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
44 /* Bits in uio_dmem_genirq_platdata.flags */
45 enum {
46 UIO_IRQ_DISABLED = 0,
47 };
48
uio_dmem_genirq_open(struct uio_info * info,struct inode * inode)49 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
50 {
51 struct uio_dmem_genirq_platdata *priv = info->priv;
52 struct uio_mem *uiomem;
53 int dmem_region = priv->dmem_region_start;
54
55 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
56
57 mutex_lock(&priv->alloc_lock);
58 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
59 void *addr;
60 if (!uiomem->size)
61 break;
62
63 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
64 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
65 if (!addr) {
66 uiomem->addr = DMEM_MAP_ERROR;
67 }
68 priv->dmem_region_vaddr[dmem_region++] = addr;
69 ++uiomem;
70 }
71 priv->refcnt++;
72
73 mutex_unlock(&priv->alloc_lock);
74 /* Wait until the Runtime PM code has woken up the device */
75 pm_runtime_get_sync(&priv->pdev->dev);
76 return 0;
77 }
78
uio_dmem_genirq_release(struct uio_info * info,struct inode * inode)79 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
80 {
81 struct uio_dmem_genirq_platdata *priv = info->priv;
82 struct uio_mem *uiomem;
83 int dmem_region = priv->dmem_region_start;
84
85 /* Tell the Runtime PM code that the device has become idle */
86 pm_runtime_put_sync(&priv->pdev->dev);
87
88 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
89
90 mutex_lock(&priv->alloc_lock);
91
92 priv->refcnt--;
93 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
94 if (!uiomem->size)
95 break;
96 if (priv->dmem_region_vaddr[dmem_region]) {
97 dma_free_coherent(&priv->pdev->dev, uiomem->size,
98 priv->dmem_region_vaddr[dmem_region],
99 uiomem->addr);
100 }
101 uiomem->addr = DMEM_MAP_ERROR;
102 ++dmem_region;
103 ++uiomem;
104 }
105
106 mutex_unlock(&priv->alloc_lock);
107 return 0;
108 }
109
uio_dmem_genirq_handler(int irq,struct uio_info * dev_info)110 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
111 {
112 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
113
114 /* Just disable the interrupt in the interrupt controller, and
115 * remember the state so we can allow user space to enable it later.
116 */
117
118 spin_lock(&priv->lock);
119 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
120 disable_irq_nosync(irq);
121 spin_unlock(&priv->lock);
122
123 return IRQ_HANDLED;
124 }
125
uio_dmem_genirq_irqcontrol(struct uio_info * dev_info,s32 irq_on)126 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
127 {
128 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
129 unsigned long flags;
130
131 /* Allow user space to enable and disable the interrupt
132 * in the interrupt controller, but keep track of the
133 * state to prevent per-irq depth damage.
134 *
135 * Serialize this operation to support multiple tasks and concurrency
136 * with irq handler on SMP systems.
137 */
138
139 spin_lock_irqsave(&priv->lock, flags);
140 if (irq_on) {
141 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
142 enable_irq(dev_info->irq);
143 } else {
144 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
145 disable_irq_nosync(dev_info->irq);
146 }
147 spin_unlock_irqrestore(&priv->lock, flags);
148
149 return 0;
150 }
151
uio_dmem_genirq_pm_disable(void * data)152 static void uio_dmem_genirq_pm_disable(void *data)
153 {
154 struct device *dev = data;
155
156 pm_runtime_disable(dev);
157 }
158
uio_dmem_genirq_probe(struct platform_device * pdev)159 static int uio_dmem_genirq_probe(struct platform_device *pdev)
160 {
161 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
162 struct uio_info *uioinfo = &pdata->uioinfo;
163 struct uio_dmem_genirq_platdata *priv;
164 struct uio_mem *uiomem;
165 int ret = -EINVAL;
166 int i;
167
168 if (pdev->dev.of_node) {
169 /* alloc uioinfo for one device */
170 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo), GFP_KERNEL);
171 if (!uioinfo) {
172 dev_err(&pdev->dev, "unable to kmalloc\n");
173 return -ENOMEM;
174 }
175 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
176 pdev->dev.of_node);
177 uioinfo->version = "devicetree";
178 }
179
180 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
181 dev_err(&pdev->dev, "missing platform_data\n");
182 return -EINVAL;
183 }
184
185 if (uioinfo->handler || uioinfo->irqcontrol ||
186 uioinfo->irq_flags & IRQF_SHARED) {
187 dev_err(&pdev->dev, "interrupt configuration error\n");
188 return -EINVAL;
189 }
190
191 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
192 if (!priv) {
193 dev_err(&pdev->dev, "unable to kmalloc\n");
194 return -ENOMEM;
195 }
196
197 ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
198 if (ret) {
199 dev_err(&pdev->dev, "DMA enable failed\n");
200 return ret;
201 }
202
203 priv->uioinfo = uioinfo;
204 spin_lock_init(&priv->lock);
205 priv->flags = 0; /* interrupt is enabled to begin with */
206 priv->pdev = pdev;
207 mutex_init(&priv->alloc_lock);
208
209 if (!uioinfo->irq) {
210 /* Multiple IRQs are not supported */
211 ret = platform_get_irq(pdev, 0);
212 if (ret == -ENXIO && pdev->dev.of_node)
213 ret = UIO_IRQ_NONE;
214 else if (ret < 0)
215 return ret;
216 uioinfo->irq = ret;
217 }
218
219 if (uioinfo->irq) {
220 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
221
222 /*
223 * If a level interrupt, dont do lazy disable. Otherwise the
224 * irq will fire again since clearing of the actual cause, on
225 * device level, is done in userspace
226 * irqd_is_level_type() isn't used since isn't valid until
227 * irq is configured.
228 */
229 if (irq_data &&
230 irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
231 dev_dbg(&pdev->dev, "disable lazy unmask\n");
232 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
233 }
234 }
235
236 uiomem = &uioinfo->mem[0];
237
238 for (i = 0; i < pdev->num_resources; ++i) {
239 struct resource *r = &pdev->resource[i];
240
241 if (r->flags != IORESOURCE_MEM)
242 continue;
243
244 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
245 dev_warn(&pdev->dev, "device has more than "
246 __stringify(MAX_UIO_MAPS)
247 " I/O memory resources.\n");
248 break;
249 }
250
251 uiomem->memtype = UIO_MEM_PHYS;
252 uiomem->addr = r->start;
253 uiomem->size = resource_size(r);
254 ++uiomem;
255 }
256
257 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
258 priv->num_dmem_regions = pdata->num_dynamic_regions;
259
260 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
261 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
262 dev_warn(&pdev->dev, "device has more than "
263 __stringify(MAX_UIO_MAPS)
264 " dynamic and fixed memory regions.\n");
265 break;
266 }
267 uiomem->memtype = UIO_MEM_PHYS;
268 uiomem->addr = DMEM_MAP_ERROR;
269 uiomem->size = pdata->dynamic_region_sizes[i];
270 ++uiomem;
271 }
272
273 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
274 uiomem->size = 0;
275 ++uiomem;
276 }
277
278 /* This driver requires no hardware specific kernel code to handle
279 * interrupts. Instead, the interrupt handler simply disables the
280 * interrupt in the interrupt controller. User space is responsible
281 * for performing hardware specific acknowledge and re-enabling of
282 * the interrupt in the interrupt controller.
283 *
284 * Interrupt sharing is not supported.
285 */
286
287 uioinfo->handler = uio_dmem_genirq_handler;
288 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
289 uioinfo->open = uio_dmem_genirq_open;
290 uioinfo->release = uio_dmem_genirq_release;
291 uioinfo->priv = priv;
292
293 /* Enable Runtime PM for this device:
294 * The device starts in suspended state to allow the hardware to be
295 * turned off by default. The Runtime PM bus code should power on the
296 * hardware and enable clocks at open().
297 */
298 pm_runtime_enable(&pdev->dev);
299
300 ret = devm_add_action_or_reset(&pdev->dev, uio_dmem_genirq_pm_disable, &pdev->dev);
301 if (ret)
302 return ret;
303
304 return devm_uio_register_device(&pdev->dev, priv->uioinfo);
305 }
306
uio_dmem_genirq_runtime_nop(struct device * dev)307 static int uio_dmem_genirq_runtime_nop(struct device *dev)
308 {
309 /* Runtime PM callback shared between ->runtime_suspend()
310 * and ->runtime_resume(). Simply returns success.
311 *
312 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
313 * are used at open() and release() time. This allows the
314 * Runtime PM code to turn off power to the device while the
315 * device is unused, ie before open() and after release().
316 *
317 * This Runtime PM callback does not need to save or restore
318 * any registers since user space is responsbile for hardware
319 * register reinitialization after open().
320 */
321 return 0;
322 }
323
324 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
325 .runtime_suspend = uio_dmem_genirq_runtime_nop,
326 .runtime_resume = uio_dmem_genirq_runtime_nop,
327 };
328
329 #ifdef CONFIG_OF
330 static const struct of_device_id uio_of_genirq_match[] = {
331 { /* empty for now */ },
332 };
333 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
334 #endif
335
336 static struct platform_driver uio_dmem_genirq = {
337 .probe = uio_dmem_genirq_probe,
338 .driver = {
339 .name = DRIVER_NAME,
340 .pm = &uio_dmem_genirq_dev_pm_ops,
341 .of_match_table = of_match_ptr(uio_of_genirq_match),
342 },
343 };
344
345 module_platform_driver(uio_dmem_genirq);
346
347 MODULE_AUTHOR("Damian Hobson-Garcia");
348 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
349 MODULE_LICENSE("GPL v2");
350 MODULE_ALIAS("platform:" DRIVER_NAME);
351