xref: /linux/drivers/uio/uio_dmem_genirq.c (revision 9a6b55ac) 
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 
24 #include <linux/of.h>
25 #include <linux/of_platform.h>
26 #include <linux/of_address.h>
27 
28 #define DRIVER_NAME "uio_dmem_genirq"
29 #define DMEM_MAP_ERROR (~0)
30 
31 struct uio_dmem_genirq_platdata {
32 	struct uio_info *uioinfo;
33 	spinlock_t lock;
34 	unsigned long flags;
35 	struct platform_device *pdev;
36 	unsigned int dmem_region_start;
37 	unsigned int num_dmem_regions;
38 	void *dmem_region_vaddr[MAX_UIO_MAPS];
39 	struct mutex alloc_lock;
40 	unsigned int refcnt;
41 };
42 
43 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
44 {
45 	struct uio_dmem_genirq_platdata *priv = info->priv;
46 	struct uio_mem *uiomem;
47 	int ret = 0;
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 ret;
72 }
73 
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 
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 	if (!test_and_set_bit(0, &priv->flags))
114 		disable_irq_nosync(irq);
115 
116 	return IRQ_HANDLED;
117 }
118 
119 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
120 {
121 	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
122 	unsigned long flags;
123 
124 	/* Allow user space to enable and disable the interrupt
125 	 * in the interrupt controller, but keep track of the
126 	 * state to prevent per-irq depth damage.
127 	 *
128 	 * Serialize this operation to support multiple tasks.
129 	 */
130 
131 	spin_lock_irqsave(&priv->lock, flags);
132 	if (irq_on) {
133 		if (test_and_clear_bit(0, &priv->flags))
134 			enable_irq(dev_info->irq);
135 	} else {
136 		if (!test_and_set_bit(0, &priv->flags))
137 			disable_irq(dev_info->irq);
138 	}
139 	spin_unlock_irqrestore(&priv->lock, flags);
140 
141 	return 0;
142 }
143 
144 static int uio_dmem_genirq_probe(struct platform_device *pdev)
145 {
146 	struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
147 	struct uio_info *uioinfo = &pdata->uioinfo;
148 	struct uio_dmem_genirq_platdata *priv;
149 	struct uio_mem *uiomem;
150 	int ret = -EINVAL;
151 	int i;
152 
153 	if (pdev->dev.of_node) {
154 		/* alloc uioinfo for one device */
155 		uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
156 		if (!uioinfo) {
157 			ret = -ENOMEM;
158 			dev_err(&pdev->dev, "unable to kmalloc\n");
159 			goto bad2;
160 		}
161 		uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
162 					       pdev->dev.of_node);
163 		uioinfo->version = "devicetree";
164 	}
165 
166 	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
167 		dev_err(&pdev->dev, "missing platform_data\n");
168 		goto bad0;
169 	}
170 
171 	if (uioinfo->handler || uioinfo->irqcontrol ||
172 	    uioinfo->irq_flags & IRQF_SHARED) {
173 		dev_err(&pdev->dev, "interrupt configuration error\n");
174 		goto bad0;
175 	}
176 
177 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
178 	if (!priv) {
179 		ret = -ENOMEM;
180 		dev_err(&pdev->dev, "unable to kmalloc\n");
181 		goto bad0;
182 	}
183 
184 	dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
185 
186 	priv->uioinfo = uioinfo;
187 	spin_lock_init(&priv->lock);
188 	priv->flags = 0; /* interrupt is enabled to begin with */
189 	priv->pdev = pdev;
190 	mutex_init(&priv->alloc_lock);
191 
192 	if (!uioinfo->irq) {
193 		/* Multiple IRQs are not supported */
194 		ret = platform_get_irq(pdev, 0);
195 		if (ret == -ENXIO && pdev->dev.of_node)
196 			ret = UIO_IRQ_NONE;
197 		else if (ret < 0)
198 			goto bad1;
199 		uioinfo->irq = ret;
200 	}
201 	uiomem = &uioinfo->mem[0];
202 
203 	for (i = 0; i < pdev->num_resources; ++i) {
204 		struct resource *r = &pdev->resource[i];
205 
206 		if (r->flags != IORESOURCE_MEM)
207 			continue;
208 
209 		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
210 			dev_warn(&pdev->dev, "device has more than "
211 					__stringify(MAX_UIO_MAPS)
212 					" I/O memory resources.\n");
213 			break;
214 		}
215 
216 		uiomem->memtype = UIO_MEM_PHYS;
217 		uiomem->addr = r->start;
218 		uiomem->size = resource_size(r);
219 		++uiomem;
220 	}
221 
222 	priv->dmem_region_start = uiomem - &uioinfo->mem[0];
223 	priv->num_dmem_regions = pdata->num_dynamic_regions;
224 
225 	for (i = 0; i < pdata->num_dynamic_regions; ++i) {
226 		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
227 			dev_warn(&pdev->dev, "device has more than "
228 					__stringify(MAX_UIO_MAPS)
229 					" dynamic and fixed memory regions.\n");
230 			break;
231 		}
232 		uiomem->memtype = UIO_MEM_PHYS;
233 		uiomem->addr = DMEM_MAP_ERROR;
234 		uiomem->size = pdata->dynamic_region_sizes[i];
235 		++uiomem;
236 	}
237 
238 	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
239 		uiomem->size = 0;
240 		++uiomem;
241 	}
242 
243 	/* This driver requires no hardware specific kernel code to handle
244 	 * interrupts. Instead, the interrupt handler simply disables the
245 	 * interrupt in the interrupt controller. User space is responsible
246 	 * for performing hardware specific acknowledge and re-enabling of
247 	 * the interrupt in the interrupt controller.
248 	 *
249 	 * Interrupt sharing is not supported.
250 	 */
251 
252 	uioinfo->handler = uio_dmem_genirq_handler;
253 	uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
254 	uioinfo->open = uio_dmem_genirq_open;
255 	uioinfo->release = uio_dmem_genirq_release;
256 	uioinfo->priv = priv;
257 
258 	/* Enable Runtime PM for this device:
259 	 * The device starts in suspended state to allow the hardware to be
260 	 * turned off by default. The Runtime PM bus code should power on the
261 	 * hardware and enable clocks at open().
262 	 */
263 	pm_runtime_enable(&pdev->dev);
264 
265 	ret = uio_register_device(&pdev->dev, priv->uioinfo);
266 	if (ret) {
267 		dev_err(&pdev->dev, "unable to register uio device\n");
268 		pm_runtime_disable(&pdev->dev);
269 		goto bad1;
270 	}
271 
272 	platform_set_drvdata(pdev, priv);
273 	return 0;
274  bad1:
275 	kfree(priv);
276  bad0:
277 	/* kfree uioinfo for OF */
278 	if (pdev->dev.of_node)
279 		kfree(uioinfo);
280  bad2:
281 	return ret;
282 }
283 
284 static int uio_dmem_genirq_remove(struct platform_device *pdev)
285 {
286 	struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
287 
288 	uio_unregister_device(priv->uioinfo);
289 	pm_runtime_disable(&pdev->dev);
290 
291 	priv->uioinfo->handler = NULL;
292 	priv->uioinfo->irqcontrol = NULL;
293 
294 	/* kfree uioinfo for OF */
295 	if (pdev->dev.of_node)
296 		kfree(priv->uioinfo);
297 
298 	kfree(priv);
299 	return 0;
300 }
301 
302 static int uio_dmem_genirq_runtime_nop(struct device *dev)
303 {
304 	/* Runtime PM callback shared between ->runtime_suspend()
305 	 * and ->runtime_resume(). Simply returns success.
306 	 *
307 	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
308 	 * are used at open() and release() time. This allows the
309 	 * Runtime PM code to turn off power to the device while the
310 	 * device is unused, ie before open() and after release().
311 	 *
312 	 * This Runtime PM callback does not need to save or restore
313 	 * any registers since user space is responsbile for hardware
314 	 * register reinitialization after open().
315 	 */
316 	return 0;
317 }
318 
319 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
320 	.runtime_suspend = uio_dmem_genirq_runtime_nop,
321 	.runtime_resume = uio_dmem_genirq_runtime_nop,
322 };
323 
324 #ifdef CONFIG_OF
325 static const struct of_device_id uio_of_genirq_match[] = {
326 	{ /* empty for now */ },
327 };
328 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
329 #endif
330 
331 static struct platform_driver uio_dmem_genirq = {
332 	.probe = uio_dmem_genirq_probe,
333 	.remove = uio_dmem_genirq_remove,
334 	.driver = {
335 		.name = DRIVER_NAME,
336 		.pm = &uio_dmem_genirq_dev_pm_ops,
337 		.of_match_table = of_match_ptr(uio_of_genirq_match),
338 	},
339 };
340 
341 module_platform_driver(uio_dmem_genirq);
342 
343 MODULE_AUTHOR("Damian Hobson-Garcia");
344 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
345 MODULE_LICENSE("GPL v2");
346 MODULE_ALIAS("platform:" DRIVER_NAME);
347