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1/*2 * Timer device implementation for SGI UV platform.3 *4 * This file is subject to the terms and conditions of the GNU General Public5 * License. See the file "COPYING" in the main directory of this archive6 * 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 32MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");33MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");34MODULE_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 41static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,42 unsigned long arg);43static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);44 45/*46 * Period in femtoseconds (10^-15 s)47 */48static unsigned long uv_mmtimer_femtoperiod;49 50static 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_mmtimer59 * @file: file structure for the device60 * @cmd: command to execute61 * @arg: optional argument to command62 *63 * Executes the command specified by @cmd. Returns 0 for success, < 0 for64 * failure.65 *66 * Valid commands:67 *68 * %MMTIMER_GETOFFSET - Should return the offset (relative to the start69 * 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 * seconds73 *74 * %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address75 * specified by @arg76 *77 * %MMTIMER_GETBITS - Returns the number of bits in the clock's counter78 *79 * %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace80 *81 * %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it82 * in the address specified by @arg.83 */84static 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 is93 * 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 else101 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 userspace141 * @file: file structure for the device142 * @vma: VMA to map the registers into143 *144 * Calls remap_pfn_range() to map the clock's registers into145 * the calling process' address space.146 */147static 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 175static struct miscdevice uv_mmtimer_miscdev = {176 MISC_DYNAMIC_MINOR,177 UV_MMTIMER_NAME,178 &uv_mmtimer_fops179};180 181 182/**183 * uv_mmtimer_init - device initialization routine184 *185 * Does initial setup for the uv_mmtimer device.186 */187static 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 variable196 */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 220module_init(uv_mmtimer_init);221