LXR linux/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
  30static 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
  39static 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
  86err0:
  87        device_for_each_child(&pdev->dev, NULL, ocp2scp_remove_devices);
  88
  89        return ret;
  90}
  91
  92static 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
 101static const struct of_device_id omap_ocp2scp_id_table[] = {
 102        { .compatible = "ti,omap-ocp2scp" },
 103        { .compatible = "ti,am437x-ocp2scp" },
 104        {}
 105};
 106MODULE_DEVICE_TABLE(of, omap_ocp2scp_id_table);
 107#endif
 108
 109static 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
 118module_platform_driver(omap_ocp2scp_driver);
 119
 120MODULE_ALIAS("platform:omap-ocp2scp");
 121MODULE_AUTHOR("Texas Instruments Inc.");
 122MODULE_DESCRIPTION("OMAP OCP2SCP driver");
 123MODULE_LICENSE("GPL v2");
 124