\n",
 128                         block->start,
 129                         block->start + block->size);
 130
 131                 block++;
 132         }
 133
 134         /* the last chunk marks the end of the region */
 135         rblocks[nblocks - 1].start = size;
 136         rblocks[nblocks - 1].size = 0;
 137         list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);
 138
 139         list_sort(NULL, &reserve_list, sram_reserve_cmp);
 140
 141         cur_start = 0;
 142
 143         list_for_each_entry(block, &reserve_list, list) {
 144                 /* can only happen if sections overlap */
 145                 if (block->start < cur_start) {
 146                         dev_err(&pdev->dev,
 147                                 "block at 0x%x starts after current offset 0x%lx\n",
 148                                 block->start, cur_start);
 149                         ret = -EINVAL;
 150                         goto err_chunks;
 151                 }
 152
 153                 /* current start is in a reserved block, so continue after it */
 154                 if (block->start == cur_start) {
 155                         cur_start = block->start + block->size;
 156                         continue;
 157                 }
 158
 159                 /*
 160                  * allocate the space between the current starting
 161                  * address and the following reserved block, or the
 162                  * end of the region.
 163                  */
 164                 cur_size = block->start - cur_start;
 165
 166                 dev_dbg(&pdev->dev, "adding chunk 0x%lx-0x%lx\n",
 167                         cur_start, cur_start + cur_size);
 168                 ret = gen_pool_add_virt(sram->pool,
 169                                 (unsigned long)virt_base + cur_start,
 170                                 res->start + cur_start, cur_size, -1);
 171                 if (ret < 0)
 172                         goto err_chunks;
 173
 174                 /* next allocation after this reserved block */
 175                 cur_start = block->start + block->size;
 176         }
 177
 178         kfree(rblocks);
 179
 180         platform_set_drvdata(pdev, sram);
 181
 182         dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
 183
 184         return 0;
 185
 186 err_chunks:
 187         kfree(rblocks);
 188 err_alloc:
 189         if (sram->clk)
 190                 clk_disable_unprepare(sram->clk);
 191         return ret;
 192 }
 193
 194 static int sram_remove(struct platform_device *pdev)
 195 {
 196         struct sram_dev *sram = platform_get_drvdata(pdev);
 197
 198         if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
 199                 dev_dbg(&pdev->dev, "removed while SRAM allocated\n");
 200
 201         if (sram->clk)
 202                 clk_disable_unprepare(sram->clk);
 203
 204         return 0;
 205 }
 206
 207 #ifdef CONFIG_OF
 208 static struct of_device_id sram_dt_ids[] = {
 209         { .compatible = "mmio-sram" },
 210         {}
 211 };
 212 #endif
 213
 214 static struct platform_driver sram_driver = {
 215         .driver = {
 216                 .name = "sram",
 217                 .of_match_table = of_match_ptr(sram_dt_ids),
 218         },
 219         .probe = sram_probe,
 220         .remove = sram_remove,
 221 };
 222
 223 static int __init sram_init(void)
 224 {
 225         return platform_driver_register(&sram_driver);
 226 }
 227
 228 postcore_initcall(sram_init);