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| 1 | +/* |
| 2 | + * rcar-fcp.c -- R-Car Frame Compression Processor Driver |
| 3 | + * |
| 4 | + * Copyright (C) 2016 Renesas Electronics Corporation |
| 5 | + * |
| 6 | + * Contact: Laurent Pinchart ([email protected]) |
| 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 <[email protected]>"); |
| 180 | +MODULE_DESCRIPTION("Renesas FCP Driver"); |
| 181 | +MODULE_LICENSE("GPL"); |
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