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 #define MMDC_MAPSR 0x404
21 #define BP_MMDC_MAPSR_PSD 0
22 #define BP_MMDC_MAPSR_PSS 4
23
imx_mmdc_probe(struct platform_device * pdev)24 static int imx_mmdc_probe(struct platform_device *pdev)
25 {
26 struct device_node *np = pdev->dev.of_node;
27 void __iomem *mmdc_base, *reg;
28 u32 val;
29 int timeout = 0x400;
30
31 mmdc_base = of_iomap(np, 0);
32 WARN_ON(!mmdc_base);
33
34 reg = mmdc_base + MMDC_MAPSR;
35
36 /* Enable automatic power saving */
37 val = readl_relaxed(reg);
38 val &= ~(1 << BP_MMDC_MAPSR_PSD);
39 writel_relaxed(val, reg);
40
41 /* Ensure it's successfully enabled */
42 while (!(readl_relaxed(reg) & 1 << BP_MMDC_MAPSR_PSS) && --timeout)
43 cpu_relax();
44
45 if (unlikely(!timeout)) {
46 pr_warn("%s: failed to enable automatic power saving\n",
47 __func__);
48 return -EBUSY;
49 }
50
51 return 0;
52 }
53
54 static struct of_device_id imx_mmdc_dt_ids[] = {
55 { .compatible = "fsl,imx6q-mmdc", },
56 { /* sentinel */ }
57 };
58
59 static struct platform_driver imx_mmdc_driver = {
60 .driver = {
61 .name = "imx-mmdc",
62 .owner = THIS_MODULE,
63 .of_match_table = imx_mmdc_dt_ids,
64 },
65 .probe = imx_mmdc_probe,
66 };
67
imx_mmdc_init(void)68 static int __init imx_mmdc_init(void)
69 {
70 return platform_driver_register(&imx_mmdc_driver);
71 }
72 postcore_initcall(imx_mmdc_init);
73