1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * drivers/uio/uio_pdrv_genirq.c 4 * 5 * Userspace I/O platform driver with generic IRQ handling code. 6 * 7 * Copyright (C) 2008 Magnus Damm 8 * 9 * Based on uio_pdrv.c by Uwe Kleine-Koenig, 10 * Copyright (C) 2008 by Digi International Inc. 11 * All rights reserved. 12 */ 13 14 #include <linux/platform_device.h> 15 #include <linux/uio_driver.h> 16 #include <linux/spinlock.h> 17 #include <linux/bitops.h> 18 #include <linux/module.h> 19 #include <linux/interrupt.h> 20 #include <linux/stringify.h> 21 #include <linux/pm_runtime.h> 22 #include <linux/slab.h> 23 #include <linux/irq.h> 24 25 #include <linux/of.h> 26 #include <linux/mod_devicetable.h> 27 #include <linux/property.h> 28 29 #define DRIVER_NAME "uio_pdrv_genirq" 30 31 struct uio_pdrv_genirq_platdata { 32 struct uio_info *uioinfo; 33 spinlock_t lock; 34 unsigned long flags; 35 struct platform_device *pdev; 36 }; 37 38 /* Bits in uio_pdrv_genirq_platdata.flags */ 39 enum { 40 UIO_IRQ_DISABLED = 0, 41 }; 42 43 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode) 44 { 45 struct uio_pdrv_genirq_platdata *priv = info->priv; 46 47 /* Wait until the Runtime PM code has woken up the device */ 48 pm_runtime_get_sync(&priv->pdev->dev); 49 return 0; 50 } 51 52 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode) 53 { 54 struct uio_pdrv_genirq_platdata *priv = info->priv; 55 56 /* Tell the Runtime PM code that the device has become idle */ 57 pm_runtime_put_sync(&priv->pdev->dev); 58 return 0; 59 } 60 61 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info) 62 { 63 struct uio_pdrv_genirq_platdata *priv = dev_info->priv; 64 65 /* Just disable the interrupt in the interrupt controller, and 66 * remember the state so we can allow user space to enable it later. 67 */ 68 69 spin_lock(&priv->lock); 70 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) 71 disable_irq_nosync(irq); 72 spin_unlock(&priv->lock); 73 74 return IRQ_HANDLED; 75 } 76 77 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) 78 { 79 struct uio_pdrv_genirq_platdata *priv = dev_info->priv; 80 unsigned long flags; 81 82 /* Allow user space to enable and disable the interrupt 83 * in the interrupt controller, but keep track of the 84 * state to prevent per-irq depth damage. 85 * 86 * Serialize this operation to support multiple tasks and concurrency 87 * with irq handler on SMP systems. 88 */ 89 90 spin_lock_irqsave(&priv->lock, flags); 91 if (irq_on) { 92 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags)) 93 enable_irq(dev_info->irq); 94 } else { 95 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) 96 disable_irq_nosync(dev_info->irq); 97 } 98 spin_unlock_irqrestore(&priv->lock, flags); 99 100 return 0; 101 } 102 103 static void uio_pdrv_genirq_cleanup(void *data) 104 { 105 struct device *dev = data; 106 107 pm_runtime_disable(dev); 108 } 109 110 static int uio_pdrv_genirq_probe(struct platform_device *pdev) 111 { 112 struct uio_info *uioinfo = dev_get_platdata(&pdev->dev); 113 struct fwnode_handle *node = dev_fwnode(&pdev->dev); 114 struct uio_pdrv_genirq_platdata *priv; 115 struct uio_mem *uiomem; 116 int ret = -EINVAL; 117 int i; 118 119 if (node) { 120 const char *name; 121 122 /* alloc uioinfo for one device */ 123 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo), 124 GFP_KERNEL); 125 if (!uioinfo) { 126 dev_err(&pdev->dev, "unable to kmalloc\n"); 127 return -ENOMEM; 128 } 129 130 if (!device_property_read_string(&pdev->dev, "linux,uio-name", &name)) 131 uioinfo->name = devm_kstrdup(&pdev->dev, name, GFP_KERNEL); 132 else 133 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, 134 "%pfwP", node); 135 136 uioinfo->version = "devicetree"; 137 /* Multiple IRQs are not supported */ 138 } 139 140 if (!uioinfo || !uioinfo->name || !uioinfo->version) { 141 dev_err(&pdev->dev, "missing platform_data\n"); 142 return ret; 143 } 144 145 if (uioinfo->handler || uioinfo->irqcontrol || 146 uioinfo->irq_flags & IRQF_SHARED) { 147 dev_err(&pdev->dev, "interrupt configuration error\n"); 148 return ret; 149 } 150 151 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); 152 if (!priv) { 153 dev_err(&pdev->dev, "unable to kmalloc\n"); 154 return -ENOMEM; 155 } 156 157 priv->uioinfo = uioinfo; 158 spin_lock_init(&priv->lock); 159 priv->flags = 0; /* interrupt is enabled to begin with */ 160 priv->pdev = pdev; 161 162 if (!uioinfo->irq) { 163 ret = platform_get_irq_optional(pdev, 0); 164 uioinfo->irq = ret; 165 if (ret == -ENXIO) 166 uioinfo->irq = UIO_IRQ_NONE; 167 else if (ret == -EPROBE_DEFER) 168 return ret; 169 else if (ret < 0) { 170 dev_err(&pdev->dev, "failed to get IRQ\n"); 171 return ret; 172 } 173 } 174 175 if (uioinfo->irq) { 176 /* 177 * If a level interrupt, dont do lazy disable. Otherwise the 178 * irq will fire again since clearing of the actual cause, on 179 * device level, is done in userspace 180 * irqd_is_level_type() isn't used since isn't valid until 181 * irq is configured. 182 */ 183 if (irq_get_trigger_type(uioinfo->irq) & IRQ_TYPE_LEVEL_MASK) { 184 dev_dbg(&pdev->dev, "disable lazy unmask\n"); 185 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY); 186 } 187 } 188 189 uiomem = &uioinfo->mem[0]; 190 191 for (i = 0; i < pdev->num_resources; ++i) { 192 struct resource *r = &pdev->resource[i]; 193 194 if (r->flags != IORESOURCE_MEM) 195 continue; 196 197 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { 198 dev_warn(&pdev->dev, "device has more than " 199 __stringify(MAX_UIO_MAPS) 200 " I/O memory resources.\n"); 201 break; 202 } 203 204 uiomem->memtype = UIO_MEM_PHYS; 205 uiomem->addr = r->start & PAGE_MASK; 206 uiomem->offs = r->start & ~PAGE_MASK; 207 uiomem->size = (uiomem->offs + resource_size(r) 208 + PAGE_SIZE - 1) & PAGE_MASK; 209 uiomem->name = r->name; 210 ++uiomem; 211 } 212 213 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { 214 uiomem->size = 0; 215 ++uiomem; 216 } 217 218 /* This driver requires no hardware specific kernel code to handle 219 * interrupts. Instead, the interrupt handler simply disables the 220 * interrupt in the interrupt controller. User space is responsible 221 * for performing hardware specific acknowledge and re-enabling of 222 * the interrupt in the interrupt controller. 223 * 224 * Interrupt sharing is not supported. 225 */ 226 227 uioinfo->handler = uio_pdrv_genirq_handler; 228 uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol; 229 uioinfo->open = uio_pdrv_genirq_open; 230 uioinfo->release = uio_pdrv_genirq_release; 231 uioinfo->priv = priv; 232 233 /* Enable Runtime PM for this device: 234 * The device starts in suspended state to allow the hardware to be 235 * turned off by default. The Runtime PM bus code should power on the 236 * hardware and enable clocks at open(). 237 */ 238 pm_runtime_enable(&pdev->dev); 239 240 ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup, 241 &pdev->dev); 242 if (ret) 243 return ret; 244 245 ret = devm_uio_register_device(&pdev->dev, priv->uioinfo); 246 if (ret) 247 dev_err(&pdev->dev, "unable to register uio device\n"); 248 249 return ret; 250 } 251 252 static int uio_pdrv_genirq_runtime_nop(struct device *dev) 253 { 254 /* Runtime PM callback shared between ->runtime_suspend() 255 * and ->runtime_resume(). Simply returns success. 256 * 257 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync() 258 * are used at open() and release() time. This allows the 259 * Runtime PM code to turn off power to the device while the 260 * device is unused, ie before open() and after release(). 261 * 262 * This Runtime PM callback does not need to save or restore 263 * any registers since user space is responsbile for hardware 264 * register reinitialization after open(). 265 */ 266 return 0; 267 } 268 269 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = { 270 .runtime_suspend = uio_pdrv_genirq_runtime_nop, 271 .runtime_resume = uio_pdrv_genirq_runtime_nop, 272 }; 273 274 #ifdef CONFIG_OF 275 static struct of_device_id uio_of_genirq_match[] = { 276 { /* This is filled with module_parm */ }, 277 { /* Sentinel */ }, 278 }; 279 MODULE_DEVICE_TABLE(of, uio_of_genirq_match); 280 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0); 281 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio"); 282 #endif 283 284 static struct platform_driver uio_pdrv_genirq = { 285 .probe = uio_pdrv_genirq_probe, 286 .driver = { 287 .name = DRIVER_NAME, 288 .pm = &uio_pdrv_genirq_dev_pm_ops, 289 .of_match_table = of_match_ptr(uio_of_genirq_match), 290 }, 291 }; 292 293 module_platform_driver(uio_pdrv_genirq); 294 295 MODULE_AUTHOR("Magnus Damm"); 296 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling"); 297 MODULE_LICENSE("GPL v2"); 298 MODULE_ALIAS("platform:" DRIVER_NAME); 299