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 };
  56
  57 /**
  58  * uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
  59  * @file: file structure for the device
  60  * @cmd: command to execute
  61  * @arg: optional argument to command
  62  *
  63  * Executes the command specified by @cmd.  Returns 0 for success, < 0 for
  64  * failure.
  65  *
  66  * Valid commands:
  67  *
  68  * %MMTIMER_GETOFFSET - Should return the offset (relative to the start
  69  * of the page where the registers are mapped) for the counter in question.
  70  *
  71  * %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
  72  * seconds
  73  *
  74  * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
  75  * specified by @arg
  76  *
  77  * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
  78  *
  79  * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
  80  *
  81  * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
  82  * in the address specified by @arg.
  83  */
  84 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
  85                                                 unsigned long arg)
  86 {
  87         int ret = 0;
  88
  89         switch (cmd) {
  90         case MMTIMER_GETOFFSET: /* offset of the counter */
  91                 /*
  92                  * UV RTC register is on its own page
  93                  */
  94                 if (PAGE_SIZE <= (1 << 16))
  95                         ret = ((UV_LOCAL_MMR_BASE | UVH_RTC) & (PAGE_SIZE-1))
  96                                 / 8;
  97                 else
  98                         ret = -ENOSYS;
  99                 break;
 100
 101         case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
 102                 if (copy_to_user((unsigned long __user *)arg,
 103                                 &uv_mmtimer_femtoperiod, sizeof(unsigned long)))
 104                         ret = -EFAULT;
 105                 break;
 106
 107         case MMTIMER_GETFREQ: /* frequency in Hz */
 108                 if (copy_to_user((unsigned long __user *)arg,
 109                                 &sn_rtc_cycles_per_second,
 110                                 sizeof(unsigned long)))
 111                         ret = -EFAULT;
 112                 break;
 113
 114         case MMTIMER_GETBITS: /* number of bits in the clock */
 115                 ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
 116                 break;
 117
 118         case MMTIMER_MMAPAVAIL: /* can we mmap the clock into userspace? */
 119                 ret = (PAGE_SIZE <= (1 << 16)) ? 1 : 0;
 120                 break;
 121
 122         case MMTIMER_GETCOUNTER:
 123                 if (copy_to_user((unsigned long __user *)arg,
 124                                 (unsigned long *)uv_local_mmr_address(UVH_RTC),
 125                                 sizeof(unsigned long)))
 126                         ret = -EFAULT;
 127                 break;
 128         default:
 129                 ret = -ENOTTY;
 130                 break;
 131         }
 132         return ret;
 133 }
 134
 135 /**
 136  * uv_mmtimer_mmap - maps the clock's registers into userspace
 137  * @file: file structure for the device
 138  * @vma: VMA to map the registers into
 139  *
 140  * Calls remap_pfn_range() to map the clock's registers into
 141  * the calling process' address space.
 142  */
 143 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
 144 {
 145         unsigned long uv_mmtimer_addr;
 146
 147         if (vma->vm_end - vma->vm_start != PAGE_SIZE)
 148                 return -EINVAL;
 149
 150         if (vma->vm_flags & VM_WRITE)
 151                 return -EPERM;
 152
 153         if (PAGE_SIZE > (1 << 16))
 154                 return -ENOSYS;
 155
 156         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 157
 158         uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
 159         uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
 160         uv_mmtimer_addr &= 0xfffffffffffffffUL;
 161
 162         if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
 163                                         PAGE_SIZE, vma->vm_page_prot)) {
 164                 printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
 165                 return -EAGAIN;
 166         }
 167
 168         return 0;
 169 }
 170
 171 static struct miscdevice uv_mmtimer_miscdev = {
 172         MISC_DYNAMIC_MINOR,
 173         UV_MMTIMER_NAME,
 174         &uv_mmtimer_fops
 175 };
 176
 177
 178 /**
 179  * uv_mmtimer_init - device initialization routine
 180  *
 181  * Does initial setup for the uv_mmtimer device.
 182  */
 183 static int __init uv_mmtimer_init(void)
 184 {
 185         if (!is_uv_system()) {
 186                 printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
 187                 return -1;
 188         }
 189
 190         /*
 191          * Sanity check the cycles/sec variable
 192          */
 193         if (sn_rtc_cycles_per_second < 100000) {
 194                 printk(KERN_ERR "%s: unable to determine clock frequency\n",
 195                        UV_MMTIMER_NAME);
 196                 return -1;
 197         }
 198
 199         uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
 200                                 sn_rtc_cycles_per_second / 2) /
 201                                 sn_rtc_cycles_per_second;
 202
 203         if (misc_register(&uv_mmtimer_miscdev)) {
 204                 printk(KERN_ERR "%s: failed to register device\n",
 205                        UV_MMTIMER_NAME);
 206                 return -1;
 207         }
 208
 209         printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
 210                 UV_MMTIMER_VERSION,
 211                 sn_rtc_cycles_per_second/(unsigned long)1E6);
 212
 213         return 0;
 214 }
 215
 216 module_init(uv_mmtimer_init);