drivers/bus/omap-ocp2scp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * omap-ocp2scp.c - transform ocp interface protocol to scp protocol
   4  *
   5  * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com
   6  * Author: Kishon Vijay Abraham I <kishon@ti.com>
   7  */
   8
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/err.h>
  13 #include <linux/pm_runtime.h>
  14 #include <linux/of.h>
  15 #include <linux/of_platform.h>
  16
  17 #define OCP2SCP_TIMING 0x18
  18 #define SYNC2_MASK 0xf
  19
  20 static int ocp2scp_remove_devices(struct device *dev, void *c)
  21 {
  22         struct platform_device *pdev = to_platform_device(dev);
  23
  24         platform_device_unregister(pdev);
  25
  26         return 0;
  27 }
  28
  29 static int omap_ocp2scp_probe(struct platform_device *pdev)
  30 {
  31         int ret;
  32         u32 reg;
  33         void __iomem *regs;
  34         struct resource *res;
  35         struct device_node *np = pdev->dev.of_node;
  36
  37         if (np) {
  38                 ret = of_platform_populate(np, NULL, NULL, &pdev->dev);
  39                 if (ret) {
  40                         dev_err(&pdev->dev,
  41                             "failed to add resources for ocp2scp child\n");
  42                         goto err0;
  43                 }
  44         }
  45
  46         pm_runtime_enable(&pdev->dev);
  47         /*
  48          * As per AM572x TRM: http://www.ti.com/lit/ug/spruhz6/spruhz6.pdf
  49          * under section 26.3.2.2, table 26-26 OCP2SCP TIMING Caution;
  50          * As per OMAP4430 TRM: http://www.ti.com/lit/ug/swpu231ap/swpu231ap.pdf
  51          * under section 23.12.6.2.2 , Table 23-1213 OCP2SCP TIMING Caution;
  52          * As per OMAP4460 TRM: http://www.ti.com/lit/ug/swpu235ab/swpu235ab.pdf
  53          * under section 23.12.6.2.2, Table 23-1213 OCP2SCP TIMING Caution;
  54          * As per OMAP543x TRM http://www.ti.com/lit/pdf/swpu249
  55          * under section 27.3.2.2, Table 27-27 OCP2SCP TIMING Caution;
  56          *
  57          * Read path of OCP2SCP is not working properly due to low reset value
  58          * of SYNC2 parameter in OCP2SCP. Suggested reset value is 0x6 or more.
  59          */
  60         if (!of_device_is_compatible(np, "ti,am437x-ocp2scp")) {
  61                 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  62                 regs = devm_ioremap_resource(&pdev->dev, res);
  63                 if (IS_ERR(regs)) {
  64                         ret = PTR_ERR(regs);
  65                         goto err1;
  66                 }
  67
  68                 pm_runtime_get_sync(&pdev->dev);
  69                 reg = readl_relaxed(regs + OCP2SCP_TIMING);
  70                 reg &= ~(SYNC2_MASK);
  71                 reg |= 0x6;
  72                 writel_relaxed(reg, regs + OCP2SCP_TIMING);
  73                 pm_runtime_put_sync(&pdev->dev);
  74         }
  75
  76         return 0;
  77
  78 err1:
  79         pm_runtime_disable(&pdev->dev);
  80
  81 err0:
  82         device_for_each_child(&pdev->dev, NULL, ocp2scp_remove_devices);
  83
  84         return ret;
  85 }
  86
  87 static int omap_ocp2scp_remove(struct platform_device *pdev)
  88 {
  89         pm_runtime_disable(&pdev->dev);
  90         device_for_each_child(&pdev->dev, NULL, ocp2scp_remove_devices);
  91
  92         return 0;
  93 }
  94
  95 #ifdef CONFIG_OF
  96 static const struct of_device_id omap_ocp2scp_id_table[] = {
  97         { .compatible = "ti,omap-ocp2scp" },
  98         { .compatible = "ti,am437x-ocp2scp" },
  99         {}
 100 };
 101 MODULE_DEVICE_TABLE(of, omap_ocp2scp_id_table);
 102 #endif
 103
 104 static struct platform_driver omap_ocp2scp_driver = {
 105         .probe          = omap_ocp2scp_probe,
 106         .remove         = omap_ocp2scp_remove,
 107         .driver         = {
 108                 .name   = "omap-ocp2scp",
 109                 .of_match_table = of_match_ptr(omap_ocp2scp_id_table),
 110         },
 111 };
 112
 113 module_platform_driver(omap_ocp2scp_driver);
 114
 115 MODULE_ALIAS("platform:omap-ocp2scp");
 116 MODULE_AUTHOR("Texas Instruments Inc.");
 117 MODULE_DESCRIPTION("OMAP OCP2SCP driver");
 118 MODULE_LICENSE("GPL v2");