/*
* ipmi_kcs_sm.c
*
* State machine for handling IPMI KCS interfaces.
*
* Author: MontaVista Software, Inc.
* Corey Minyard <minyard@mvista.com>
* source@mvista.com
*
* Copyright 2002 MontaVista Software Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* This state machine is taken from the state machine in the IPMI spec,
* pretty much verbatim. If you have questions about the states, see
* that document.
*/
#include <linux/kernel.h> /* For printk. */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/string.h>
#include <linux/jiffies.h>
#include <linux/ipmi_msgdefs.h> /* for completion codes */
#include "ipmi_si_sm.h"
/* kcs_debug is a bit-field
* KCS_DEBUG_ENABLE - turned on for now
* KCS_DEBUG_MSG - commands and their responses
* KCS_DEBUG_STATES - state machine
*/
#define KCS_DEBUG_STATES 4
#define KCS_DEBUG_MSG 2
#define KCS_DEBUG_ENABLE 1
static int kcs_debug;
module_param(kcs_debug, int, 0644);
MODULE_PARM_DESC(kcs_debug, "debug bitmask, 1=enable, 2=messages, 4=states");
/* The states the KCS driver may be in. */
enum kcs_states {
/* The KCS interface is currently doing nothing. */
KCS_IDLE,
/*
* We are starting an operation. The data is in the output
* buffer, but nothing has been done to the interface yet. This
* was added to the state machine in the spec to wait for the
* initial IBF.
*/
KCS_START_OP,
/* We have written a write cmd to the interface. */
KCS_WAIT_WRITE_START,
/* We are writing bytes to the interface. */
KCS_WAIT_WRITE,
/*
* We have written the write end cmd to the interface, and
* still need to write the last byte.
*/
KCS_WAIT_WRITE_END,
/* We are waiting to read data from the interface. */
KCS_WAIT_READ,
/*
* State to transition to the error handler, this was added to
* the state machine in the spec to be sure IBF was there.
*/
KCS_ERROR0,
/*
* First stage error handler, wait for the interface to
* respond.
*/
KCS_ERROR1,
/*
* The abort cmd has been written, wait for the interface to
* respond.
*/
KCS_ERROR2,
/*
* We wrote some data to the interface, wait for it to switch
* to read mode.
*/
KCS_ERROR3,
/* The hardware failed to follow the state machine. */
KCS_HOSED
};
#define MAX_KCS_READ_SIZE IPMI_MAX_MSG_LENGTH
#define MAX_KCS_WRITE_SIZE IPMI_MAX_MSG_LENGTH
/* Timeouts in microseconds. */
#define IBF_RETRY_TIMEOUT (5*USEC_PER_SEC)
#define OBF_RETRY_TIMEOUT (5*USEC_PER_SEC)
#define MAX_ERROR_RETRIES 10
#define ERROR0_OBF_WAIT_JIFFIES (2*HZ)
struct si_sm_data {
enum kcs_states state;
struct si_sm_io *io;
unsigned char write_data[MAX_KCS_WRITE_SIZE];
int write_pos;
int write_count;
int orig_write_count;
unsigned char read_data[MAX_KCS_READ_SIZE];
int read_pos;
int truncated;
unsigned int error_retries;
long ibf_timeout;
long obf_timeout;
unsigned long error0_timeout;
};
static unsigned int init_kcs_data(struct si_sm_data *kcs,
struct si_sm_io *io)
{
kcs->state = KCS_IDLE;
kcs->io = io;
kcs->write_pos = 0;
kcs->write_count = 0;
kcs->orig_write_count = 0;
kcs->read_pos = 0;
kcs->error_retries = 0;
kcs->truncated = 0;
kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
kcs->obf_timeout = OBF_RETRY_TIMEOUT;
/* Reserve 2 I/O bytes. */
return 2;
}
static inline unsigned char read_status(struct si_sm_data *kcs)
{
return kcs->io->inputb(kcs->io, 1);
}
static inline unsigned char read_data(struct si_sm_data *kcs)
{
return kcs->io->inputb(kcs->io, 0);
}
static inline void write_cmd(struct si_sm_data *kcs, unsigned char data)
{
kcs->io->outputb(kcs->io, 1, data);
}
static inline void write_data(struct si_sm_data *kcs, unsigned char data)
{
kcs->io->outputb(kcs->io, 0, data);
}
/* Control codes. */
#define KCS_GET_STATUS_ABORT 0x60
#define KCS_WRITE_START 0x61
#define KCS_WRITE_END 0x62
#define KCS_READ_BYTE 0x68
/* Status bits. */
#define GET_STATUS_STATE(status) (((status) >> 6) & 0x03)
#define KCS_IDLE_STATE 0
#define KCS_READ_STATE 1
#define KCS_WRITE_STATE 2
#define KCS_ERROR_STATE 3
#define GET_STATUS_ATN(status) ((status) & 0x04)
#define GET_STATUS_IBF(status) ((status) & 0x02)
#define GET_STATUS_OBF(status) ((status) & 0x01)
static inline void write_next_byte(struct si_sm_data *kcs)
{
write_data(kcs, kcs->write_data[kcs->write_pos]);
(kcs->write_pos)++;
(kcs->write_count)--;
}
static inline void start_error_recovery(struct si_sm_data *kcs, char *reason)
{
(kcs->error_retries)++;
if (kcs->error_retries > MAX_ERROR_RETRIES) {
if (kcs_debug & KCS_DEBUG_ENABLE)
printk(KERN_DEBUG "ipmi_kcs_sm: kcs hosed: %s\n",
reason);
kcs->state = KCS_HOSED;
} else {
kcs->error0_timeout = jiffies + ERROR0_OBF_WAIT_JIFFIES;
kcs->state = KCS_ERROR0;
}
}
static inline void read_next_byte(struct si_sm_data *kcs)
{
if (kcs->read_pos >= MAX_KCS_READ_SIZE) {
/* Throw the data away and mark it truncated. */
read_data(kcs);
kcs->truncated = 1;
} else {
kcs->read_data[kcs->read_pos] = read_data(kcs);
(kcs->read_pos)++;
}
write_data(kcs, KCS_READ_BYTE);
}
static inline int check_ibf(struct si_sm_data *kcs, unsigned char status,
long time)
{
if (GET_STATUS_IBF(status)) {
kcs->ibf_timeout -= time;
if (kcs->ibf_timeout < 0) {
start_error_recovery(kcs, "IBF not ready in time");
kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
return 1;
}
return 0;
}
kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
return 1;
}
static inline int check_obf(struct si_sm_data *kcs, unsigned char status,
long time)
{
if (!GET_STATUS_OBF(status)) {
kcs->obf_timeout -= time;
if (kcs->obf_timeout < 0) {
start_error_recovery(kcs, "OBF not ready in time");
return 1;
}
return 0;
}
kcs->obf_timeout = OBF_RETRY_TIMEOUT;
return 1;
}
static void clear_obf(struct si_sm_data *kcs, unsigned char status)
{
if (GET_STATUS_OBF(status))
read_data(kcs);
}
static void restart_kcs_transaction(struct si_sm_data *kcs)
{
kcs->write_count = kcs->orig_write_count;
kcs->write_pos = 0;
kcs->read_pos = 0;
kcs->state = KCS_WAIT_WRITE_START;
kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
kcs->obf_timeout = OBF_RETRY_TIMEOUT;
write_cmd(kcs, KCS_WRITE_START);
}
static int start_kcs_transaction(struct si_sm_data *kcs, unsigned char *data,
unsigned int size)
{
unsigned int i;
if (size < 2)
return IPMI_REQ_LEN_INVALID_ERR;
if (size > MAX_KCS_WRITE_SIZE)
return IPMI_REQ_LEN_EXCEEDED_ERR;
if ((kcs->state != KCS_IDLE) && (kcs->state != KCS_HOSED))
return IPMI_NOT_IN_MY_STATE_ERR;
if (kcs_debug & KCS_DEBUG_MSG) {
printk(KERN_DEBUG "start_kcs_transaction -");
for (i = 0; i < size; i++)
printk(" %02x", (unsigned char) (data [i]));
printk("\n");
}
kcs->error_retries = 0;
memcpy(kcs->write_data, data, size);
kcs->write_count = size;
kcs->orig_write_count = size;
kcs->write_pos = 0;
kcs->read_pos = 0;
kcs->state = KCS_START_OP;
kcs->ibf_timeout = IBF_RETRY_TIMEOUT;
kcs->obf_timeout = OBF_RETRY_TIMEOUT;
return 0;
}
static int get_kcs_result(struct si_sm_data *kcs, unsigned char *data,
unsigned int length)
{
if (length < kcs->read_pos) {
kcs->read_pos = length;
kcs->truncated = 1;
}
memcpy(data, kcs->read_data, kcs->read_pos);
if ((length >= 3) && (kcs->read_pos < 3)) {
/* Guarantee that we return at least 3 bytes, with an
error in the third byte if it is too short. */
data[2] = IPMI_ERR_UNSPECIFIED;
kcs->read_pos = 3;
}
if (kcs->truncated) {
/*
* Report a truncated error. We might overwrite
* another error, but that's too bad, the user needs
* to know it was truncated.
*/
data[2] = IPMI_ERR_MSG_TRUNCATED;
kcs->truncated = 0;
}
return kcs->read_pos;
}
/*
* This implements the state machine defined in the IPMI manual, see
* that for details on how this works. Divide that flowchart into
* sections delimited by "Wait for IBF" and this will become clear.
*/
static enum si_sm_result kcs_event(struct si_sm_data *kcs, long time)
{
unsigned char status;
unsigned char state;
status = read_status(kcs);
if (kcs_debug & KCS_DEBUG_STATES)
printk(KERN_DEBUG "KCS: State = %d, %x\n", kcs->state, status);
/* All states wait for ibf, so just do it here. */
if (!check_ibf(kcs, status, time))
return SI_SM_CALL_WITH_DELAY;
/* Just about everything looks at the KCS state, so grab that, too. */
state = GET_STATUS_STATE(status);
switch (kcs->state) {
case KCS_IDLE:
/* If there's and interrupt source, turn it off. */
clear_obf(kcs, status);
if (GET_STATUS_ATN(status))
return SI_SM_ATTN;
else
return SI_SM_IDLE;
case KCS_START_OP:
if (state != KCS_IDLE_STATE) {
start_error_recovery(kcs,
"State machine not idle at start");
break;
}
clear_obf(kcs, status);
write_cmd(kcs, KCS_WRITE_START);
kcs->state = KCS_WAIT_WRITE_START;
break;
case KCS_WAIT_WRITE_START:
if (state != KCS_WRITE_STATE) {
start_error_recovery(
kcs,
"Not in write state at write start");
break;
}
read_data(kcs);
if (kcs->write_count == 1) {
write_cmd(kcs, KCS_WRITE_END);
kcs->state = KCS_WAIT_WRITE_END;
} else {
write_next_byte(kcs);
kcs->state = KCS_WAIT_WRITE;
}
break;
case KCS_WAIT_WRITE:
if (state != KCS_WRITE_STATE) {
start_error_recovery(kcs,
"Not in write state for write");
break;
}
clear_obf(kcs, status);
if (kcs->write_count == 1) {
write_cmd(kcs, KCS_WRITE_END);
kcs->state = KCS_WAIT_WRITE_END;
} else {
write_next_byte(kcs);
}
break;
case KCS_WAIT_WRITE_END:
if (state != KCS_WRITE_STATE) {
start_error_recovery(kcs,
"Not in write state"
" for write end");
break;
}
clear_obf(kcs, status);
write_next_byte(kcs);
kcs->state = KCS_WAIT_READ;
break;
case KCS_WAIT_READ:
if ((state != KCS_READ_STATE) && (state != KCS_IDLE_STATE)) {
start_error_recovery(
kcs,
"Not in read or idle in read state");
break;
}
if (state == KCS_READ_STATE) {
if (!check_obf(kcs, status, time))
return SI_SM_CALL_WITH_DELAY;
read_next_byte(kcs);
} else {
/*
* We don't implement this exactly like the state
* machine in the spec. Some broken hardware
* does not write the final dummy byte to the
* read register. Thus obf will never go high
* here. We just go straight to idle, and we
* handle clearing out obf in idle state if it
* happens to come in.
*/
clear_obf(kcs, status);
kcs->orig_write_count = 0;
kcs->state = KCS_IDLE;
return SI_SM_TRANSACTION_COMPLETE;
}
break;
case KCS_ERROR0:
clear_obf(kcs, status);
status = read_status(kcs);
if (GET_STATUS_OBF(status))
/* controller isn't responding */
if (time_before(jiffies, kcs->error0_timeout))
return SI_SM_CALL_WITH_TICK_DELAY;
write_cmd(kcs, KCS_GET_STATUS_ABORT);
kcs->state = KCS_ERROR1;
break;
case KCS_ERROR1:
clear_obf(kcs, status);
write_data(kcs, 0);
kcs->state = KCS_ERROR2;
break;
case KCS_ERROR2:
if (state != KCS_READ_STATE) {
start_error_recovery(kcs,
"Not in read state for error2");
break;
}
if (!check_obf(kcs, status, time))
return SI_SM_CALL_WITH_DELAY;
clear_obf(kcs, status);
write_data(kcs, KCS_READ_BYTE);
kcs->state = KCS_ERROR3;
break;
case KCS_ERROR3:
if (state != KCS_IDLE_STATE) {
start_error_recovery(kcs,
"Not in idle state for error3");
break;
}
if (!check_obf(kcs, status, time))
return SI_SM_CALL_WITH_DELAY;
clear_obf(kcs, status);
if (kcs->orig_write_count) {
restart_kcs_transaction(kcs);
} else {
kcs->state = KCS_IDLE;
return SI_SM_TRANSACTION_COMPLETE;
}
break;
case KCS_HOSED:
break;
}
if (kcs->state == KCS_HOSED) {
init_kcs_data(kcs, kcs->io);
return SI_SM_HOSED;
}
return SI_SM_CALL_WITHOUT_DELAY;
}
static int kcs_size(void)
{
return sizeof(struct si_sm_data);
}
static int kcs_detect(struct si_sm_data *kcs)
{
/*
* It's impossible for the KCS status register to be all 1's,
* (assuming a properly functioning, self-initialized BMC)
* but that's what you get from reading a bogus address, so we
* test that first.
*/
if (read_status(kcs) == 0xff)
return 1;
return 0;
}
static void kcs_cleanup(struct si_sm_data *kcs)
{
}
struct si_sm_handlers kcs_smi_handlers = {
.init_data = init_kcs_data,
.start_transaction = start_kcs_transaction,
.get_result = get_kcs_result,
.event = kcs_event,
.detect = kcs_detect,
.cleanup = kcs_cleanup,
.size = kcs_size,
};