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
34struct 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
46static 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
77static 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
108static 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
122static 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 } else {
139 if (!test_and_set_bit(0, &priv->flags))
140 disable_irq(dev_info->irq);
141 }
142 spin_unlock_irqrestore(&priv->lock, flags);
143
144 return 0;
145}
146
147static int uio_dmem_genirq_probe(struct platform_device *pdev)
148{
149 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
150 struct uio_info *uioinfo = &pdata->uioinfo;
151 struct uio_dmem_genirq_platdata *priv;
152 struct uio_mem *uiomem;
153 int ret = -EINVAL;
154 int i;
155
156 if (pdev->dev.of_node) {
157 int irq;
158
159 /* alloc uioinfo for one device */
160 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
161 if (!uioinfo) {
162 ret = -ENOMEM;
163 dev_err(&pdev->dev, "unable to kmalloc\n");
164 goto bad2;
165 }
166 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
167 pdev->dev.of_node);
168 uioinfo->version = "devicetree";
169
170 /* Multiple IRQs are not supported */
171 irq = platform_get_irq(pdev, 0);
172 if (irq == -ENXIO)
173 uioinfo->irq = UIO_IRQ_NONE;
174 else
175 uioinfo->irq = irq;
176 }
177
178 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
179 dev_err(&pdev->dev, "missing platform_data\n");
180 goto bad0;
181 }
182
183 if (uioinfo->handler || uioinfo->irqcontrol ||
184 uioinfo->irq_flags & IRQF_SHARED) {
185 dev_err(&pdev->dev, "interrupt configuration error\n");
186 goto bad0;
187 }
188
189 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
190 if (!priv) {
191 ret = -ENOMEM;
192 dev_err(&pdev->dev, "unable to kmalloc\n");
193 goto bad0;
194 }
195
196 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
197
198 priv->uioinfo = uioinfo;
199 spin_lock_init(&priv->lock);
200 priv->flags = 0; /* interrupt is enabled to begin with */
201 priv->pdev = pdev;
202 mutex_init(&priv->alloc_lock);
203
204 if (!uioinfo->irq) {
205 ret = platform_get_irq(pdev, 0);
206 if (ret < 0) {
207 dev_err(&pdev->dev, "failed to get IRQ\n");
208 goto bad1;
209 }
210 uioinfo->irq = ret;
211 }
212 uiomem = &uioinfo->mem[0];
213
214 for (i = 0; i < pdev->num_resources; ++i) {
215 struct resource *r = &pdev->resource[i];
216
217 if (r->flags != IORESOURCE_MEM)
218 continue;
219
220 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
221 dev_warn(&pdev->dev, "device has more than "
222 __stringify(MAX_UIO_MAPS)
223 " I/O memory resources.\n");
224 break;
225 }
226
227 uiomem->memtype = UIO_MEM_PHYS;
228 uiomem->addr = r->start;
229 uiomem->size = resource_size(r);
230 ++uiomem;
231 }
232
233 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
234 priv->num_dmem_regions = pdata->num_dynamic_regions;
235
236 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
237 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
238 dev_warn(&pdev->dev, "device has more than "
239 __stringify(MAX_UIO_MAPS)
240 " dynamic and fixed memory regions.\n");
241 break;
242 }
243 uiomem->memtype = UIO_MEM_PHYS;
244 uiomem->addr = DMEM_MAP_ERROR;
245 uiomem->size = pdata->dynamic_region_sizes[i];
246 ++uiomem;
247 }
248
249 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
250 uiomem->size = 0;
251 ++uiomem;
252 }
253
254 /* This driver requires no hardware specific kernel code to handle
255 * interrupts. Instead, the interrupt handler simply disables the
256 * interrupt in the interrupt controller. User space is responsible
257 * for performing hardware specific acknowledge and re-enabling of
258 * the interrupt in the interrupt controller.
259 *
260 * Interrupt sharing is not supported.
261 */
262
263 uioinfo->handler = uio_dmem_genirq_handler;
264 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
265 uioinfo->open = uio_dmem_genirq_open;
266 uioinfo->release = uio_dmem_genirq_release;
267 uioinfo->priv = priv;
268
269 /* Enable Runtime PM for this device:
270 * The device starts in suspended state to allow the hardware to be
271 * turned off by default. The Runtime PM bus code should power on the
272 * hardware and enable clocks at open().
273 */
274 pm_runtime_enable(&pdev->dev);
275
276 ret = uio_register_device(&pdev->dev, priv->uioinfo);
277 if (ret) {
278 dev_err(&pdev->dev, "unable to register uio device\n");
279 pm_runtime_disable(&pdev->dev);
280 goto bad1;
281 }
282
283 platform_set_drvdata(pdev, priv);
284 return 0;
285 bad1:
286 kfree(priv);
287 bad0:
288 /* kfree uioinfo for OF */
289 if (pdev->dev.of_node)
290 kfree(uioinfo);
291 bad2:
292 return ret;
293}
294
295static int uio_dmem_genirq_remove(struct platform_device *pdev)
296{
297 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
298
299 uio_unregister_device(priv->uioinfo);
300 pm_runtime_disable(&pdev->dev);
301
302 priv->uioinfo->handler = NULL;
303 priv->uioinfo->irqcontrol = NULL;
304
305 /* kfree uioinfo for OF */
306 if (pdev->dev.of_node)
307 kfree(priv->uioinfo);
308
309 kfree(priv);
310 return 0;
311}
312
313static int uio_dmem_genirq_runtime_nop(struct device *dev)
314{
315 /* Runtime PM callback shared between ->runtime_suspend()
316 * and ->runtime_resume(). Simply returns success.
317 *
318 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
319 * are used at open() and release() time. This allows the
320 * Runtime PM code to turn off power to the device while the
321 * device is unused, ie before open() and after release().
322 *
323 * This Runtime PM callback does not need to save or restore
324 * any registers since user space is responsbile for hardware
325 * register reinitialization after open().
326 */
327 return 0;
328}
329
330static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
331 .runtime_suspend = uio_dmem_genirq_runtime_nop,
332 .runtime_resume = uio_dmem_genirq_runtime_nop,
333};
334
335#ifdef CONFIG_OF
336static const struct of_device_id uio_of_genirq_match[] = {
337 { /* empty for now */ },
338};
339MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
340#endif
341
342static struct platform_driver uio_dmem_genirq = {
343 .probe = uio_dmem_genirq_probe,
344 .remove = uio_dmem_genirq_remove,
345 .driver = {
346 .name = DRIVER_NAME,
347 .pm = &uio_dmem_genirq_dev_pm_ops,
348 .of_match_table = of_match_ptr(uio_of_genirq_match),
349 },
350};
351
352module_platform_driver(uio_dmem_genirq);
353
354MODULE_AUTHOR("Damian Hobson-Garcia");
355MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
356MODULE_LICENSE("GPL v2");
357MODULE_ALIAS("platform:" DRIVER_NAME);
358