1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * drivers/uio/uio_dmem_genirq.c
4 *
5 * Userspace I/O platform driver with generic IRQ handling code.
6 *
7 * Copyright (C) 2012 Damian Hobson-Garcia
8 *
9 * Based on uio_pdrv_genirq.c by Magnus Damm
10 */
11
12 #include <linux/platform_device.h>
13 #include <linux/uio_driver.h>
14 #include <linux/spinlock.h>
15 #include <linux/bitops.h>
16 #include <linux/module.h>
17 #include <linux/interrupt.h>
18 #include <linux/platform_data/uio_dmem_genirq.h>
19 #include <linux/stringify.h>
20 #include <linux/pm_runtime.h>
21 #include <linux/dma-mapping.h>
22 #include <linux/slab.h>
23 #include <linux/irq.h>
24
25 #include <linux/of.h>
26 #include <linux/of_platform.h>
27 #include <linux/of_address.h>
28
29 #define DRIVER_NAME "uio_dmem_genirq"
30 #define DMEM_MAP_ERROR (~0)
31
32 struct uio_dmem_genirq_platdata {
33 struct uio_info *uioinfo;
34 spinlock_t lock;
35 unsigned long flags;
36 struct platform_device *pdev;
37 unsigned int dmem_region_start;
38 unsigned int num_dmem_regions;
39 void *dmem_region_vaddr[MAX_UIO_MAPS];
40 struct mutex alloc_lock;
41 unsigned int refcnt;
42 };
43
uio_dmem_genirq_open(struct uio_info * info,struct inode * inode)44 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
45 {
46 struct uio_dmem_genirq_platdata *priv = info->priv;
47 struct uio_mem *uiomem;
48 int dmem_region = priv->dmem_region_start;
49
50 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
51
52 mutex_lock(&priv->alloc_lock);
53 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
54 void *addr;
55 if (!uiomem->size)
56 break;
57
58 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
59 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
60 if (!addr) {
61 uiomem->addr = DMEM_MAP_ERROR;
62 }
63 priv->dmem_region_vaddr[dmem_region++] = addr;
64 ++uiomem;
65 }
66 priv->refcnt++;
67
68 mutex_unlock(&priv->alloc_lock);
69 /* Wait until the Runtime PM code has woken up the device */
70 pm_runtime_get_sync(&priv->pdev->dev);
71 return 0;
72 }
73
uio_dmem_genirq_release(struct uio_info * info,struct inode * inode)74 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
75 {
76 struct uio_dmem_genirq_platdata *priv = info->priv;
77 struct uio_mem *uiomem;
78 int dmem_region = priv->dmem_region_start;
79
80 /* Tell the Runtime PM code that the device has become idle */
81 pm_runtime_put_sync(&priv->pdev->dev);
82
83 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
84
85 mutex_lock(&priv->alloc_lock);
86
87 priv->refcnt--;
88 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
89 if (!uiomem->size)
90 break;
91 if (priv->dmem_region_vaddr[dmem_region]) {
92 dma_free_coherent(&priv->pdev->dev, uiomem->size,
93 priv->dmem_region_vaddr[dmem_region],
94 uiomem->addr);
95 }
96 uiomem->addr = DMEM_MAP_ERROR;
97 ++dmem_region;
98 ++uiomem;
99 }
100
101 mutex_unlock(&priv->alloc_lock);
102 return 0;
103 }
104
uio_dmem_genirq_handler(int irq,struct uio_info * dev_info)105 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
106 {
107 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
108
109 /* Just disable the interrupt in the interrupt controller, and
110 * remember the state so we can allow user space to enable it later.
111 */
112
113 spin_lock(&priv->lock);
114 if (!test_and_set_bit(0, &priv->flags))
115 disable_irq_nosync(irq);
116 spin_unlock(&priv->lock);
117
118 return IRQ_HANDLED;
119 }
120
uio_dmem_genirq_irqcontrol(struct uio_info * dev_info,s32 irq_on)121 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
122 {
123 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
124 unsigned long flags;
125
126 /* Allow user space to enable and disable the interrupt
127 * in the interrupt controller, but keep track of the
128 * state to prevent per-irq depth damage.
129 *
130 * Serialize this operation to support multiple tasks and concurrency
131 * with irq handler on SMP systems.
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_nosync(dev_info->irq);
141 }
142 spin_unlock_irqrestore(&priv->lock, flags);
143
144 return 0;
145 }
146
uio_dmem_genirq_probe(struct platform_device * pdev)147 static 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 /* alloc uioinfo for one device */
158 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
159 if (!uioinfo) {
160 ret = -ENOMEM;
161 dev_err(&pdev->dev, "unable to kmalloc\n");
162 goto bad2;
163 }
164 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
165 pdev->dev.of_node);
166 uioinfo->version = "devicetree";
167 }
168
169 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
170 dev_err(&pdev->dev, "missing platform_data\n");
171 goto bad0;
172 }
173
174 if (uioinfo->handler || uioinfo->irqcontrol ||
175 uioinfo->irq_flags & IRQF_SHARED) {
176 dev_err(&pdev->dev, "interrupt configuration error\n");
177 goto bad0;
178 }
179
180 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
181 if (!priv) {
182 ret = -ENOMEM;
183 dev_err(&pdev->dev, "unable to kmalloc\n");
184 goto bad0;
185 }
186
187 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
188
189 priv->uioinfo = uioinfo;
190 spin_lock_init(&priv->lock);
191 priv->flags = 0; /* interrupt is enabled to begin with */
192 priv->pdev = pdev;
193 mutex_init(&priv->alloc_lock);
194
195 if (!uioinfo->irq) {
196 /* Multiple IRQs are not supported */
197 ret = platform_get_irq(pdev, 0);
198 if (ret == -ENXIO && pdev->dev.of_node)
199 ret = UIO_IRQ_NONE;
200 else if (ret < 0)
201 goto bad1;
202 uioinfo->irq = ret;
203 }
204
205 if (uioinfo->irq) {
206 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
207
208 /*
209 * If a level interrupt, dont do lazy disable. Otherwise the
210 * irq will fire again since clearing of the actual cause, on
211 * device level, is done in userspace
212 * irqd_is_level_type() isn't used since isn't valid until
213 * irq is configured.
214 */
215 if (irq_data &&
216 irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
217 dev_dbg(&pdev->dev, "disable lazy unmask\n");
218 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
219 }
220 }
221
222 uiomem = &uioinfo->mem[0];
223
224 for (i = 0; i < pdev->num_resources; ++i) {
225 struct resource *r = &pdev->resource[i];
226
227 if (r->flags != IORESOURCE_MEM)
228 continue;
229
230 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
231 dev_warn(&pdev->dev, "device has more than "
232 __stringify(MAX_UIO_MAPS)
233 " I/O memory resources.\n");
234 break;
235 }
236
237 uiomem->memtype = UIO_MEM_PHYS;
238 uiomem->addr = r->start;
239 uiomem->size = resource_size(r);
240 ++uiomem;
241 }
242
243 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
244 priv->num_dmem_regions = pdata->num_dynamic_regions;
245
246 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
247 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
248 dev_warn(&pdev->dev, "device has more than "
249 __stringify(MAX_UIO_MAPS)
250 " dynamic and fixed memory regions.\n");
251 break;
252 }
253 uiomem->memtype = UIO_MEM_PHYS;
254 uiomem->addr = DMEM_MAP_ERROR;
255 uiomem->size = pdata->dynamic_region_sizes[i];
256 ++uiomem;
257 }
258
259 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
260 uiomem->size = 0;
261 ++uiomem;
262 }
263
264 /* This driver requires no hardware specific kernel code to handle
265 * interrupts. Instead, the interrupt handler simply disables the
266 * interrupt in the interrupt controller. User space is responsible
267 * for performing hardware specific acknowledge and re-enabling of
268 * the interrupt in the interrupt controller.
269 *
270 * Interrupt sharing is not supported.
271 */
272
273 uioinfo->handler = uio_dmem_genirq_handler;
274 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
275 uioinfo->open = uio_dmem_genirq_open;
276 uioinfo->release = uio_dmem_genirq_release;
277 uioinfo->priv = priv;
278
279 /* Enable Runtime PM for this device:
280 * The device starts in suspended state to allow the hardware to be
281 * turned off by default. The Runtime PM bus code should power on the
282 * hardware and enable clocks at open().
283 */
284 pm_runtime_enable(&pdev->dev);
285
286 ret = uio_register_device(&pdev->dev, priv->uioinfo);
287 if (ret) {
288 dev_err(&pdev->dev, "unable to register uio device\n");
289 pm_runtime_disable(&pdev->dev);
290 goto bad1;
291 }
292
293 platform_set_drvdata(pdev, priv);
294 return 0;
295 bad1:
296 kfree(priv);
297 bad0:
298 /* kfree uioinfo for OF */
299 if (pdev->dev.of_node)
300 kfree(uioinfo);
301 bad2:
302 return ret;
303 }
304
uio_dmem_genirq_remove(struct platform_device * pdev)305 static int uio_dmem_genirq_remove(struct platform_device *pdev)
306 {
307 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
308
309 uio_unregister_device(priv->uioinfo);
310 pm_runtime_disable(&pdev->dev);
311
312 priv->uioinfo->handler = NULL;
313 priv->uioinfo->irqcontrol = NULL;
314
315 /* kfree uioinfo for OF */
316 if (pdev->dev.of_node)
317 kfree(priv->uioinfo);
318
319 kfree(priv);
320 return 0;
321 }
322
uio_dmem_genirq_runtime_nop(struct device * dev)323 static int uio_dmem_genirq_runtime_nop(struct device *dev)
324 {
325 /* Runtime PM callback shared between ->runtime_suspend()
326 * and ->runtime_resume(). Simply returns success.
327 *
328 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
329 * are used at open() and release() time. This allows the
330 * Runtime PM code to turn off power to the device while the
331 * device is unused, ie before open() and after release().
332 *
333 * This Runtime PM callback does not need to save or restore
334 * any registers since user space is responsbile for hardware
335 * register reinitialization after open().
336 */
337 return 0;
338 }
339
340 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
341 .runtime_suspend = uio_dmem_genirq_runtime_nop,
342 .runtime_resume = uio_dmem_genirq_runtime_nop,
343 };
344
345 #ifdef CONFIG_OF
346 static const struct of_device_id uio_of_genirq_match[] = {
347 { /* empty for now */ },
348 };
349 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
350 #endif
351
352 static struct platform_driver uio_dmem_genirq = {
353 .probe = uio_dmem_genirq_probe,
354 .remove = uio_dmem_genirq_remove,
355 .driver = {
356 .name = DRIVER_NAME,
357 .pm = &uio_dmem_genirq_dev_pm_ops,
358 .of_match_table = of_match_ptr(uio_of_genirq_match),
359 },
360 };
361
362 module_platform_driver(uio_dmem_genirq);
363
364 MODULE_AUTHOR("Damian Hobson-Garcia");
365 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
366 MODULE_LICENSE("GPL v2");
367 MODULE_ALIAS("platform:" DRIVER_NAME);
368