WSL2-Linux-Kernel/drivers/uio/uio_dmem_genirq.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* drivers/uio/uio_dmem_genirq.c
*
* Userspace I/O platform driver with generic IRQ handling code.
*
* Copyright (C) 2012 Damian Hobson-Garcia
*
* Based on uio_pdrv_genirq.c by Magnus Damm
*/
#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/platform_data/uio_dmem_genirq.h>
#include <linux/stringify.h>
#include <linux/pm_runtime.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
uio: disable lazy irq disable to avoid double fire uio_pdrv_genirq and uio_dmem_genirq interrupts are handled in userspace. So the condition for the interrupt hasn't normally not been cleared when top half returns. disable_irq_nosync is called in top half, but since that normally is lazy the irq isn't actually disabled. For level triggered interrupts this will always result in a spurious additional fire since the level in to the interrupt controller still is active. The actual interrupt handler isn't run though since this spurious irq is just recorded, and later on discared (for level). This commit disables lazy masking for level triggered interrupts. It leaves edge triggered interrupts as before, because they work with the lazy scheme. All other UIO drivers already seem to clear the interrupt cause at driver levels. Example of double fire. First goes all the way up to uio_pdrv_genirq_handler, second is terminated in handle_fasteoi_irq and marked as pending. <idle>-0 [000] d... 8.245870: gic_handle_irq: irq 29 <idle>-0 [000] d.h. 8.245873: uio_pdrv_genirq_handler: disable irq 29 <idle>-0 [000] d... 8.245878: gic_handle_irq: irq 29 <idle>-0 [000] d.h. 8.245880: handle_fasteoi_irq: irq 29 PENDING HInt-34 [001] d... 8.245897: uio_pdrv_genirq_irqcontrol: enable irq 29 Tested on 5.7rc2 using uio_pdrv_genirq and a custom Xilinx MPSoC board. Signed-off-by: Thommy Jakobsson <thommyj@gmail.com> Link: https://lore.kernel.org/r/20200628141229.16121-1-thommyj@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-28 17:12:29 +03:00
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_address.h>
#define DRIVER_NAME "uio_dmem_genirq"
#define DMEM_MAP_ERROR (~0)
struct uio_dmem_genirq_platdata {
struct uio_info *uioinfo;
spinlock_t lock;
unsigned long flags;
struct platform_device *pdev;
unsigned int dmem_region_start;
unsigned int num_dmem_regions;
void *dmem_region_vaddr[MAX_UIO_MAPS];
struct mutex alloc_lock;
unsigned int refcnt;
};
static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
{
struct uio_dmem_genirq_platdata *priv = info->priv;
struct uio_mem *uiomem;
int dmem_region = priv->dmem_region_start;
uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
mutex_lock(&priv->alloc_lock);
while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
void *addr;
if (!uiomem->size)
break;
addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
(dma_addr_t *)&uiomem->addr, GFP_KERNEL);
if (!addr) {
uiomem->addr = DMEM_MAP_ERROR;
}
priv->dmem_region_vaddr[dmem_region++] = addr;
++uiomem;
}
priv->refcnt++;
mutex_unlock(&priv->alloc_lock);
/* Wait until the Runtime PM code has woken up the device */
pm_runtime_get_sync(&priv->pdev->dev);
return 0;
}
static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
{
struct uio_dmem_genirq_platdata *priv = info->priv;
struct uio_mem *uiomem;
int dmem_region = priv->dmem_region_start;
/* Tell the Runtime PM code that the device has become idle */
pm_runtime_put_sync(&priv->pdev->dev);
uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
mutex_lock(&priv->alloc_lock);
priv->refcnt--;
while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
if (!uiomem->size)
break;
if (priv->dmem_region_vaddr[dmem_region]) {
dma_free_coherent(&priv->pdev->dev, uiomem->size,
priv->dmem_region_vaddr[dmem_region],
uiomem->addr);
}
uiomem->addr = DMEM_MAP_ERROR;
++dmem_region;
++uiomem;
}
mutex_unlock(&priv->alloc_lock);
return 0;
}
static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
{
struct uio_dmem_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.
*/
if (!test_and_set_bit(0, &priv->flags))
disable_irq_nosync(irq);
return IRQ_HANDLED;
}
static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
{
struct uio_dmem_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.
*/
spin_lock_irqsave(&priv->lock, flags);
if (irq_on) {
if (test_and_clear_bit(0, &priv->flags))
enable_irq(dev_info->irq);
spin_unlock_irqrestore(&priv->lock, flags);
} else {
if (!test_and_set_bit(0, &priv->flags)) {
spin_unlock_irqrestore(&priv->lock, flags);
disable_irq(dev_info->irq);
}
}
return 0;
}
static void uio_dmem_genirq_pm_disable(void *data)
{
struct device *dev = data;
pm_runtime_disable(dev);
}
static int uio_dmem_genirq_probe(struct platform_device *pdev)
{
struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
struct uio_info *uioinfo = &pdata->uioinfo;
struct uio_dmem_genirq_platdata *priv;
struct uio_mem *uiomem;
int ret = -EINVAL;
int i;
if (pdev->dev.of_node) {
/* 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;
}
uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
pdev->dev.of_node);
uioinfo->version = "devicetree";
}
if (!uioinfo || !uioinfo->name || !uioinfo->version) {
dev_err(&pdev->dev, "missing platform_data\n");
return -EINVAL;
}
if (uioinfo->handler || uioinfo->irqcontrol ||
uioinfo->irq_flags & IRQF_SHARED) {
dev_err(&pdev->dev, "interrupt configuration error\n");
return -EINVAL;
}
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv) {
dev_err(&pdev->dev, "unable to kmalloc\n");
return -ENOMEM;
}
dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
priv->uioinfo = uioinfo;
spin_lock_init(&priv->lock);
priv->flags = 0; /* interrupt is enabled to begin with */
priv->pdev = pdev;
mutex_init(&priv->alloc_lock);
if (!uioinfo->irq) {
/* Multiple IRQs are not supported */
ret = platform_get_irq(pdev, 0);
if (ret == -ENXIO && pdev->dev.of_node)
ret = UIO_IRQ_NONE;
else if (ret < 0)
return ret;
uioinfo->irq = ret;
}
uio: disable lazy irq disable to avoid double fire uio_pdrv_genirq and uio_dmem_genirq interrupts are handled in userspace. So the condition for the interrupt hasn't normally not been cleared when top half returns. disable_irq_nosync is called in top half, but since that normally is lazy the irq isn't actually disabled. For level triggered interrupts this will always result in a spurious additional fire since the level in to the interrupt controller still is active. The actual interrupt handler isn't run though since this spurious irq is just recorded, and later on discared (for level). This commit disables lazy masking for level triggered interrupts. It leaves edge triggered interrupts as before, because they work with the lazy scheme. All other UIO drivers already seem to clear the interrupt cause at driver levels. Example of double fire. First goes all the way up to uio_pdrv_genirq_handler, second is terminated in handle_fasteoi_irq and marked as pending. <idle>-0 [000] d... 8.245870: gic_handle_irq: irq 29 <idle>-0 [000] d.h. 8.245873: uio_pdrv_genirq_handler: disable irq 29 <idle>-0 [000] d... 8.245878: gic_handle_irq: irq 29 <idle>-0 [000] d.h. 8.245880: handle_fasteoi_irq: irq 29 PENDING HInt-34 [001] d... 8.245897: uio_pdrv_genirq_irqcontrol: enable irq 29 Tested on 5.7rc2 using uio_pdrv_genirq and a custom Xilinx MPSoC board. Signed-off-by: Thommy Jakobsson <thommyj@gmail.com> Link: https://lore.kernel.org/r/20200628141229.16121-1-thommyj@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-28 17:12:29 +03:00
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;
uiomem->size = resource_size(r);
++uiomem;
}
priv->dmem_region_start = uiomem - &uioinfo->mem[0];
priv->num_dmem_regions = pdata->num_dynamic_regions;
for (i = 0; i < pdata->num_dynamic_regions; ++i) {
if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
dev_warn(&pdev->dev, "device has more than "
__stringify(MAX_UIO_MAPS)
" dynamic and fixed memory regions.\n");
break;
}
uiomem->memtype = UIO_MEM_PHYS;
uiomem->addr = DMEM_MAP_ERROR;
uiomem->size = pdata->dynamic_region_sizes[i];
++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_dmem_genirq_handler;
uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
uioinfo->open = uio_dmem_genirq_open;
uioinfo->release = uio_dmem_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_dmem_genirq_pm_disable, &pdev->dev);
if (ret)
return ret;
return devm_uio_register_device(&pdev->dev, priv->uioinfo);
}
static int uio_dmem_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_dmem_genirq_dev_pm_ops = {
.runtime_suspend = uio_dmem_genirq_runtime_nop,
.runtime_resume = uio_dmem_genirq_runtime_nop,
};
#ifdef CONFIG_OF
static const struct of_device_id uio_of_genirq_match[] = {
{ /* empty for now */ },
};
MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
#endif
static struct platform_driver uio_dmem_genirq = {
.probe = uio_dmem_genirq_probe,
.driver = {
.name = DRIVER_NAME,
.pm = &uio_dmem_genirq_dev_pm_ops,
.of_match_table = of_match_ptr(uio_of_genirq_match),
},
};
module_platform_driver(uio_dmem_genirq);
MODULE_AUTHOR("Damian Hobson-Garcia");
MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);