ifx_i2c.c File Reference

This file implements the wrapper API Layer for IFX I2C protocol v2.00. More...

#include "ifx_i2c.h"
#include "pal_os_event.h"
#include "ifx_i2c_presentation_layer.h"

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Functions
optiga_lib_status_t	ifx_i2c_open (ifx_i2c_context_t *p_ctx)
	Initializes the IFX I2C protocol stack for a given context. More...
optiga_lib_status_t	ifx_i2c_reset (ifx_i2c_context_t *p_ctx, ifx_i2c_reset_type_t reset_type)
	Resets the I2C slave. More...
optiga_lib_status_t	ifx_i2c_transceive (ifx_i2c_context_t *p_ctx, const uint8_t *p_tx_data, uint16_t tx_data_length, uint8_t *p_rx_buffer, uint16_t *p_rx_buffer_len)
	Sends a command and receives a response for the command. More...
optiga_lib_status_t	ifx_i2c_close (ifx_i2c_context_t *p_ctx)
	Closes the IFX I2C protocol stack for a given context. More...
optiga_lib_status_t	ifx_i2c_set_slave_address (ifx_i2c_context_t *p_ctx, uint8_t slave_address, uint8_t persistent)
	Sets the slave address of the target device. More...

Detailed Description

This file implements the wrapper API Layer for IFX I2C protocol v2.00.

Copyright

MIT License

Copyright (c) 2019 Infineon Technologies AG

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE

\endcopyright

Author

Infineon Technologies AG

Function Documentation

ifx_i2c_close()

optiga_lib_status_t ifx_i2c_close

(

ifx_i2c_context_t *

p_ctx

)

Closes the IFX I2C protocol stack for a given context.

ifx_i2c_close()

Closes the IFX I2C protocol stack for a given context.

• De-Initializes the I2C slave device.
• Power downs the I2C slave.

Precondition

• None

Note

• manage_contex_operation : Used for manage context.The value of the parameter is not modified by the IFX I2C protocol stack.
  • The values for manage_contex_operation must be one of the below
    • IFX_I2C_SESSION_CONTEXT_SAVE : save active secure session.
    • IFX_I2C_SESSION_CONTEXT_NONE : for no manage context operation.

Parameters

[in,out]

p_ctx

Pointer to ifx_i2c_context_t, must not be NULL

Return values

IFX_I2C_STACK_SUCCESS

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ifx_i2c_open()

optiga_lib_status_t ifx_i2c_open

(

ifx_i2c_context_t *

p_ctx

)

Initializes the IFX I2C protocol stack for a given context.

ifx_i2c_open()

Initializes the IFX I2C protocol stack for the given context.

• Performs a reset sequence.
  
• Initializes the I2C slave device.
  
• Initializes the IFX I2C protocol stack and registers the event callbacks.
• Negotiates the frame size and bit rate with the I2C slave.

Precondition

• None

Note

• The values of registers MAX_SCL_FREQU and DATA_REG_LEN, read from slave are not validated.
• At present, only single instance of ifx_i2c_context_t is supported.
• The following parameters in ifx_i2c_context_t must be initialized with appropriate values
  
  • slave address : Address of I2C slave
  • frame_size : Frame size in bytes. Minimum supported value is 16 bytes.
    
    • It is recommended not to use a value greater than the slave's frame size.
    • The user specified frame size is written to I2C slave's frame size register. The frame size register is read back from I2C slave. This frame value is used by the IFX I2C protocol even if it is not equal to the user specified value.
  • frequency : Frequency/speed of I2C master in KHz.
    • This must be lowest of the maximum frequency supported by the devices (master/slave) connected on the bus.
    • Initial negotiation starts with a frequency of 100KHz.
    • If the user specified frequency is more than 400 KHz, the I2C slave is configured to operate in "Fm+" mode, otherwise the I2C slave is configured for "SM & Fm" mode.
      
    • If the user specified frequency negotiation fails, the I2C master frequency remains at 100KHz
      
  • upper_layer_event_handler : Upper layer event handler. This is invoked when ifx_i2c_open() is asynchronously completed.
  • upper_layer_ctx : Context of upper layer.
  • p_slave_vdd_pin : GPIO pin for VDD. If not set, cold reset is not done.
  • p_slave_reset_pin : GPIO pin for Reset. If not set, warm reset is not done.
  • manage_contex_operation : Used for manage context.The value of the parameter is not modified by the IFX I2C protocol stack.
    • The values for manage_contex_operation must be one of the below.
      • IFX_I2C_SESSION_CONTEXT_RESTORE : restore the saved secure session.
      • IFX_I2C_SESSION_CONTEXT_NONE : for no manage context operation.

Parameters

[in,out]

p_ctx

Pointer to ifx_i2c_context_t, must not be NULL

Return values

IFX_I2C_STACK_SUCCESS
IFX_I2C_STACK_ERROR

ifx_i2c_reset()

optiga_lib_status_t ifx_i2c_reset	(	ifx_i2c_context_t *	p_ctx,
		ifx_i2c_reset_type_t	reset_type
	)

Resets the I2C slave.

ifx_i2c_reset()

Resets the I2C slave and initializes the IFX I2C protocol stack for the given context.

• Resets the I2C slave.
• Initializes the IFX I2C protocol stack.
• Re-Initializes and negotiates the frame size and bit rate with the I2C slave. The values remain same as that in previous ifx_i2c_open().

Precondition

• IFX I2C protocol stack must be initialized.

Note

• For COLD and WARM reset type: If the GPIO(VDD and/or reset) pins are not configured,
  the API continues without any failure return status
  

Parameters

[in,out]	p_ctx	Pointer to ifx_i2c_context_t, must not be NULL
[in,out]	reset_type	type of reset

Return values

IFX_I2C_STACK_SUCCESS
IFX_I2C_STACK_ERROR

ifx_i2c_set_slave_address()

optiga_lib_status_t ifx_i2c_set_slave_address	(	ifx_i2c_context_t *	p_ctx,
		uint8_t	slave_address,
		uint8_t	persistent
	)

Sets the slave address of the target device.

Writes new I2C slave Address to the target device.

• This API is implemented in synchronous mode.
• If the write fails due to the following reasons, this API repeats the write for PL_POLLING_MAX_CNT times with a fixed interval of PL_POLLING_INVERVAL_US microseconds and exits with respective return status.
  • I2C bus is in busy state, returns IFX_I2C_STACK_BUSY
  • No-acknowledge(NACK) received from slave, returns IFX_I2C_STACK_ERROR
  • I2C errors, returns IFX_I2C_STACK_ERROR
• Only bits [6:0] from parameter "slave_address" are considered as slave address. Hence the bit 7 is ignored.
• Slave address validation is not done in the implementation. Provide a valid slave address as input.

Precondition

• IFX I2C protocol stack must be initialized.

Note

• If persistent mode is selected, the IFX I2C context slave address will be over-written with the new slave address. Even after IFX I2C open/reset, all future executions will use the new slave address.
  
• If volatile mode is selected, the pal_i2c_context slave address will be over-written with the new slave address. This persists only till the next ifx_i2c open/reset is called.

Parameters

[in,out]	p_ctx	Pointer to ifx_i2c_context_t
[in]	slave_address	Holds new slave address[7 Bit] to be set.
[in]	persistent	0 - To set the Slave address until next reset. Non-zero - To set the slave address to persistent memory.

Return values

IFX_I2C_STACK_SUCCESS
IFX_I2C_STACK_ERROR

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ifx_i2c_transceive()

optiga_lib_status_t ifx_i2c_transceive	(	ifx_i2c_context_t *	p_ctx,
		const uint8_t *	p_tx_data,
		uint16_t	tx_data_length,
		uint8_t *	p_rx_buffer,
		uint16_t *	p_rx_buffer_len
	)

Sends a command and receives a response for the command.

ifx_i2c_transceive()

Sends a command and receives a response for the command.

• Transmit data(Command) to I2C slave.
• Receive data(Response) from I2C slave.

Precondition

• IFX I2C protocol stack must be initialized.

Note

• The actual number of bytes received is stored in p_rx_buffer_len. In case of error, p_rx_buffer_len is set to 0.
  
• The p_rx_buffer must be large enough to accommodate the response data from the slave. The p_rx_buffer_len parameter must specify the length of the receive buffer correctly. If the size of p_rx_data is zero or insufficient to copy the response bytes then IFX_I2C_STACK_MEM_ERROR error is returned.
• If establishing a secure channel fails, IFX_I2C_HANDSHAKE_ERROR is returned.
• If IFX_I2C_SESSION_ERROR is returned, a new session must be established.
• If presentation layer is enabled and the command data protection is selected, the input data provided will be modified because the data will be encrypted in the same input buffer. Hence a copy of the input data must be preserved by the caller of this API, if needed.
• The following parameters in ifx_i2c_context_t must be initialized with appropriate values
  
  • upper_layer_event_handler : Upper layer event handler, if it is different from that in ifx_i2c_open(). This is invoked when ifx_i2c_transceive is asynchronously completed.
  • upper_layer_ctx : Context of upper layer, if it is different from that in ifx_i2c_open.
  • protection_level : Used for secure communication.The value of the parameter is not modified by the IFX I2C protocol stack.
    • The values for protection_level must be one of the below
      • NO_PROTECTION : data from master and slave is unprotected
      • MASTER_PROTECTION : data from master is protected and data from slave is unprotected
      • SLAVE_PROTECTION : data from master is unprotected and data from is slave protected
      • FULL_PROTECTION : data from master and slave protected
      • To re-establish secure channel, bitwise-OR protection_level with RE_ESTABLISH
  • If Presentation Layer is enabled,
    • Additional buffer size is required to handle encryption and decryption functionality.
  • The total buffer size with the additional presentation layer overhead is explained in the figure below. Please provide the lengths and data buffers as specified below.
    • The transmit and receive data buffers need additional overhead of IFX_I2C_PRL_OVERHEAD_SIZE bytes along with Tx/Rx data(payload) size.
    • Provide the command data, starting from the IFX_I2C_DATA_OFFSET location in the transmit buffer.
    • In the receive buffer, the response (received data) from the OPTIGA will be stored from the IFX_I2C_DATA_OFFSET location. Read the response from this offset.
    • Provide the length of command data (tx_data_length) with the payload length excluding the additional overhead.
    • Provide the length of response data (p_rx_buffer_len) in-order to copy the response to the buffer provided.
  • If the master sequence number or expected slave sequence for next payload transmission crosses 0xFFFFFFF0, master renegotiate a new secure channel and then sends the payload to slave.
    

    ifx_i2c_transceive()

Parameters

[in,out]	p_ctx	Pointer to ifx_i2c_context_t, must not be NULL
[in]	p_tx_data	Pointer to the write transmit buffer
[in]	tx_data_length	Length of the write data buffer
[in,out]	p_rx_buffer	Pointer to the receive data buffer
[in,out]	p_rx_buffer_len	Pointer to the length of the receive data buffer

Return values

IFX_I2C_STACK_SUCCESS
IFX_I2C_STACK_ERROR
IFX_I2C_STACK_MEM_ERROR
IFX_I2C_HANDSHAKE_ERROR
IFX_I2C_SESSION_ERROR

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