mmdc.c
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/*
* Copyright 2011-2014 Freescale Semiconductor, Inc.
* Copyright 2011 Linaro Ltd.
*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#define MMDC_MAPSR 0x404
#define BP_MMDC_MAPSR_PSD 0
#define BP_MMDC_MAPSR_PSS 4
#define MMDC_MDMISC 0x18
#define BM_MMDC_MDMISC_DDR_TYPE 0x18
#define BP_MMDC_MDMISC_DDR_TYPE 0x3
static int ddr_type;
static int imx_mmdc_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
void __iomem *mmdc_base, *reg;
u32 val;
int timeout = 0x400;
mmdc_base = of_iomap(np, 0);
WARN_ON(!mmdc_base);
reg = mmdc_base + MMDC_MDMISC;
/* Get ddr type */
val = readl_relaxed(reg);
val &= BM_MMDC_MDMISC_DDR_TYPE;
val >>= BP_MMDC_MDMISC_DDR_TYPE;
ddr_type = val;
reg = mmdc_base + MMDC_MAPSR;
/* Enable automatic power saving */
val = readl_relaxed(reg);
val &= ~(1 << BP_MMDC_MAPSR_PSD);
writel_relaxed(val, reg);
/* Ensure it's successfully enabled */
while (!(readl_relaxed(reg) & 1 << BP_MMDC_MAPSR_PSS) && --timeout)
cpu_relax();
if (unlikely(!timeout)) {
pr_warn("%s: failed to enable automatic power saving\n",
__func__);
return -EBUSY;
}
return 0;
}
int imx_mmdc_get_ddr_type(void)
{
return ddr_type;
}
static struct of_device_id imx_mmdc_dt_ids[] = {
{ .compatible = "fsl,imx6q-mmdc", },
{ /* sentinel */ }
};
static struct platform_driver imx_mmdc_driver = {
.driver = {
.name = "imx-mmdc",
.owner = THIS_MODULE,
.of_match_table = imx_mmdc_dt_ids,
},
.probe = imx_mmdc_probe,
};
static int __init imx_mmdc_init(void)
{
return platform_driver_register(&imx_mmdc_driver);
}
postcore_initcall(imx_mmdc_init);