diff options
Diffstat (limited to 'drivers/char/ipmi/ipmi_kcs_sm.c')
| -rw-r--r-- | drivers/char/ipmi/ipmi_kcs_sm.c | 531 |
1 files changed, 531 insertions, 0 deletions
diff --git a/drivers/char/ipmi/ipmi_kcs_sm.c b/drivers/char/ipmi/ipmi_kcs_sm.c new file mode 100644 index 000000000..f4ea9f472 --- /dev/null +++ b/drivers/char/ipmi/ipmi_kcs_sm.c @@ -0,0 +1,531 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * 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 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) { + kcs->obf_timeout = OBF_RETRY_TIMEOUT; + 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) +{ +} + +const 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, +}; |