diff options
Diffstat (limited to 'drivers/char/uv_mmtimer.c')
| -rw-r--r-- | drivers/char/uv_mmtimer.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/drivers/char/uv_mmtimer.c b/drivers/char/uv_mmtimer.c new file mode 100644 index 0000000000..956ebe2080 --- /dev/null +++ b/drivers/char/uv_mmtimer.c @@ -0,0 +1,220 @@ +/* + * Timer device implementation for SGI UV platform. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (c) 2009 Silicon Graphics, Inc. All rights reserved. + * + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/ioctl.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/fs.h> +#include <linux/mmtimer.h> +#include <linux/miscdevice.h> +#include <linux/posix-timers.h> +#include <linux/interrupt.h> +#include <linux/time.h> +#include <linux/math64.h> + +#include <asm/genapic.h> +#include <asm/uv/uv_hub.h> +#include <asm/uv/bios.h> +#include <asm/uv/uv.h> + +MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>"); +MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer"); +MODULE_LICENSE("GPL"); + +/* name of the device, usually in /dev */ +#define UV_MMTIMER_NAME "mmtimer" +#define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer" +#define UV_MMTIMER_VERSION "1.0" + +static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd, + unsigned long arg); +static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma); + +/* + * Period in femtoseconds (10^-15 s) + */ +static unsigned long uv_mmtimer_femtoperiod; + +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; +} + +/** + * uv_mmtimer_mmap - maps the clock's registers into userspace + * @file: file structure for the device + * @vma: VMA to map the registers into + * + * Calls remap_pfn_range() to map the clock's registers into + * the calling process' address space. + */ +static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma) +{ + unsigned long uv_mmtimer_addr; + + if (vma->vm_end - vma->vm_start != PAGE_SIZE) + return -EINVAL; + + if (vma->vm_flags & VM_WRITE) + return -EPERM; + + if (PAGE_SIZE > (1 << 16)) + return -ENOSYS; + + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); + + uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC; + uv_mmtimer_addr &= ~(PAGE_SIZE - 1); + uv_mmtimer_addr &= 0xfffffffffffffffUL; + + if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT, + PAGE_SIZE, vma->vm_page_prot)) { + printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n"); + return -EAGAIN; + } + + return 0; +} + +static struct miscdevice uv_mmtimer_miscdev = { + MISC_DYNAMIC_MINOR, + UV_MMTIMER_NAME, + &uv_mmtimer_fops +}; + + +/** + * uv_mmtimer_init - device initialization routine + * + * Does initial setup for the uv_mmtimer device. + */ +static int __init uv_mmtimer_init(void) +{ + if (!is_uv_system()) { + printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME); + return -1; + } + + /* + * Sanity check the cycles/sec variable + */ + if (sn_rtc_cycles_per_second < 100000) { + printk(KERN_ERR "%s: unable to determine clock frequency\n", + UV_MMTIMER_NAME); + return -1; + } + + uv_mmtimer_femtoperiod = ((unsigned long)1E15 + + sn_rtc_cycles_per_second / 2) / + sn_rtc_cycles_per_second; + + if (misc_register(&uv_mmtimer_miscdev)) { + printk(KERN_ERR "%s: failed to register device\n", + UV_MMTIMER_NAME); + return -1; + } + + printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC, + UV_MMTIMER_VERSION, + sn_rtc_cycles_per_second/(unsigned long)1E6); + + return 0; +} + +module_init(uv_mmtimer_init); |