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); 222