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/module.h>
22#include <linux/interrupt.h>
23#include <linux/stringify.h>
24#include <linux/pm_runtime.h>
25#include <linux/slab.h>
26
27#include <linux/of.h>
28#include <linux/of_platform.h>
29#include <linux/of_address.h>
30
31#define DRIVER_NAME "uio_pdrv_genirq"
32
33struct uio_pdrv_genirq_platdata {
34 struct uio_info *uioinfo;
35 spinlock_t lock;
36 unsigned long flags;
37 struct platform_device *pdev;
38};
39
40/* Bits in uio_pdrv_genirq_platdata.flags */
41enum {
42 UIO_IRQ_DISABLED = 0,
43};
44
45static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
46{
47 struct uio_pdrv_genirq_platdata *priv = info->priv;
48
49 /* Wait until the Runtime PM code has woken up the device */
50 pm_runtime_get_sync(&priv->pdev->dev);
51 return 0;
52}
53
54static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
55{
56 struct uio_pdrv_genirq_platdata *priv = info->priv;
57
58 /* Tell the Runtime PM code that the device has become idle */
59 pm_runtime_put_sync(&priv->pdev->dev);
60 return 0;
61}
62
63static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
64{
65 struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
66
67 /* Just disable the interrupt in the interrupt controller, and
68 * remember the state so we can allow user space to enable it later.
69 */
70
71 spin_lock(&priv->lock);
72 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
73 disable_irq_nosync(irq);
74 spin_unlock(&priv->lock);
75
76 return IRQ_HANDLED;
77}
78
79static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
80{
81 struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
82 unsigned long flags;
83
84 /* Allow user space to enable and disable the interrupt
85 * in the interrupt controller, but keep track of the
86 * state to prevent per-irq depth damage.
87 *
88 * Serialize this operation to support multiple tasks and concurrency
89 * with irq handler on SMP systems.
90 */
91
92 spin_lock_irqsave(&priv->lock, flags);
93 if (irq_on) {
94 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
95 enable_irq(dev_info->irq);
96 } else {
97 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
98 disable_irq_nosync(dev_info->irq);
99 }
100 spin_unlock_irqrestore(&priv->lock, flags);
101
102 return 0;
103}
104
105static int uio_pdrv_genirq_probe(struct platform_device *pdev)
106{
107 struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
108 struct uio_pdrv_genirq_platdata *priv;
109 struct uio_mem *uiomem;
110 int ret = -EINVAL;
111 int i;
112
113 if (pdev->dev.of_node) {
114 /* alloc uioinfo for one device */
115 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
116 GFP_KERNEL);
117 if (!uioinfo) {
118 dev_err(&pdev->dev, "unable to kmalloc\n");
119 return -ENOMEM;
120 }
121 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
122 pdev->dev.of_node);
123 uioinfo->version = "devicetree";
124 /* Multiple IRQs are not supported */
125 }
126
127 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
128 dev_err(&pdev->dev, "missing platform_data\n");
129 return ret;
130 }
131
132 if (uioinfo->handler || uioinfo->irqcontrol ||
133 uioinfo->irq_flags & IRQF_SHARED) {
134 dev_err(&pdev->dev, "interrupt configuration error\n");
135 return ret;
136 }
137
138 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
139 if (!priv) {
140 dev_err(&pdev->dev, "unable to kmalloc\n");
141 return -ENOMEM;
142 }
143
144 priv->uioinfo = uioinfo;
145 spin_lock_init(&priv->lock);
146 priv->flags = 0; /* interrupt is enabled to begin with */
147 priv->pdev = pdev;
148
149 if (!uioinfo->irq) {
150 ret = platform_get_irq(pdev, 0);
151 uioinfo->irq = ret;
152 if (ret == -ENXIO && pdev->dev.of_node)
153 uioinfo->irq = UIO_IRQ_NONE;
154 else if (ret < 0) {
155 dev_err(&pdev->dev, "failed to get IRQ\n");
156 return ret;
157 }
158 }
159
160 uiomem = &uioinfo->mem[0];
161
162 for (i = 0; i < pdev->num_resources; ++i) {
163 struct resource *r = &pdev->resource[i];
164
165 if (r->flags != IORESOURCE_MEM)
166 continue;
167
168 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
169 dev_warn(&pdev->dev, "device has more than "
170 __stringify(MAX_UIO_MAPS)
171 " I/O memory resources.\n");
172 break;
173 }
174
175 uiomem->memtype = UIO_MEM_PHYS;
176 uiomem->addr = r->start;
177 uiomem->size = resource_size(r);
178 uiomem->name = r->name;
179 ++uiomem;
180 }
181
182 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
183 uiomem->size = 0;
184 ++uiomem;
185 }
186
187 /* This driver requires no hardware specific kernel code to handle
188 * interrupts. Instead, the interrupt handler simply disables the
189 * interrupt in the interrupt controller. User space is responsible
190 * for performing hardware specific acknowledge and re-enabling of
191 * the interrupt in the interrupt controller.
192 *
193 * Interrupt sharing is not supported.
194 */
195
196 uioinfo->handler = uio_pdrv_genirq_handler;
197 uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
198 uioinfo->open = uio_pdrv_genirq_open;
199 uioinfo->release = uio_pdrv_genirq_release;
200 uioinfo->priv = priv;
201
202 /* Enable Runtime PM for this device:
203 * The device starts in suspended state to allow the hardware to be
204 * turned off by default. The Runtime PM bus code should power on the
205 * hardware and enable clocks at open().
206 */
207 pm_runtime_enable(&pdev->dev);
208
209 ret = uio_register_device(&pdev->dev, priv->uioinfo);
210 if (ret) {
211 dev_err(&pdev->dev, "unable to register uio device\n");
212 pm_runtime_disable(&pdev->dev);
213 return ret;
214 }
215
216 platform_set_drvdata(pdev, priv);
217 return 0;
218}
219
220static int uio_pdrv_genirq_remove(struct platform_device *pdev)
221{
222 struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
223
224 uio_unregister_device(priv->uioinfo);
225 pm_runtime_disable(&pdev->dev);
226
227 priv->uioinfo->handler = NULL;
228 priv->uioinfo->irqcontrol = NULL;
229
230 return 0;
231}
232
233static int uio_pdrv_genirq_runtime_nop(struct device *dev)
234{
235 /* Runtime PM callback shared between ->runtime_suspend()
236 * and ->runtime_resume(). Simply returns success.
237 *
238 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
239 * are used at open() and release() time. This allows the
240 * Runtime PM code to turn off power to the device while the
241 * device is unused, ie before open() and after release().
242 *
243 * This Runtime PM callback does not need to save or restore
244 * any registers since user space is responsbile for hardware
245 * register reinitialization after open().
246 */
247 return 0;
248}
249
250static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
251 .runtime_suspend = uio_pdrv_genirq_runtime_nop,
252 .runtime_resume = uio_pdrv_genirq_runtime_nop,
253};
254
255#ifdef CONFIG_OF
256static struct of_device_id uio_of_genirq_match[] = {
257 { /* This is filled with module_parm */ },
258 { /* Sentinel */ },
259};
260MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
261module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
262MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
263#endif
264
265static struct platform_driver uio_pdrv_genirq = {
266 .probe = uio_pdrv_genirq_probe,
267 .remove = uio_pdrv_genirq_remove,
268 .driver = {
269 .name = DRIVER_NAME,
270 .pm = &uio_pdrv_genirq_dev_pm_ops,
271 .of_match_table = of_match_ptr(uio_of_genirq_match),
272 },
273};
274
275module_platform_driver(uio_pdrv_genirq);
276
277MODULE_AUTHOR("Magnus Damm");
278MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
279MODULE_LICENSE("GPL v2");
280MODULE_ALIAS("platform:" DRIVER_NAME);
281