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