drivers/char/uv_mmtimer.c

0001 /*
0002  * Timer device implementation for SGI UV platform.
0003  *
0004  * This file is subject to the terms and conditions of the GNU General Public
0005  * License.  See the file "COPYING" in the main directory of this archive
0006  * for more details.
0007  *
0008  * Copyright (c) 2009 Silicon Graphics, Inc.  All rights reserved.
0009  *
0010  */
0011
0012 #include <linux/types.h>
0013 #include <linux/kernel.h>
0014 #include <linux/ioctl.h>
0015 #include <linux/module.h>
0016 #include <linux/init.h>
0017 #include <linux/errno.h>
0018 #include <linux/mm.h>
0019 #include <linux/fs.h>
0020 #include <linux/mmtimer.h>
0021 #include <linux/miscdevice.h>
0022 #include <linux/posix-timers.h>
0023 #include <linux/interrupt.h>
0024 #include <linux/time.h>
0025 #include <linux/math64.h>
0026
0027 #include <asm/genapic.h>
0028 #include <asm/uv/uv_hub.h>
0029 #include <asm/uv/bios.h>
0030 #include <asm/uv/uv.h>
0031
0032 MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
0033 MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
0034 MODULE_LICENSE("GPL");
0035
0036 /* name of the device, usually in /dev */
0037 #define UV_MMTIMER_NAME "mmtimer"
0038 #define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
0039 #define UV_MMTIMER_VERSION "1.0"
0040
0041 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
0042                         unsigned long arg);
0043 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
0044
0045 /*
0046  * Period in femtoseconds (10^-15 s)
0047  */
0048 static unsigned long uv_mmtimer_femtoperiod;
0049
0050 static const struct file_operations uv_mmtimer_fops = {
0051     .owner = THIS_MODULE,
0052     .mmap = uv_mmtimer_mmap,
0053     .unlocked_ioctl = uv_mmtimer_ioctl,
0054     .llseek = noop_llseek,
0055 };
0056
0057 /**
0058  * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
0059  * @file: file structure for the device
0060  * @cmd: command to execute
0061  * @arg: optional argument to command
0062  *
0063  * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
0064  * failure.
0065  *
0066  * Valid commands:
0067  *
0068  * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
0069  * of the page where the registers are mapped) for the counter in question.
0070  *
0071  * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
0072  * seconds
0073  *
0074  * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
0075  * specified by @arg
0076  *
0077  * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
0078  *
0079  * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
0080  *
0081  * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
0082  * in the address specified by @arg.
0083  */
0084 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
0085                         unsigned long arg)
0086 {
0087     int ret = 0;
0088
0089     switch (cmd) {
0090     case MMTIMER_GETOFFSET: /* offset of the counter */
0091         /*
0092          * Starting with HUB rev 2.0, the UV RTC register is
0093          * replicated across all cachelines of it's own page.
0094          * This allows faster simultaneous reads from a given socket.
0095          *
0096          * The offset returned is in 64 bit units.
0097          */
0098         if (uv_get_min_hub_revision_id() == 1)
0099             ret = 0;
0100         else
0101             ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
0102                     PAGE_SIZE) / 8;
0103         break;
0104
0105     case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
0106         if (copy_to_user((unsigned long __user *)arg,
0107                 &uv_mmtimer_femtoperiod, sizeof(unsigned long)))
0108             ret = -EFAULT;
0109         break;
0110
0111     case MMTIMER_GETFREQ: /* frequency in Hz */
0112         if (copy_to_user((unsigned long __user *)arg,
0113                 &sn_rtc_cycles_per_second,
0114                 sizeof(unsigned long)))
0115             ret = -EFAULT;
0116         break;
0117
0118     case MMTIMER_GETBITS: /* number of bits in the clock */
0119         ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
0120         break;
0121
0122     case MMTIMER_MMAPAVAIL:
0123         ret = 1;
0124         break;
0125
0126     case MMTIMER_GETCOUNTER:
0127         if (copy_to_user((unsigned long __user *)arg,
0128                 (unsigned long *)uv_local_mmr_address(UVH_RTC),
0129                 sizeof(unsigned long)))
0130             ret = -EFAULT;
0131         break;
0132     default:
0133         ret = -ENOTTY;
0134         break;
0135     }
0136     return ret;
0137 }
0138
0139 /**
0140  * uv_mmtimer_mmap - maps the clock's registers into userspace
0141  * @file: file structure for the device
0142  * @vma: VMA to map the registers into
0143  *
0144  * Calls remap_pfn_range() to map the clock's registers into
0145  * the calling process' address space.
0146  */
0147 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
0148 {
0149     unsigned long uv_mmtimer_addr;
0150
0151     if (vma->vm_end - vma->vm_start != PAGE_SIZE)
0152         return -EINVAL;
0153
0154     if (vma->vm_flags & VM_WRITE)
0155         return -EPERM;
0156
0157     if (PAGE_SIZE > (1 << 16))
0158         return -ENOSYS;
0159
0160     vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
0161
0162     uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
0163     uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
0164     uv_mmtimer_addr &= 0xfffffffffffffffUL;
0165
0166     if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
0167                     PAGE_SIZE, vma->vm_page_prot)) {
0168         printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
0169         return -EAGAIN;
0170     }
0171
0172     return 0;
0173 }
0174
0175 static struct miscdevice uv_mmtimer_miscdev = {
0176     MISC_DYNAMIC_MINOR,
0177     UV_MMTIMER_NAME,
0178     &uv_mmtimer_fops
0179 };
0180
0181
0182 /**
0183  * uv_mmtimer_init - device initialization routine
0184  *
0185  * Does initial setup for the uv_mmtimer device.
0186  */
0187 static int __init uv_mmtimer_init(void)
0188 {
0189     if (!is_uv_system()) {
0190         printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
0191         return -1;
0192     }
0193
0194     /*
0195      * Sanity check the cycles/sec variable
0196      */
0197     if (sn_rtc_cycles_per_second < 100000) {
0198         printk(KERN_ERR "%s: unable to determine clock frequency\n",
0199                UV_MMTIMER_NAME);
0200         return -1;
0201     }
0202
0203     uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
0204                 sn_rtc_cycles_per_second / 2) /
0205                 sn_rtc_cycles_per_second;
0206
0207     if (misc_register(&uv_mmtimer_miscdev)) {
0208         printk(KERN_ERR "%s: failed to register device\n",
0209                UV_MMTIMER_NAME);
0210         return -1;
0211     }
0212
0213     printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
0214         UV_MMTIMER_VERSION,
0215         sn_rtc_cycles_per_second/(unsigned long)1E6);
0216
0217     return 0;
0218 }
0219
0220 module_init(uv_mmtimer_init);