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 27 #include <asm/genapic.h> 28 #include <asm/uv/uv_hub.h> 29 #include <asm/uv/bios.h> 30 #include <asm/uv/uv.h> 31 32 MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>"); 33 MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer"); 34 MODULE_LICENSE("GPL"); 35 36 /* name of the device, usually in /dev */ 37 #define UV_MMTIMER_NAME "mmtimer" 38 #define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer" 39 #define UV_MMTIMER_VERSION "1.0" 40 41 static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd, 42 unsigned long arg); 43 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma); 44 45 /* 46 * Period in femtoseconds (10^-15 s) 47 */ 48 static unsigned long uv_mmtimer_femtoperiod; 49 50 static const struct file_operations uv_mmtimer_fops = { 51 .owner = THIS_MODULE, 52 .mmap = uv_mmtimer_mmap, 53 .unlocked_ioctl = uv_mmtimer_ioctl, 54 .llseek = noop_llseek, 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 * Starting with HUB rev 2.0, the UV RTC register is 93 * replicated across all cachelines of it's own page. 94 * This allows faster simultaneous reads from a given socket. 95 * 96 * The offset returned is in 64 bit units. 97 */ 98 if (uv_get_min_hub_revision_id() == 1) 99 ret = 0; 100 else 101 ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) % 102 PAGE_SIZE) / 8; 103 break; 104 105 case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */ 106 if (copy_to_user((unsigned long __user *)arg, 107 &uv_mmtimer_femtoperiod, sizeof(unsigned long))) 108 ret = -EFAULT; 109 break; 110 111 case MMTIMER_GETFREQ: /* frequency in Hz */ 112 if (copy_to_user((unsigned long __user *)arg, 113 &sn_rtc_cycles_per_second, 114 sizeof(unsigned long))) 115 ret = -EFAULT; 116 break; 117 118 case MMTIMER_GETBITS: /* number of bits in the clock */ 119 ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK); 120 break; 121 122 case MMTIMER_MMAPAVAIL: 123 ret = 1; 124 break; 125 126 case MMTIMER_GETCOUNTER: 127 if (copy_to_user((unsigned long __user *)arg, 128 (unsigned long *)uv_local_mmr_address(UVH_RTC), 129 sizeof(unsigned long))) 130 ret = -EFAULT; 131 break; 132 default: 133 ret = -ENOTTY; 134 break; 135 } 136 return ret; 137 } 138 139 /** 140 * uv_mmtimer_mmap - maps the clock's registers into userspace 141 * @file: file structure for the device 142 * @vma: VMA to map the registers into 143 * 144 * Calls remap_pfn_range() to map the clock's registers into 145 * the calling process' address space. 146 */ 147 static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma) 148 { 149 unsigned long uv_mmtimer_addr; 150 151 if (vma->vm_end - vma->vm_start != PAGE_SIZE) 152 return -EINVAL; 153 154 if (vma->vm_flags & VM_WRITE) 155 return -EPERM; 156 157 if (PAGE_SIZE > (1 << 16)) 158 return -ENOSYS; 159 160 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 161 162 uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC; 163 uv_mmtimer_addr &= ~(PAGE_SIZE - 1); 164 uv_mmtimer_addr &= 0xfffffffffffffffUL; 165 166 if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT, 167 PAGE_SIZE, vma->vm_page_prot)) { 168 printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n"); 169 return -EAGAIN; 170 } 171 172 return 0; 173 } 174 175 static struct miscdevice uv_mmtimer_miscdev = { 176 MISC_DYNAMIC_MINOR, 177 UV_MMTIMER_NAME, 178 &uv_mmtimer_fops 179 }; 180 181 182 /** 183 * uv_mmtimer_init - device initialization routine 184 * 185 * Does initial setup for the uv_mmtimer device. 186 */ 187 static int __init uv_mmtimer_init(void) 188 { 189 if (!is_uv_system()) { 190 printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME); 191 return -1; 192 } 193 194 /* 195 * Sanity check the cycles/sec variable 196 */ 197 if (sn_rtc_cycles_per_second < 100000) { 198 printk(KERN_ERR "%s: unable to determine clock frequency\n", 199 UV_MMTIMER_NAME); 200 return -1; 201 } 202 203 uv_mmtimer_femtoperiod = ((unsigned long)1E15 + 204 sn_rtc_cycles_per_second / 2) / 205 sn_rtc_cycles_per_second; 206 207 if (misc_register(&uv_mmtimer_miscdev)) { 208 printk(KERN_ERR "%s: failed to register device\n", 209 UV_MMTIMER_NAME); 210 return -1; 211 } 212 213 printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC, 214 UV_MMTIMER_VERSION, 215 sn_rtc_cycles_per_second/(unsigned long)1E6); 216 217 return 0; 218 } 219 220 module_init(uv_mmtimer_init); 221