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/platform_device.h>
  28 #include <linux/slab.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/genalloc.h>
  31
  32 #define SRAM_GRANULARITY        32
  33
  34 struct sram_dev {
  35         struct gen_pool *pool;
  36         struct clk *clk;
  37 };
  38
  39 static int sram_probe(struct platform_device *pdev)
  40 {
  41         void __iomem *virt_base;
  42         struct sram_dev *sram;
  43         struct resource *res;
  44         unsigned long size;
  45         int ret;
  46
  47         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  48         if (!res)
  49                 return -EINVAL;
  50
  51         size = resource_size(res);
  52
  53         virt_base = devm_request_and_ioremap(&pdev->dev, res);
  54         if (!virt_base)
  55                 return -EADDRNOTAVAIL;
  56
  57         sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
  58         if (!sram)
  59                 return -ENOMEM;
  60
  61         sram->clk = devm_clk_get(&pdev->dev, NULL);
  62         if (IS_ERR(sram->clk))
  63                 sram->clk = NULL;
  64         else
  65                 clk_prepare_enable(sram->clk);
  66
  67         sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
  68         if (!sram->pool)
  69                 return -ENOMEM;
  70
  71         ret = gen_pool_add_virt(sram->pool, (unsigned long)virt_base,
  72                                 res->start, size, -1);
  73         if (ret < 0) {
  74                 gen_pool_destroy(sram->pool);
  75                 return ret;
  76         }
  77
  78         platform_set_drvdata(pdev, sram);
  79
  80         dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
  81
  82         return 0;
  83 }
  84
  85 static int sram_remove(struct platform_device *pdev)
  86 {
  87         struct sram_dev *sram = platform_get_drvdata(pdev);
  88
  89         if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
  90                 dev_dbg(&pdev->dev, "removed while SRAM allocated\n");
  91
  92         gen_pool_destroy(sram->pool);
  93
  94         if (sram->clk)
  95                 clk_disable_unprepare(sram->clk);
  96
  97         return 0;
  98 }
  99
 100 #ifdef CONFIG_OF
 101 static struct of_device_id sram_dt_ids[] = {
 102         { .compatible = "mmio-sram" },
 103         {}
 104 };
 105 #endif
 106
 107 static struct platform_driver sram_driver = {
 108         .driver = {
 109                 .name = "sram",
 110                 .of_match_table = of_match_ptr(sram_dt_ids),
 111         },
 112         .probe = sram_probe,
 113         .remove = sram_remove,
 114 };
 115
 116 static int __init sram_init(void)
 117 {
 118         return platform_driver_register(&sram_driver);
 119 }
 120
 121 postcore_initcall(sram_init);