1 /*
2 * drivers/uio/uio_dmem_genirq.c
3 *
4 * Userspace I/O platform driver with generic IRQ handling code.
5 *
6 * Copyright (C) 2012 Damian Hobson-Garcia
7 *
8 * Based on uio_pdrv_genirq.c by Magnus Damm
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License version 2 as published by
12 * the Free Software Foundation.
13 */
14
15 #include <linux/platform_device.h>
16 #include <linux/uio_driver.h>
17 #include <linux/spinlock.h>
18 #include <linux/bitops.h>
19 #include <linux/module.h>
20 #include <linux/interrupt.h>
21 #include <linux/platform_data/uio_dmem_genirq.h>
22 #include <linux/stringify.h>
23 #include <linux/pm_runtime.h>
24 #include <linux/dma-mapping.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_dmem_genirq"
32 #define DMEM_MAP_ERROR (~0)
33
34 struct uio_dmem_genirq_platdata {
35 struct uio_info *uioinfo;
36 spinlock_t lock;
37 unsigned long flags;
38 struct platform_device *pdev;
39 unsigned int dmem_region_start;
40 unsigned int num_dmem_regions;
41 void *dmem_region_vaddr[MAX_UIO_MAPS];
42 struct mutex alloc_lock;
43 unsigned int refcnt;
44 };
45
uio_dmem_genirq_open(struct uio_info * info,struct inode * inode)46 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
47 {
48 struct uio_dmem_genirq_platdata *priv = info->priv;
49 struct uio_mem *uiomem;
50 int ret = 0;
51 int dmem_region = priv->dmem_region_start;
52
53 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
54
55 mutex_lock(&priv->alloc_lock);
56 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
57 void *addr;
58 if (!uiomem->size)
59 break;
60
61 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
62 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
63 if (!addr) {
64 uiomem->addr = DMEM_MAP_ERROR;
65 }
66 priv->dmem_region_vaddr[dmem_region++] = addr;
67 ++uiomem;
68 }
69 priv->refcnt++;
70
71 mutex_unlock(&priv->alloc_lock);
72 /* Wait until the Runtime PM code has woken up the device */
73 pm_runtime_get_sync(&priv->pdev->dev);
74 return ret;
75 }
76
uio_dmem_genirq_release(struct uio_info * info,struct inode * inode)77 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
78 {
79 struct uio_dmem_genirq_platdata *priv = info->priv;
80 struct uio_mem *uiomem;
81 int dmem_region = priv->dmem_region_start;
82
83 /* Tell the Runtime PM code that the device has become idle */
84 pm_runtime_put_sync(&priv->pdev->dev);
85
86 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
87
88 mutex_lock(&priv->alloc_lock);
89
90 priv->refcnt--;
91 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
92 if (!uiomem->size)
93 break;
94 if (priv->dmem_region_vaddr[dmem_region]) {
95 dma_free_coherent(&priv->pdev->dev, uiomem->size,
96 priv->dmem_region_vaddr[dmem_region],
97 uiomem->addr);
98 }
99 uiomem->addr = DMEM_MAP_ERROR;
100 ++dmem_region;
101 ++uiomem;
102 }
103
104 mutex_unlock(&priv->alloc_lock);
105 return 0;
106 }
107
uio_dmem_genirq_handler(int irq,struct uio_info * dev_info)108 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
109 {
110 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
111
112 /* Just disable the interrupt in the interrupt controller, and
113 * remember the state so we can allow user space to enable it later.
114 */
115
116 if (!test_and_set_bit(0, &priv->flags))
117 disable_irq_nosync(irq);
118
119 return IRQ_HANDLED;
120 }
121
uio_dmem_genirq_irqcontrol(struct uio_info * dev_info,s32 irq_on)122 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
123 {
124 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
125 unsigned long flags;
126
127 /* Allow user space to enable and disable the interrupt
128 * in the interrupt controller, but keep track of the
129 * state to prevent per-irq depth damage.
130 *
131 * Serialize this operation to support multiple tasks.
132 */
133
134 spin_lock_irqsave(&priv->lock, flags);
135 if (irq_on) {
136 if (test_and_clear_bit(0, &priv->flags))
137 enable_irq(dev_info->irq);
138 spin_unlock_irqrestore(&priv->lock, flags);
139 } else {
140 if (!test_and_set_bit(0, &priv->flags)) {
141 spin_unlock_irqrestore(&priv->lock, flags);
142 disable_irq(dev_info->irq);
143 }
144 }
145
146 return 0;
147 }
148
uio_dmem_genirq_probe(struct platform_device * pdev)149 static int uio_dmem_genirq_probe(struct platform_device *pdev)
150 {
151 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
152 struct uio_info *uioinfo = &pdata->uioinfo;
153 struct uio_dmem_genirq_platdata *priv;
154 struct uio_mem *uiomem;
155 int ret = -EINVAL;
156 int i;
157
158 if (pdev->dev.of_node) {
159 int irq;
160
161 /* alloc uioinfo for one device */
162 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
163 if (!uioinfo) {
164 ret = -ENOMEM;
165 dev_err(&pdev->dev, "unable to kmalloc\n");
166 goto bad2;
167 }
168 uioinfo->name = pdev->dev.of_node->name;
169 uioinfo->version = "devicetree";
170
171 /* Multiple IRQs are not supported */
172 irq = platform_get_irq(pdev, 0);
173 if (irq == -ENXIO)
174 uioinfo->irq = UIO_IRQ_NONE;
175 else
176 uioinfo->irq = irq;
177 }
178
179 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
180 dev_err(&pdev->dev, "missing platform_data\n");
181 goto bad0;
182 }
183
184 if (uioinfo->handler || uioinfo->irqcontrol ||
185 uioinfo->irq_flags & IRQF_SHARED) {
186 dev_err(&pdev->dev, "interrupt configuration error\n");
187 goto bad0;
188 }
189
190 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
191 if (!priv) {
192 ret = -ENOMEM;
193 dev_err(&pdev->dev, "unable to kmalloc\n");
194 goto bad0;
195 }
196
197 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
198
199 priv->uioinfo = uioinfo;
200 spin_lock_init(&priv->lock);
201 priv->flags = 0; /* interrupt is enabled to begin with */
202 priv->pdev = pdev;
203 mutex_init(&priv->alloc_lock);
204
205 if (!uioinfo->irq) {
206 ret = platform_get_irq(pdev, 0);
207 if (ret < 0) {
208 dev_err(&pdev->dev, "failed to get IRQ\n");
209 goto bad1;
210 }
211 uioinfo->irq = ret;
212 }
213 uiomem = &uioinfo->mem[0];
214
215 for (i = 0; i < pdev->num_resources; ++i) {
216 struct resource *r = &pdev->resource[i];
217
218 if (r->flags != IORESOURCE_MEM)
219 continue;
220
221 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
222 dev_warn(&pdev->dev, "device has more than "
223 __stringify(MAX_UIO_MAPS)
224 " I/O memory resources.\n");
225 break;
226 }
227
228 uiomem->memtype = UIO_MEM_PHYS;
229 uiomem->addr = r->start;
230 uiomem->size = resource_size(r);
231 ++uiomem;
232 }
233
234 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
235 priv->num_dmem_regions = pdata->num_dynamic_regions;
236
237 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
238 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
239 dev_warn(&pdev->dev, "device has more than "
240 __stringify(MAX_UIO_MAPS)
241 " dynamic and fixed memory regions.\n");
242 break;
243 }
244 uiomem->memtype = UIO_MEM_PHYS;
245 uiomem->addr = DMEM_MAP_ERROR;
246 uiomem->size = pdata->dynamic_region_sizes[i];
247 ++uiomem;
248 }
249
250 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
251 uiomem->size = 0;
252 ++uiomem;
253 }
254
255 /* This driver requires no hardware specific kernel code to handle
256 * interrupts. Instead, the interrupt handler simply disables the
257 * interrupt in the interrupt controller. User space is responsible
258 * for performing hardware specific acknowledge and re-enabling of
259 * the interrupt in the interrupt controller.
260 *
261 * Interrupt sharing is not supported.
262 */
263
264 uioinfo->handler = uio_dmem_genirq_handler;
265 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
266 uioinfo->open = uio_dmem_genirq_open;
267 uioinfo->release = uio_dmem_genirq_release;
268 uioinfo->priv = priv;
269
270 /* Enable Runtime PM for this device:
271 * The device starts in suspended state to allow the hardware to be
272 * turned off by default. The Runtime PM bus code should power on the
273 * hardware and enable clocks at open().
274 */
275 pm_runtime_enable(&pdev->dev);
276
277 ret = uio_register_device(&pdev->dev, priv->uioinfo);
278 if (ret) {
279 dev_err(&pdev->dev, "unable to register uio device\n");
280 pm_runtime_disable(&pdev->dev);
281 goto bad1;
282 }
283
284 platform_set_drvdata(pdev, priv);
285 return 0;
286 bad1:
287 kfree(priv);
288 bad0:
289 /* kfree uioinfo for OF */
290 if (pdev->dev.of_node)
291 kfree(uioinfo);
292 bad2:
293 return ret;
294 }
295
uio_dmem_genirq_remove(struct platform_device * pdev)296 static int uio_dmem_genirq_remove(struct platform_device *pdev)
297 {
298 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
299
300 uio_unregister_device(priv->uioinfo);
301 pm_runtime_disable(&pdev->dev);
302
303 priv->uioinfo->handler = NULL;
304 priv->uioinfo->irqcontrol = NULL;
305
306 /* kfree uioinfo for OF */
307 if (pdev->dev.of_node)
308 kfree(priv->uioinfo);
309
310 kfree(priv);
311 return 0;
312 }
313
uio_dmem_genirq_runtime_nop(struct device * dev)314 static int uio_dmem_genirq_runtime_nop(struct device *dev)
315 {
316 /* Runtime PM callback shared between ->runtime_suspend()
317 * and ->runtime_resume(). Simply returns success.
318 *
319 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
320 * are used at open() and release() time. This allows the
321 * Runtime PM code to turn off power to the device while the
322 * device is unused, ie before open() and after release().
323 *
324 * This Runtime PM callback does not need to save or restore
325 * any registers since user space is responsbile for hardware
326 * register reinitialization after open().
327 */
328 return 0;
329 }
330
331 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
332 .runtime_suspend = uio_dmem_genirq_runtime_nop,
333 .runtime_resume = uio_dmem_genirq_runtime_nop,
334 };
335
336 #ifdef CONFIG_OF
337 static const struct of_device_id uio_of_genirq_match[] = {
338 { /* empty for now */ },
339 };
340 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
341 #endif
342
343 static struct platform_driver uio_dmem_genirq = {
344 .probe = uio_dmem_genirq_probe,
345 .remove = uio_dmem_genirq_remove,
346 .driver = {
347 .name = DRIVER_NAME,
348 .pm = &uio_dmem_genirq_dev_pm_ops,
349 .of_match_table = of_match_ptr(uio_of_genirq_match),
350 },
351 };
352
353 module_platform_driver(uio_dmem_genirq);
354
355 MODULE_AUTHOR("Damian Hobson-Garcia");
356 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
357 MODULE_LICENSE("GPL v2");
358 MODULE_ALIAS("platform:" DRIVER_NAME);
359