1* Software Delegated Exception Interface (SDEI) 2 3Firmware implementing the SDEI functions described in ARM document number 4ARM DEN 0054A ("Software Delegated Exception Interface") can be used by 5Linux to receive notification of events such as those generated by 6firmware-first error handling, or from an IRQ that has been promoted to 7a firmware-assisted NMI. 8 9The interface provides a number of API functions for registering callbacks 10and enabling/disabling events. Functions are invoked by trapping to the 11privilege level of the SDEI firmware (specified as part of the binding 12below) and passing arguments in a manner specified by the "SMC Calling 13Convention (ARM DEN 0028B): 14 15 r0 => 32-bit Function ID / return value 16 {r1 - r3} => Parameters 17 18Note that the immediate field of the trapping instruction must be set 19to #0. 20 21The SDEI_EVENT_REGISTER function registers a callback in the kernel 22text to handle the specified event number. 23 24The sdei node should be a child node of '/firmware' and have required 25properties: 26 27 - compatible : should contain: 28 * "arm,sdei-1.0" : For implementations complying to SDEI version 1.x. 29 30 - method : The method of calling the SDEI firmware. Permitted 31 values are: 32 * "smc" : SMC #0, with the register assignments specified in this 33 binding. 34 * "hvc" : HVC #0, with the register assignments specified in this 35 binding. 36Example: 37 firmware { 38 sdei { 39 compatible = "arm,sdei-1.0"; 40 method = "smc"; 41 }; 42 }; 43