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
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_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 */
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 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 */
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_fops
179};
180
181
182/**
183 * uv_mmtimer_init - device initialization routine
184 *
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 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
220module_init(uv_mmtimer_init);
221