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
  30 static int ddr_type;
  31
  32 static 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
  68 int imx_mmdc_get_ddr_type(void)
  69 {
  70         return ddr_type;
  71 }
  72
  73 static const struct of_device_id imx_mmdc_dt_ids[] = {
  74         { .compatible = "fsl,imx6q-mmdc", },
  75         { /* sentinel */ }
  76 };
  77
  78 static 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
  86 static int __init imx_mmdc_init(void)
  87 {
  88         return platform_driver_register(&imx_mmdc_driver);
  89 }
  90 postcore_initcall(imx_mmdc_init);