2 * drivers/uio/uio_dmem_genirq.c
4 * Userspace I/O platform driver with generic IRQ handling code.
6 * Copyright (C) 2012 Damian Hobson-Garcia
8 * Based on uio_pdrv_genirq.c by Magnus Damm
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License version 2 as published by
12 * the Free Software Foundation.
15 #include <linux/platform_device.h>
16 #include <linux/uio_driver.h>
17 #include <linux/spinlock.h>
18 #include <linux/bitops.h>
19 #include <linux/module.h>
20 #include <linux/interrupt.h>
21 #include <linux/platform_data/uio_dmem_genirq.h>
22 #include <linux/stringify.h>
23 #include <linux/pm_runtime.h>
24 #include <linux/dma-mapping.h>
25 #include <linux/slab.h>
28 #include <linux/of_platform.h>
29 #include <linux/of_address.h>
31 #define DRIVER_NAME "uio_dmem_genirq"
32 #define DMEM_MAP_ERROR (~0)
34 struct uio_dmem_genirq_platdata {
35 struct uio_info *uioinfo;
38 struct platform_device *pdev;
39 unsigned int dmem_region_start;
40 unsigned int num_dmem_regions;
41 void *dmem_region_vaddr[MAX_UIO_MAPS];
42 struct mutex alloc_lock;
46 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
48 struct uio_dmem_genirq_platdata *priv = info->priv;
49 struct uio_mem *uiomem;
51 int dmem_region = priv->dmem_region_start;
53 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
55 mutex_lock(&priv->alloc_lock);
56 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
61 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
62 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
64 uiomem->addr = DMEM_MAP_ERROR;
66 priv->dmem_region_vaddr[dmem_region++] = addr;
71 mutex_unlock(&priv->alloc_lock);
72 /* Wait until the Runtime PM code has woken up the device */
73 pm_runtime_get_sync(&priv->pdev->dev);
77 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
79 struct uio_dmem_genirq_platdata *priv = info->priv;
80 struct uio_mem *uiomem;
81 int dmem_region = priv->dmem_region_start;
83 /* Tell the Runtime PM code that the device has become idle */
84 pm_runtime_put_sync(&priv->pdev->dev);
86 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
88 mutex_lock(&priv->alloc_lock);
91 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
94 if (priv->dmem_region_vaddr[dmem_region]) {
95 dma_free_coherent(&priv->pdev->dev, uiomem->size,
96 priv->dmem_region_vaddr[dmem_region],
99 uiomem->addr = DMEM_MAP_ERROR;
104 mutex_unlock(&priv->alloc_lock);
108 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
110 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
112 /* Just disable the interrupt in the interrupt controller, and
113 * remember the state so we can allow user space to enable it later.
116 spin_lock(&priv->lock);
117 if (!test_and_set_bit(0, &priv->flags))
118 disable_irq_nosync(irq);
119 spin_unlock(&priv->lock);
124 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
126 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
129 /* Allow user space to enable and disable the interrupt
130 * in the interrupt controller, but keep track of the
131 * state to prevent per-irq depth damage.
133 * Serialize this operation to support multiple tasks and concurrency
134 * with irq handler on SMP systems.
137 spin_lock_irqsave(&priv->lock, flags);
139 if (test_and_clear_bit(0, &priv->flags))
140 enable_irq(dev_info->irq);
142 if (!test_and_set_bit(0, &priv->flags))
143 disable_irq_nosync(dev_info->irq);
145 spin_unlock_irqrestore(&priv->lock, flags);
150 static int uio_dmem_genirq_probe(struct platform_device *pdev)
152 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
153 struct uio_info *uioinfo = &pdata->uioinfo;
154 struct uio_dmem_genirq_platdata *priv;
155 struct uio_mem *uiomem;
159 if (pdev->dev.of_node) {
162 /* alloc uioinfo for one device */
163 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
166 dev_err(&pdev->dev, "unable to kmalloc\n");
169 uioinfo->name = pdev->dev.of_node->name;
170 uioinfo->version = "devicetree";
172 /* Multiple IRQs are not supported */
173 irq = platform_get_irq(pdev, 0);
175 uioinfo->irq = UIO_IRQ_NONE;
180 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
181 dev_err(&pdev->dev, "missing platform_data\n");
185 if (uioinfo->handler || uioinfo->irqcontrol ||
186 uioinfo->irq_flags & IRQF_SHARED) {
187 dev_err(&pdev->dev, "interrupt configuration error\n");
191 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
194 dev_err(&pdev->dev, "unable to kmalloc\n");
198 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
200 priv->uioinfo = uioinfo;
201 spin_lock_init(&priv->lock);
202 priv->flags = 0; /* interrupt is enabled to begin with */
204 mutex_init(&priv->alloc_lock);
207 ret = platform_get_irq(pdev, 0);
209 dev_err(&pdev->dev, "failed to get IRQ\n");
214 uiomem = &uioinfo->mem[0];
216 for (i = 0; i < pdev->num_resources; ++i) {
217 struct resource *r = &pdev->resource[i];
219 if (r->flags != IORESOURCE_MEM)
222 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
223 dev_warn(&pdev->dev, "device has more than "
224 __stringify(MAX_UIO_MAPS)
225 " I/O memory resources.\n");
229 uiomem->memtype = UIO_MEM_PHYS;
230 uiomem->addr = r->start;
231 uiomem->size = resource_size(r);
235 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
236 priv->num_dmem_regions = pdata->num_dynamic_regions;
238 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
239 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
240 dev_warn(&pdev->dev, "device has more than "
241 __stringify(MAX_UIO_MAPS)
242 " dynamic and fixed memory regions.\n");
245 uiomem->memtype = UIO_MEM_PHYS;
246 uiomem->addr = DMEM_MAP_ERROR;
247 uiomem->size = pdata->dynamic_region_sizes[i];
251 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
256 /* This driver requires no hardware specific kernel code to handle
257 * interrupts. Instead, the interrupt handler simply disables the
258 * interrupt in the interrupt controller. User space is responsible
259 * for performing hardware specific acknowledge and re-enabling of
260 * the interrupt in the interrupt controller.
262 * Interrupt sharing is not supported.
265 uioinfo->handler = uio_dmem_genirq_handler;
266 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
267 uioinfo->open = uio_dmem_genirq_open;
268 uioinfo->release = uio_dmem_genirq_release;
269 uioinfo->priv = priv;
271 /* Enable Runtime PM for this device:
272 * The device starts in suspended state to allow the hardware to be
273 * turned off by default. The Runtime PM bus code should power on the
274 * hardware and enable clocks at open().
276 pm_runtime_enable(&pdev->dev);
278 ret = uio_register_device(&pdev->dev, priv->uioinfo);
280 dev_err(&pdev->dev, "unable to register uio device\n");
281 pm_runtime_disable(&pdev->dev);
285 platform_set_drvdata(pdev, priv);
290 /* kfree uioinfo for OF */
291 if (pdev->dev.of_node)
297 static int uio_dmem_genirq_remove(struct platform_device *pdev)
299 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
301 uio_unregister_device(priv->uioinfo);
302 pm_runtime_disable(&pdev->dev);
304 priv->uioinfo->handler = NULL;
305 priv->uioinfo->irqcontrol = NULL;
307 /* kfree uioinfo for OF */
308 if (pdev->dev.of_node)
309 kfree(priv->uioinfo);
315 static int uio_dmem_genirq_runtime_nop(struct device *dev)
317 /* Runtime PM callback shared between ->runtime_suspend()
318 * and ->runtime_resume(). Simply returns success.
320 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
321 * are used at open() and release() time. This allows the
322 * Runtime PM code to turn off power to the device while the
323 * device is unused, ie before open() and after release().
325 * This Runtime PM callback does not need to save or restore
326 * any registers since user space is responsbile for hardware
327 * register reinitialization after open().
332 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
333 .runtime_suspend = uio_dmem_genirq_runtime_nop,
334 .runtime_resume = uio_dmem_genirq_runtime_nop,
338 static const struct of_device_id uio_of_genirq_match[] = {
339 { /* empty for now */ },
341 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
344 static struct platform_driver uio_dmem_genirq = {
345 .probe = uio_dmem_genirq_probe,
346 .remove = uio_dmem_genirq_remove,
349 .pm = &uio_dmem_genirq_dev_pm_ops,
350 .of_match_table = of_match_ptr(uio_of_genirq_match),
354 module_platform_driver(uio_dmem_genirq);
356 MODULE_AUTHOR("Damian Hobson-Garcia");
357 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
358 MODULE_LICENSE("GPL v2");
359 MODULE_ALIAS("platform:" DRIVER_NAME);