From 102b0d2daa97dae68d3eed54d8fe37a9cc38a892 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 11:13:47 +0200 Subject: Adding upstream version 2.8.0+dfsg. Signed-off-by: Daniel Baumann --- services/std_svc/sdei/sdei_state.c | 150 +++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 services/std_svc/sdei/sdei_state.c (limited to 'services/std_svc/sdei/sdei_state.c') diff --git a/services/std_svc/sdei/sdei_state.c b/services/std_svc/sdei/sdei_state.c new file mode 100644 index 0000000..1b448e6 --- /dev/null +++ b/services/std_svc/sdei/sdei_state.c @@ -0,0 +1,150 @@ +/* + * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include +#include + +#include + +#include "sdei_private.h" + +/* Aliases for SDEI handler states: 'R'unning, 'E'nabled, and re'G'istered */ +#define r_ 0U +#define R_ (1u << SDEI_STATF_RUNNING) + +#define e_ 0U +#define E_ (1u << SDEI_STATF_ENABLED) + +#define g_ 0U +#define G_ (1u << SDEI_STATF_REGISTERED) + +/* All possible composite handler states */ +#define reg_ (r_ | e_ | g_) +#define reG_ (r_ | e_ | G_) +#define rEg_ (r_ | E_ | g_) +#define rEG_ (r_ | E_ | G_) +#define Reg_ (R_ | e_ | g_) +#define ReG_ (R_ | e_ | G_) +#define REg_ (R_ | E_ | g_) +#define REG_ (R_ | E_ | G_) + +#define MAX_STATES (REG_ + 1u) + +/* Invalid state */ +#define SDEI_STATE_INVALID ((sdei_state_t) (-1)) + +/* No change in state */ +#define SDEI_STATE_NOP ((sdei_state_t) (-2)) + +#define X___ SDEI_STATE_INVALID +#define NOP_ SDEI_STATE_NOP + +/* Ensure special states don't overlap with valid ones */ +CASSERT(X___ > REG_, sdei_state_overlap_invalid); +CASSERT(NOP_ > REG_, sdei_state_overlap_nop); + +/* + * SDEI handler state machine: refer to sections 6.1 and 6.1.2 of the SDEI v1.0 + * specification (ARM DEN0054A). + * + * Not all calls contribute to handler state transition. This table is also used + * to validate whether a call is permissible at a given handler state: + * + * - X___ denotes a forbidden transition; + * - NOP_ denotes a permitted transition, but there's no change in state; + * - Otherwise, XXX_ gives the new state. + * + * DISP[atch] is a transition added for the implementation, but is not mentioned + * in the spec. + * + * Those calls that the spec mentions as can be made any time don't picture in + * this table. + */ + +static const sdei_state_t sdei_state_table[MAX_STATES][DO_MAX] = { +/* + * Action: REG REL ENA DISA UREG ROUT CTX COMP COMPR DISP + * Notes: [3] [1] [3] [3][4] [2] + */ + /* Handler unregistered, disabled, and not running. This is the default state. */ +/* 0 */ [reg_] = { reG_, NOP_, X___, X___, X___, X___, X___, X___, X___, X___, }, + + /* Handler unregistered and running */ +/* 4 */ [Reg_] = { X___, X___, X___, X___, X___, X___, NOP_, reg_, reg_, X___, }, + + /* Handler registered */ +/* 1 */ [reG_] = { X___, X___, rEG_, NOP_, reg_, NOP_, X___, X___, X___, X___, }, + + /* Handler registered and running */ +/* 5 */ [ReG_] = { X___, X___, REG_, NOP_, Reg_, X___, NOP_, reG_, reG_, X___, }, + + /* Handler registered and enabled */ +/* 3 */ [rEG_] = { X___, X___, NOP_, reG_, reg_, X___, X___, X___, X___, REG_, }, + + /* Handler registered, enabled, and running */ +/* 7 */ [REG_] = { X___, X___, NOP_, ReG_, Reg_, X___, NOP_, rEG_, rEG_, X___, }, + + /* + * Invalid states: no valid transition would leave the handler in these + * states; and no transition from these states is possible either. + */ + + /* + * Handler can't be enabled without being registered. I.e., XEg is + * impossible. + */ +/* 2 */ [rEg_] = { X___, X___, X___, X___, X___, X___, X___, X___, X___, X___, }, +/* 6 */ [REg_] = { X___, X___, X___, X___, X___, X___, X___, X___, X___, X___, }, +}; + +/* + * [1] Unregister will always also disable the event, so the new state will have + * Xeg. + * [2] Event is considered for dispatch only when it's both registered and + * enabled. + * [3] Never causes change in state. + * [4] Only allowed when running. + */ + +/* + * Given an action, transition the state of an event by looking up the state + * table above: + * + * - Return false for invalid transition; + * - Return true for valid transition that causes no change in state; + * - Otherwise, update state and return true. + * + * This function assumes that the caller holds necessary locks. If the + * transition has constrains other than the state table describes, the caller is + * expected to restore the previous state. See sdei_event_register() for + * example. + */ +bool can_sdei_state_trans(sdei_entry_t *se, sdei_action_t act) +{ + sdei_state_t next; + + assert(act < DO_MAX); + if (se->state >= MAX_STATES) { + WARN(" event state invalid: %x\n", se->state); + return false; + } + + next = sdei_state_table[se->state][act]; + switch (next) { + case SDEI_STATE_INVALID: + return false; + + case SDEI_STATE_NOP: + return true; + + default: + /* Valid transition. Update state. */ + SDEI_LOG(" event state 0x%x => 0x%x\n", se->state, next); + se->state = next; + + return true; + } +} -- cgit v1.2.3