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 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode) 41 { 42 struct uio_pdrv_genirq_platdata *priv = info->priv; 43 44 /* Wait until the Runtime PM code has woken up the device */ 45 pm_runtime_get_sync(&priv->pdev->dev); 46 return 0; 47 } 48 49 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode) 50 { 51 struct uio_pdrv_genirq_platdata *priv = info->priv; 52 53 /* Tell the Runtime PM code that the device has become idle */ 54 pm_runtime_put_sync(&priv->pdev->dev); 55 return 0; 56 } 57 58 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info) 59 { 60 struct uio_pdrv_genirq_platdata *priv = dev_info->priv; 61 62 /* Just disable the interrupt in the interrupt controller, and 63 * remember the state so we can allow user space to enable it later. 64 */ 65 66 if (!test_and_set_bit(0, &priv->flags)) 67 disable_irq_nosync(irq); 68 69 return IRQ_HANDLED; 70 } 71 72 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) 73 { 74 struct uio_pdrv_genirq_platdata *priv = dev_info->priv; 75 unsigned long flags; 76 77 /* Allow user space to enable and disable the interrupt 78 * in the interrupt controller, but keep track of the 79 * state to prevent per-irq depth damage. 80 * 81 * Serialize this operation to support multiple tasks. 82 */ 83 84 spin_lock_irqsave(&priv->lock, flags); 85 if (irq_on) { 86 if (test_and_clear_bit(0, &priv->flags)) 87 enable_irq(dev_info->irq); 88 } else { 89 if (!test_and_set_bit(0, &priv->flags)) 90 disable_irq(dev_info->irq); 91 } 92 spin_unlock_irqrestore(&priv->lock, flags); 93 94 return 0; 95 } 96 97 static int uio_pdrv_genirq_probe(struct platform_device *pdev) 98 { 99 struct uio_info *uioinfo = pdev->dev.platform_data; 100 struct uio_pdrv_genirq_platdata *priv; 101 struct uio_mem *uiomem; 102 int ret = -EINVAL; 103 int i; 104 105 if (pdev->dev.of_node) { 106 int irq; 107 108 /* alloc uioinfo for one device */ 109 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL); 110 if (!uioinfo) { 111 ret = -ENOMEM; 112 dev_err(&pdev->dev, "unable to kmalloc\n"); 113 goto bad2; 114 } 115 uioinfo->name = pdev->dev.of_node->name; 116 uioinfo->version = "devicetree"; 117 118 /* Multiple IRQs are not supported */ 119 irq = platform_get_irq(pdev, 0); 120 if (irq == -ENXIO) 121 uioinfo->irq = UIO_IRQ_NONE; 122 else 123 uioinfo->irq = irq; 124 } 125 126 if (!uioinfo || !uioinfo->name || !uioinfo->version) { 127 dev_err(&pdev->dev, "missing platform_data\n"); 128 goto bad0; 129 } 130 131 if (uioinfo->handler || uioinfo->irqcontrol || 132 uioinfo->irq_flags & IRQF_SHARED) { 133 dev_err(&pdev->dev, "interrupt configuration error\n"); 134 goto bad0; 135 } 136 137 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 138 if (!priv) { 139 ret = -ENOMEM; 140 dev_err(&pdev->dev, "unable to kmalloc\n"); 141 goto bad0; 142 } 143 144 priv->uioinfo = uioinfo; 145 spin_lock_init(&priv->lock); 146 priv->flags = 0; /* interrupt is enabled to begin with */ 147 priv->pdev = pdev; 148 149 if (!uioinfo->irq) { 150 ret = platform_get_irq(pdev, 0); 151 if (ret < 0) { 152 dev_err(&pdev->dev, "failed to get IRQ\n"); 153 goto bad0; 154 } 155 uioinfo->irq = ret; 156 } 157 uiomem = &uioinfo->mem[0]; 158 159 for (i = 0; i < pdev->num_resources; ++i) { 160 struct resource *r = &pdev->resource[i]; 161 162 if (r->flags != IORESOURCE_MEM) 163 continue; 164 165 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { 166 dev_warn(&pdev->dev, "device has more than " 167 __stringify(MAX_UIO_MAPS) 168 " I/O memory resources.\n"); 169 break; 170 } 171 172 uiomem->memtype = UIO_MEM_PHYS; 173 uiomem->addr = r->start; 174 uiomem->size = resource_size(r); 175 uiomem->name = r->name; 176 ++uiomem; 177 } 178 179 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { 180 uiomem->size = 0; 181 ++uiomem; 182 } 183 184 /* This driver requires no hardware specific kernel code to handle 185 * interrupts. Instead, the interrupt handler simply disables the 186 * interrupt in the interrupt controller. User space is responsible 187 * for performing hardware specific acknowledge and re-enabling of 188 * the interrupt in the interrupt controller. 189 * 190 * Interrupt sharing is not supported. 191 */ 192 193 uioinfo->handler = uio_pdrv_genirq_handler; 194 uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol; 195 uioinfo->open = uio_pdrv_genirq_open; 196 uioinfo->release = uio_pdrv_genirq_release; 197 uioinfo->priv = priv; 198 199 /* Enable Runtime PM for this device: 200 * The device starts in suspended state to allow the hardware to be 201 * turned off by default. The Runtime PM bus code should power on the 202 * hardware and enable clocks at open(). 203 */ 204 pm_runtime_enable(&pdev->dev); 205 206 ret = uio_register_device(&pdev->dev, priv->uioinfo); 207 if (ret) { 208 dev_err(&pdev->dev, "unable to register uio device\n"); 209 goto bad1; 210 } 211 212 platform_set_drvdata(pdev, priv); 213 return 0; 214 bad1: 215 kfree(priv); 216 pm_runtime_disable(&pdev->dev); 217 bad0: 218 /* kfree uioinfo for OF */ 219 if (pdev->dev.of_node) 220 kfree(uioinfo); 221 bad2: 222 return ret; 223 } 224 225 static int uio_pdrv_genirq_remove(struct platform_device *pdev) 226 { 227 struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev); 228 229 uio_unregister_device(priv->uioinfo); 230 pm_runtime_disable(&pdev->dev); 231 232 priv->uioinfo->handler = NULL; 233 priv->uioinfo->irqcontrol = NULL; 234 235 /* kfree uioinfo for OF */ 236 if (pdev->dev.of_node) 237 kfree(priv->uioinfo); 238 239 kfree(priv); 240 return 0; 241 } 242 243 static int uio_pdrv_genirq_runtime_nop(struct device *dev) 244 { 245 /* Runtime PM callback shared between ->runtime_suspend() 246 * and ->runtime_resume(). Simply returns success. 247 * 248 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync() 249 * are used at open() and release() time. This allows the 250 * Runtime PM code to turn off power to the device while the 251 * device is unused, ie before open() and after release(). 252 * 253 * This Runtime PM callback does not need to save or restore 254 * any registers since user space is responsbile for hardware 255 * register reinitialization after open(). 256 */ 257 return 0; 258 } 259 260 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = { 261 .runtime_suspend = uio_pdrv_genirq_runtime_nop, 262 .runtime_resume = uio_pdrv_genirq_runtime_nop, 263 }; 264 265 #ifdef CONFIG_OF 266 static const struct of_device_id uio_of_genirq_match[] = { 267 { /* empty for now */ }, 268 }; 269 MODULE_DEVICE_TABLE(of, uio_of_genirq_match); 270 #else 271 # define uio_of_genirq_match NULL 272 #endif 273 274 static struct platform_driver uio_pdrv_genirq = { 275 .probe = uio_pdrv_genirq_probe, 276 .remove = uio_pdrv_genirq_remove, 277 .driver = { 278 .name = DRIVER_NAME, 279 .owner = THIS_MODULE, 280 .pm = &uio_pdrv_genirq_dev_pm_ops, 281 .of_match_table = uio_of_genirq_match, 282 }, 283 }; 284 285 module_platform_driver(uio_pdrv_genirq); 286 287 MODULE_AUTHOR("Magnus Damm"); 288 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling"); 289 MODULE_LICENSE("GPL v2"); 290 MODULE_ALIAS("platform:" DRIVER_NAME); 291