core/pldm: Implement PLDM requester

Implement a way for sending PLDM requests for specific PLDM commands.

Send a PLDM request message. Wait for corresponding response message,
which once received, is returned to the caller.

If there's data available, return success only if data is a PLDM response
message that matches instance, pldm_type and command code.

Reviewed-by: Abhishek Singh Tomar <abhishek@linux.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.ibm.com>
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>

4 files changed, 351 insertions, 2 deletions

diff --git a/core/pldm/Makefile.inc b/core/pldm/Makefile.inc
index 9aa72a7..f2328a4 100644
--- a/core/pldm/Makefile.inc
+++ b/core/pldm/Makefile.inc
@@ -7,7 +7,7 @@ SUBDIRS += $(PLDM_DIR)
 CPPFLAGS += -I$(SRC)/pldm/include/
 CPPFLAGS += -I$(SRC)/pldm/include/libpldm/oem/ibm/
 
-PLDM_OBJS = pldm-mctp.o pldm-responder.o
+PLDM_OBJS = pldm-mctp.o pldm-responder.o pldm-requester.o
 
 PLDM = $(PLDM_DIR)/built-in.a
 $(PLDM): $(PLDM_OBJS:%=$(PLDM_DIR)/%)
diff --git a/core/pldm/pldm-mctp.c b/core/pldm/pldm-mctp.c
index 0e6a7e3..569fe25 100644
--- a/core/pldm/pldm-mctp.c
+++ b/core/pldm/pldm-mctp.c
@@ -54,6 +54,9 @@ int pldm_mctp_message_rx(uint8_t eid, bool tag_owner, uint8_t msg_tag,
 	}
 
 	switch (rx->hdrinf.msg_type) {
+	case PLDM_RESPONSE:
+		rc = pldm_requester_handle_response(rx);
+	break;
 	case PLDM_REQUEST:
 		rc = pldm_responder_handle_request(rx);
 	break;
@@ -71,16 +74,18 @@ out:
 
 int pldm_mctp_init(void)
 {
-	int nbr_elt = 2, rc = OPAL_SUCCESS;
+	int nbr_elt = 3, rc = OPAL_SUCCESS;
 
 	int (*pldm_config[])(void) = {
 		ast_mctp_init,		/* MCTP Binding */
 		pldm_responder_init,	/* Register mandatory commands we'll respond to */
+		pldm_requester_init,	/* Requester implementation */
 	};
 
 	const char *pldm_config_error[] = {
 		"Failed to bind MCTP",
 		"Failed to register mandatory commands",
+		"Failed to configure requister",
 	};
 
 	prlog(PR_NOTICE, "%s - Getting PLDM data\n", __func__);
diff --git a/core/pldm/pldm-requester.c b/core/pldm/pldm-requester.c
new file mode 100644
index 0000000..9830cda
--- /dev/null
+++ b/core/pldm/pldm-requester.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+// Copyright 2022 IBM Corp.
+
+#define pr_fmt(fmt) "PLDM: " fmt
+
+#include <cpu.h>
+#include <stdio.h>
+#include <string.h>
+#include <timebase.h>
+#include <ast.h>
+#include <libpldm/utils.h>
+#include "pldm.h"
+
+#define TIMEOUT_MS 8000
+
+struct pldm_request {
+	struct list_node link;
+
+	/* originating request params */
+	struct pldm_header_info hdrinf;
+
+	/* messages requested */
+	struct pldm_tx_data *tx;
+
+	/* timeout handling */
+	struct timer timeout;
+	uint64_t timeout_ms;
+	uint64_t start_time;
+
+	/* completion callback */
+	void (*complete)(struct pldm_rx_data *rx, void *data);
+	void *complete_data;
+};
+
+struct pldm_response {
+	void **msg;
+	size_t *msg_size;
+	bool done;
+	int rc;
+};
+
+/* pldm requests queue */
+static struct lock pldm_requests_lock = LOCK_UNLOCKED;
+static LIST_HEAD(list_pldm_requests);
+
+static struct pldm_request *active_request;
+
+static bool matches_request(const struct pldm_rx_data *rx,
+			    const struct pldm_request *req)
+{
+	if (req->hdrinf.instance != rx->hdrinf.instance)
+		return false;
+	if (req->hdrinf.pldm_type != rx->hdrinf.pldm_type)
+		return false;
+	if (req->hdrinf.command != rx->hdrinf.command)
+		return false;
+
+	return true;
+}
+
+static void send_and_wait_complete(struct pldm_rx_data *rx, void *data)
+{
+	struct pldm_response *resp = (struct pldm_response *)data;
+	int len;
+
+	if (rx != NULL) {
+		len = rx->msg_len;
+		*resp->msg_size = len;
+		*resp->msg = zalloc(len);
+		memcpy(*resp->msg, rx->msg, len);
+
+		resp->rc = OPAL_SUCCESS;
+	} else {
+		*resp->msg_size = 0;
+		*resp->msg = NULL;
+		resp->rc = OPAL_TIMEOUT;
+	}
+
+	resp->done = true;
+}
+
+static void handle_response(struct pldm_rx_data *rx)
+{
+	uint64_t now;
+
+	if (active_request == NULL) {
+		prlog(PR_ERR, "%s: No active request\n", __func__);
+		return;
+	}
+
+	/* unactivate the timer */
+	if (rx != NULL)
+		cancel_timer(&active_request->timeout);
+
+	if (active_request->complete)
+		active_request->complete(rx, active_request->complete_data);
+
+	now = mftb();
+	prlog(PR_TRACE, "%s: Finished after %ldms, t:%d c:%d i:%d\n",
+			__func__,
+			tb_to_msecs(now - active_request->start_time),
+			active_request->hdrinf.pldm_type,
+			active_request->hdrinf.command,
+			active_request->hdrinf.instance);
+
+	free(active_request->tx);
+	free(active_request);
+	active_request = NULL;
+}
+
+/*
+ * Timeout :(
+ */
+static void expiry(struct timer *t __unused, void *data, uint64_t now __unused)
+{
+	struct pldm_request *req = (struct pldm_request *)data;
+
+	if (active_request == NULL) {
+		prlog(PR_ERR, "request timedout! (active request NULL)\n");
+		return;
+	}
+
+	prlog(PR_ERR, "PLDM: request timedout! (active request: t:0x%x c:0x%x i:%d)\n",
+		      active_request->hdrinf.pldm_type,
+		      active_request->hdrinf.command,
+		      active_request->hdrinf.instance);
+
+	prlog(PR_ERR, "PLDM: Original request t:0x%x c:0x%x i:%d -----\n",
+			req->hdrinf.pldm_type,
+			req->hdrinf.command, req->hdrinf.instance);
+
+	/* no data received. Finish the procedure */
+	handle_response(NULL);
+}
+
+/*
+ * Handle PLDM message received from the PLDM terminus over MCTP
+ */
+int pldm_requester_handle_response(struct pldm_rx_data *rx)
+{
+	/* check the message received */
+	if (active_request == NULL) {
+		prlog(PR_ERR, "%s: No active request. "
+			      "Response received t:%d c:%d i:%d\n",
+			      __func__,
+			      rx->hdrinf.pldm_type,
+			      rx->hdrinf.command,
+			      rx->hdrinf.instance);
+		return OPAL_WRONG_STATE;
+	}
+
+	if (!matches_request(rx, active_request)) {
+		prlog(PR_ERR, "%s: Unexpected response! t:%d c:%d i:%d want %d,%d,%d\n",
+			      __func__,
+			      rx->hdrinf.pldm_type,
+			      rx->hdrinf.command,
+			      rx->hdrinf.instance,
+			      active_request->hdrinf.pldm_type,
+			      active_request->hdrinf.command,
+			      active_request->hdrinf.instance);
+		return OPAL_WRONG_STATE;
+	}
+
+	/* The expected message seems correct */
+	handle_response(rx);
+
+	return OPAL_SUCCESS;
+}
+
+/*
+ * Send the PLDM request
+ */
+static void requests_poller(void *data __unused)
+{
+	int rc = OPAL_SUCCESS;
+
+	lock(&pldm_requests_lock);
+
+	/* wait for the end of the processing of the current request */
+	if (active_request) {
+		unlock(&pldm_requests_lock);
+		return;
+	}
+
+	/* no new request to handle */
+	if (list_empty(&list_pldm_requests)) {
+		unlock(&pldm_requests_lock);
+		return;
+	}
+
+	/* remove the first entry in a list */
+	active_request = list_pop(&list_pldm_requests,
+				  struct pldm_request,
+				  link);
+
+	unlock(&pldm_requests_lock);
+
+	/* Start timer to control a timeout from the PLDM terminus */
+	init_timer(&active_request->timeout, expiry, active_request);
+	schedule_timer(&active_request->timeout,
+		       msecs_to_tb(active_request->timeout_ms));
+	active_request->start_time = mftb();
+
+	/* Send PLDM message over MCTP */
+	prlog(PR_TRACE, "%s: Sending request to BMC t:%d c:%d i:%d -----\n",
+			__func__,
+			active_request->hdrinf.pldm_type,
+			active_request->hdrinf.command,
+			active_request->hdrinf.instance);
+
+	rc = pldm_mctp_message_tx(active_request->tx);
+	if (rc)
+		prlog(PR_ERR, "%s: Error %d while sending request\n",
+		      __func__, rc);
+}
+
+/*
+ * Add PLDM request in the queue
+ */
+static int queue_request(struct pldm_tx_data *tx,
+			 uint64_t timeout_ms,
+			 void (*complete)(struct pldm_rx_data *rx, void *data),
+			 void *complete_data)
+{
+	struct pldm_request *pending;
+	struct pldm_msg *pldm_msg;
+	size_t tx_size;
+
+	tx_size = sizeof(struct pldm_tx_data) + tx->data_size;
+
+	pending = zalloc(sizeof(struct pldm_request));
+	if (!pending) {
+		prlog(PR_ERR, "%s: failed to allocate request\n", __func__);
+		return OPAL_NO_MEM;
+	}
+
+	pending->timeout_ms	= timeout_ms;
+	pending->complete	= complete;
+	pending->complete_data	= complete_data;
+	pending->tx		= zalloc(tx_size);
+	if (!pending->tx) {
+		free(pending);
+		prlog(PR_ERR, "%s: failed to allocate pldm packet (size: 0x%lx)\n",
+			      __func__, tx_size);
+		return OPAL_NO_MEM;
+	}
+
+	memcpy(pending->tx, tx, tx_size);
+
+	pldm_msg = (struct pldm_msg *)tx->data;
+	if (unpack_pldm_header(&pldm_msg->hdr, &pending->hdrinf)) {
+		free(pending->tx);
+		free(pending);
+		prlog(PR_ERR, "%s: error parsing pldm header\n", __func__);
+		return OPAL_PARAMETER;
+	}
+
+	/* add an entry at the end of a linked list */
+	prlog(PR_TRACE, "%s: Add request t:%d c:%d i:%d -----\n",
+			__func__,
+			pending->hdrinf.pldm_type,
+			pending->hdrinf.command,
+			pending->hdrinf.instance);
+
+	lock(&pldm_requests_lock);
+	list_add_tail(&list_pldm_requests, &pending->link);
+	unlock(&pldm_requests_lock);
+
+	return OPAL_SUCCESS;
+}
+
+/*
+ * Queue a PLDM request and don't wait.
+ * When a response is received, call the associated callback.
+ */
+int pldm_requester_queue(struct pldm_tx_data *tx,
+			 void (*complete)(struct pldm_rx_data *rx, void *data),
+			 void *complete_data)
+{
+	int rc = OPAL_SUCCESS;
+
+	/* Queue PLDM request */
+	rc = queue_request(tx, TIMEOUT_MS, complete, complete_data);
+	if (rc) {
+		prlog(PR_ERR, "%s: error %d while queuing request\n",
+			      __func__, rc);
+		return rc;
+	}
+
+	return rc;
+}
+
+/*
+ * Queue a PLDM request and spin until we get a response.
+ */
+int pldm_requester_queue_and_wait(struct pldm_tx_data *tx,
+				  void **msg, size_t *msg_size)
+{
+	struct pldm_response *resp;
+	int rc = OPAL_SUCCESS;
+
+	resp = zalloc(sizeof(struct pldm_response));
+	if (!resp) {
+		prlog(PR_ERR, "%s: failed to allocate response\n", __func__);
+		return OPAL_NO_MEM;
+	}
+
+	resp->msg = msg;
+	resp->msg_size = msg_size;
+
+	rc = pldm_requester_queue(tx, send_and_wait_complete, resp);
+	if (rc)
+		goto out;
+
+	/* wait for a response from the BMC */
+	for (;;) {
+		if (resp->done)
+			break;
+
+		time_wait_ms(5);
+	}
+	rc = resp->rc;
+
+out:
+	free(resp);
+	return rc;
+}
+
+int pldm_requester_init(void)
+{
+	/* requests poller */
+	opal_add_poller(requests_poller, NULL);
+
+	return OPAL_SUCCESS;
+}
diff --git a/core/pldm/pldm.h b/core/pldm/pldm.h
index d6eda42..7c7da9f 100644
--- a/core/pldm/pldm.h
+++ b/core/pldm/pldm.h
@@ -47,4 +47,13 @@ int pldm_mctp_message_rx(uint8_t eid, bool tag_owner, uint8_t msg_tag,
 int pldm_responder_handle_request(struct pldm_rx_data *rx);
 int pldm_responder_init(void);
 
+/* Requester support */
+int pldm_requester_handle_response(struct pldm_rx_data *rx);
+int pldm_requester_queue(struct pldm_tx_data *tx,
+			 void (*complete)(struct pldm_rx_data *rx, void *data),
+			 void *complete_data);
+int pldm_requester_queue_and_wait(struct pldm_tx_data *tx,
+				  void **msg, size_t *msg_size);
+int pldm_requester_init(void);
+
 #endif /* __COREPLDM_H__ */