drivers/sh/intc/userimask.c

Source file repositories/reference/linux-study-clean/drivers/sh/intc/userimask.c

File Facts

System
Linux kernel
Corpus path
drivers/sh/intc/userimask.c
Extension
.c
Size
2256 bytes
Lines
96
Domain
Driver Families
Bucket
drivers/sh
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

#define pr_fmt(fmt) "intc: " fmt

#include <linux/errno.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/stat.h>
#include <linux/sizes.h>
#include "internals.h"

static void __iomem *uimask;

static ssize_t
show_intc_userimask(struct device *dev,
		    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", (__raw_readl(uimask) >> 4) & 0xf);
}

static ssize_t
store_intc_userimask(struct device *dev,
		     struct device_attribute *attr,
		     const char *buf, size_t count)
{
	unsigned long level;
	int ret;

	ret = kstrtoul(buf, 10, &level);
	if (ret != 0)
		return ret;

	/*
	 * Minimal acceptable IRQ levels are in the 2 - 16 range, but
	 * these are chomped so as to not interfere with normal IRQs.
	 *
	 * Level 1 is a special case on some CPUs in that it's not
	 * directly settable, but given that USERIMASK cuts off below a
	 * certain level, we don't care about this limitation here.
	 * Level 0 on the other hand equates to user masking disabled.
	 *
	 * We use the default priority level as a cut off so that only
	 * special case opt-in IRQs can be mangled.
	 */
	if (level >= intc_get_dfl_prio_level())
		return -EINVAL;

	__raw_writel(0xa5 << 24 | level << 4, uimask);

	return count;
}

static DEVICE_ATTR(userimask, S_IRUSR | S_IWUSR,
		   show_intc_userimask, store_intc_userimask);


static int __init userimask_sysdev_init(void)
{
	struct device *dev_root;
	int ret = 0;

	if (unlikely(!uimask))
		return -ENXIO;

	dev_root = bus_get_dev_root(&intc_subsys);
	if (dev_root) {
		ret = device_create_file(dev_root, &dev_attr_userimask);
		put_device(dev_root);
	}
	return ret;
}
late_initcall(userimask_sysdev_init);

int register_intc_userimask(unsigned long addr)
{
	if (unlikely(uimask))
		return -EBUSY;

	uimask = ioremap(addr, SZ_4K);
	if (unlikely(!uimask))
		return -ENOMEM;

	pr_info("userimask support registered for levels 0 -> %d\n",
		intc_get_dfl_prio_level() - 1);

	return 0;
}

Annotation

Implementation Notes