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linux/drivers/char/uv_mmtimer.c

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/*
* Timer device implementation for SGI UV platform.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (c) 2009 Silicon Graphics, Inc. All rights reserved.
*
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ioctl.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/mmtimer.h>
#include <linux/miscdevice.h>
#include <linux/posix-timers.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/math64.h>
#include <asm/genapic.h>
#include <asm/uv/uv_hub.h>
#include <asm/uv/bios.h>
#include <asm/uv/uv.h>
MODULE_AUTHOR("Dimitri Sivanich <sivanich@sgi.com>");
MODULE_DESCRIPTION("SGI UV Memory Mapped RTC Timer");
MODULE_LICENSE("GPL");
/* name of the device, usually in /dev */
#define UV_MMTIMER_NAME "mmtimer"
#define UV_MMTIMER_DESC "SGI UV Memory Mapped RTC Timer"
#define UV_MMTIMER_VERSION "1.0"
static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma);
/*
* Period in femtoseconds (10^-15 s)
*/
static unsigned long uv_mmtimer_femtoperiod;
static const struct file_operations uv_mmtimer_fops = {
.owner = THIS_MODULE,
.mmap = uv_mmtimer_mmap,
.unlocked_ioctl = uv_mmtimer_ioctl,
llseek: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 16:52:59 +00:00
.llseek = noop_llseek,
};
/**
* uv_mmtimer_ioctl - ioctl interface for /dev/uv_mmtimer
* @file: file structure for the device
* @cmd: command to execute
* @arg: optional argument to command
*
* Executes the command specified by @cmd. Returns 0 for success, < 0 for
* failure.
*
* Valid commands:
*
* %MMTIMER_GETOFFSET - Should return the offset (relative to the start
* of the page where the registers are mapped) for the counter in question.
*
* %MMTIMER_GETRES - Returns the resolution of the clock in femto (10^-15)
* seconds
*
* %MMTIMER_GETFREQ - Copies the frequency of the clock in Hz to the address
* specified by @arg
*
* %MMTIMER_GETBITS - Returns the number of bits in the clock's counter
*
* %MMTIMER_MMAPAVAIL - Returns 1 if registers can be mmap'd into userspace
*
* %MMTIMER_GETCOUNTER - Gets the current value in the counter and places it
* in the address specified by @arg.
*/
static long uv_mmtimer_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = 0;
switch (cmd) {
case MMTIMER_GETOFFSET: /* offset of the counter */
/*
* Starting with HUB rev 2.0, the UV RTC register is
* replicated across all cachelines of it's own page.
* This allows faster simultaneous reads from a given socket.
*
* The offset returned is in 64 bit units.
*/
if (uv_get_min_hub_revision_id() == 1)
ret = 0;
else
ret = ((uv_blade_processor_id() * L1_CACHE_BYTES) %
PAGE_SIZE) / 8;
break;
case MMTIMER_GETRES: /* resolution of the clock in 10^-15 s */
if (copy_to_user((unsigned long __user *)arg,
&uv_mmtimer_femtoperiod, sizeof(unsigned long)))
ret = -EFAULT;
break;
case MMTIMER_GETFREQ: /* frequency in Hz */
if (copy_to_user((unsigned long __user *)arg,
&sn_rtc_cycles_per_second,
sizeof(unsigned long)))
ret = -EFAULT;
break;
case MMTIMER_GETBITS: /* number of bits in the clock */
ret = hweight64(UVH_RTC_REAL_TIME_CLOCK_MASK);
break;
case MMTIMER_MMAPAVAIL:
ret = 1;
break;
case MMTIMER_GETCOUNTER:
if (copy_to_user((unsigned long __user *)arg,
(unsigned long *)uv_local_mmr_address(UVH_RTC),
sizeof(unsigned long)))
ret = -EFAULT;
break;
default:
ret = -ENOTTY;
break;
}
return ret;
}
/**
* uv_mmtimer_mmap - maps the clock's registers into userspace
* @file: file structure for the device
* @vma: VMA to map the registers into
*
* Calls remap_pfn_range() to map the clock's registers into
* the calling process' address space.
*/
static int uv_mmtimer_mmap(struct file *file, struct vm_area_struct *vma)
{
unsigned long uv_mmtimer_addr;
if (vma->vm_end - vma->vm_start != PAGE_SIZE)
return -EINVAL;
if (vma->vm_flags & VM_WRITE)
return -EPERM;
if (PAGE_SIZE > (1 << 16))
return -ENOSYS;
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
uv_mmtimer_addr = UV_LOCAL_MMR_BASE | UVH_RTC;
uv_mmtimer_addr &= ~(PAGE_SIZE - 1);
uv_mmtimer_addr &= 0xfffffffffffffffUL;
if (remap_pfn_range(vma, vma->vm_start, uv_mmtimer_addr >> PAGE_SHIFT,
PAGE_SIZE, vma->vm_page_prot)) {
printk(KERN_ERR "remap_pfn_range failed in uv_mmtimer_mmap\n");
return -EAGAIN;
}
return 0;
}
static struct miscdevice uv_mmtimer_miscdev = {
MISC_DYNAMIC_MINOR,
UV_MMTIMER_NAME,
&uv_mmtimer_fops
};
/**
* uv_mmtimer_init - device initialization routine
*
* Does initial setup for the uv_mmtimer device.
*/
static int __init uv_mmtimer_init(void)
{
if (!is_uv_system()) {
printk(KERN_ERR "%s: Hardware unsupported\n", UV_MMTIMER_NAME);
return -1;
}
/*
* Sanity check the cycles/sec variable
*/
if (sn_rtc_cycles_per_second < 100000) {
printk(KERN_ERR "%s: unable to determine clock frequency\n",
UV_MMTIMER_NAME);
return -1;
}
uv_mmtimer_femtoperiod = ((unsigned long)1E15 +
sn_rtc_cycles_per_second / 2) /
sn_rtc_cycles_per_second;
if (misc_register(&uv_mmtimer_miscdev)) {
printk(KERN_ERR "%s: failed to register device\n",
UV_MMTIMER_NAME);
return -1;
}
printk(KERN_INFO "%s: v%s, %ld MHz\n", UV_MMTIMER_DESC,
UV_MMTIMER_VERSION,
sn_rtc_cycles_per_second/(unsigned long)1E6);
return 0;
}
module_init(uv_mmtimer_init);