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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 
 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");
124 

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