Parameters

conststructi2c_client*client

Handle to slave device

char*buf

Where to store data read from slave

intcount

How many bytes to read, must be less than 64k since msg.len is u16

Description

Returns negative errno, or else the number of bytes read.

Parameters

conststructi2c_client*client

Handle to slave device

char*buf

Where to store data read from slave, must be safe to use with DMA

intcount

How many bytes to read, must be less than 64k since msg.len is u16

Description

Returns negative errno, or else the number of bytes read.

Parameters

conststructi2c_client*client

Handle to slave device

constchar*buf

Data that will be written to the slave

intcount

How many bytes to write, must be less than 64k since msg.len is u16

Description

Returns negative errno, or else the number of bytes written.

Parameters

conststructi2c_client*client

Handle to slave device

constchar*buf

Data that will be written to the slave, must be safe to use with DMA

intcount

How many bytes to write, must be less than 64k since msg.len is u16

Description

Returns negative errno, or else the number of bytes written.

Definition:

struct i2c_device_identity {    u16 manufacturer_id;#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS                0;#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_1              1;#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_2              2;#define I2C_DEVICE_ID_NXP_SEMICONDUCTORS_3              3;#define I2C_DEVICE_ID_RAMTRON_INTERNATIONAL             4;#define I2C_DEVICE_ID_ANALOG_DEVICES                    5;#define I2C_DEVICE_ID_STMICROELECTRONICS                6;#define I2C_DEVICE_ID_ON_SEMICONDUCTOR                  7;#define I2C_DEVICE_ID_SPRINTEK_CORPORATION              8;#define I2C_DEVICE_ID_ESPROS_PHOTONICS_AG               9;#define I2C_DEVICE_ID_FUJITSU_SEMICONDUCTOR            10;#define I2C_DEVICE_ID_FLIR                             11;#define I2C_DEVICE_ID_O2MICRO                          12;#define I2C_DEVICE_ID_ATMEL                            13;#define I2C_DEVICE_ID_NONE                         0xffff;    u16 part_id;    u8 die_revision;};

Members

manufacturer_id

0 - 4095, database maintained by NXP

part_id

0 - 511, according to manufacturer

die_revision

0 - 7, according to manufacturer

Constants

I2C_DRV_ACPI_WAIVE_D0_PROBE

Don’t put the device in D0 state for probe

Definition:

struct i2c_driver {    unsigned int class;    int (*probe)(struct i2c_client *client);    void (*remove)(struct i2c_client *client);    void (*shutdown)(struct i2c_client *client);    void (*alert)(struct i2c_client *client, enum i2c_alert_protocol protocol, unsigned int data);    int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);    struct device_driver driver;    const struct i2c_device_id *id_table;    int (*detect)(struct i2c_client *client, struct i2c_board_info *info);    const unsigned short *address_list;    struct list_head clients;    u32 flags;};

Members

class

What kind of i2c device we instantiate (for detect)

probe

Callback for device binding

remove

Callback for device unbinding

shutdown

Callback for device shutdown

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)

flags

A bitmask of flags defined inenumi2c_driver_flags

Definition:

struct i2c_client {    unsigned short flags;#define I2C_CLIENT_PEC          0x04;#define I2C_CLIENT_TEN          0x10;#define I2C_CLIENT_SLAVE        0x20;#define I2C_CLIENT_HOST_NOTIFY  0x40;#define I2C_CLIENT_WAKE         0x80;#define I2C_CLIENT_SCCB         0x9000;    unsigned short addr;    char name[I2C_NAME_SIZE];    struct i2c_adapter *adapter;    struct device dev;    int init_irq;    int irq;    struct list_head detected;#if IS_ENABLED(CONFIG_I2C_SLAVE);    i2c_slave_cb_t slave_cb;#endif;    void *devres_group_id;    struct dentry *debugfs;};

Members

flags

see I2C_CLIENT_* for possible flags

addr

Address used on the I2C bus connected to the parent adapter.

name

Indicates the type of the device, usually a chip name that’sgeneric enough to hide second-sourcing and compatible revisions.

adapter

manages the bus segment hosting this I2C device

dev

Driver model device node for the slave.

init_irq

IRQ that was set at initialization

irq

indicates the IRQ generated by this device (if any)

detected

member of an i2c_driver.clients list or i2c-core’suserspace_devices list

slave_cb

Callback when I2C slave mode of an adapter is used. The adaptercalls it to pass on slave events to the slave driver.

devres_group_id

id of the devres group that will be created for resourcesacquired when probing this device.

debugfs

pointer to the debugfs subdirectory which the I2C core createdfor this client.

Definition:

struct i2c_board_info {    char type[I2C_NAME_SIZE];    unsigned short  flags;    unsigned short  addr;    const char      *dev_name;    void *platform_data;    struct fwnode_handle *fwnode;    const struct software_node *swnode;    const struct resource *resources;    unsigned int    num_resources;    int irq;};

Members

type

chip type, to initialize i2c_client.name

flags

to initialize i2c_client.flags

addr

stored in i2c_client.addr

dev_name

Overrides the default <busnr>-<addr> dev_name if set

platform_data

stored in i2c_client.dev.platform_data

fwnode

device node supplied by the platform firmware

swnode

software node for the device

resources

resources associated with the device

num_resources

number of resources in theresources array

irq

stored in i2c_client.irq

Parameters

dev_type

identifies the device type

dev_addr

the device’s address on the bus.

Description

This macro initializes essential fields of astructi2c_board_info,declaring what has been provided on a particular board. Optionalfields (such as associated irq, or device-specific platform_data)are provided using conventional syntax.

Definition:

struct i2c_algorithm {    union {        int (*xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);        int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);    };    union {        int (*xfer_atomic)(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);        int (*master_xfer_atomic)(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);    int (*smbus_xfer_atomic)(struct i2c_adapter *adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data);    u32 (*functionality)(struct i2c_adapter *adap);#if IS_ENABLED(CONFIG_I2C_SLAVE);    union {        int (*reg_target)(struct i2c_client *client);        int (*reg_slave)(struct i2c_client *client);    };    union {        int (*unreg_target)(struct i2c_client *client);        int (*unreg_slave)(struct i2c_client *client);    };#endif;};

Members

{unnamed_union}

anonymous

xfer

Transfer a given number of messages defined by the msgs array viathe specified adapter.

master_xfer

deprecated, usexfer

{unnamed_union}

anonymous

xfer_atomic

Same asxfer. Yet, only using atomic context so e.g. PMICscan be accessed very late before shutdown. Optional.

master_xfer_atomic

deprecated, usexfer_atomic

smbus_xfer

Issue SMBus transactions to the given I2C adapter. If thisis not present, then the bus layer will try and convert the SMBus callsinto I2C transfers instead.

smbus_xfer_atomic

Same assmbus_xfer. Yet, only using atomic contextso e.g. PMICs can be accessed very late before shutdown. Optional.

functionality

Return the flags that this algorithm/adapter pair supportsfrom theI2C_FUNC_* flags.

{unnamed_union}

anonymous

reg_target

Register given client to local target mode of this adapter

reg_slave

deprecated, usereg_target

{unnamed_union}

anonymous

unreg_target

Unregister given client from local target mode of this adapter

unreg_slave

deprecated, useunreg_target

Definition:

struct i2c_lock_operations {    void (*lock_bus)(struct i2c_adapter *adapter, unsigned int flags);    int (*trylock_bus)(struct i2c_adapter *adapter, unsigned int flags);    void (*unlock_bus)(struct i2c_adapter *adapter, unsigned int flags);};

Members

lock_bus

Get exclusive access to an I2C bus segment

trylock_bus

Try to get exclusive access to an I2C bus segment

unlock_bus

Release exclusive access to an I2C bus segment

Definition:

struct i2c_timings {    u32 bus_freq_hz;    u32 scl_rise_ns;    u32 scl_fall_ns;    u32 scl_int_delay_ns;    u32 sda_fall_ns;    u32 sda_hold_ns;    u32 digital_filter_width_ns;    u32 analog_filter_cutoff_freq_hz;};

Members

bus_freq_hz

the bus frequency in Hz

scl_rise_ns

time SCL signal takes to rise in ns; t(r) in the I2C specification

scl_fall_ns

time SCL signal takes to fall in ns; t(f) in the I2C specification

scl_int_delay_ns

time IP core additionally needs to setup SCL in ns

sda_fall_ns

time SDA signal takes to fall in ns; t(f) in the I2C specification

sda_hold_ns

time IP core additionally needs to hold SDA in ns

digital_filter_width_ns

width in ns of spikes on i2c lines that the IP coredigital filter can filter out

analog_filter_cutoff_freq_hz

threshold frequency for the low pass IP coreanalog filter

Definition:

struct i2c_bus_recovery_info {    int (*recover_bus)(struct i2c_adapter *adap);    int (*get_scl)(struct i2c_adapter *adap);    void (*set_scl)(struct i2c_adapter *adap, int val);    int (*get_sda)(struct i2c_adapter *adap);    void (*set_sda)(struct i2c_adapter *adap, int val);    int (*get_bus_free)(struct i2c_adapter *adap);    void (*prepare_recovery)(struct i2c_adapter *adap);    void (*unprepare_recovery)(struct i2c_adapter *adap);    struct gpio_desc *scl_gpiod;    struct gpio_desc *sda_gpiod;    struct pinctrl *pinctrl;    struct pinctrl_state *pins_default;    struct pinctrl_state *pins_gpio;};

Members

recover_bus

Recover routine. Either pass driver’srecover_bus() routine, ori2c_generic_scl_recovery().

get_scl

This gets current value of SCL line. Mandatory for generic SCLrecovery. Populated internally for generic GPIO recovery.

set_scl

This sets/clears the SCL line. Mandatory for generic SCL recovery.Populated internally for generic GPIO recovery.

get_sda

This gets current value of SDA line. This orset_sda() is mandatoryfor generic SCL recovery. Populated internally, if sda_gpio is a validGPIO, for generic GPIO recovery.

set_sda

This sets/clears the SDA line. This orget_sda() is mandatory forgeneric SCL recovery. Populated internally, if sda_gpio is a valid GPIO,for generic GPIO recovery.

get_bus_free

Returns the bus free state as seen from the IP core in case ithas a more complex internal logic than just reading SDA. Optional.

prepare_recovery

This will be called before starting recovery. Platform mayconfigure padmux here for SDA/SCL line or something else they want.

unprepare_recovery

This will be called after completing recovery. Platformmay configure padmux here for SDA/SCL line or something else they want.

scl_gpiod

gpiod of the SCL line. Only required for GPIO recovery.

sda_gpiod

gpiod of the SDA line. Only required for GPIO recovery.

pinctrl

pinctrl used by GPIO recovery to change the state of the I2C pins.Optional.

pins_default

default pinctrl state of SCL/SDA lines, when they are assignedto the I2C bus. Optional. Populated internally for GPIO recovery, ifstate with the name PINCTRL_STATE_DEFAULT is found and pinctrl is valid.

pins_gpio

recovery pinctrl state of SCL/SDA lines, when they are used asGPIOs. Optional. Populated internally for GPIO recovery, if this stateis called “gpio” or “recovery” and pinctrl is valid.

Definition:

struct i2c_adapter_quirks {    u64 flags;    int max_num_msgs;    u16 max_write_len;    u16 max_read_len;    u16 max_comb_1st_msg_len;    u16 max_comb_2nd_msg_len;};

Members

flags

see I2C_AQ_* for possible flags and read below

max_num_msgs

maximum number of messages per transfer

max_write_len

maximum length of a write message

max_read_len

maximum length of a read message

max_comb_1st_msg_len

maximum length of the first msg in a combined message

max_comb_2nd_msg_len

maximum length of the second msg in a combined message

Parameters

structi2c_adapter*adapter

Target I2C bus segment

unsignedintflags

I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENTlocks only this branch in the adapter tree

Parameters

structi2c_adapter*adapter

Target I2C bus segment

unsignedintflags

I2C_LOCK_ROOT_ADAPTER tries to locks the root i2c adapter,I2C_LOCK_SEGMENT tries to lock only this branch in the adapter tree

Return

true if the I2C bus segment is locked, false otherwise

Parameters

structi2c_adapter*adapter

Target I2C bus segment

unsignedintflags

I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENTunlocks only this branch in the adapter tree

Parameters

structi2c_adapter*adap

Adapter to mark as suspended

Description

When using this helper to mark an adapter as suspended, the core will rejectfurther transfers to this adapter. The usage of this helper is optional butrecommended for devices having distinct handlers for system suspend andruntime suspend. More complex devices are free to implement custom solutionsto reject transfers when suspended.

Parameters

structi2c_adapter*adap

Adapter to mark as resumed

Description

When using this helper to mark an adapter as resumed, the core will allowfurther transfers to this adapter. See also further notes toi2c_mark_adapter_suspended().

Parameters

structi2c_adapter*adap

i2c adapter

u64quirks

quirk flags

Return

true if the adapter has all the specified quirk flags, false if not

Parameters

__i2c_driver

i2c_driver struct

Description

Helper macro for I2C drivers which do not do anything special in moduleinit/exit. This eliminates a lot of boilerplate. Each module may onlyuse this macro once, and calling it replacesmodule_init() andmodule_exit()

Parameters

__i2c_driver

i2c_driver struct

Description

Helper macro for I2C drivers which do not do anything special in theirinit. This eliminates a lot of boilerplate. Each driver may onlyuse this macro once, and calling it replacesdevice_initcall().

Parameters

intbusnum

identifies the bus to which these devices belong

structi2c_board_infoconst*info

vector of i2c device descriptors

unsignedlen

how many descriptors in the vector; may be zero to reservethe specified bus number.

Description

Systems using the Linux I2C driver stack can declare tables of board infowhile they initialize. This should be done in board-specific init codeneararch_initcall() time, or equivalent, before any I2C adapter driver isregistered. For example, mainboard init code could define several devices,as could the init code for each daughtercard in a board stack.

The I2C devices will be created later, after the adapter for the relevantbus has been registered. After that moment, standard driver model toolsare used to bind “new style” I2C drivers to the devices. The bus numberfor any device declared using this routine is not available for dynamicallocation.

The board info passed can safely be __initdata, but be careful of embeddedpointers (for platform_data, functions, etc) since that won’t be copied.

Parameters

structdevice*dev

device, probably from some driver model iterator

Description

When traversing the driver model tree, perhaps using driver modeliterators likedevice_for_each_child(), you can’t assume very muchabout the nodes you find. Use this function to avoid oopses causedby wrongly treating some non-I2C device as an i2c_client.

Parameters

structi2c_adapter*adap

the adapter managing the device

structi2c_board_infoconst*info

describes one I2C device; bus_num is ignored

Context

can sleep

Description

Create an i2c device. Binding is handled through driver modelprobe()/remove() methods. A driver may be bound to this device when wereturn from this function, or any later moment (e.g. maybe hotplugging willload the driver module). This call is not appropriate for use by mainboardinitialization logic, which usually runs during anarch_initcall() longbefore any i2c_adapter could exist.

This returns the new i2c client, which may be saved for later use withi2c_unregister_device(); or an ERR_PTR to describe the error.

Parameters

structi2c_client*client

value returned from i2c_new_*_device()

Context

can sleep

Parameters

structfwnode_handle*fwnode

structfwnode_handle corresponding to thestructi2c_client

Description

Look up and return thestructi2c_client corresponding to thefwnode.If no client can be found, orfwnode is NULL, this returns NULL.

The user must call put_device(client->dev) once done with the i2c client.

Parameters

structi2c_adapter*adapter

the adapter managing the device

u16address

seven bit address to be used

Context

can sleep

Description

This returns an I2C client bound to the “dummy” driver, intended for usewith devices that consume multiple addresses. Examples of such chipsinclude various EEPROMS (like 24c04 and 24c08 models).

These dummy devices have two main uses. First, most I2C and SMBus callsexcepti2c_transfer() need a client handle; the dummy will be that handle.And second, this prevents the specified address from being bound to adifferent driver.

This returns the new i2c client, which should be saved for later use withi2c_unregister_device(); or an ERR_PTR to describe the error.

Parameters

structdevice*dev

device the managed resource is bound to

structi2c_adapter*adapter

the adapter managing the device

u16address

seven bit address to be used

Context

can sleep

Description

This is the device-managed version ofi2c_new_dummy_device. It returns thenew i2c client or an ERR_PTR in case of an error.

Parameters

structi2c_client*client

Handle to the primary client

constchar*name

Handle to specify which secondary address to get

u16default_addr

Used as a fallback if no secondary address was specified

Context

can sleep

Description

I2C clients can be composed of multiple I2C slaves bound together in a singlecomponent. The I2C client driver then binds to the master I2C slave and needsto create I2C dummy clients to communicate with all the other slaves.

This function creates and returns an I2C dummy client whose I2C address isretrieved from the platform firmware based on the given slave name. If noaddress is specified by the firmware default_addr is used.

On DT-based platforms the address is retrieved from the “reg” property entrycell whose “reg-names” value matches the slave name.

This returns the new i2c client, which should be saved for later use withi2c_unregister_device(); or an ERR_PTR to describe the error.

Parameters

structdevice*dev

device, probably from some driver model iterator

Description

When traversing the driver model tree, perhaps using driver modeliterators likedevice_for_each_child(), you can’t assume very muchabout the nodes you find. Use this function to avoid oopses causedby wrongly treating some non-I2C device as an i2c_adapter.

Parameters

structi2c_adapter*adap

the adapter

unsignedshortaddr

the I2C address of the notifying device

Context

can’t sleep

Description

Helper function to be called from an I2C bus driver’s interrupthandler. It will schedule the Host Notify IRQ.

Parameters

structi2c_adapter*adapter

the adapter to add

Context

can sleep

Description

This routine is used to declare an I2C adapter when its bus numberdoesn’t matter or when its bus number is specified by an dt alias.Examples of bases when the bus number doesn’t matter: I2C adaptersdynamically added by USB links or PCI plugin cards.

When this returns zero, a new bus number was allocated and storedin adap->nr, and the specified adapter became available for clients.Otherwise, a negative errno value is returned.

Parameters

structi2c_adapter*adap

the adapter to register (with adap->nr initialized)

Context

can sleep

Description

This routine is used to declare an I2C adapter when its bus numbermatters. For example, use it for I2C adapters from system-on-chip CPUs,or otherwise built in to the system’s mainboard, and where i2c_board_infois used to properly configure I2C devices.

If the requested bus number is set to -1, then this function will behaveidentically to i2c_add_adapter, and will dynamically assign a bus number.

If no devices have pre-been declared for this bus, then be sure toregister the adapter before any dynamically allocated ones. Otherwisethe required bus ID may not be available.

When this returns zero, the specified adapter became available forclients using the bus number provided in adap->nr. Also, the tableof I2C devices pre-declared usingi2c_register_board_info() is scanned,and the appropriate driver model device nodes are created. Otherwise, anegative errno value is returned.

Parameters

structi2c_adapter*adap

the adapter being unregistered

Context

can sleep

Description

This unregisters an I2C adapter which was previously registeredbyi2c_add_adapter ori2c_add_numbered_adapter.

Parameters

structdevice*dev

managing device for adding this I2C adapter

structi2c_adapter*adapter

the adapter to add

Context

can sleep

Description

Add adapter with dynamic bus number, same withi2c_add_adapter()but the adapter will be auto deleted on driver detach.

Parameters

structfwnode_handle*fwnode

structfwnode_handle corresponding to thestructi2c_adapter

Description

Look up and return thestructi2c_adapter corresponding to thefwnode.If no adapter can be found, orfwnode is NULL, this returns NULL.

The user must call put_device(adapter->dev) once done with the i2c adapter.

Parameters

structfwnode_handle*fwnode

structfwnode_handle corresponding to thestructi2c_adapter

Description

Look up and return thestructi2c_adapter corresponding to thefwnode,and increment the adapter module’s use count. If no adapter can be found,orfwnode is NULL, this returns NULL.

The user must call i2c_put_adapter(adapter) once done with the i2c adapter.Note that this is different fromi2c_find_adapter_by_node().

Parameters

structdevice*dev

The device to scan for I2C timing properties

structi2c_timings*t

the i2c_timingsstructto be filled with values

booluse_defaults

bool to use sane defaults derived from the I2C specificationwhen properties are not found, otherwise don’t update

Description

Scan the device for the generic I2C properties describing timing parametersfor the signal and fill the givenstructwith the results. If a property wasnot found and use_defaults was true, then maximum timings are assumed whichare derived from the I2C specification. If use_defaults is not used, theresults will be as before, so drivers can apply their own defaults beforecalling this helper. The latter is mainly intended for avoiding regressionsof existing drivers which want to switch to this function. New driversalmost always should use the defaults.

Parameters

structi2c_driver*driver

the driver being unregistered

Context

can sleep

Parameters

structi2c_adapter*adap

Handle to I2C bus

structi2c_msg*msgs

One or more messages to execute before STOP is issued toterminate the operation; each message begins with a START.

intnum

Number of messages to be executed.

Description

Returns negative errno, else the number of messages executed.

Adapter lock must be held when calling this function. No debug loggingtakes place.

Parameters

structi2c_adapter*adap

Handle to I2C bus

structi2c_msg*msgs

One or more messages to execute before STOP is issued toterminate the operation; each message begins with a START.

intnum

Number of messages to be executed.

Description

Returns negative errno, else the number of messages executed.

Note that there is no requirement that each message be sent tothe same slave address, although that is the most common model.

Parameters

conststructi2c_client*client

Handle to slave device

char*buf

Where the data is stored

intcount

How many bytes to transfer, must be less than 64k since msg.len is u16

u16flags

The flags to be used for the message, e.g. I2C_M_RD for reads

Description

Returns negative errno, or else the number of bytes transferred.

Parameters

conststructi2c_client*client

The device to query

structi2c_device_identity*id

The queried information

Description

Returns negative errno on error, zero on success.

Parameters

conststructi2c_client*client

the device to query. The device must be bound to a driver

Description

Returns a pointer to the matching entry if found, NULL otherwise.

Parameters

structi2c_msg*msg

the message to be checked

unsignedintthreshold

the minimum number of bytes for which using DMA makes sense.Should at least be 1.

Return

NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.Or a valid pointer to be used with DMA. After use, release it bycallingi2c_put_dma_safe_msg_buf().

Description

This function must only be called from process context!

Parameters

u8*buf

the buffer obtained fromi2c_get_dma_safe_msg_buf(). May be NULL.

structi2c_msg*msg

the message which the buffer corresponds to

boolxferred

bool saying if the message was transferred

Parameters

u8crc

previous return crc8 value

u8*p

pointer to data buffer.

size_tcount

number of bytes in data buffer.

Description

Incremental CRC8 over count bytes in the array pointed to by p

Parameters

conststructi2c_client*client

Handle to slave device

Description

This executes the SMBus “receive byte” protocol, returning negative errnoelse the byte received from the device.

Parameters

conststructi2c_client*client

Handle to slave device

u8value

Byte to be sent

Description

This executes the SMBus “send byte” protocol, returning negative errnoelse zero on success.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

Description

This executes the SMBus “read byte” protocol, returning negative errnoelse a data byte received from the device.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

u8value

Byte being written

Description

This executes the SMBus “write byte” protocol, returning negative errnoelse zero on success.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

Description

This executes the SMBus “read word” protocol, returning negative errnoelse a 16-bit unsigned “word” received from the device.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

u16value

16-bit “word” being written

Description

This executes the SMBus “write word” protocol, returning negative errnoelse zero on success.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

u8*values

Byte array into which data will be read; big enough to holdthe data returned by the slave. SMBus allows at most 32 bytes.

Description

This executes the SMBus “block read” protocol, returning negative errnoelse the number of data bytes in the slave’s response.

Note that using this function requires that the client’s adapter supportthe I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter driverssupport this; its emulation through I2C messaging relies on a specificmechanism (I2C_M_RECV_LEN) which may not be implemented.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

u8length

Size of data block; SMBus allows at most 32 bytes

constu8*values

Byte array which will be written.

Description

This executes the SMBus “block write” protocol, returning negative errnoelse zero on success.

Parameters

structi2c_adapter*adapter

Handle to I2C bus

u16addr

Address of SMBus slave on that bus

unsignedshortflags

I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)

charread_write

I2C_SMBUS_READ or I2C_SMBUS_WRITE

u8command

Byte interpreted by slave, for protocols which use such bytes

intprotocol

SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL

unioni2c_smbus_data*data

Data to be read or written

Description

This executes an SMBus protocol operation, and returns a negativeerrno code else zero on success.

Parameters

conststructi2c_client*client

Handle to slave device

u8command

Byte interpreted by slave

u8length

Size of data block; SMBus allows at most I2C_SMBUS_BLOCK_MAX bytes

u8*values

Byte array into which data will be read; big enough to holdthe data returned by the slave. SMBus allows at mostI2C_SMBUS_BLOCK_MAX bytes.

Description

This executes the SMBus “block read” protocol if supported by the adapter.If block read is not supported, it emulates it using either word or byteread protocols depending on availability.

The addresses of the I2C slave device that are accessed with this functionmust be mapped to a linear region, so that a block read will have the sameeffect as a byte read. Before using this function you must double-checkif the I2C slave does support exchanging a block transfer with a bytetransfer.

Parameters

structi2c_adapter*adapter

the target adapter

structi2c_smbus_alert_setup*setup

setup data for the SMBus alert handler

Context

can sleep

Description

Setup handling of the SMBus alert protocol on a given I2C bus segment.

Handling can be done either through our IRQ handler, or by theadapter (from its handler, periodic polling, or whatever).

This returns the ara client, which should be saved for later use withi2c_handle_smbus_alert() and ultimatelyi2c_unregister_device(); or anERRPTR to indicate an error.