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Linux/drivers/uio/uio_pdrv_genirq.c

  1 /*
  2  * drivers/uio/uio_pdrv_genirq.c
  3  *
  4  * Userspace I/O platform driver with generic IRQ handling code.
  5  *
  6  * Copyright (C) 2008 Magnus Damm
  7  *
  8  * Based on uio_pdrv.c by Uwe Kleine-Koenig,
  9  * Copyright (C) 2008 by Digi International Inc.
 10  * All rights reserved.
 11  *
 12  * This program is free software; you can redistribute it and/or modify it
 13  * under the terms of the GNU General Public License version 2 as published by
 14  * the Free Software Foundation.
 15  */
 16 
 17 #include <linux/platform_device.h>
 18 #include <linux/uio_driver.h>
 19 #include <linux/spinlock.h>
 20 #include <linux/bitops.h>
 21 #include <linux/module.h>
 22 #include <linux/interrupt.h>
 23 #include <linux/stringify.h>
 24 #include <linux/pm_runtime.h>
 25 #include <linux/slab.h>
 26 
 27 #include <linux/of.h>
 28 #include <linux/of_platform.h>
 29 #include <linux/of_address.h>
 30 
 31 #define DRIVER_NAME "uio_pdrv_genirq"
 32 
 33 struct uio_pdrv_genirq_platdata {
 34         struct uio_info *uioinfo;
 35         spinlock_t lock;
 36         unsigned long flags;
 37         struct platform_device *pdev;
 38 };
 39 
 40 /* Bits in uio_pdrv_genirq_platdata.flags */
 41 enum {
 42         UIO_IRQ_DISABLED = 0,
 43 };
 44 
 45 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
 46 {
 47         struct uio_pdrv_genirq_platdata *priv = info->priv;
 48 
 49         /* Wait until the Runtime PM code has woken up the device */
 50         pm_runtime_get_sync(&priv->pdev->dev);
 51         return 0;
 52 }
 53 
 54 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
 55 {
 56         struct uio_pdrv_genirq_platdata *priv = info->priv;
 57 
 58         /* Tell the Runtime PM code that the device has become idle */
 59         pm_runtime_put_sync(&priv->pdev->dev);
 60         return 0;
 61 }
 62 
 63 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
 64 {
 65         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
 66 
 67         /* Just disable the interrupt in the interrupt controller, and
 68          * remember the state so we can allow user space to enable it later.
 69          */
 70 
 71         spin_lock(&priv->lock);
 72         if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
 73                 disable_irq_nosync(irq);
 74         spin_unlock(&priv->lock);
 75 
 76         return IRQ_HANDLED;
 77 }
 78 
 79 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
 80 {
 81         struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
 82         unsigned long flags;
 83 
 84         /* Allow user space to enable and disable the interrupt
 85          * in the interrupt controller, but keep track of the
 86          * state to prevent per-irq depth damage.
 87          *
 88          * Serialize this operation to support multiple tasks and concurrency
 89          * with irq handler on SMP systems.
 90          */
 91 
 92         spin_lock_irqsave(&priv->lock, flags);
 93         if (irq_on) {
 94                 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
 95                         enable_irq(dev_info->irq);
 96         } else {
 97                 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
 98                         disable_irq_nosync(dev_info->irq);
 99         }
100         spin_unlock_irqrestore(&priv->lock, flags);
101 
102         return 0;
103 }
104 
105 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
106 {
107         struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
108         struct uio_pdrv_genirq_platdata *priv;
109         struct uio_mem *uiomem;
110         int ret = -EINVAL;
111         int i;
112 
113         if (pdev->dev.of_node) {
114                 /* alloc uioinfo for one device */
115                 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
116                                        GFP_KERNEL);
117                 if (!uioinfo) {
118                         dev_err(&pdev->dev, "unable to kmalloc\n");
119                         return -ENOMEM;
120                 }
121                 uioinfo->name = pdev->dev.of_node->name;
122                 uioinfo->version = "devicetree";
123                 /* Multiple IRQs are not supported */
124         }
125 
126         if (!uioinfo || !uioinfo->name || !uioinfo->version) {
127                 dev_err(&pdev->dev, "missing platform_data\n");
128                 return ret;
129         }
130 
131         if (uioinfo->handler || uioinfo->irqcontrol ||
132             uioinfo->irq_flags & IRQF_SHARED) {
133                 dev_err(&pdev->dev, "interrupt configuration error\n");
134                 return ret;
135         }
136 
137         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
138         if (!priv) {
139                 dev_err(&pdev->dev, "unable to kmalloc\n");
140                 return -ENOMEM;
141         }
142 
143         priv->uioinfo = uioinfo;
144         spin_lock_init(&priv->lock);
145         priv->flags = 0; /* interrupt is enabled to begin with */
146         priv->pdev = pdev;
147 
148         if (!uioinfo->irq) {
149                 ret = platform_get_irq(pdev, 0);
150                 uioinfo->irq = ret;
151                 if (ret == -ENXIO && pdev->dev.of_node)
152                         uioinfo->irq = UIO_IRQ_NONE;
153                 else if (ret < 0) {
154                         dev_err(&pdev->dev, "failed to get IRQ\n");
155                         return ret;
156                 }
157         }
158 
159         uiomem = &uioinfo->mem[0];
160 
161         for (i = 0; i < pdev->num_resources; ++i) {
162                 struct resource *r = &pdev->resource[i];
163 
164                 if (r->flags != IORESOURCE_MEM)
165                         continue;
166 
167                 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
168                         dev_warn(&pdev->dev, "device has more than "
169                                         __stringify(MAX_UIO_MAPS)
170                                         " I/O memory resources.\n");
171                         break;
172                 }
173 
174                 uiomem->memtype = UIO_MEM_PHYS;
175                 uiomem->addr = r->start;
176                 uiomem->size = resource_size(r);
177                 uiomem->name = r->name;
178                 ++uiomem;
179         }
180 
181         while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
182                 uiomem->size = 0;
183                 ++uiomem;
184         }
185 
186         /* This driver requires no hardware specific kernel code to handle
187          * interrupts. Instead, the interrupt handler simply disables the
188          * interrupt in the interrupt controller. User space is responsible
189          * for performing hardware specific acknowledge and re-enabling of
190          * the interrupt in the interrupt controller.
191          *
192          * Interrupt sharing is not supported.
193          */
194 
195         uioinfo->handler = uio_pdrv_genirq_handler;
196         uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
197         uioinfo->open = uio_pdrv_genirq_open;
198         uioinfo->release = uio_pdrv_genirq_release;
199         uioinfo->priv = priv;
200 
201         /* Enable Runtime PM for this device:
202          * The device starts in suspended state to allow the hardware to be
203          * turned off by default. The Runtime PM bus code should power on the
204          * hardware and enable clocks at open().
205          */
206         pm_runtime_enable(&pdev->dev);
207 
208         ret = uio_register_device(&pdev->dev, priv->uioinfo);
209         if (ret) {
210                 dev_err(&pdev->dev, "unable to register uio device\n");
211                 pm_runtime_disable(&pdev->dev);
212                 return ret;
213         }
214 
215         platform_set_drvdata(pdev, priv);
216         return 0;
217 }
218 
219 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
220 {
221         struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
222 
223         uio_unregister_device(priv->uioinfo);
224         pm_runtime_disable(&pdev->dev);
225 
226         priv->uioinfo->handler = NULL;
227         priv->uioinfo->irqcontrol = NULL;
228 
229         return 0;
230 }
231 
232 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
233 {
234         /* Runtime PM callback shared between ->runtime_suspend()
235          * and ->runtime_resume(). Simply returns success.
236          *
237          * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
238          * are used at open() and release() time. This allows the
239          * Runtime PM code to turn off power to the device while the
240          * device is unused, ie before open() and after release().
241          *
242          * This Runtime PM callback does not need to save or restore
243          * any registers since user space is responsbile for hardware
244          * register reinitialization after open().
245          */
246         return 0;
247 }
248 
249 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
250         .runtime_suspend = uio_pdrv_genirq_runtime_nop,
251         .runtime_resume = uio_pdrv_genirq_runtime_nop,
252 };
253 
254 #ifdef CONFIG_OF
255 static struct of_device_id uio_of_genirq_match[] = {
256         { /* This is filled with module_parm */ },
257         { /* Sentinel */ },
258 };
259 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
260 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
261 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
262 #endif
263 
264 static struct platform_driver uio_pdrv_genirq = {
265         .probe = uio_pdrv_genirq_probe,
266         .remove = uio_pdrv_genirq_remove,
267         .driver = {
268                 .name = DRIVER_NAME,
269                 .owner = THIS_MODULE,
270                 .pm = &uio_pdrv_genirq_dev_pm_ops,
271                 .of_match_table = of_match_ptr(uio_of_genirq_match),
272         },
273 };
274 
275 module_platform_driver(uio_pdrv_genirq);
276 
277 MODULE_AUTHOR("Magnus Damm");
278 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
279 MODULE_LICENSE("GPL v2");
280 MODULE_ALIAS("platform:" DRIVER_NAME);
281 

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