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Diffstat (limited to 'drivers/char/ipmi/ipmi_kcs_sm.c')
-rw-r--r--drivers/char/ipmi/ipmi_kcs_sm.c536
1 files changed, 536 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..efda90dcf
--- /dev/null
+++ b/drivers/char/ipmi/ipmi_kcs_sm.c
@@ -0,0 +1,536 @@
+// 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.
+ */
+
+#define DEBUG /* So dev_dbg() is always available. */
+
+#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)
+ dev_dbg(kcs->io->dev, "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)) {
+ dev_warn(kcs->io->dev, "KCS in invalid state %d\n", kcs->state);
+ return IPMI_NOT_IN_MY_STATE_ERR;
+ }
+
+ if (kcs_debug & KCS_DEBUG_MSG) {
+ dev_dbg(kcs->io->dev, "%s -", __func__);
+ for (i = 0; i < size; i++)
+ pr_cont(" %02x", data[i]);
+ pr_cont("\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)
+ dev_dbg(kcs->io->dev,
+ "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,
+};
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