android_kernel_xiaomi_sm8350/drivers/misc/hdpuftrs/hdpu_cpustate.c
Arjan van de Ven d54b1fdb1d [PATCH] mark struct file_operations const 5
Many struct file_operations in the kernel can be "const".  Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data.  In addition it'll catch accidental writes at compile time to
these shared resources.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:45 -08:00

249 lines
5.0 KiB
C

/*
* Sky CPU State Driver
*
* Copyright (C) 2002 Brian Waite
*
* This driver allows use of the CPU state bits
* It exports the /dev/sky_cpustate and also
* /proc/sky_cpustate pseudo-file for status information.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/miscdevice.h>
#include <linux/pci.h>
#include <linux/proc_fs.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#include <linux/hdpu_features.h>
#define SKY_CPUSTATE_VERSION "1.1"
static int hdpu_cpustate_probe(struct platform_device *pdev);
static int hdpu_cpustate_remove(struct platform_device *pdev);
struct cpustate_t cpustate;
static int cpustate_get_ref(int excl)
{
int retval = -EBUSY;
spin_lock(&cpustate.lock);
if (cpustate.excl)
goto out_busy;
if (excl) {
if (cpustate.open_count)
goto out_busy;
cpustate.excl = 1;
}
cpustate.open_count++;
retval = 0;
out_busy:
spin_unlock(&cpustate.lock);
return retval;
}
static int cpustate_free_ref(void)
{
spin_lock(&cpustate.lock);
cpustate.excl = 0;
cpustate.open_count--;
spin_unlock(&cpustate.lock);
return 0;
}
unsigned char cpustate_get_state(void)
{
return cpustate.cached_val;
}
void cpustate_set_state(unsigned char new_state)
{
unsigned int state = (new_state << 21);
#ifdef DEBUG_CPUSTATE
printk("CPUSTATE -> 0x%x\n", new_state);
#endif
spin_lock(&cpustate.lock);
cpustate.cached_val = new_state;
writel((0xff << 21), cpustate.clr_addr);
writel(state, cpustate.set_addr);
spin_unlock(&cpustate.lock);
}
/*
* Now all the various file operations that we export.
*/
static ssize_t cpustate_read(struct file *file, char *buf,
size_t count, loff_t * ppos)
{
unsigned char data;
if (count < 0)
return -EFAULT;
if (count == 0)
return 0;
data = cpustate_get_state();
if (copy_to_user(buf, &data, sizeof(unsigned char)))
return -EFAULT;
return sizeof(unsigned char);
}
static ssize_t cpustate_write(struct file *file, const char *buf,
size_t count, loff_t * ppos)
{
unsigned char data;
if (count < 0)
return -EFAULT;
if (count == 0)
return 0;
if (copy_from_user((unsigned char *)&data, buf, sizeof(unsigned char)))
return -EFAULT;
cpustate_set_state(data);
return sizeof(unsigned char);
}
static int cpustate_open(struct inode *inode, struct file *file)
{
return cpustate_get_ref((file->f_flags & O_EXCL));
}
static int cpustate_release(struct inode *inode, struct file *file)
{
return cpustate_free_ref();
}
/*
* Info exported via "/proc/sky_cpustate".
*/
static int cpustate_read_proc(char *page, char **start, off_t off,
int count, int *eof, void *data)
{
char *p = page;
int len = 0;
p += sprintf(p, "CPU State: %04x\n", cpustate_get_state());
len = p - page;
if (len <= off + count)
*eof = 1;
*start = page + off;
len -= off;
if (len > count)
len = count;
if (len < 0)
len = 0;
return len;
}
static struct platform_driver hdpu_cpustate_driver = {
.probe = hdpu_cpustate_probe,
.remove = hdpu_cpustate_remove,
.driver = {
.name = HDPU_CPUSTATE_NAME,
},
};
/*
* The various file operations we support.
*/
static const struct file_operations cpustate_fops = {
owner:THIS_MODULE,
open:cpustate_open,
release:cpustate_release,
read:cpustate_read,
write:cpustate_write,
fasync:NULL,
poll:NULL,
ioctl:NULL,
llseek:no_llseek,
};
static struct miscdevice cpustate_dev = {
MISC_DYNAMIC_MINOR,
"sky_cpustate",
&cpustate_fops
};
static int hdpu_cpustate_probe(struct platform_device *pdev)
{
struct resource *res;
struct proc_dir_entry *proc_de;
int ret;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
cpustate.set_addr = (unsigned long *)res->start;
cpustate.clr_addr = (unsigned long *)res->end - 1;
ret = misc_register(&cpustate_dev);
if (ret) {
printk(KERN_WARNING "sky_cpustate: Unable to register misc "
"device.\n");
cpustate.set_addr = NULL;
cpustate.clr_addr = NULL;
return ret;
}
proc_de = create_proc_read_entry("sky_cpustate", 0, 0,
cpustate_read_proc, NULL);
if (proc_de == NULL)
printk(KERN_WARNING "sky_cpustate: Unable to create proc "
"dir entry\n");
printk(KERN_INFO "Sky CPU State Driver v" SKY_CPUSTATE_VERSION "\n");
return 0;
}
static int hdpu_cpustate_remove(struct platform_device *pdev)
{
cpustate.set_addr = NULL;
cpustate.clr_addr = NULL;
remove_proc_entry("sky_cpustate", NULL);
misc_deregister(&cpustate_dev);
return 0;
}
static int __init cpustate_init(void)
{
int rc;
rc = platform_driver_register(&hdpu_cpustate_driver);
return rc;
}
static void __exit cpustate_exit(void)
{
platform_driver_unregister(&hdpu_cpustate_driver);
}
module_init(cpustate_init);
module_exit(cpustate_exit);
MODULE_AUTHOR("Brian Waite");
MODULE_LICENSE("GPL");