[Skiboot] [PATCH V4 04/21] core/pldm: Add PLDM responder support

Christophe Lombard clombard at linux.vnet.ibm.com
Thu Apr 14 23:43:47 AEST 2022


PLDM defines data representations and commands that abstract the platform
management hardware.

A PLDM Terminus (or responder) is defined as the point of communication
termination for PLDM messages and the PLDM functions associated with those
messages.
A PLDM terminus is not required to process more than one request at a time
(that is, it can be "single threaded" and does not have to accept and act
on new requests until it has finished responding to any previous request).

Some PLDM control and discovery requests (PLDM_TYPE = PLDM_BASE) are
mandatory a PLDM terminus has to answer.

These following mandatory PLDM command codes for PLDM messaging control
and discovery will be defined in next patches.
    GetTID          0x02
    GetPLDMVersion  0x03
    GetPLDMTypes    0x04
    GetPLDMCommands 0x05

Signed-off-by: Christophe Lombard <clombard at linux.vnet.ibm.com>
---
 core/pldm/Makefile.inc     |   2 +-
 core/pldm/pldm-common.c    |  18 ++++-
 core/pldm/pldm-responder.c | 136 +++++++++++++++++++++++++++++++++++++
 core/pldm/pldm.h           |   6 ++
 4 files changed, 160 insertions(+), 2 deletions(-)
 create mode 100644 core/pldm/pldm-responder.c

diff --git a/core/pldm/Makefile.inc b/core/pldm/Makefile.inc
index 005c7b94..3909c86f 100644
--- a/core/pldm/Makefile.inc
+++ b/core/pldm/Makefile.inc
@@ -7,7 +7,7 @@ SUBDIRS += $(PLDM_DIR)
 CPPFLAGS += -I$(SRC)/pldm/libpldm/
 CPPFLAGS += -I$(SRC)/pldm/ibm/libpldm/
 
-PLDM_OBJS = pldm-common.o
+PLDM_OBJS = pldm-common.o pldm-responder.o
 
 PLDM = $(PLDM_DIR)/built-in.a
 $(PLDM): $(PLDM_OBJS:%=$(PLDM_DIR)/%)
diff --git a/core/pldm/pldm-common.c b/core/pldm/pldm-common.c
index 5271dfbd..d6ab3273 100644
--- a/core/pldm/pldm-common.c
+++ b/core/pldm/pldm-common.c
@@ -75,6 +75,14 @@ static int pldm_handle(uint8_t eid, const uint8_t *buf, int len)
 		return OPAL_EMPTY;
 	}
 
+	switch (rx.hdrinf.msg_type) {
+	case PLDM_REQUEST:
+		return pldm_rx_handle_request(&rx);
+	break;
+	default:
+	break;
+	}
+
 	return OPAL_UNSUPPORTED;
 }
 
@@ -105,9 +113,17 @@ int pldm_mctp_init(void)
 
 	/* MCTP Binding */
 	rc = ast_mctp_init(pldm_rx_message);
-	if (rc)
+	if (rc) {
 		prlog(PR_ERR, "Failed to bind MCTP\n");
+		goto out;
+	}
+
+	/* Register mandatory commands we'll respond to */
+	rc = pldm_mctp_responder_init();
+	if (rc)
+		prlog(PR_ERR, "Failed to register mandatory commands\n");
 
+out:
 	prlog(PR_NOTICE, "%s - done, rc: %d\n", __func__, rc);
 	return rc;
 }
diff --git a/core/pldm/pldm-responder.c b/core/pldm/pldm-responder.c
new file mode 100644
index 00000000..7e5ca52f
--- /dev/null
+++ b/core/pldm/pldm-responder.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+// Copyright 2022 IBM Corp.
+
+#define pr_fmt(fmt) "PLDM: " fmt
+
+#include <bitmap.h>
+#include <cpu.h>
+#include <opal.h>
+#include <stdio.h>
+#include <string.h>
+#include <pldm/libpldm/utils.h>
+#include "pldm.h"
+
+struct pldm_cmd {
+	const char *name;
+	int pldm_cmd_id;
+
+	int (*handler)(const struct pldm_rx_data *req);
+
+	struct list_node link; /* link in the msg type's command list */
+};
+
+/*
+ * Send a response with just a completion code and no payload
+ */
+static int pldm_cc_resp(const struct pldm_rx_data *req, uint8_t type,
+			uint8_t command, uint8_t cc)
+{
+	char response_msg[PKT_SIZE(uint8_t)];
+	int rc;
+
+	memset(response_msg, 0, sizeof(response_msg));
+
+	encode_cc_only_resp(req->hdrinf.instance,
+			    type,
+			    command,
+			    cc,
+			    (struct pldm_msg *)response_msg);
+
+	rc = pldm_send(req->source_eid, response_msg, sizeof(response_msg));
+	if (rc) {
+		prlog(PR_ERR, "Failed to send response message containing only cc, "
+			      "rc = %d, cc = %d\n", rc, cc);
+		return OPAL_HARDWARE;
+	}
+
+	return OPAL_SUCCESS;
+}
+
+/*
+ * PLDM Type / Command wrangling.
+ */
+LIST_HEAD(pldm_type_list);
+
+static const struct pldm_type *find_type(int type_id)
+{
+	struct pldm_type *iter;
+
+	list_for_each(&pldm_type_list, iter, link) {
+		if (iter->pldm_type_id == type_id)
+			return iter;
+	}
+
+	return NULL;
+}
+
+static const struct pldm_cmd *find_cmd(const struct pldm_type *type, int cmd)
+{
+	struct pldm_cmd *iter;
+
+	list_for_each(&type->commands, iter, link)
+		if (iter->pldm_cmd_id == cmd)
+			return iter;
+
+	return NULL;
+}
+
+static void pldm_add_type(struct pldm_type *new_type)
+{
+	assert(new_type->pldm_type_id < 32); /* limited by GetPLDMTypes */
+	assert(!find_type(new_type->pldm_type_id));
+
+	list_head_init(&new_type->commands);
+	list_add_tail(&pldm_type_list, &new_type->link);
+
+	prlog(PR_DEBUG, "Registered type %s (%d)\n",
+	      new_type->name, new_type->pldm_type_id);
+}
+
+/*
+ * PLDM Base commands support
+ */
+static struct pldm_type pldm_base_type = {
+	.name = "base",
+	.pldm_type_id = PLDM_BASE,
+	.version = { 0xF1, 0xF0, 0xF0, 0x00 },
+};
+
+int pldm_rx_handle_request(struct pldm_rx_data *rx)
+{
+	const struct pldm_type *t;
+	const struct pldm_cmd *c;
+
+	prlog(PR_INFO, "Receive PLDM request from BMC, type: 0x%x, command: 0x%x\n",
+			rx->hdrinf.pldm_type, rx->hdrinf.command);
+
+	t = find_type(rx->hdrinf.pldm_type);
+	if (!t) {
+		prlog(PR_ERR, "Type not supported, type: 0x%x\n",
+			      rx->hdrinf.pldm_type);
+		pldm_cc_resp(rx, rx->hdrinf.pldm_type,
+			     rx->hdrinf.command,
+			     PLDM_ERROR_INVALID_PLDM_TYPE);
+		return OPAL_UNSUPPORTED;
+	}
+
+	c = find_cmd(t, rx->hdrinf.command);
+	if (!c) {
+		prlog(PR_ERR, "Command not supported, type: 0x%x, command: 0x%x\n",
+			      rx->hdrinf.pldm_type, rx->hdrinf.command);
+		pldm_cc_resp(rx, rx->hdrinf.pldm_type,
+			     rx->hdrinf.command,
+			     PLDM_ERROR_UNSUPPORTED_PLDM_CMD);
+		return OPAL_UNSUPPORTED;
+	}
+
+	return c->handler(rx);
+}
+
+int pldm_mctp_responder_init(void)
+{
+	/* Register mandatory commands we'll respond to - DSP0240 */
+	pldm_add_type(&pldm_base_type);
+
+	return OPAL_SUCCESS;
+}
diff --git a/core/pldm/pldm.h b/core/pldm/pldm.h
index 84649cf1..2887bd32 100644
--- a/core/pldm/pldm.h
+++ b/core/pldm/pldm.h
@@ -20,6 +20,8 @@ void printbuf(const char *name, const char *msg, int len);
 #define BMC_EID  8
 #define HOST_EID 9
 
+#define PKT_SIZE(x) (sizeof(struct pldm_msg_hdr) + sizeof(x))
+
 struct pldm_rx_data {
 	struct pldm_header_info hdrinf; /* parsed message header */
 
@@ -39,4 +41,8 @@ struct pldm_type {
 
 int pldm_send(uint8_t dest_id, uint8_t *buf, int len);
 
+/* Responder support */
+int pldm_rx_handle_request(struct pldm_rx_data *rx);
+int pldm_mctp_responder_init(void);
+
 #endif /* __COREPLDM_H__ */
-- 
2.35.1



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