linux/drivers/char/pc8736x_gpio.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

354 lines
8.8 KiB
C

/* linux/drivers/char/pc8736x_gpio.c
National Semiconductor PC8736x GPIO driver. Allows a user space
process to play with the GPIO pins.
Copyright (c) 2005,2006 Jim Cromie <jim.cromie@gmail.com>
adapted from linux/drivers/char/scx200_gpio.c
Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>,
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/mutex.h>
#include <linux/nsc_gpio.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#define DEVNAME "pc8736x_gpio"
MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
MODULE_DESCRIPTION("NatSemi/Winbond PC-8736x GPIO Pin Driver");
MODULE_LICENSE("GPL");
static int major; /* default to dynamic major */
module_param(major, int, 0);
MODULE_PARM_DESC(major, "Major device number");
static DEFINE_MUTEX(pc8736x_gpio_config_lock);
static unsigned pc8736x_gpio_base;
static u8 pc8736x_gpio_shadow[4];
#define SIO_BASE1 0x2E /* 1st command-reg to check */
#define SIO_BASE2 0x4E /* alt command-reg to check */
#define SIO_SID 0x20 /* SuperI/O ID Register */
#define SIO_SID_PC87365 0xe5 /* Expected value in ID Register for PC87365 */
#define SIO_SID_PC87366 0xe9 /* Expected value in ID Register for PC87366 */
#define SIO_CF1 0x21 /* chip config, bit0 is chip enable */
#define PC8736X_GPIO_RANGE 16 /* ioaddr range */
#define PC8736X_GPIO_CT 32 /* minors matching 4 8 bit ports */
#define SIO_UNIT_SEL 0x7 /* unit select reg */
#define SIO_UNIT_ACT 0x30 /* unit enable */
#define SIO_GPIO_UNIT 0x7 /* unit number of GPIO */
#define SIO_VLM_UNIT 0x0D
#define SIO_TMS_UNIT 0x0E
/* config-space addrs to read/write each unit's runtime addr */
#define SIO_BASE_HADDR 0x60
#define SIO_BASE_LADDR 0x61
/* GPIO config-space pin-control addresses */
#define SIO_GPIO_PIN_SELECT 0xF0
#define SIO_GPIO_PIN_CONFIG 0xF1
#define SIO_GPIO_PIN_EVENT 0xF2
static unsigned char superio_cmd = 0;
static unsigned char selected_device = 0xFF; /* bogus start val */
/* GPIO port runtime access, functionality */
static int port_offset[] = { 0, 4, 8, 10 }; /* non-uniform offsets ! */
/* static int event_capable[] = { 1, 1, 0, 0 }; ports 2,3 are hobbled */
#define PORT_OUT 0
#define PORT_IN 1
#define PORT_EVT_EN 2
#define PORT_EVT_STST 3
static struct platform_device *pdev; /* use in dev_*() */
static inline void superio_outb(int addr, int val)
{
outb_p(addr, superio_cmd);
outb_p(val, superio_cmd + 1);
}
static inline int superio_inb(int addr)
{
outb_p(addr, superio_cmd);
return inb_p(superio_cmd + 1);
}
static int pc8736x_superio_present(void)
{
int id;
/* try the 2 possible values, read a hardware reg to verify */
superio_cmd = SIO_BASE1;
id = superio_inb(SIO_SID);
if (id == SIO_SID_PC87365 || id == SIO_SID_PC87366)
return superio_cmd;
superio_cmd = SIO_BASE2;
id = superio_inb(SIO_SID);
if (id == SIO_SID_PC87365 || id == SIO_SID_PC87366)
return superio_cmd;
return 0;
}
static void device_select(unsigned devldn)
{
superio_outb(SIO_UNIT_SEL, devldn);
selected_device = devldn;
}
static void select_pin(unsigned iminor)
{
/* select GPIO port/pin from device minor number */
device_select(SIO_GPIO_UNIT);
superio_outb(SIO_GPIO_PIN_SELECT,
((iminor << 1) & 0xF0) | (iminor & 0x7));
}
static inline u32 pc8736x_gpio_configure_fn(unsigned index, u32 mask, u32 bits,
u32 func_slct)
{
u32 config, new_config;
mutex_lock(&pc8736x_gpio_config_lock);
device_select(SIO_GPIO_UNIT);
select_pin(index);
/* read current config value */
config = superio_inb(func_slct);
/* set new config */
new_config = (config & mask) | bits;
superio_outb(func_slct, new_config);
mutex_unlock(&pc8736x_gpio_config_lock);
return config;
}
static u32 pc8736x_gpio_configure(unsigned index, u32 mask, u32 bits)
{
return pc8736x_gpio_configure_fn(index, mask, bits,
SIO_GPIO_PIN_CONFIG);
}
static int pc8736x_gpio_get(unsigned minor)
{
int port, bit, val;
port = minor >> 3;
bit = minor & 7;
val = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_IN);
val >>= bit;
val &= 1;
dev_dbg(&pdev->dev, "_gpio_get(%d from %x bit %d) == val %d\n",
minor, pc8736x_gpio_base + port_offset[port] + PORT_IN, bit,
val);
return val;
}
static void pc8736x_gpio_set(unsigned minor, int val)
{
int port, bit, curval;
minor &= 0x1f;
port = minor >> 3;
bit = minor & 7;
curval = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_OUT);
dev_dbg(&pdev->dev, "addr:%x cur:%x bit-pos:%d cur-bit:%x + new:%d -> bit-new:%d\n",
pc8736x_gpio_base + port_offset[port] + PORT_OUT,
curval, bit, (curval & ~(1 << bit)), val, (val << bit));
val = (curval & ~(1 << bit)) | (val << bit);
dev_dbg(&pdev->dev, "gpio_set(minor:%d port:%d bit:%d)"
" %2x -> %2x\n", minor, port, bit, curval, val);
outb_p(val, pc8736x_gpio_base + port_offset[port] + PORT_OUT);
curval = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_OUT);
val = inb_p(pc8736x_gpio_base + port_offset[port] + PORT_IN);
dev_dbg(&pdev->dev, "wrote %x, read: %x\n", curval, val);
pc8736x_gpio_shadow[port] = val;
}
static int pc8736x_gpio_current(unsigned minor)
{
int port, bit;
minor &= 0x1f;
port = minor >> 3;
bit = minor & 7;
return ((pc8736x_gpio_shadow[port] >> bit) & 0x01);
}
static void pc8736x_gpio_change(unsigned index)
{
pc8736x_gpio_set(index, !pc8736x_gpio_current(index));
}
static struct nsc_gpio_ops pc8736x_gpio_ops = {
.owner = THIS_MODULE,
.gpio_config = pc8736x_gpio_configure,
.gpio_dump = nsc_gpio_dump,
.gpio_get = pc8736x_gpio_get,
.gpio_set = pc8736x_gpio_set,
.gpio_change = pc8736x_gpio_change,
.gpio_current = pc8736x_gpio_current
};
static int pc8736x_gpio_open(struct inode *inode, struct file *file)
{
unsigned m = iminor(inode);
file->private_data = &pc8736x_gpio_ops;
dev_dbg(&pdev->dev, "open %d\n", m);
if (m >= PC8736X_GPIO_CT)
return -EINVAL;
return nonseekable_open(inode, file);
}
static const struct file_operations pc8736x_gpio_fileops = {
.owner = THIS_MODULE,
.open = pc8736x_gpio_open,
.write = nsc_gpio_write,
.read = nsc_gpio_read,
.llseek = no_llseek,
};
static void __init pc8736x_init_shadow(void)
{
int port;
/* read the current values driven on the GPIO signals */
for (port = 0; port < 4; ++port)
pc8736x_gpio_shadow[port]
= inb_p(pc8736x_gpio_base + port_offset[port]
+ PORT_OUT);
}
static struct cdev pc8736x_gpio_cdev;
static int __init pc8736x_gpio_init(void)
{
int rc;
dev_t devid;
pdev = platform_device_alloc(DEVNAME, 0);
if (!pdev)
return -ENOMEM;
rc = platform_device_add(pdev);
if (rc) {
rc = -ENODEV;
goto undo_platform_dev_alloc;
}
dev_info(&pdev->dev, "NatSemi pc8736x GPIO Driver Initializing\n");
if (!pc8736x_superio_present()) {
rc = -ENODEV;
dev_err(&pdev->dev, "no device found\n");
goto undo_platform_dev_add;
}
pc8736x_gpio_ops.dev = &pdev->dev;
/* Verify that chip and it's GPIO unit are both enabled.
My BIOS does this, so I take minimum action here
*/
rc = superio_inb(SIO_CF1);
if (!(rc & 0x01)) {
rc = -ENODEV;
dev_err(&pdev->dev, "device not enabled\n");
goto undo_platform_dev_add;
}
device_select(SIO_GPIO_UNIT);
if (!superio_inb(SIO_UNIT_ACT)) {
rc = -ENODEV;
dev_err(&pdev->dev, "GPIO unit not enabled\n");
goto undo_platform_dev_add;
}
/* read the GPIO unit base addr that chip responds to */
pc8736x_gpio_base = (superio_inb(SIO_BASE_HADDR) << 8
| superio_inb(SIO_BASE_LADDR));
if (!request_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE, DEVNAME)) {
rc = -ENODEV;
dev_err(&pdev->dev, "GPIO ioport %x busy\n",
pc8736x_gpio_base);
goto undo_platform_dev_add;
}
dev_info(&pdev->dev, "GPIO ioport %x reserved\n", pc8736x_gpio_base);
if (major) {
devid = MKDEV(major, 0);
rc = register_chrdev_region(devid, PC8736X_GPIO_CT, DEVNAME);
} else {
rc = alloc_chrdev_region(&devid, 0, PC8736X_GPIO_CT, DEVNAME);
major = MAJOR(devid);
}
if (rc < 0) {
dev_err(&pdev->dev, "register-chrdev failed: %d\n", rc);
goto undo_request_region;
}
if (!major) {
major = rc;
dev_dbg(&pdev->dev, "got dynamic major %d\n", major);
}
pc8736x_init_shadow();
/* ignore minor errs, and succeed */
cdev_init(&pc8736x_gpio_cdev, &pc8736x_gpio_fileops);
cdev_add(&pc8736x_gpio_cdev, devid, PC8736X_GPIO_CT);
return 0;
undo_request_region:
release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
undo_platform_dev_add:
platform_device_del(pdev);
undo_platform_dev_alloc:
platform_device_put(pdev);
return rc;
}
static void __exit pc8736x_gpio_cleanup(void)
{
dev_dbg(&pdev->dev, "cleanup\n");
cdev_del(&pc8736x_gpio_cdev);
unregister_chrdev_region(MKDEV(major,0), PC8736X_GPIO_CT);
release_region(pc8736x_gpio_base, PC8736X_GPIO_RANGE);
platform_device_del(pdev);
platform_device_put(pdev);
}
module_init(pc8736x_gpio_init);
module_exit(pc8736x_gpio_cleanup);