drivers/char/uv_mmtimer.c

   1 /*
   2  * Timer device implementation for SGI UV platform.
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (c) 2009 Silicon Graphics, Inc.  All rights reserved.
   9  *
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/ioctl.h>
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/errno.h>
  18 #include <linux/mm.h>
  19 #include <linux/fs.h>
  20 #include <linux/mmtimer.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/posix-timers.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/time.h>
  25 #include <linux/math64.h>
  26 #include <linux/smp_lock.h>
  27
  28 #include <asm/genapic.h>
  29 #include <asm/uv/uv_hub.h>
  30 #include <asm/uv/bios.h>
  31 #include <asm/uv/uv.h>
  32
  33 MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
  34 MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
  35 MODULE_LICENSE("GPL");
  36
  37 /* name of the device, usually in /dev */
  38 #define UV_MMTIMER_NAME "mmtimer"
  39 #define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
  40 #define UV_MMTIMER_VERSION "1.0"
  41
  42 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
  43                                                 unsigned long arg);
  44 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
  45
  46 /*
  47  * Period in femtoseconds (10^-15 s)
  48  */
  49 static unsigned long uv_mmtimer_femtoperiod;
  50
  51 static const struct file_operations uv_mmtimer_fops = {
  52         .owner = THIS_MODULE,
  53         .mmap = uv_mmtimer_mmap,
  54         .unlocked_ioctl = uv_mmtimer_ioctl,
  55         .llseek = noop_llseek,
  56 };
  57
  58 /**
  59  * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
  60  * @file: file structure for the device
  61  * @cmd: command to execute
  62  * @arg: optional argument to command
  63  *
  64  * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
  65  * failure.
  66  *
  67  * Valid commands:
  68  *
  69  * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
  70  * of the page where the registers are mapped) for the counter in question.
  71  *
  72  * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
  73  * seconds
  74  *
  75  * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
  76  * specified by @arg
  77  *
  78  * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
  79  *
  80  * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
  81  *
  82  * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
  83  * in the address specified by @arg.
  84  */
  85 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
  86                                                 unsigned long arg)
  87 {
  88         int ret = 0;
  89
  90         switch (cmd) {
  91         case MMTIMER_GETOFFSET: /* offset of the counter */
  92                 /*
  93                  * Starting with HUB rev 2.0, the UV RTC register is
  94                  * replicated across all cachelines of it's own page.
  95                  * This allows faster simultaneous reads from a given socket.
  96                  *
  97                  * The offset returned is in 64 bit units.
  98                  */
  99                 if (uv_get_min_hub_revision_id() == 1)
 100                         ret = 0;
 101                 else
 102                         ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
 103                                         PAGE_SIZE) / 8;
 104                 break;
 105
 106         case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
 107                 if (copy_to_user((unsigned long __user *)arg,
 108                                 &uv_mmtimer_femtoperiod, sizeof(unsigned long)))
 109                         ret = -EFAULT;
 110                 break;
 111
 112         case MMTIMER_GETFREQ: /* frequency in Hz */
 113                 if (copy_to_user((unsigned long __user *)arg,
 114                                 &sn_rtc_cycles_per_second,
 115                                 sizeof(unsigned long)))
 116                         ret = -EFAULT;
 117                 break;
 118
 119         case MMTIMER_GETBITS: /* number of bits in the clock */
 120                 ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
 121                 break;
 122
 123         case MMTIMER_MMAPAVAIL:
 124                 ret = 1;
 125                 break;
 126
 127         case MMTIMER_GETCOUNTER:
 128                 if (copy_to_user((unsigned long __user *)arg,
 129                                 (unsigned long *)uv_local_mmr_address(UVH_RTC),
 130                                 sizeof(unsigned long)))
 131                         ret = -EFAULT;
 132                 break;
 133         default:
 134                 ret = -ENOTTY;
 135                 break;
 136         }
 137         return ret;
 138 }
 139
 140 /**
 141  * uv_mmtimer_mmap - maps the clock's registers into userspace
 142  * @file: file structure for the device
 143  * @vma: VMA to map the registers into
 144  *
 145  * Calls remap_pfn_range() to map the clock's registers into
 146  * the calling process' address space.
 147  */
 148 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
 149 {
 150         unsigned long uv_mmtimer_addr;
 151
 152         if (vma->vm_end - vma->vm_start != PAGE_SIZE)
 153                 return -EINVAL;
 154
 155         if (vma->vm_flags & VM_WRITE)
 156                 return -EPERM;
 157
 158         if (PAGE_SIZE > (1 << 16))
 159                 return -ENOSYS;
 160
 161         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 162
 163         uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
 164         uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
 165         uv_mmtimer_addr &= 0xfffffffffffffffUL;
 166
 167         if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
 168                                         PAGE_SIZE, vma->vm_page_prot)) {
 169                 printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
 170                 return -EAGAIN;
 171         }
 172
 173         return 0;
 174 }
 175
 176 static struct miscdevice uv_mmtimer_miscdev = {
 177         MISC_DYNAMIC_MINOR,
 178         UV_MMTIMER_NAME,
 179         &uv_mmtimer_fops
 180 };
 181
 182
 183 /**
 184  * uv_mmtimer_init - device initialization routine
 185  *
 186  * Does initial setup for the uv_mmtimer device.
 187  */
 188 static int __init uv_mmtimer_init(void)
 189 {
 190         if (!is_uv_system()) {
 191                 printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
 192                 return -1;
 193         }
 194
 195         /*
 196          * Sanity check the cycles/sec variable
 197          */
 198         if (sn_rtc_cycles_per_second < 100000) {
 199                 printk(KERN_ERR "%s: unable to determine clock frequency\n",
 200                        UV_MMTIMER_NAME);
 201                 return -1;
 202         }
 203
 204         uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
 205                                 sn_rtc_cycles_per_second / 2) /
 206                                 sn_rtc_cycles_per_second;
 207
 208         if (misc_register(&uv_mmtimer_miscdev)) {
 209                 printk(KERN_ERR "%s: failed to register device\n",
 210                        UV_MMTIMER_NAME);
 211                 return -1;
 212         }
 213
 214         printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
 215                 UV_MMTIMER_VERSION,
 216                 sn_rtc_cycles_per_second/(unsigned long)1E6);
 217
 218         return 0;
 219 }
 220
 221 module_init(uv_mmtimer_init);