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); 217