1 /* 2 * drivers/uio/uio_dmem_genirq.c 3 * 4 * Userspace I/O platform driver with generic IRQ handling code. 5 * 6 * Copyright (C) 2012 Damian Hobson-Garcia 7 * 8 * Based on uio_pdrv_genirq.c by Magnus Damm 9 * 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. 13 */ 14 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> 26 27 #include <linux/of.h> 28 #include <linux/of_platform.h> 29 #include <linux/of_address.h> 30 31 #define DRIVER_NAME "uio_dmem_genirq" 32 #define DMEM_MAP_ERROR (~0) 33 34 struct uio_dmem_genirq_platdata { 35 struct uio_info *uioinfo; 36 spinlock_t lock; 37 unsigned long flags; 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; 43 unsigned int refcnt; 44 }; 45 46 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode) 47 { 48 struct uio_dmem_genirq_platdata *priv = info->priv; 49 struct uio_mem *uiomem; 50 int ret = 0; 51 int dmem_region = priv->dmem_region_start; 52 53 uiomem = &priv->uioinfo->mem[priv->dmem_region_start]; 54 55 mutex_lock(&priv->alloc_lock); 56 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) { 57 void *addr; 58 if (!uiomem->size) 59 break; 60 61 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size, 62 (dma_addr_t *)&uiomem->addr, GFP_KERNEL); 63 if (!addr) { 64 uiomem->addr = DMEM_MAP_ERROR; 65 } 66 priv->dmem_region_vaddr[dmem_region++] = addr; 67 ++uiomem; 68 } 69 priv->refcnt++; 70 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); 74 return ret; 75 } 76 77 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode) 78 { 79 struct uio_dmem_genirq_platdata *priv = info->priv; 80 struct uio_mem *uiomem; 81 int dmem_region = priv->dmem_region_start; 82 83 /* Tell the Runtime PM code that the device has become idle */ 84 pm_runtime_put_sync(&priv->pdev->dev); 85 86 uiomem = &priv->uioinfo->mem[priv->dmem_region_start]; 87 88 mutex_lock(&priv->alloc_lock); 89 90 priv->refcnt--; 91 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) { 92 if (!uiomem->size) 93 break; 94 if (priv->dmem_region_vaddr[dmem_region]) { 95 dma_free_coherent(&priv->pdev->dev, uiomem->size, 96 priv->dmem_region_vaddr[dmem_region], 97 uiomem->addr); 98 } 99 uiomem->addr = DMEM_MAP_ERROR; 100 ++dmem_region; 101 ++uiomem; 102 } 103 104 mutex_unlock(&priv->alloc_lock); 105 return 0; 106 } 107 108 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info) 109 { 110 struct uio_dmem_genirq_platdata *priv = dev_info->priv; 111 112 /* Just disable the interrupt in the interrupt controller, and 113 * remember the state so we can allow user space to enable it later. 114 */ 115 116 if (!test_and_set_bit(0, &priv->flags)) 117 disable_irq_nosync(irq); 118 119 return IRQ_HANDLED; 120 } 121 122 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) 123 { 124 struct uio_dmem_genirq_platdata *priv = dev_info->priv; 125 unsigned long flags; 126 127 /* Allow user space to enable and disable the interrupt 128 * in the interrupt controller, but keep track of the 129 * state to prevent per-irq depth damage. 130 * 131 * Serialize this operation to support multiple tasks. 132 */ 133 134 spin_lock_irqsave(&priv->lock, flags); 135 if (irq_on) { 136 if (test_and_clear_bit(0, &priv->flags)) 137 enable_irq(dev_info->irq); 138 } else { 139 if (!test_and_set_bit(0, &priv->flags)) 140 disable_irq(dev_info->irq); 141 } 142 spin_unlock_irqrestore(&priv->lock, flags); 143 144 return 0; 145 } 146 147 static int uio_dmem_genirq_probe(struct platform_device *pdev) 148 { 149 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev); 150 struct uio_info *uioinfo = &pdata->uioinfo; 151 struct uio_dmem_genirq_platdata *priv; 152 struct uio_mem *uiomem; 153 int ret = -EINVAL; 154 int i; 155 156 if (pdev->dev.of_node) { 157 int irq; 158 159 /* alloc uioinfo for one device */ 160 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL); 161 if (!uioinfo) { 162 ret = -ENOMEM; 163 dev_err(&pdev->dev, "unable to kmalloc\n"); 164 goto bad2; 165 } 166 uioinfo->name = pdev->dev.of_node->name; 167 uioinfo->version = "devicetree"; 168 169 /* Multiple IRQs are not supported */ 170 irq = platform_get_irq(pdev, 0); 171 if (irq == -ENXIO) 172 uioinfo->irq = UIO_IRQ_NONE; 173 else 174 uioinfo->irq = irq; 175 } 176 177 if (!uioinfo || !uioinfo->name || !uioinfo->version) { 178 dev_err(&pdev->dev, "missing platform_data\n"); 179 goto bad0; 180 } 181 182 if (uioinfo->handler || uioinfo->irqcontrol || 183 uioinfo->irq_flags & IRQF_SHARED) { 184 dev_err(&pdev->dev, "interrupt configuration error\n"); 185 goto bad0; 186 } 187 188 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 189 if (!priv) { 190 ret = -ENOMEM; 191 dev_err(&pdev->dev, "unable to kmalloc\n"); 192 goto bad0; 193 } 194 195 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32)); 196 197 priv->uioinfo = uioinfo; 198 spin_lock_init(&priv->lock); 199 priv->flags = 0; /* interrupt is enabled to begin with */ 200 priv->pdev = pdev; 201 mutex_init(&priv->alloc_lock); 202 203 if (!uioinfo->irq) { 204 ret = platform_get_irq(pdev, 0); 205 if (ret < 0) { 206 dev_err(&pdev->dev, "failed to get IRQ\n"); 207 goto bad1; 208 } 209 uioinfo->irq = ret; 210 } 211 uiomem = &uioinfo->mem[0]; 212 213 for (i = 0; i < pdev->num_resources; ++i) { 214 struct resource *r = &pdev->resource[i]; 215 216 if (r->flags != IORESOURCE_MEM) 217 continue; 218 219 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { 220 dev_warn(&pdev->dev, "device has more than " 221 __stringify(MAX_UIO_MAPS) 222 " I/O memory resources.\n"); 223 break; 224 } 225 226 uiomem->memtype = UIO_MEM_PHYS; 227 uiomem->addr = r->start; 228 uiomem->size = resource_size(r); 229 ++uiomem; 230 } 231 232 priv->dmem_region_start = i; 233 priv->num_dmem_regions = pdata->num_dynamic_regions; 234 235 for (i = 0; i < pdata->num_dynamic_regions; ++i) { 236 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { 237 dev_warn(&pdev->dev, "device has more than " 238 __stringify(MAX_UIO_MAPS) 239 " dynamic and fixed memory regions.\n"); 240 break; 241 } 242 uiomem->memtype = UIO_MEM_PHYS; 243 uiomem->addr = DMEM_MAP_ERROR; 244 uiomem->size = pdata->dynamic_region_sizes[i]; 245 ++uiomem; 246 } 247 248 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { 249 uiomem->size = 0; 250 ++uiomem; 251 } 252 253 /* This driver requires no hardware specific kernel code to handle 254 * interrupts. Instead, the interrupt handler simply disables the 255 * interrupt in the interrupt controller. User space is responsible 256 * for performing hardware specific acknowledge and re-enabling of 257 * the interrupt in the interrupt controller. 258 * 259 * Interrupt sharing is not supported. 260 */ 261 262 uioinfo->handler = uio_dmem_genirq_handler; 263 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol; 264 uioinfo->open = uio_dmem_genirq_open; 265 uioinfo->release = uio_dmem_genirq_release; 266 uioinfo->priv = priv; 267 268 /* Enable Runtime PM for this device: 269 * The device starts in suspended state to allow the hardware to be 270 * turned off by default. The Runtime PM bus code should power on the 271 * hardware and enable clocks at open(). 272 */ 273 pm_runtime_enable(&pdev->dev); 274 275 ret = uio_register_device(&pdev->dev, priv->uioinfo); 276 if (ret) { 277 dev_err(&pdev->dev, "unable to register uio device\n"); 278 pm_runtime_disable(&pdev->dev); 279 goto bad1; 280 } 281 282 platform_set_drvdata(pdev, priv); 283 return 0; 284 bad1: 285 kfree(priv); 286 bad0: 287 /* kfree uioinfo for OF */ 288 if (pdev->dev.of_node) 289 kfree(uioinfo); 290 bad2: 291 return ret; 292 } 293 294 static int uio_dmem_genirq_remove(struct platform_device *pdev) 295 { 296 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev); 297 298 uio_unregister_device(priv->uioinfo); 299 pm_runtime_disable(&pdev->dev); 300 301 priv->uioinfo->handler = NULL; 302 priv->uioinfo->irqcontrol = NULL; 303 304 /* kfree uioinfo for OF */ 305 if (pdev->dev.of_node) 306 kfree(priv->uioinfo); 307 308 kfree(priv); 309 return 0; 310 } 311 312 static int uio_dmem_genirq_runtime_nop(struct device *dev) 313 { 314 /* Runtime PM callback shared between ->runtime_suspend() 315 * and ->runtime_resume(). Simply returns success. 316 * 317 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync() 318 * are used at open() and release() time. This allows the 319 * Runtime PM code to turn off power to the device while the 320 * device is unused, ie before open() and after release(). 321 * 322 * This Runtime PM callback does not need to save or restore 323 * any registers since user space is responsbile for hardware 324 * register reinitialization after open(). 325 */ 326 return 0; 327 } 328 329 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = { 330 .runtime_suspend = uio_dmem_genirq_runtime_nop, 331 .runtime_resume = uio_dmem_genirq_runtime_nop, 332 }; 333 334 #ifdef CONFIG_OF 335 static const struct of_device_id uio_of_genirq_match[] = { 336 { /* empty for now */ }, 337 }; 338 MODULE_DEVICE_TABLE(of, uio_of_genirq_match); 339 #endif 340 341 static struct platform_driver uio_dmem_genirq = { 342 .probe = uio_dmem_genirq_probe, 343 .remove = uio_dmem_genirq_remove, 344 .driver = { 345 .name = DRIVER_NAME, 346 .pm = &uio_dmem_genirq_dev_pm_ops, 347 .of_match_table = of_match_ptr(uio_of_genirq_match), 348 }, 349 }; 350 351 module_platform_driver(uio_dmem_genirq); 352 353 MODULE_AUTHOR("Damian Hobson-Garcia"); 354 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory."); 355 MODULE_LICENSE("GPL v2"); 356 MODULE_ALIAS("platform:" DRIVER_NAME); 357