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