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linux/drivers/char/tb0219.c
Arnd Bergmann 6038f373a3 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>
2010-10-15 15:53:27 +02:00

373 lines
7.8 KiB
C
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/*
* Driver for TANBAC TB0219 base board.
*
* Copyright (C) 2005 Yoichi Yuasa <yuasa@linux-mips.org>
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/platform_device.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <asm/io.h>
#include <asm/reboot.h>
#include <asm/vr41xx/giu.h>
#include <asm/vr41xx/tb0219.h>
MODULE_AUTHOR("Yoichi Yuasa <yuasa@linux-mips.org>");
MODULE_DESCRIPTION("TANBAC TB0219 base board driver");
MODULE_LICENSE("GPL");
static int major; /* default is dynamic major device number */
module_param(major, int, 0);
MODULE_PARM_DESC(major, "Major device number");
static void (*old_machine_restart)(char *command);
static void __iomem *tb0219_base;
static DEFINE_SPINLOCK(tb0219_lock);
#define tb0219_read(offset) readw(tb0219_base + (offset))
#define tb0219_write(offset, value) writew((value), tb0219_base + (offset))
#define TB0219_START 0x0a000000UL
#define TB0219_SIZE 0x20UL
#define TB0219_LED 0x00
#define TB0219_GPIO_INPUT 0x02
#define TB0219_GPIO_OUTPUT 0x04
#define TB0219_DIP_SWITCH 0x06
#define TB0219_MISC 0x08
#define TB0219_RESET 0x0e
#define TB0219_PCI_SLOT1_IRQ_STATUS 0x10
#define TB0219_PCI_SLOT2_IRQ_STATUS 0x12
#define TB0219_PCI_SLOT3_IRQ_STATUS 0x14
typedef enum {
TYPE_LED,
TYPE_GPIO_OUTPUT,
} tb0219_type_t;
/*
* Minor device number
* 0 = 7 segment LED
*
* 16 = GPIO IN 0
* 17 = GPIO IN 1
* 18 = GPIO IN 2
* 19 = GPIO IN 3
* 20 = GPIO IN 4
* 21 = GPIO IN 5
* 22 = GPIO IN 6
* 23 = GPIO IN 7
*
* 32 = GPIO OUT 0
* 33 = GPIO OUT 1
* 34 = GPIO OUT 2
* 35 = GPIO OUT 3
* 36 = GPIO OUT 4
* 37 = GPIO OUT 5
* 38 = GPIO OUT 6
* 39 = GPIO OUT 7
*
* 48 = DIP switch 1
* 49 = DIP switch 2
* 50 = DIP switch 3
* 51 = DIP switch 4
* 52 = DIP switch 5
* 53 = DIP switch 6
* 54 = DIP switch 7
* 55 = DIP switch 8
*/
static inline char get_led(void)
{
return (char)tb0219_read(TB0219_LED);
}
static inline char get_gpio_input_pin(unsigned int pin)
{
uint16_t values;
values = tb0219_read(TB0219_GPIO_INPUT);
if (values & (1 << pin))
return '1';
return '0';
}
static inline char get_gpio_output_pin(unsigned int pin)
{
uint16_t values;
values = tb0219_read(TB0219_GPIO_OUTPUT);
if (values & (1 << pin))
return '1';
return '0';
}
static inline char get_dip_switch(unsigned int pin)
{
uint16_t values;
values = tb0219_read(TB0219_DIP_SWITCH);
if (values & (1 << pin))
return '1';
return '0';
}
static inline int set_led(char command)
{
tb0219_write(TB0219_LED, command);
return 0;
}
static inline int set_gpio_output_pin(unsigned int pin, char command)
{
unsigned long flags;
uint16_t value;
if (command != '0' && command != '1')
return -EINVAL;
spin_lock_irqsave(&tb0219_lock, flags);
value = tb0219_read(TB0219_GPIO_OUTPUT);
if (command == '0')
value &= ~(1 << pin);
else
value |= 1 << pin;
tb0219_write(TB0219_GPIO_OUTPUT, value);
spin_unlock_irqrestore(&tb0219_lock, flags);
return 0;
}
static ssize_t tanbac_tb0219_read(struct file *file, char __user *buf, size_t len,
loff_t *ppos)
{
unsigned int minor;
char value;
minor = iminor(file->f_path.dentry->d_inode);
switch (minor) {
case 0:
value = get_led();
break;
case 16 ... 23:
value = get_gpio_input_pin(minor - 16);
break;
case 32 ... 39:
value = get_gpio_output_pin(minor - 32);
break;
case 48 ... 55:
value = get_dip_switch(minor - 48);
break;
default:
return -EBADF;
}
if (len <= 0)
return -EFAULT;
if (put_user(value, buf))
return -EFAULT;
return 1;
}
static ssize_t tanbac_tb0219_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
unsigned int minor;
tb0219_type_t type;
size_t i;
int retval = 0;
char c;
minor = iminor(file->f_path.dentry->d_inode);
switch (minor) {
case 0:
type = TYPE_LED;
break;
case 32 ... 39:
type = TYPE_GPIO_OUTPUT;
break;
default:
return -EBADF;
}
for (i = 0; i < len; i++) {
if (get_user(c, data + i))
return -EFAULT;
switch (type) {
case TYPE_LED:
retval = set_led(c);
break;
case TYPE_GPIO_OUTPUT:
retval = set_gpio_output_pin(minor - 32, c);
break;
}
if (retval < 0)
break;
}
return i;
}
static int tanbac_tb0219_open(struct inode *inode, struct file *file)
{
unsigned int minor;
minor = iminor(inode);
switch (minor) {
case 0:
case 16 ... 23:
case 32 ... 39:
case 48 ... 55:
return nonseekable_open(inode, file);
default:
break;
}
return -EBADF;
}
static int tanbac_tb0219_release(struct inode *inode, struct file *file)
{
return 0;
}
static const struct file_operations tb0219_fops = {
.owner = THIS_MODULE,
.read = tanbac_tb0219_read,
.write = tanbac_tb0219_write,
.open = tanbac_tb0219_open,
.release = tanbac_tb0219_release,
.llseek = no_llseek,
};
static void tb0219_restart(char *command)
{
tb0219_write(TB0219_RESET, 0);
}
static void tb0219_pci_irq_init(void)
{
/* PCI Slot 1 */
vr41xx_set_irq_trigger(TB0219_PCI_SLOT1_PIN, IRQ_TRIGGER_LEVEL, IRQ_SIGNAL_THROUGH);
vr41xx_set_irq_level(TB0219_PCI_SLOT1_PIN, IRQ_LEVEL_LOW);
/* PCI Slot 2 */
vr41xx_set_irq_trigger(TB0219_PCI_SLOT2_PIN, IRQ_TRIGGER_LEVEL, IRQ_SIGNAL_THROUGH);
vr41xx_set_irq_level(TB0219_PCI_SLOT2_PIN, IRQ_LEVEL_LOW);
/* PCI Slot 3 */
vr41xx_set_irq_trigger(TB0219_PCI_SLOT3_PIN, IRQ_TRIGGER_LEVEL, IRQ_SIGNAL_THROUGH);
vr41xx_set_irq_level(TB0219_PCI_SLOT3_PIN, IRQ_LEVEL_LOW);
}
static int __devinit tb0219_probe(struct platform_device *dev)
{
int retval;
if (request_mem_region(TB0219_START, TB0219_SIZE, "TB0219") == NULL)
return -EBUSY;
tb0219_base = ioremap(TB0219_START, TB0219_SIZE);
if (tb0219_base == NULL) {
release_mem_region(TB0219_START, TB0219_SIZE);
return -ENOMEM;
}
retval = register_chrdev(major, "TB0219", &tb0219_fops);
if (retval < 0) {
iounmap(tb0219_base);
tb0219_base = NULL;
release_mem_region(TB0219_START, TB0219_SIZE);
return retval;
}
old_machine_restart = _machine_restart;
_machine_restart = tb0219_restart;
tb0219_pci_irq_init();
if (major == 0) {
major = retval;
printk(KERN_INFO "TB0219: major number %d\n", major);
}
return 0;
}
static int __devexit tb0219_remove(struct platform_device *dev)
{
_machine_restart = old_machine_restart;
iounmap(tb0219_base);
tb0219_base = NULL;
release_mem_region(TB0219_START, TB0219_SIZE);
return 0;
}
static struct platform_device *tb0219_platform_device;
static struct platform_driver tb0219_device_driver = {
.probe = tb0219_probe,
.remove = __devexit_p(tb0219_remove),
.driver = {
.name = "TB0219",
.owner = THIS_MODULE,
},
};
static int __init tanbac_tb0219_init(void)
{
int retval;
tb0219_platform_device = platform_device_alloc("TB0219", -1);
if (!tb0219_platform_device)
return -ENOMEM;
retval = platform_device_add(tb0219_platform_device);
if (retval < 0) {
platform_device_put(tb0219_platform_device);
return retval;
}
retval = platform_driver_register(&tb0219_device_driver);
if (retval < 0)
platform_device_unregister(tb0219_platform_device);
return retval;
}
static void __exit tanbac_tb0219_exit(void)
{
platform_driver_unregister(&tb0219_device_driver);
platform_device_unregister(tb0219_platform_device);
}
module_init(tanbac_tb0219_init);
module_exit(tanbac_tb0219_exit);
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