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c767db0a MD |
1 | /* |
2 | * drivers/uio/uio_pdrv_genirq.c | |
3 | * | |
4 | * Userspace I/O platform driver with generic IRQ handling code. | |
5 | * | |
6 | * Copyright (C) 2008 Magnus Damm | |
7 | * | |
8 | * Based on uio_pdrv.c by Uwe Kleine-Koenig, | |
9 | * Copyright (C) 2008 by Digi International Inc. | |
10 | * All rights reserved. | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or modify it | |
13 | * under the terms of the GNU General Public License version 2 as published by | |
14 | * the Free Software Foundation. | |
15 | */ | |
16 | ||
17 | #include <linux/platform_device.h> | |
18 | #include <linux/uio_driver.h> | |
19 | #include <linux/spinlock.h> | |
20 | #include <linux/bitops.h> | |
21 | #include <linux/interrupt.h> | |
22 | #include <linux/stringify.h> | |
23 | ||
24 | #define DRIVER_NAME "uio_pdrv_genirq" | |
25 | ||
26 | struct uio_pdrv_genirq_platdata { | |
27 | struct uio_info *uioinfo; | |
28 | spinlock_t lock; | |
29 | unsigned long flags; | |
30 | }; | |
31 | ||
32 | static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info) | |
33 | { | |
34 | struct uio_pdrv_genirq_platdata *priv = dev_info->priv; | |
35 | ||
36 | /* Just disable the interrupt in the interrupt controller, and | |
37 | * remember the state so we can allow user space to enable it later. | |
38 | */ | |
39 | ||
40 | if (!test_and_set_bit(0, &priv->flags)) | |
41 | disable_irq_nosync(irq); | |
42 | ||
43 | return IRQ_HANDLED; | |
44 | } | |
45 | ||
46 | static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) | |
47 | { | |
48 | struct uio_pdrv_genirq_platdata *priv = dev_info->priv; | |
49 | unsigned long flags; | |
50 | ||
51 | /* Allow user space to enable and disable the interrupt | |
52 | * in the interrupt controller, but keep track of the | |
53 | * state to prevent per-irq depth damage. | |
54 | * | |
55 | * Serialize this operation to support multiple tasks. | |
56 | */ | |
57 | ||
58 | spin_lock_irqsave(&priv->lock, flags); | |
59 | if (irq_on) { | |
60 | if (test_and_clear_bit(0, &priv->flags)) | |
61 | enable_irq(dev_info->irq); | |
62 | } else { | |
63 | if (!test_and_set_bit(0, &priv->flags)) | |
64 | disable_irq(dev_info->irq); | |
65 | } | |
66 | spin_unlock_irqrestore(&priv->lock, flags); | |
67 | ||
68 | return 0; | |
69 | } | |
70 | ||
71 | static int uio_pdrv_genirq_probe(struct platform_device *pdev) | |
72 | { | |
73 | struct uio_info *uioinfo = pdev->dev.platform_data; | |
74 | struct uio_pdrv_genirq_platdata *priv; | |
75 | struct uio_mem *uiomem; | |
76 | int ret = -EINVAL; | |
77 | int i; | |
78 | ||
79 | if (!uioinfo || !uioinfo->name || !uioinfo->version) { | |
80 | dev_err(&pdev->dev, "missing platform_data\n"); | |
81 | goto bad0; | |
82 | } | |
83 | ||
84 | if (uioinfo->handler || uioinfo->irqcontrol || uioinfo->irq_flags) { | |
85 | dev_err(&pdev->dev, "interrupt configuration error\n"); | |
86 | goto bad0; | |
87 | } | |
88 | ||
89 | priv = kzalloc(sizeof(*priv), GFP_KERNEL); | |
90 | if (!priv) { | |
91 | ret = -ENOMEM; | |
92 | dev_err(&pdev->dev, "unable to kmalloc\n"); | |
93 | goto bad0; | |
94 | } | |
95 | ||
96 | priv->uioinfo = uioinfo; | |
97 | spin_lock_init(&priv->lock); | |
98 | priv->flags = 0; /* interrupt is enabled to begin with */ | |
99 | ||
100 | uiomem = &uioinfo->mem[0]; | |
101 | ||
102 | for (i = 0; i < pdev->num_resources; ++i) { | |
103 | struct resource *r = &pdev->resource[i]; | |
104 | ||
105 | if (r->flags != IORESOURCE_MEM) | |
106 | continue; | |
107 | ||
108 | if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { | |
109 | dev_warn(&pdev->dev, "device has more than " | |
110 | __stringify(MAX_UIO_MAPS) | |
111 | " I/O memory resources.\n"); | |
112 | break; | |
113 | } | |
114 | ||
115 | uiomem->memtype = UIO_MEM_PHYS; | |
116 | uiomem->addr = r->start; | |
117 | uiomem->size = r->end - r->start + 1; | |
118 | ++uiomem; | |
119 | } | |
120 | ||
121 | while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { | |
122 | uiomem->size = 0; | |
123 | ++uiomem; | |
124 | } | |
125 | ||
126 | /* This driver requires no hardware specific kernel code to handle | |
127 | * interrupts. Instead, the interrupt handler simply disables the | |
128 | * interrupt in the interrupt controller. User space is responsible | |
129 | * for performing hardware specific acknowledge and re-enabling of | |
130 | * the interrupt in the interrupt controller. | |
131 | * | |
132 | * Interrupt sharing is not supported. | |
133 | */ | |
134 | ||
135 | uioinfo->irq_flags = IRQF_DISABLED; | |
136 | uioinfo->handler = uio_pdrv_genirq_handler; | |
137 | uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol; | |
138 | uioinfo->priv = priv; | |
139 | ||
140 | ret = uio_register_device(&pdev->dev, priv->uioinfo); | |
141 | if (ret) { | |
142 | dev_err(&pdev->dev, "unable to register uio device\n"); | |
143 | goto bad1; | |
144 | } | |
145 | ||
146 | platform_set_drvdata(pdev, priv); | |
147 | return 0; | |
148 | bad1: | |
149 | kfree(priv); | |
150 | bad0: | |
151 | return ret; | |
152 | } | |
153 | ||
154 | static int uio_pdrv_genirq_remove(struct platform_device *pdev) | |
155 | { | |
156 | struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev); | |
157 | ||
158 | uio_unregister_device(priv->uioinfo); | |
159 | kfree(priv); | |
160 | return 0; | |
161 | } | |
162 | ||
163 | static struct platform_driver uio_pdrv_genirq = { | |
164 | .probe = uio_pdrv_genirq_probe, | |
165 | .remove = uio_pdrv_genirq_remove, | |
166 | .driver = { | |
167 | .name = DRIVER_NAME, | |
168 | .owner = THIS_MODULE, | |
169 | }, | |
170 | }; | |
171 | ||
172 | static int __init uio_pdrv_genirq_init(void) | |
173 | { | |
174 | return platform_driver_register(&uio_pdrv_genirq); | |
175 | } | |
176 | ||
177 | static void __exit uio_pdrv_genirq_exit(void) | |
178 | { | |
179 | platform_driver_unregister(&uio_pdrv_genirq); | |
180 | } | |
181 | ||
182 | module_init(uio_pdrv_genirq_init); | |
183 | module_exit(uio_pdrv_genirq_exit); | |
184 | ||
185 | MODULE_AUTHOR("Magnus Damm"); | |
186 | MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling"); | |
187 | MODULE_LICENSE("GPL v2"); | |
188 | MODULE_ALIAS("platform:" DRIVER_NAME); |