drivers/bus/omap-ocp2scp.c

   1 /*
   2  * omap-ocp2scp.c - transform ocp interface protocol to scp protocol
   3  *
   4  * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * Author: Kishon Vijay Abraham I <kishon@ti.com>
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  */
  18
  19 #include <linux/io.h>
  20 #include <linux/module.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/err.h>
  23 #include <linux/pm_runtime.h>
  24 #include <linux/of.h>
  25 #include <linux/of_platform.h>
  26
  27 #define OCP2SCP_TIMING 0x18
  28 #define SYNC2_MASK 0xf
  29
  30 static int ocp2scp_remove_devices(struct device *dev, void *c)
  31 {
  32         struct platform_device *pdev = to_platform_device(dev);
  33
  34         platform_device_unregister(pdev);
  35
  36         return 0;
  37 }
  38
  39 static int omap_ocp2scp_probe(struct platform_device *pdev)
  40 {
  41         int ret;
  42         u32 reg;
  43         void __iomem *regs;
  44         struct resource *res;
  45         struct device_node *np = pdev->dev.of_node;
  46
  47         if (np) {
  48                 ret = of_platform_populate(np, NULL, NULL, &pdev->dev);
  49                 if (ret) {
  50                         dev_err(&pdev->dev,
  51                             "failed to add resources for ocp2scp child\n");
  52                         goto err0;
  53                 }
  54         }
  55
  56         pm_runtime_enable(&pdev->dev);
  57         /*
  58          * As per AM572x TRM: http://www.ti.com/lit/ug/spruhz6/spruhz6.pdf
  59          * under section 26.3.2.2, table 26-26 OCP2SCP TIMING Caution;
  60          * As per OMAP4430 TRM: http://www.ti.com/lit/ug/swpu231ap/swpu231ap.pdf
  61          * under section 23.12.6.2.2 , Table 23-1213 OCP2SCP TIMING Caution;
  62          * As per OMAP4460 TRM: http://www.ti.com/lit/ug/swpu235ab/swpu235ab.pdf
  63          * under section 23.12.6.2.2, Table 23-1213 OCP2SCP TIMING Caution;
  64          * As per OMAP543x TRM http://www.ti.com/lit/pdf/swpu249
  65          * under section 27.3.2.2, Table 27-27 OCP2SCP TIMING Caution;
  66          *
  67          * Read path of OCP2SCP is not working properly due to low reset value
  68          * of SYNC2 parameter in OCP2SCP. Suggested reset value is 0x6 or more.
  69          */
  70         if (!of_device_is_compatible(np, "ti,am437x-ocp2scp")) {
  71                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  72                 regs = devm_ioremap_resource(&pdev->dev, res);
  73                 if (IS_ERR(regs))
  74                         goto err0;
  75
  76                 pm_runtime_get_sync(&pdev->dev);
  77                 reg = readl_relaxed(regs + OCP2SCP_TIMING);
  78                 reg &= ~(SYNC2_MASK);
  79                 reg |= 0x6;
  80                 writel_relaxed(reg, regs + OCP2SCP_TIMING);
  81                 pm_runtime_put_sync(&pdev->dev);
  82         }
  83
  84         return 0;
  85
  86 err0:
  87         device_for_each_child(&pdev->dev, NULL, ocp2scp_remove_devices);
  88
  89         return ret;
  90 }
  91
  92 static int omap_ocp2scp_remove(struct platform_device *pdev)
  93 {
  94         pm_runtime_disable(&pdev->dev);
  95         device_for_each_child(&pdev->dev, NULL, ocp2scp_remove_devices);
  96
  97         return 0;
  98 }
  99
 100 #ifdef CONFIG_OF
 101 static const struct of_device_id omap_ocp2scp_id_table[] = {
 102         { .compatible = "ti,omap-ocp2scp" },
 103         { .compatible = "ti,am437x-ocp2scp" },
 104         {}
 105 };
 106 MODULE_DEVICE_TABLE(of, omap_ocp2scp_id_table);
 107 #endif
 108
 109 static struct platform_driver omap_ocp2scp_driver = {
 110         .probe          = omap_ocp2scp_probe,
 111         .remove         = omap_ocp2scp_remove,
 112         .driver         = {
 113                 .name   = "omap-ocp2scp",
 114                 .of_match_table = of_match_ptr(omap_ocp2scp_id_table),
 115         },
 116 };
 117
 118 module_platform_driver(omap_ocp2scp_driver);
 119
 120 MODULE_ALIAS("platform:omap-ocp2scp");
 121 MODULE_AUTHOR("Texas Instruments Inc.");
 122 MODULE_DESCRIPTION("OMAP OCP2SCP driver");
 123 MODULE_LICENSE("GPL v2");