// SPDX-License-Identifier: GPL-2.0-only /* * drivers/uio/uio_pdrv_genirq.c * * Userspace I/O platform driver with generic IRQ handling code. * * Copyright (C) 2008 Magnus Damm * * Based on uio_pdrv.c by Uwe Kleine-Koenig, * Copyright (C) 2008 by Digi International Inc. * All rights reserved. */ #include <linux/platform_device.h> #include <linux/uio_driver.h> #include <linux/spinlock.h> #include <linux/bitops.h> #include <linux/module.h> #include <linux/interrupt.h> #include <linux/stringify.h> #include <linux/pm_runtime.h> #include <linux/slab.h> #include <linux/irq.h> #include <linux/of.h> #include <linux/mod_devicetable.h> #include <linux/property.h> #define DRIVER_NAME "uio_pdrv_genirq" struct uio_pdrv_genirq_platdata { struct uio_info *uioinfo; spinlock_t lock; unsigned long flags; struct platform_device *pdev; }; /* Bits in uio_pdrv_genirq_platdata.flags */ enum { UIO_IRQ_DISABLED = 0, }; static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode) { struct uio_pdrv_genirq_platdata *priv = info->priv; /* Wait until the Runtime PM code has woken up the device */ pm_runtime_get_sync(&priv->pdev->dev); return 0; } static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode) { struct uio_pdrv_genirq_platdata *priv = info->priv; /* Tell the Runtime PM code that the device has become idle */ pm_runtime_put_sync(&priv->pdev->dev); return 0; } static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info) { struct uio_pdrv_genirq_platdata *priv = dev_info->priv; /* Just disable the interrupt in the interrupt controller, and * remember the state so we can allow user space to enable it later. */ spin_lock(&priv->lock); if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) disable_irq_nosync(irq); spin_unlock(&priv->lock); return IRQ_HANDLED; } static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) { struct uio_pdrv_genirq_platdata *priv = dev_info->priv; unsigned long flags; /* Allow user space to enable and disable the interrupt * in the interrupt controller, but keep track of the * state to prevent per-irq depth damage. * * Serialize this operation to support multiple tasks and concurrency * with irq handler on SMP systems. */ spin_lock_irqsave(&priv->lock, flags); if (irq_on) { if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags)) enable_irq(dev_info->irq); } else { if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) disable_irq_nosync(dev_info->irq); } spin_unlock_irqrestore(&priv->lock, flags); return 0; } static void uio_pdrv_genirq_cleanup(void *data) { struct device *dev = data; pm_runtime_disable(dev); } static int uio_pdrv_genirq_probe(struct platform_device *pdev) { struct uio_info *uioinfo = dev_get_platdata(&pdev->dev); struct fwnode_handle *node = dev_fwnode(&pdev->dev); struct uio_pdrv_genirq_platdata *priv; struct uio_mem *uiomem; int ret = -EINVAL; int i; if (node) { const char *name; /* alloc uioinfo for one device */ uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo), GFP_KERNEL); if (!uioinfo) { dev_err(&pdev->dev, "unable to kmalloc\n"); return -ENOMEM; } if (!device_property_read_string(&pdev->dev, "linux,uio-name", &name)) uioinfo->name = devm_kstrdup(&pdev->dev, name, GFP_KERNEL); else uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pfwP", node); uioinfo->version = "devicetree"; /* Multiple IRQs are not supported */ } if (!uioinfo || !uioinfo->name || !uioinfo->version) { dev_err(&pdev->dev, "missing platform_data\n"); return ret; } if (uioinfo->handler || uioinfo->irqcontrol || uioinfo->irq_flags & IRQF_SHARED) { dev_err(&pdev->dev, "interrupt configuration error\n"); return ret; } priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); if (!priv) { dev_err(&pdev->dev, "unable to kmalloc\n"); return -ENOMEM; } priv->uioinfo = uioinfo; spin_lock_init(&priv->lock); priv->flags = 0; /* interrupt is enabled to begin with */ priv->pdev = pdev; if (!uioinfo->irq) { ret = platform_get_irq_optional(pdev, 0); uioinfo->irq = ret; if (ret == -ENXIO) uioinfo->irq = UIO_IRQ_NONE; else if (ret == -EPROBE_DEFER) return ret; else if (ret < 0) { dev_err(&pdev->dev, "failed to get IRQ\n"); return ret; } } if (uioinfo->irq) { struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq); /* * If a level interrupt, dont do lazy disable. Otherwise the * irq will fire again since clearing of the actual cause, on * device level, is done in userspace * irqd_is_level_type() isn't used since isn't valid until * irq is configured. */ if (irq_data && irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) { dev_dbg(&pdev->dev, "disable lazy unmask\n"); irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY); } } uiomem = &uioinfo->mem[0]; for (i = 0; i < pdev->num_resources; ++i) { struct resource *r = &pdev->resource[i]; if (r->flags != IORESOURCE_MEM) continue; if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { dev_warn(&pdev->dev, "device has more than " __stringify(MAX_UIO_MAPS) " I/O memory resources.\n"); break; } uiomem->memtype = UIO_MEM_PHYS; uiomem->addr = r->start & PAGE_MASK; uiomem->offs = r->start & ~PAGE_MASK; uiomem->size = (uiomem->offs + resource_size(r) + PAGE_SIZE - 1) & PAGE_MASK; uiomem->name = r->name; ++uiomem; } while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { uiomem->size = 0; ++uiomem; } /* This driver requires no hardware specific kernel code to handle * interrupts. Instead, the interrupt handler simply disables the * interrupt in the interrupt controller. User space is responsible * for performing hardware specific acknowledge and re-enabling of * the interrupt in the interrupt controller. * * Interrupt sharing is not supported. */ uioinfo->handler = uio_pdrv_genirq_handler; uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol; uioinfo->open = uio_pdrv_genirq_open; uioinfo->release = uio_pdrv_genirq_release; uioinfo->priv = priv; /* Enable Runtime PM for this device: * The device starts in suspended state to allow the hardware to be * turned off by default. The Runtime PM bus code should power on the * hardware and enable clocks at open(). */ pm_runtime_enable(&pdev->dev); ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup, &pdev->dev); if (ret) return ret; ret = devm_uio_register_device(&pdev->dev, priv->uioinfo); if (ret) dev_err(&pdev->dev, "unable to register uio device\n"); return ret; } static int uio_pdrv_genirq_runtime_nop(struct device *dev) { /* Runtime PM callback shared between ->runtime_suspend() * and ->runtime_resume(). Simply returns success. * * In this driver pm_runtime_get_sync() and pm_runtime_put_sync() * are used at open() and release() time. This allows the * Runtime PM code to turn off power to the device while the * device is unused, ie before open() and after release(). * * This Runtime PM callback does not need to save or restore * any registers since user space is responsbile for hardware * register reinitialization after open(). */ return 0; } static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = { .runtime_suspend = uio_pdrv_genirq_runtime_nop, .runtime_resume = uio_pdrv_genirq_runtime_nop, }; #ifdef CONFIG_OF static struct of_device_id uio_of_genirq_match[] = { { /* This is filled with module_parm */ }, { /* Sentinel */ }, }; MODULE_DEVICE_TABLE(of, uio_of_genirq_match); module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0); MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio"); #endif static struct platform_driver uio_pdrv_genirq = { .probe = uio_pdrv_genirq_probe, .driver = { .name = DRIVER_NAME, .pm = &uio_pdrv_genirq_dev_pm_ops, .of_match_table = of_match_ptr(uio_of_genirq_match), }, }; module_platform_driver(uio_pdrv_genirq); MODULE_AUTHOR("Magnus Damm"); MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:" DRIVER_NAME);