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 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq); 177 178 /* 179 * If a level interrupt, dont do lazy disable. Otherwise the 180 * irq will fire again since clearing of the actual cause, on 181 * device level, is done in userspace 182 * irqd_is_level_type() isn't used since isn't valid until 183 * irq is configured. 184 */ 185 if (irq_data && 186 irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) { 187 dev_dbg(&pdev->dev, "disable lazy unmask\n"); 188 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY); 189 } 190 } 191 192 uiomem = &uioinfo->mem[0]; 193 194 for (i = 0; i < pdev->num_resources; ++i) { 195 struct resource *r = &pdev->resource[i]; 196 197 if (r->flags != IORESOURCE_MEM) 198 continue; 199 200 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { 201 dev_warn(&pdev->dev, "device has more than " 202 __stringify(MAX_UIO_MAPS) 203 " I/O memory resources.\n"); 204 break; 205 } 206 207 uiomem->memtype = UIO_MEM_PHYS; 208 uiomem->addr = r->start & PAGE_MASK; 209 uiomem->offs = r->start & ~PAGE_MASK; 210 uiomem->size = (uiomem->offs + resource_size(r) 211 + PAGE_SIZE - 1) & PAGE_MASK; 212 uiomem->name = r->name; 213 ++uiomem; 214 } 215 216 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { 217 uiomem->size = 0; 218 ++uiomem; 219 } 220 221 /* This driver requires no hardware specific kernel code to handle 222 * interrupts. Instead, the interrupt handler simply disables the 223 * interrupt in the interrupt controller. User space is responsible 224 * for performing hardware specific acknowledge and re-enabling of 225 * the interrupt in the interrupt controller. 226 * 227 * Interrupt sharing is not supported. 228 */ 229 230 uioinfo->handler = uio_pdrv_genirq_handler; 231 uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol; 232 uioinfo->open = uio_pdrv_genirq_open; 233 uioinfo->release = uio_pdrv_genirq_release; 234 uioinfo->priv = priv; 235 236 /* Enable Runtime PM for this device: 237 * The device starts in suspended state to allow the hardware to be 238 * turned off by default. The Runtime PM bus code should power on the 239 * hardware and enable clocks at open(). 240 */ 241 pm_runtime_enable(&pdev->dev); 242 243 ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup, 244 &pdev->dev); 245 if (ret) 246 return ret; 247 248 ret = devm_uio_register_device(&pdev->dev, priv->uioinfo); 249 if (ret) 250 dev_err(&pdev->dev, "unable to register uio device\n"); 251 252 return ret; 253 } 254 255 static int uio_pdrv_genirq_runtime_nop(struct device *dev) 256 { 257 /* Runtime PM callback shared between ->runtime_suspend() 258 * and ->runtime_resume(). Simply returns success. 259 * 260 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync() 261 * are used at open() and release() time. This allows the 262 * Runtime PM code to turn off power to the device while the 263 * device is unused, ie before open() and after release(). 264 * 265 * This Runtime PM callback does not need to save or restore 266 * any registers since user space is responsbile for hardware 267 * register reinitialization after open(). 268 */ 269 return 0; 270 } 271 272 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = { 273 .runtime_suspend = uio_pdrv_genirq_runtime_nop, 274 .runtime_resume = uio_pdrv_genirq_runtime_nop, 275 }; 276 277 #ifdef CONFIG_OF 278 static struct of_device_id uio_of_genirq_match[] = { 279 { /* This is filled with module_parm */ }, 280 { /* Sentinel */ }, 281 }; 282 MODULE_DEVICE_TABLE(of, uio_of_genirq_match); 283 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0); 284 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio"); 285 #endif 286 287 static struct platform_driver uio_pdrv_genirq = { 288 .probe = uio_pdrv_genirq_probe, 289 .driver = { 290 .name = DRIVER_NAME, 291 .pm = &uio_pdrv_genirq_dev_pm_ops, 292 .of_match_table = of_match_ptr(uio_of_genirq_match), 293 }, 294 }; 295 296 module_platform_driver(uio_pdrv_genirq); 297 298 MODULE_AUTHOR("Magnus Damm"); 299 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling"); 300 MODULE_LICENSE("GPL v2"); 301 MODULE_ALIAS("platform:" DRIVER_NAME); 302