drivers/char/uv_mmtimer.c

Source file repositories/reference/linux-study-clean/drivers/char/uv_mmtimer.c

File Facts

System
Linux kernel
Corpus path
drivers/char/uv_mmtimer.c
Extension
.c
Size
5647 bytes
Lines
221
Domain
Driver Families
Bucket
drivers/char
Inferred role
Driver Families: operation-table or driver-model contract
Status
pattern 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

static const struct file_operations uv_mmtimer_fops = {
	.owner = THIS_MODULE,
	.mmap =	uv_mmtimer_mmap,
	.unlocked_ioctl = uv_mmtimer_ioctl,
	.llseek = noop_llseek,
};

/**
 * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
 * @file: file structure for the device
 * @cmd: command to execute
 * @arg: optional argument to command
 *
 * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
 * failure.
 *
 * Valid commands:
 *
 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
 * of the page where the registers are mapped) for the counter in question.
 *
 * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
 * seconds
 *
 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
 * specified by @arg
 *
 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
 *
 * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
 *
 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
 * in the address specified by @arg.
 */
static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
						unsigned long arg)
{
	int ret = 0;

	switch (cmd) {
	case MMTIMER_GETOFFSET:	/* offset of the counter */
		/*
		 * Starting with HUB rev 2.0, the UV RTC register is
		 * replicated across all cachelines of it's own page.
		 * This allows faster simultaneous reads from a given socket.
		 *
		 * The offset returned is in 64 bit units.
		 */
		if (uv_get_min_hub_revision_id() == 1)
			ret = 0;
		else
			ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
					PAGE_SIZE) / 8;
		break;

	case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
		if (copy_to_user((unsigned long __user *)arg,
				&uv_mmtimer_femtoperiod, sizeof(unsigned long)))
			ret = -EFAULT;
		break;

	case MMTIMER_GETFREQ: /* frequency in Hz */
		if (copy_to_user((unsigned long __user *)arg,
				&sn_rtc_cycles_per_second,
				sizeof(unsigned long)))
			ret = -EFAULT;
		break;

	case MMTIMER_GETBITS: /* number of bits in the clock */
		ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
		break;

	case MMTIMER_MMAPAVAIL:
		ret = 1;
		break;

	case MMTIMER_GETCOUNTER:
		if (copy_to_user((unsigned long __user *)arg,
				(unsigned long *)uv_local_mmr_address(UVH_RTC),
				sizeof(unsigned long)))
			ret = -EFAULT;
		break;
	default:
		ret = -ENOTTY;
		break;
	}
	return ret;
}

/**

Annotation

Implementation Notes