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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 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 |
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