LXR linux/arch/arm/mach-imx/mmdc.c

   1/*
   2 * Copyright 2011 Freescale Semiconductor, Inc.
   3 * Copyright 2011 Linaro Ltd.
   4 *
   5 * The code contained herein is licensed under the GNU General Public
   6 * License. You may obtain a copy of the GNU General Public License
   7 * Version 2 or later at the following locations:
   8 *
   9 * http://www.opensource.org/licenses/gpl-license.html
  10 * http://www.gnu.org/copyleft/gpl.html
  11 */
  12
  13#include <linux/init.h>
  14#include <linux/io.h>
  15#include <linux/module.h>
  16#include <linux/of.h>
  17#include <linux/of_address.h>
  18#include <linux/of_device.h>
  19
  20#include "common.h"
  21
  22#define MMDC_MAPSR              0x404
  23#define BP_MMDC_MAPSR_PSD       0
  24#define BP_MMDC_MAPSR_PSS       4
  25
  26#define MMDC_MDMISC             0x18
  27#define BM_MMDC_MDMISC_DDR_TYPE 0x18
  28#define BP_MMDC_MDMISC_DDR_TYPE 0x3
  29
  30static int ddr_type;
  31
  32static int imx_mmdc_probe(struct platform_device *pdev)
  33{
  34        struct device_node *np = pdev->dev.of_node;
  35        void __iomem *mmdc_base, *reg;
  36        u32 val;
  37        int timeout = 0x400;
  38
  39        mmdc_base = of_iomap(np, 0);
  40        WARN_ON(!mmdc_base);
  41
  42        reg = mmdc_base + MMDC_MDMISC;
  43        /* Get ddr type */
  44        val = readl_relaxed(reg);
  45        ddr_type = (val & BM_MMDC_MDMISC_DDR_TYPE) >>
  46                 BP_MMDC_MDMISC_DDR_TYPE;
  47
  48        reg = mmdc_base + MMDC_MAPSR;
  49
  50        /* Enable automatic power saving */
  51        val = readl_relaxed(reg);
  52        val &= ~(1 << BP_MMDC_MAPSR_PSD);
  53        writel_relaxed(val, reg);
  54
  55        /* Ensure it's successfully enabled */
  56        while (!(readl_relaxed(reg) & 1 << BP_MMDC_MAPSR_PSS) && --timeout)
  57                cpu_relax();
  58
  59        if (unlikely(!timeout)) {
  60                pr_warn("%s: failed to enable automatic power saving\n",
  61                        __func__);
  62                return -EBUSY;
  63        }
  64
  65        return 0;
  66}
  67
  68int imx_mmdc_get_ddr_type(void)
  69{
  70        return ddr_type;
  71}
  72
  73static const struct of_device_id imx_mmdc_dt_ids[] = {
  74        { .compatible = "fsl,imx6q-mmdc", },
  75        { /* sentinel */ }
  76};
  77
  78static struct platform_driver imx_mmdc_driver = {
  79        .driver         = {
  80                .name   = "imx-mmdc",
  81                .of_match_table = imx_mmdc_dt_ids,
  82        },
  83        .probe          = imx_mmdc_probe,
  84};
  85
  86static int __init imx_mmdc_init(void)
  87{
  88        return platform_driver_register(&imx_mmdc_driver);
  89}
  90postcore_initcall(imx_mmdc_init);
  91