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
 32struct 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 */
 45enum {
 46	UIO_IRQ_DISABLED = 0,
 47};
 48
 49static 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
 79static 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
110static 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
126static 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
152static void uio_dmem_genirq_pm_disable(void *data)
153{
154	struct device *dev = data;
155
156	pm_runtime_disable(dev);
157}
158
159static 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
307static 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
324static 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
330static const struct of_device_id uio_of_genirq_match[] = {
331	{ /* empty for now */ },
332};
333MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
334#endif
335
336static 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
345module_platform_driver(uio_dmem_genirq);
346
347MODULE_AUTHOR("Damian Hobson-Garcia");
348MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
349MODULE_LICENSE("GPL v2");
350MODULE_ALIAS("platform:" DRIVER_NAME);