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kernel-ark/include/linux/i2c.h
Lars-Peter Clausen 71546300c8 i2c: Make return type of i2c_del_adapter() void 
i2c_del_adapter() is usually called from a drivers remove callback. The Linux
device driver model does not allow the remove callback to fail and all resources
allocated in the probe callback need to be freed, as well as all resources which
have been provided to the rest of the kernel(for example a I2C adapter) need to
be revoked. So any function revoking such resources isn't allowed to fail
either. i2c_del_adapter() adheres to this requirement and will never fail. But
i2c_del_adapter()'s return type is int, which may cause driver authors to think
that it can fail. This led to code constructs like:

	ret = i2c_del_adapter(...);
	BUG_ON(ret);

Since i2c_del_adapter() always returns 0 the BUG_ON is never hit and essentially
becomes dead code, which means it can be removed. Making the return type of
i2c_del_adapter() void makes it explicit that the function will never fail and
should prevent constructs like the above from re-appearing in the kernel code.

All callers of i2c_del_adapter() have already been updated in a previous patch
to ignore the return value, so the conversion of the return type from int to
void can be done without causing any build failures.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2013-04-02 07:06:17 +02:00

552 lines
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/* ------------------------------------------------------------------------- */
/* */
/* i2c.h - definitions for the i2c-bus interface */
/* */
/* ------------------------------------------------------------------------- */
/* Copyright (C) 1995-2000 Simon G. Vogl
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., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301 USA. */
/* ------------------------------------------------------------------------- */
/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
Frodo Looijaard <frodol@dds.nl> */
#ifndef _LINUX_I2C_H
#define _LINUX_I2C_H
#include <linux/mod_devicetable.h>
#include <linux/device.h> /* for struct device */
#include <linux/sched.h> /* for completion */
#include <linux/mutex.h>
#include <linux/of.h> /* for struct device_node */
#include <linux/swab.h> /* for swab16 */
#include <uapi/linux/i2c.h>
extern struct bus_type i2c_bus_type;
extern struct device_type i2c_adapter_type;
/* --- General options ------------------------------------------------ */
struct i2c_msg;
struct i2c_algorithm;
struct i2c_adapter;
struct i2c_client;
struct i2c_driver;
union i2c_smbus_data;
struct i2c_board_info;
struct module;
#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
/*
* The master routines are the ones normally used to transmit data to devices
* on a bus (or read from them). Apart from two basic transfer functions to
* transmit one message at a time, a more complex version can be used to
* transmit an arbitrary number of messages without interruption.
* @count must be be less than 64k since msg.len is u16.
*/
extern int i2c_master_send(const struct i2c_client *client, const char *buf,
int count);
extern int i2c_master_recv(const struct i2c_client *client, char *buf,
int count);
/* Transfer num messages.
*/
extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num);
/* Unlocked flavor */
extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num);
/* This is the very generalized SMBus access routine. You probably do not
want to use this, though; one of the functions below may be much easier,
and probably just as fast.
Note that we use i2c_adapter here, because you do not need a specific
smbus adapter to call this function. */
extern s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
unsigned short flags, char read_write, u8 command,
int size, union i2c_smbus_data *data);
/* Now follow the 'nice' access routines. These also document the calling
conventions of i2c_smbus_xfer. */
extern s32 i2c_smbus_read_byte(const struct i2c_client *client);
extern s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value);
extern s32 i2c_smbus_read_byte_data(const struct i2c_client *client,
u8 command);
extern s32 i2c_smbus_write_byte_data(const struct i2c_client *client,
u8 command, u8 value);
extern s32 i2c_smbus_read_word_data(const struct i2c_client *client,
u8 command);
extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,
u8 command, u16 value);
static inline s32
i2c_smbus_read_word_swapped(const struct i2c_client *client, u8 command)
{
s32 value = i2c_smbus_read_word_data(client, command);
return (value < 0) ? value : swab16(value);
}
static inline s32
i2c_smbus_write_word_swapped(const struct i2c_client *client,
u8 command, u16 value)
{
return i2c_smbus_write_word_data(client, command, swab16(value));
}
/* Returns the number of read bytes */
extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,
u8 command, u8 *values);
extern s32 i2c_smbus_write_block_data(const struct i2c_client *client,
u8 command, u8 length, const u8 *values);
/* Returns the number of read bytes */
extern s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client,
u8 command, u8 length, u8 *values);
extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
u8 command, u8 length,
const u8 *values);
#endif /* I2C */
/**
* struct i2c_driver - represent an I2C device driver
* @class: What kind of i2c device we instantiate (for detect)
* @attach_adapter: Callback for bus addition (deprecated)
* @probe: Callback for device binding
* @remove: Callback for device unbinding
* @shutdown: Callback for device shutdown
* @suspend: Callback for device suspend
* @resume: Callback for device resume
* @alert: Alert callback, for example for the SMBus alert protocol
* @command: Callback for bus-wide signaling (optional)
* @driver: Device driver model driver
* @id_table: List of I2C devices supported by this driver
* @detect: Callback for device detection
* @address_list: The I2C addresses to probe (for detect)
* @clients: List of detected clients we created (for i2c-core use only)
*
* The driver.owner field should be set to the module owner of this driver.
* The driver.name field should be set to the name of this driver.
*
* For automatic device detection, both @detect and @address_list must
* be defined. @class should also be set, otherwise only devices forced
* with module parameters will be created. The detect function must
* fill at least the name field of the i2c_board_info structure it is
* handed upon successful detection, and possibly also the flags field.
*
* If @detect is missing, the driver will still work fine for enumerated
* devices. Detected devices simply won't be supported. This is expected
* for the many I2C/SMBus devices which can't be detected reliably, and
* the ones which can always be enumerated in practice.
*
* The i2c_client structure which is handed to the @detect callback is
* not a real i2c_client. It is initialized just enough so that you can
* call i2c_smbus_read_byte_data and friends on it. Don't do anything
* else with it. In particular, calling dev_dbg and friends on it is
* not allowed.
*/
struct i2c_driver {
unsigned int class;
/* Notifies the driver that a new bus has appeared. You should avoid
* using this, it will be removed in a near future.
*/
int (*attach_adapter)(struct i2c_adapter *) __deprecated;
/* Standard driver model interfaces */
int (*probe)(struct i2c_client *, const struct i2c_device_id *);
int (*remove)(struct i2c_client *);
/* driver model interfaces that don't relate to enumeration */
void (*shutdown)(struct i2c_client *);
int (*suspend)(struct i2c_client *, pm_message_t mesg);
int (*resume)(struct i2c_client *);
/* Alert callback, for example for the SMBus alert protocol.
* The format and meaning of the data value depends on the protocol.
* For the SMBus alert protocol, there is a single bit of data passed
* as the alert response's low bit ("event flag").
*/
void (*alert)(struct i2c_client *, unsigned int data);
/* a ioctl like command that can be used to perform specific functions
* with the device.
*/
int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);
struct device_driver driver;
const struct i2c_device_id *id_table;
/* Device detection callback for automatic device creation */
int (*detect)(struct i2c_client *, struct i2c_board_info *);
const unsigned short *address_list;
struct list_head clients;
};
#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
/**
* struct i2c_client - represent an I2C slave device
* @flags: I2C_CLIENT_TEN indicates the device uses a ten bit chip address;
* I2C_CLIENT_PEC indicates it uses SMBus Packet Error Checking
* @addr: Address used on the I2C bus connected to the parent adapter.
* @name: Indicates the type of the device, usually a chip name that's
* generic enough to hide second-sourcing and compatible revisions.
* @adapter: manages the bus segment hosting this I2C device
* @driver: device's driver, hence pointer to access routines
* @dev: Driver model device node for the slave.
* @irq: indicates the IRQ generated by this device (if any)
* @detected: member of an i2c_driver.clients list or i2c-core's
* userspace_devices list
*
* An i2c_client identifies a single device (i.e. chip) connected to an
* i2c bus. The behaviour exposed to Linux is defined by the driver
* managing the device.
*/
struct i2c_client {
unsigned short flags; /* div., see below */
unsigned short addr; /* chip address - NOTE: 7bit */
/* addresses are stored in the */
/* _LOWER_ 7 bits */
char name[I2C_NAME_SIZE];
struct i2c_adapter *adapter; /* the adapter we sit on */
struct i2c_driver *driver; /* and our access routines */
struct device dev; /* the device structure */
int irq; /* irq issued by device */
struct list_head detected;
};
#define to_i2c_client(d) container_of(d, struct i2c_client, dev)
extern struct i2c_client *i2c_verify_client(struct device *dev);
extern struct i2c_adapter *i2c_verify_adapter(struct device *dev);
static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
{
struct device * const dev = container_of(kobj, struct device, kobj);
return to_i2c_client(dev);
}
static inline void *i2c_get_clientdata(const struct i2c_client *dev)
{
return dev_get_drvdata(&dev->dev);
}
static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
{
dev_set_drvdata(&dev->dev, data);
}
/**
* struct i2c_board_info - template for device creation
* @type: chip type, to initialize i2c_client.name
* @flags: to initialize i2c_client.flags
* @addr: stored in i2c_client.addr
* @platform_data: stored in i2c_client.dev.platform_data
* @archdata: copied into i2c_client.dev.archdata
* @of_node: pointer to OpenFirmware device node
* @acpi_node: ACPI device node
* @irq: stored in i2c_client.irq
*
* I2C doesn't actually support hardware probing, although controllers and
* devices may be able to use I2C_SMBUS_QUICK to tell whether or not there's
* a device at a given address. Drivers commonly need more information than
* that, such as chip type, configuration, associated IRQ, and so on.
*
* i2c_board_info is used to build tables of information listing I2C devices
* that are present. This information is used to grow the driver model tree.
* For mainboards this is done statically using i2c_register_board_info();
* bus numbers identify adapters that aren't yet available. For add-on boards,
* i2c_new_device() does this dynamically with the adapter already known.
*/
struct i2c_board_info {
char type[I2C_NAME_SIZE];
unsigned short flags;
unsigned short addr;
void *platform_data;
struct dev_archdata *archdata;
struct device_node *of_node;
struct acpi_dev_node acpi_node;
int irq;
};
/**
* I2C_BOARD_INFO - macro used to list an i2c device and its address
* @dev_type: identifies the device type
* @dev_addr: the device's address on the bus.
*
* This macro initializes essential fields of a struct i2c_board_info,
* declaring what has been provided on a particular board. Optional
* fields (such as associated irq, or device-specific platform_data)
* are provided using conventional syntax.
*/
#define I2C_BOARD_INFO(dev_type, dev_addr) \
.type = dev_type, .addr = (dev_addr)
#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
/* Add-on boards should register/unregister their devices; e.g. a board
* with integrated I2C, a config eeprom, sensors, and a codec that's
* used in conjunction with the primary hardware.
*/
extern struct i2c_client *
i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);
/* If you don't know the exact address of an I2C device, use this variant
* instead, which can probe for device presence in a list of possible
* addresses. The "probe" callback function is optional. If it is provided,
* it must return 1 on successful probe, 0 otherwise. If it is not provided,
* a default probing method is used.
*/
extern struct i2c_client *
i2c_new_probed_device(struct i2c_adapter *adap,
struct i2c_board_info *info,
unsigned short const *addr_list,
int (*probe)(struct i2c_adapter *, unsigned short addr));
/* Common custom probe functions */
extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);
/* For devices that use several addresses, use i2c_new_dummy() to make
* client handles for the extra addresses.
*/
extern struct i2c_client *
i2c_new_dummy(struct i2c_adapter *adap, u16 address);
extern void i2c_unregister_device(struct i2c_client *);
#endif /* I2C */
/* Mainboard arch_initcall() code should register all its I2C devices.
* This is done at arch_initcall time, before declaring any i2c adapters.
* Modules for add-on boards must use other calls.
*/
#ifdef CONFIG_I2C_BOARDINFO
extern int
i2c_register_board_info(int busnum, struct i2c_board_info const *info,
unsigned n);
#else
static inline int
i2c_register_board_info(int busnum, struct i2c_board_info const *info,
unsigned n)
{
return 0;
}
#endif /* I2C_BOARDINFO */
/*
* The following structs are for those who like to implement new bus drivers:
* i2c_algorithm is the interface to a class of hardware solutions which can
* be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584
* to name two of the most common.
*/
struct i2c_algorithm {
/* If an adapter algorithm can't do I2C-level access, set master_xfer
to NULL. If an adapter algorithm can do SMBus access, set
smbus_xfer. If set to NULL, the SMBus protocol is simulated
using common I2C messages */
/* master_xfer should return the number of messages successfully
processed, or a negative value on error */
int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num);
int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,
unsigned short flags, char read_write,
u8 command, int size, union i2c_smbus_data *data);
/* To determine what the adapter supports */
u32 (*functionality) (struct i2c_adapter *);
};
/**
* struct i2c_bus_recovery_info - I2C bus recovery information
* @recover_bus: Recover routine. Either pass driver's recover_bus() routine, or
* i2c_generic_scl_recovery() or i2c_generic_gpio_recovery().
* @get_scl: This gets current value of SCL line. Mandatory for generic SCL
* recovery. Used internally for generic GPIO recovery.
* @set_scl: This sets/clears SCL line. Mandatory for generic SCL recovery. Used
* internally for generic GPIO recovery.
* @get_sda: This gets current value of SDA line. Optional for generic SCL
* recovery. Used internally, if sda_gpio is a valid GPIO, for generic GPIO
* recovery.
* @prepare_recovery: This will be called before starting recovery. Platform may
* configure padmux here for SDA/SCL line or something else they want.
* @unprepare_recovery: This will be called after completing recovery. Platform
* may configure padmux here for SDA/SCL line or something else they want.
* @scl_gpio: gpio number of the SCL line. Only required for GPIO recovery.
* @sda_gpio: gpio number of the SDA line. Only required for GPIO recovery.
*/
struct i2c_bus_recovery_info {
int (*recover_bus)(struct i2c_adapter *);
int (*get_scl)(struct i2c_adapter *);
void (*set_scl)(struct i2c_adapter *, int val);
int (*get_sda)(struct i2c_adapter *);
void (*prepare_recovery)(struct i2c_bus_recovery_info *bri);
void (*unprepare_recovery)(struct i2c_bus_recovery_info *bri);
/* gpio recovery */
int scl_gpio;
int sda_gpio;
};
int i2c_recover_bus(struct i2c_adapter *adap);
/* Generic recovery routines */
int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
int i2c_generic_scl_recovery(struct i2c_adapter *adap);
/*
* i2c_adapter is the structure used to identify a physical i2c bus along
* with the access algorithms necessary to access it.
*/
struct i2c_adapter {
struct module *owner;
unsigned int class; /* classes to allow probing for */
const struct i2c_algorithm *algo; /* the algorithm to access the bus */
void *algo_data;
/* data fields that are valid for all devices */
struct rt_mutex bus_lock;
int timeout; /* in jiffies */
int retries;
struct device dev; /* the adapter device */
int nr;
char name[48];
struct completion dev_released;
struct mutex userspace_clients_lock;
struct list_head userspace_clients;
struct i2c_bus_recovery_info *bus_recovery_info;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
static inline void *i2c_get_adapdata(const struct i2c_adapter *dev)
{
return dev_get_drvdata(&dev->dev);
}
static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
{
dev_set_drvdata(&dev->dev, data);
}
static inline struct i2c_adapter *
i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
{
struct device *parent = adapter->dev.parent;
if (parent != NULL && parent->type == &i2c_adapter_type)
return to_i2c_adapter(parent);
else
return NULL;
}
int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *));
/* Adapter locking functions, exported for shared pin cases */
void i2c_lock_adapter(struct i2c_adapter *);
void i2c_unlock_adapter(struct i2c_adapter *);
/*flags for the client struct: */
#define I2C_CLIENT_PEC 0x04 /* Use Packet Error Checking */
#define I2C_CLIENT_TEN 0x10 /* we have a ten bit chip address */
/* Must equal I2C_M_TEN below */
#define I2C_CLIENT_WAKE 0x80 /* for board_info; true iff can wake */
#define I2C_CLIENT_SCCB 0x9000 /* Use Omnivision SCCB protocol */
/* Must match I2C_M_STOP|IGNORE_NAK */
/* i2c adapter classes (bitmask) */
#define I2C_CLASS_HWMON (1<<0) /* lm_sensors, ... */
#define I2C_CLASS_DDC (1<<3) /* DDC bus on graphics adapters */
#define I2C_CLASS_SPD (1<<7) /* Memory modules */
/* Internal numbers to terminate lists */
#define I2C_CLIENT_END 0xfffeU
/* Construct an I2C_CLIENT_END-terminated array of i2c addresses */
#define I2C_ADDRS(addr, addrs...) \
((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })
/* ----- functions exported by i2c.o */
/* administration...
*/
#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
extern int i2c_add_adapter(struct i2c_adapter *);
extern void i2c_del_adapter(struct i2c_adapter *);
extern int i2c_add_numbered_adapter(struct i2c_adapter *);
extern int i2c_register_driver(struct module *, struct i2c_driver *);
extern void i2c_del_driver(struct i2c_driver *);
/* use a define to avoid include chaining to get THIS_MODULE */
#define i2c_add_driver(driver) \
i2c_register_driver(THIS_MODULE, driver)
extern struct i2c_client *i2c_use_client(struct i2c_client *client);
extern void i2c_release_client(struct i2c_client *client);
/* call the i2c_client->command() of all attached clients with
* the given arguments */
extern void i2c_clients_command(struct i2c_adapter *adap,
unsigned int cmd, void *arg);
extern struct i2c_adapter *i2c_get_adapter(int nr);
extern void i2c_put_adapter(struct i2c_adapter *adap);
/* Return the functionality mask */
static inline u32 i2c_get_functionality(struct i2c_adapter *adap)
{
return adap->algo->functionality(adap);
}
/* Return 1 if adapter supports everything we need, 0 if not. */
static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)
{
return (func & i2c_get_functionality(adap)) == func;
}
/* Return the adapter number for a specific adapter */
static inline int i2c_adapter_id(struct i2c_adapter *adap)
{
return adap->nr;
}
/**
* module_i2c_driver() - Helper macro for registering a I2C driver
* @__i2c_driver: i2c_driver struct
*
* Helper macro for I2C drivers which do not do anything special in module
* init/exit. This eliminates a lot of boilerplate. Each module may only
* use this macro once, and calling it replaces module_init() and module_exit()
*/
#define module_i2c_driver(__i2c_driver) \
module_driver(__i2c_driver, i2c_add_driver, \
i2c_del_driver)
#endif /* I2C */
#if IS_ENABLED(CONFIG_ACPI_I2C)
extern void acpi_i2c_register_devices(struct i2c_adapter *adap);
#else
static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) {}
#endif
#endif /* _LINUX_I2C_H */
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