1 // SPDX-License-Identifier: GPL-2.0-only
3 * drivers/uio/uio_dmem_genirq.c
5 * Userspace I/O platform driver with generic IRQ handling code.
7 * Copyright (C) 2012 Damian Hobson-Garcia
9 * Based on uio_pdrv_genirq.c by Magnus Damm
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>
26 #include <linux/of_platform.h>
27 #include <linux/of_address.h>
29 #define DRIVER_NAME "uio_dmem_genirq"
30 #define DMEM_MAP_ERROR (~0)
32 struct uio_dmem_genirq_platdata {
33 struct uio_info *uioinfo;
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;
44 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
46 struct uio_dmem_genirq_platdata *priv = info->priv;
47 struct uio_mem *uiomem;
48 int dmem_region = priv->dmem_region_start;
50 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
52 mutex_lock(&priv->alloc_lock);
53 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
58 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
59 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
61 uiomem->addr = DMEM_MAP_ERROR;
63 priv->dmem_region_vaddr[dmem_region++] = addr;
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);
74 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
76 struct uio_dmem_genirq_platdata *priv = info->priv;
77 struct uio_mem *uiomem;
78 int dmem_region = priv->dmem_region_start;
80 /* Tell the Runtime PM code that the device has become idle */
81 pm_runtime_put_sync(&priv->pdev->dev);
83 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
85 mutex_lock(&priv->alloc_lock);
88 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
91 if (priv->dmem_region_vaddr[dmem_region]) {
92 dma_free_coherent(&priv->pdev->dev, uiomem->size,
93 priv->dmem_region_vaddr[dmem_region],
96 uiomem->addr = DMEM_MAP_ERROR;
101 mutex_unlock(&priv->alloc_lock);
105 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
107 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
109 /* Just disable the interrupt in the interrupt controller, and
110 * remember the state so we can allow user space to enable it later.
113 spin_lock(&priv->lock);
114 if (!test_and_set_bit(0, &priv->flags))
115 disable_irq_nosync(irq);
116 spin_unlock(&priv->lock);
121 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
123 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
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.
130 * Serialize this operation to support multiple tasks and concurrency
131 * with irq handler on SMP systems.
134 spin_lock_irqsave(&priv->lock, flags);
136 if (test_and_clear_bit(0, &priv->flags))
137 enable_irq(dev_info->irq);
139 if (!test_and_set_bit(0, &priv->flags))
140 disable_irq_nosync(dev_info->irq);
142 spin_unlock_irqrestore(&priv->lock, flags);
147 static void uio_dmem_genirq_pm_disable(void *data)
149 struct device *dev = data;
151 pm_runtime_disable(dev);
154 static int uio_dmem_genirq_probe(struct platform_device *pdev)
156 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
157 struct uio_info *uioinfo = &pdata->uioinfo;
158 struct uio_dmem_genirq_platdata *priv;
159 struct uio_mem *uiomem;
163 if (pdev->dev.of_node) {
164 /* alloc uioinfo for one device */
165 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo), GFP_KERNEL);
167 dev_err(&pdev->dev, "unable to kmalloc\n");
170 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
172 uioinfo->version = "devicetree";
175 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
176 dev_err(&pdev->dev, "missing platform_data\n");
180 if (uioinfo->handler || uioinfo->irqcontrol ||
181 uioinfo->irq_flags & IRQF_SHARED) {
182 dev_err(&pdev->dev, "interrupt configuration error\n");
186 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
188 dev_err(&pdev->dev, "unable to kmalloc\n");
192 ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
194 dev_err(&pdev->dev, "DMA enable failed\n");
198 priv->uioinfo = uioinfo;
199 spin_lock_init(&priv->lock);
200 priv->flags = 0; /* interrupt is enabled to begin with */
202 mutex_init(&priv->alloc_lock);
205 /* Multiple IRQs are not supported */
206 ret = platform_get_irq(pdev, 0);
207 if (ret == -ENXIO && pdev->dev.of_node)
215 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
218 * If a level interrupt, dont do lazy disable. Otherwise the
219 * irq will fire again since clearing of the actual cause, on
220 * device level, is done in userspace
221 * irqd_is_level_type() isn't used since isn't valid until
225 irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
226 dev_dbg(&pdev->dev, "disable lazy unmask\n");
227 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
231 uiomem = &uioinfo->mem[0];
233 for (i = 0; i < pdev->num_resources; ++i) {
234 struct resource *r = &pdev->resource[i];
236 if (r->flags != IORESOURCE_MEM)
239 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
240 dev_warn(&pdev->dev, "device has more than "
241 __stringify(MAX_UIO_MAPS)
242 " I/O memory resources.\n");
246 uiomem->memtype = UIO_MEM_PHYS;
247 uiomem->addr = r->start;
248 uiomem->size = resource_size(r);
252 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
253 priv->num_dmem_regions = pdata->num_dynamic_regions;
255 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
256 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
257 dev_warn(&pdev->dev, "device has more than "
258 __stringify(MAX_UIO_MAPS)
259 " dynamic and fixed memory regions.\n");
262 uiomem->memtype = UIO_MEM_PHYS;
263 uiomem->addr = DMEM_MAP_ERROR;
264 uiomem->size = pdata->dynamic_region_sizes[i];
268 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
273 /* This driver requires no hardware specific kernel code to handle
274 * interrupts. Instead, the interrupt handler simply disables the
275 * interrupt in the interrupt controller. User space is responsible
276 * for performing hardware specific acknowledge and re-enabling of
277 * the interrupt in the interrupt controller.
279 * Interrupt sharing is not supported.
282 uioinfo->handler = uio_dmem_genirq_handler;
283 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
284 uioinfo->open = uio_dmem_genirq_open;
285 uioinfo->release = uio_dmem_genirq_release;
286 uioinfo->priv = priv;
288 /* Enable Runtime PM for this device:
289 * The device starts in suspended state to allow the hardware to be
290 * turned off by default. The Runtime PM bus code should power on the
291 * hardware and enable clocks at open().
293 pm_runtime_enable(&pdev->dev);
295 ret = devm_add_action_or_reset(&pdev->dev, uio_dmem_genirq_pm_disable, &pdev->dev);
299 return devm_uio_register_device(&pdev->dev, priv->uioinfo);
302 static int uio_dmem_genirq_runtime_nop(struct device *dev)
304 /* Runtime PM callback shared between ->runtime_suspend()
305 * and ->runtime_resume(). Simply returns success.
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().
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().
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,
325 static const struct of_device_id uio_of_genirq_match[] = {
326 { /* empty for now */ },
328 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
331 static struct platform_driver uio_dmem_genirq = {
332 .probe = uio_dmem_genirq_probe,
335 .pm = &uio_dmem_genirq_dev_pm_ops,
336 .of_match_table = of_match_ptr(uio_of_genirq_match),
340 module_platform_driver(uio_dmem_genirq);
342 MODULE_AUTHOR("Damian Hobson-Garcia");
343 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
344 MODULE_LICENSE("GPL v2");
345 MODULE_ALIAS("platform:" DRIVER_NAME);