drivers/media/platform/rcar-fcp.c

   1 /*
   2  * rcar-fcp.c  --  R-Car Frame Compression Processor Driver
   3  *
   4  * Copyright (C) 2016 Renesas Electronics Corporation
   5  *
   6  * Contact: Laurent Pinchart (laurent.pinchart@ideasonboard.com)
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  */
  13
  14 #include <linux/device.h>
  15 #include <linux/list.h>
  16 #include <linux/module.h>
  17 #include <linux/mutex.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pm_runtime.h>
  20 #include <linux/slab.h>
  21
  22 #include <media/rcar-fcp.h>
  23
  24 struct rcar_fcp_device {
  25         struct list_head list;
  26         struct device *dev;
  27 };
  28
  29 static LIST_HEAD(fcp_devices);
  30 static DEFINE_MUTEX(fcp_lock);
  31
  32 /* -----------------------------------------------------------------------------
  33  * Public API
  34  */
  35
  36 /**
  37  * rcar_fcp_get - Find and acquire a reference to an FCP instance
  38  * @np: Device node of the FCP instance
  39  *
  40  * Search the list of registered FCP instances for the instance corresponding to
  41  * the given device node.
  42  *
  43  * Return a pointer to the FCP instance, or an ERR_PTR if the instance can't be
  44  * found.
  45  */
  46 struct rcar_fcp_device *rcar_fcp_get(const struct device_node *np)
  47 {
  48         struct rcar_fcp_device *fcp;
  49
  50         mutex_lock(&fcp_lock);
  51
  52         list_for_each_entry(fcp, &fcp_devices, list) {
  53                 if (fcp->dev->of_node != np)
  54                         continue;
  55
  56                 /*
  57                  * Make sure the module won't be unloaded behind our back. This
  58                  * is a poor man's safety net, the module should really not be
  59                  * unloaded while FCP users can be active.
  60                  */
  61                 if (!try_module_get(fcp->dev->driver->owner))
  62                         fcp = NULL;
  63
  64                 goto done;
  65         }
  66
  67         fcp = ERR_PTR(-EPROBE_DEFER);
  68
  69 done:
  70         mutex_unlock(&fcp_lock);
  71         return fcp;
  72 }
  73 EXPORT_SYMBOL_GPL(rcar_fcp_get);
  74
  75 /**
  76  * rcar_fcp_put - Release a reference to an FCP instance
  77  * @fcp: The FCP instance
  78  *
  79  * Release the FCP instance acquired by a call to rcar_fcp_get().
  80  */
  81 void rcar_fcp_put(struct rcar_fcp_device *fcp)
  82 {
  83         if (fcp)
  84                 module_put(fcp->dev->driver->owner);
  85 }
  86 EXPORT_SYMBOL_GPL(rcar_fcp_put);
  87
  88 /**
  89  * rcar_fcp_enable - Enable an FCP
  90  * @fcp: The FCP instance
  91  *
  92  * Before any memory access through an FCP is performed by a module, the FCP
  93  * must be enabled by a call to this function. The enable calls are reference
  94  * counted, each successful call must be followed by one rcar_fcp_disable()
  95  * call when no more memory transfer can occur through the FCP.
  96  *
  97  * Return 0 on success or a negative error code if an error occurs. The enable
  98  * reference count isn't increased when this function returns an error.
  99  */
 100 int rcar_fcp_enable(struct rcar_fcp_device *fcp)
 101 {
 102         if (!fcp)
 103                 return 0;
 104
 105         return pm_runtime_get_sync(fcp->dev);
 106 }
 107 EXPORT_SYMBOL_GPL(rcar_fcp_enable);
 108
 109 /**
 110  * rcar_fcp_disable - Disable an FCP
 111  * @fcp: The FCP instance
 112  *
 113  * This function is the counterpart of rcar_fcp_enable(). As enable calls are
 114  * reference counted a disable call may not disable the FCP synchronously.
 115  */
 116 void rcar_fcp_disable(struct rcar_fcp_device *fcp)
 117 {
 118         if (fcp)
 119                 pm_runtime_put(fcp->dev);
 120 }
 121 EXPORT_SYMBOL_GPL(rcar_fcp_disable);
 122
 123 /* -----------------------------------------------------------------------------
 124  * Platform Driver
 125  */
 126
 127 static int rcar_fcp_probe(struct platform_device *pdev)
 128 {
 129         struct rcar_fcp_device *fcp;
 130
 131         fcp = devm_kzalloc(&pdev->dev, sizeof(*fcp), GFP_KERNEL);
 132         if (fcp == NULL)
 133                 return -ENOMEM;
 134
 135         fcp->dev = &pdev->dev;
 136
 137         pm_runtime_enable(&pdev->dev);
 138
 139         mutex_lock(&fcp_lock);
 140         list_add_tail(&fcp->list, &fcp_devices);
 141         mutex_unlock(&fcp_lock);
 142
 143         platform_set_drvdata(pdev, fcp);
 144
 145         return 0;
 146 }
 147
 148 static int rcar_fcp_remove(struct platform_device *pdev)
 149 {
 150         struct rcar_fcp_device *fcp = platform_get_drvdata(pdev);
 151
 152         mutex_lock(&fcp_lock);
 153         list_del(&fcp->list);
 154         mutex_unlock(&fcp_lock);
 155
 156         pm_runtime_disable(&pdev->dev);
 157
 158         return 0;
 159 }
 160
 161 static const struct of_device_id rcar_fcp_of_match[] = {
 162         { .compatible = "renesas,fcpv" },
 163         { },
 164 };
 165
 166 static struct platform_driver rcar_fcp_platform_driver = {
 167         .probe          = rcar_fcp_probe,
 168         .remove         = rcar_fcp_remove,
 169         .driver         = {
 170                 .name   = "rcar-fcp",
 171                 .of_match_table = rcar_fcp_of_match,
 172                 .suppress_bind_attrs = true,
 173         },
 174 };
 175
 176 module_platform_driver(rcar_fcp_platform_driver);
 177
 178 MODULE_ALIAS("rcar-fcp");
 179 MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 180 MODULE_DESCRIPTION("Renesas FCP Driver");
 181 MODULE_LICENSE("GPL");