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7b49235e LP |
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"); |