532 lines
12 KiB
C
532 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* ipmi_kcs_sm.c
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*
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* State machine for handling IPMI KCS interfaces.
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*
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* Author: MontaVista Software, Inc.
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* Corey Minyard <minyard@mvista.com>
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* source@mvista.com
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*
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* Copyright 2002 MontaVista Software Inc.
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*/
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/*
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* This state machine is taken from the state machine in the IPMI spec,
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* pretty much verbatim. If you have questions about the states, see
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* that document.
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*/
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#include <linux/kernel.h> /* For printk. */
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/string.h>
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#include <linux/jiffies.h>
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#include <linux/ipmi_msgdefs.h> /* for completion codes */
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#include "ipmi_si_sm.h"
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/* kcs_debug is a bit-field
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* KCS_DEBUG_ENABLE - turned on for now
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* KCS_DEBUG_MSG - commands and their responses
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* KCS_DEBUG_STATES - state machine
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*/
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#define KCS_DEBUG_STATES 4
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#define KCS_DEBUG_MSG 2
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#define KCS_DEBUG_ENABLE 1
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static int kcs_debug;
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module_param(kcs_debug, int, 0644);
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MODULE_PARM_DESC(kcs_debug, "debug bitmask, 1=enable, 2=messages, 4=states");
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/* The states the KCS driver may be in. */
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enum kcs_states {
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/* The KCS interface is currently doing nothing. */
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KCS_IDLE,
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/*
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* We are starting an operation. The data is in the output
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* buffer, but nothing has been done to the interface yet. This
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* was added to the state machine in the spec to wait for the
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* initial IBF.
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*/
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KCS_START_OP,
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/* We have written a write cmd to the interface. */
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KCS_WAIT_WRITE_START,
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/* We are writing bytes to the interface. */
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KCS_WAIT_WRITE,
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/*
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* We have written the write end cmd to the interface, and
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* still need to write the last byte.
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*/
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KCS_WAIT_WRITE_END,
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/* We are waiting to read data from the interface. */
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KCS_WAIT_READ,
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/*
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* State to transition to the error handler, this was added to
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* the state machine in the spec to be sure IBF was there.
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*/
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KCS_ERROR0,
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/*
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* First stage error handler, wait for the interface to
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* respond.
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*/
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KCS_ERROR1,
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/*
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* The abort cmd has been written, wait for the interface to
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* respond.
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*/
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KCS_ERROR2,
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/*
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* We wrote some data to the interface, wait for it to switch
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* to read mode.
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*/
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KCS_ERROR3,
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/* The hardware failed to follow the state machine. */
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KCS_HOSED
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};
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#define MAX_KCS_READ_SIZE IPMI_MAX_MSG_LENGTH
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#define MAX_KCS_WRITE_SIZE IPMI_MAX_MSG_LENGTH
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/* Timeouts in microseconds. */
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#define IBF_RETRY_TIMEOUT (5*USEC_PER_SEC)
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#define OBF_RETRY_TIMEOUT (5*USEC_PER_SEC)
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#define MAX_ERROR_RETRIES 10
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#define ERROR0_OBF_WAIT_JIFFIES (2*HZ)
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struct si_sm_data {
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enum kcs_states state;
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struct si_sm_io *io;
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unsigned char write_data[MAX_KCS_WRITE_SIZE];
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int write_pos;
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int write_count;
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int orig_write_count;
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unsigned char read_data[MAX_KCS_READ_SIZE];
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int read_pos;
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int truncated;
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unsigned int error_retries;
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long ibf_timeout;
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long obf_timeout;
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unsigned long error0_timeout;
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};
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static unsigned int init_kcs_data(struct si_sm_data *kcs,
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struct si_sm_io *io)
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{
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kcs->state = KCS_IDLE;
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kcs->io = io;
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kcs->write_pos = 0;
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kcs->write_count = 0;
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kcs->orig_write_count = 0;
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kcs->read_pos = 0;
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kcs->error_retries = 0;
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kcs->truncated = 0;
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kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
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kcs->obf_timeout = OBF_RETRY_TIMEOUT;
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/* Reserve 2 I/O bytes. */
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return 2;
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}
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static inline unsigned char read_status(struct si_sm_data *kcs)
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{
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return kcs->io->inputb(kcs->io, 1);
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}
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static inline unsigned char read_data(struct si_sm_data *kcs)
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{
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return kcs->io->inputb(kcs->io, 0);
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}
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static inline void write_cmd(struct si_sm_data *kcs, unsigned char data)
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{
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kcs->io->outputb(kcs->io, 1, data);
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}
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static inline void write_data(struct si_sm_data *kcs, unsigned char data)
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{
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kcs->io->outputb(kcs->io, 0, data);
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}
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/* Control codes. */
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#define KCS_GET_STATUS_ABORT 0x60
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#define KCS_WRITE_START 0x61
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#define KCS_WRITE_END 0x62
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#define KCS_READ_BYTE 0x68
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/* Status bits. */
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#define GET_STATUS_STATE(status) (((status) >> 6) & 0x03)
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#define KCS_IDLE_STATE 0
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#define KCS_READ_STATE 1
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#define KCS_WRITE_STATE 2
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#define KCS_ERROR_STATE 3
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#define GET_STATUS_ATN(status) ((status) & 0x04)
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#define GET_STATUS_IBF(status) ((status) & 0x02)
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#define GET_STATUS_OBF(status) ((status) & 0x01)
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static inline void write_next_byte(struct si_sm_data *kcs)
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{
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write_data(kcs, kcs->write_data[kcs->write_pos]);
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(kcs->write_pos)++;
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(kcs->write_count)--;
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}
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static inline void start_error_recovery(struct si_sm_data *kcs, char *reason)
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{
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(kcs->error_retries)++;
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if (kcs->error_retries > MAX_ERROR_RETRIES) {
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if (kcs_debug & KCS_DEBUG_ENABLE)
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printk(KERN_DEBUG "ipmi_kcs_sm: kcs hosed: %s\n",
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reason);
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kcs->state = KCS_HOSED;
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} else {
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kcs->error0_timeout = jiffies + ERROR0_OBF_WAIT_JIFFIES;
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kcs->state = KCS_ERROR0;
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}
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}
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static inline void read_next_byte(struct si_sm_data *kcs)
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{
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if (kcs->read_pos >= MAX_KCS_READ_SIZE) {
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/* Throw the data away and mark it truncated. */
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read_data(kcs);
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kcs->truncated = 1;
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} else {
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kcs->read_data[kcs->read_pos] = read_data(kcs);
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(kcs->read_pos)++;
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}
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write_data(kcs, KCS_READ_BYTE);
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}
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static inline int check_ibf(struct si_sm_data *kcs, unsigned char status,
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long time)
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{
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if (GET_STATUS_IBF(status)) {
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kcs->ibf_timeout -= time;
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if (kcs->ibf_timeout < 0) {
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start_error_recovery(kcs, "IBF not ready in time");
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kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
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return 1;
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}
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return 0;
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}
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kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
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return 1;
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}
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static inline int check_obf(struct si_sm_data *kcs, unsigned char status,
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long time)
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{
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if (!GET_STATUS_OBF(status)) {
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kcs->obf_timeout -= time;
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if (kcs->obf_timeout < 0) {
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kcs->obf_timeout = OBF_RETRY_TIMEOUT;
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start_error_recovery(kcs, "OBF not ready in time");
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return 1;
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}
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return 0;
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}
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kcs->obf_timeout = OBF_RETRY_TIMEOUT;
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return 1;
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}
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static void clear_obf(struct si_sm_data *kcs, unsigned char status)
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{
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if (GET_STATUS_OBF(status))
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read_data(kcs);
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}
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static void restart_kcs_transaction(struct si_sm_data *kcs)
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{
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kcs->write_count = kcs->orig_write_count;
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kcs->write_pos = 0;
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kcs->read_pos = 0;
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kcs->state = KCS_WAIT_WRITE_START;
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kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
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kcs->obf_timeout = OBF_RETRY_TIMEOUT;
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write_cmd(kcs, KCS_WRITE_START);
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}
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static int start_kcs_transaction(struct si_sm_data *kcs, unsigned char *data,
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unsigned int size)
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{
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unsigned int i;
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if (size < 2)
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return IPMI_REQ_LEN_INVALID_ERR;
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if (size > MAX_KCS_WRITE_SIZE)
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return IPMI_REQ_LEN_EXCEEDED_ERR;
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if ((kcs->state != KCS_IDLE) && (kcs->state != KCS_HOSED))
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return IPMI_NOT_IN_MY_STATE_ERR;
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if (kcs_debug & KCS_DEBUG_MSG) {
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printk(KERN_DEBUG "start_kcs_transaction -");
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for (i = 0; i < size; i++)
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pr_cont(" %02x", data[i]);
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pr_cont("\n");
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}
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kcs->error_retries = 0;
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memcpy(kcs->write_data, data, size);
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kcs->write_count = size;
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kcs->orig_write_count = size;
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kcs->write_pos = 0;
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kcs->read_pos = 0;
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kcs->state = KCS_START_OP;
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kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
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kcs->obf_timeout = OBF_RETRY_TIMEOUT;
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return 0;
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}
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static int get_kcs_result(struct si_sm_data *kcs, unsigned char *data,
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unsigned int length)
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{
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if (length < kcs->read_pos) {
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kcs->read_pos = length;
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kcs->truncated = 1;
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}
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memcpy(data, kcs->read_data, kcs->read_pos);
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if ((length >= 3) && (kcs->read_pos < 3)) {
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/* Guarantee that we return at least 3 bytes, with an
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error in the third byte if it is too short. */
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data[2] = IPMI_ERR_UNSPECIFIED;
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kcs->read_pos = 3;
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}
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if (kcs->truncated) {
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/*
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* Report a truncated error. We might overwrite
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* another error, but that's too bad, the user needs
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* to know it was truncated.
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*/
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data[2] = IPMI_ERR_MSG_TRUNCATED;
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kcs->truncated = 0;
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}
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return kcs->read_pos;
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}
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/*
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* This implements the state machine defined in the IPMI manual, see
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* that for details on how this works. Divide that flowchart into
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* sections delimited by "Wait for IBF" and this will become clear.
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*/
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static enum si_sm_result kcs_event(struct si_sm_data *kcs, long time)
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{
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unsigned char status;
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unsigned char state;
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status = read_status(kcs);
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if (kcs_debug & KCS_DEBUG_STATES)
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printk(KERN_DEBUG "KCS: State = %d, %x\n", kcs->state, status);
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/* All states wait for ibf, so just do it here. */
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if (!check_ibf(kcs, status, time))
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return SI_SM_CALL_WITH_DELAY;
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/* Just about everything looks at the KCS state, so grab that, too. */
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state = GET_STATUS_STATE(status);
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switch (kcs->state) {
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case KCS_IDLE:
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/* If there's and interrupt source, turn it off. */
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clear_obf(kcs, status);
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if (GET_STATUS_ATN(status))
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return SI_SM_ATTN;
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else
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return SI_SM_IDLE;
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case KCS_START_OP:
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if (state != KCS_IDLE_STATE) {
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start_error_recovery(kcs,
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"State machine not idle at start");
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break;
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}
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clear_obf(kcs, status);
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write_cmd(kcs, KCS_WRITE_START);
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kcs->state = KCS_WAIT_WRITE_START;
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break;
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case KCS_WAIT_WRITE_START:
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if (state != KCS_WRITE_STATE) {
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start_error_recovery(
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kcs,
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"Not in write state at write start");
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break;
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}
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read_data(kcs);
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if (kcs->write_count == 1) {
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write_cmd(kcs, KCS_WRITE_END);
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kcs->state = KCS_WAIT_WRITE_END;
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} else {
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write_next_byte(kcs);
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kcs->state = KCS_WAIT_WRITE;
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}
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break;
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case KCS_WAIT_WRITE:
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if (state != KCS_WRITE_STATE) {
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start_error_recovery(kcs,
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"Not in write state for write");
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break;
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}
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clear_obf(kcs, status);
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if (kcs->write_count == 1) {
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write_cmd(kcs, KCS_WRITE_END);
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kcs->state = KCS_WAIT_WRITE_END;
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} else {
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write_next_byte(kcs);
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}
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break;
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case KCS_WAIT_WRITE_END:
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if (state != KCS_WRITE_STATE) {
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start_error_recovery(kcs,
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"Not in write state"
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" for write end");
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break;
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}
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clear_obf(kcs, status);
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write_next_byte(kcs);
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kcs->state = KCS_WAIT_READ;
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break;
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case KCS_WAIT_READ:
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if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) {
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start_error_recovery(
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kcs,
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"Not in read or idle in read state");
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break;
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}
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if (state == KCS_READ_STATE) {
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if (!check_obf(kcs, status, time))
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return SI_SM_CALL_WITH_DELAY;
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read_next_byte(kcs);
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} else {
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/*
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* We don't implement this exactly like the state
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* machine in the spec. Some broken hardware
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* does not write the final dummy byte to the
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* read register. Thus obf will never go high
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* here. We just go straight to idle, and we
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* handle clearing out obf in idle state if it
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* happens to come in.
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*/
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clear_obf(kcs, status);
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kcs->orig_write_count = 0;
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kcs->state = KCS_IDLE;
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return SI_SM_TRANSACTION_COMPLETE;
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}
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break;
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case KCS_ERROR0:
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clear_obf(kcs, status);
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status = read_status(kcs);
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if (GET_STATUS_OBF(status))
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/* controller isn't responding */
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if (time_before(jiffies, kcs->error0_timeout))
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return SI_SM_CALL_WITH_TICK_DELAY;
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write_cmd(kcs, KCS_GET_STATUS_ABORT);
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kcs->state = KCS_ERROR1;
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break;
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case KCS_ERROR1:
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clear_obf(kcs, status);
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write_data(kcs, 0);
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kcs->state = KCS_ERROR2;
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break;
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case KCS_ERROR2:
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if (state != KCS_READ_STATE) {
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start_error_recovery(kcs,
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"Not in read state for error2");
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break;
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}
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if (!check_obf(kcs, status, time))
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return SI_SM_CALL_WITH_DELAY;
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clear_obf(kcs, status);
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write_data(kcs, KCS_READ_BYTE);
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kcs->state = KCS_ERROR3;
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break;
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case KCS_ERROR3:
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if (state != KCS_IDLE_STATE) {
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start_error_recovery(kcs,
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"Not in idle state for error3");
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break;
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}
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if (!check_obf(kcs, status, time))
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return SI_SM_CALL_WITH_DELAY;
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clear_obf(kcs, status);
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if (kcs->orig_write_count) {
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restart_kcs_transaction(kcs);
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} else {
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kcs->state = KCS_IDLE;
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return SI_SM_TRANSACTION_COMPLETE;
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}
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break;
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case KCS_HOSED:
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break;
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}
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if (kcs->state == KCS_HOSED) {
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init_kcs_data(kcs, kcs->io);
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return SI_SM_HOSED;
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}
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return SI_SM_CALL_WITHOUT_DELAY;
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}
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static int kcs_size(void)
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{
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return sizeof(struct si_sm_data);
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}
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static int kcs_detect(struct si_sm_data *kcs)
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{
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/*
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* It's impossible for the KCS status register to be all 1's,
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* (assuming a properly functioning, self-initialized BMC)
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* but that's what you get from reading a bogus address, so we
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* test that first.
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*/
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if (read_status(kcs) == 0xff)
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return 1;
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return 0;
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}
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static void kcs_cleanup(struct si_sm_data *kcs)
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{
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}
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const struct si_sm_handlers kcs_smi_handlers = {
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.init_data = init_kcs_data,
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.start_transaction = start_kcs_transaction,
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.get_result = get_kcs_result,
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.event = kcs_event,
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.detect = kcs_detect,
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|
.cleanup = kcs_cleanup,
|
|
.size = kcs_size,
|
|
};
|