[PATCH 0/5] Add support for access through an IPMB bus

[PATCH 0/5] Add support for access through an IPMB bus

[minyard]

This patch sets lets a devices that is sitting on an IPMB bus talk to
the BMC as a normal system interfaces.

It also adds the ability to message other MCs directly on the IPMB, and
it can receive commands and respond on the IPMB, too.

This is not meant as a replacement for ipmi_dev_int.c.  If you are doing
a full BMC, that's probably a better choice.  These changes are for
devices talking on the IPMB to BMCs or other MCs that might get some
commands to handle.

-corey

[PATCH 1/5] ipmi: Export ipmb_checksum()

[minyard]

From: Corey Minyard <cminyard@mvista.com>

It will be needed by the upcoming ipmb direct addressing.

Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
---
 drivers/char/ipmi/ipmi_msghandler.c | 3 ++-
 include/linux/ipmi.h                | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 13988f88f1b0..ad1a8fc379b9 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -1710,7 +1710,7 @@ int ipmi_unregister_for_cmd(struct ipmi_user *user,
 }
 EXPORT_SYMBOL(ipmi_unregister_for_cmd);
 
-static unsigned char
+unsigned char
 ipmb_checksum(unsigned char *data, int size)
 {
 	unsigned char csum = 0;
@@ -1720,6 +1720,7 @@ ipmb_checksum(unsigned char *data, int size)
 
 	return -csum;
 }
+EXPORT_SYMBOL(ipmb_checksum);
 
 static inline void format_ipmb_msg(struct ipmi_smi_msg   *smi_msg,
 				   struct kernel_ipmi_msg *msg,
diff --git a/include/linux/ipmi.h b/include/linux/ipmi.h
index 52850a02a3d0..163831a087ef 100644
--- a/include/linux/ipmi.h
+++ b/include/linux/ipmi.h
@@ -335,4 +335,7 @@ extern int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data);
 
 #define GET_DEVICE_ID_MAX_RETRY		5
 
+/* Helper function for computing the IPMB checksum of some data. */
+unsigned char ipmb_checksum(unsigned char *data, int size);
+
 #endif /* __LINUX_IPMI_H */
-- 
2.25.1

[PATCH 2/5] ipmi: Add support for IPMB direct messages

[minyard]

From: Corey Minyard <cminyard@mvista.com>

An application has come up that has a device sitting right on the IPMB
that would like to communicate with the BMC on the IPMB using normal
IPMI commands.

Sending these commands and handling the responses is easy enough, no
modifications are needed to the IPMI infrastructure.  But if this is an
application that also needs to receive IPMB commands and respond, some
way is needed to handle these incoming commands and send the responses.

Currently, the IPMI message handler only sends commands to the interface
and only receives responses from interface.  This change extends the
interface to receive commands/responses and send commands/responses.
These are formatted differently in support of receiving/sending IPMB
messages directly.

Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
---
 drivers/char/ipmi/ipmi_msghandler.c | 288 ++++++++++++++++++++++++----
 include/linux/ipmi_smi.h            |  59 ++++++
 include/uapi/linux/ipmi.h           |  14 ++
 3 files changed, 328 insertions(+), 33 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index ad1a8fc379b9..a60201d3f735 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -653,6 +653,11 @@ static int is_ipmb_bcast_addr(struct ipmi_addr *addr)
 	return addr->addr_type == IPMI_IPMB_BROADCAST_ADDR_TYPE;
 }
 
+static int is_ipmb_direct_addr(struct ipmi_addr *addr)
+{
+	return addr->addr_type == IPMI_IPMB_DIRECT_ADDR_TYPE;
+}
+
 static void free_recv_msg_list(struct list_head *q)
 {
 	struct ipmi_recv_msg *msg, *msg2;
@@ -805,6 +810,17 @@ ipmi_addr_equal(struct ipmi_addr *addr1, struct ipmi_addr *addr2)
 			&& (ipmb_addr1->lun == ipmb_addr2->lun));
 	}
 
+	if (is_ipmb_direct_addr(addr1)) {
+		struct ipmi_ipmb_direct_addr *daddr1
+			= (struct ipmi_ipmb_direct_addr *) addr1;
+		struct ipmi_ipmb_direct_addr *daddr2
+			= (struct ipmi_ipmb_direct_addr *) addr2;
+
+		return daddr1->slave_addr == daddr2->slave_addr &&
+			daddr1->rq_lun == daddr2->rq_lun &&
+			daddr1->rs_lun == daddr2->rs_lun;
+	}
+
 	if (is_lan_addr(addr1)) {
 		struct ipmi_lan_addr *lan_addr1
 			= (struct ipmi_lan_addr *) addr1;
@@ -843,6 +859,23 @@ int ipmi_validate_addr(struct ipmi_addr *addr, int len)
 		return 0;
 	}
 
+	if (is_ipmb_direct_addr(addr)) {
+		struct ipmi_ipmb_direct_addr *daddr = (void *) addr;
+
+		if (addr->channel != 0)
+			return -EINVAL;
+		if (len < sizeof(struct ipmi_ipmb_direct_addr))
+			return -EINVAL;
+
+		if (daddr->slave_addr & 0x01)
+			return -EINVAL;
+		if (daddr->rq_lun >= 4)
+			return -EINVAL;
+		if (daddr->rs_lun >= 4)
+			return -EINVAL;
+		return 0;
+	}
+
 	if (is_lan_addr(addr)) {
 		if (len < sizeof(struct ipmi_lan_addr))
 			return -EINVAL;
@@ -862,6 +895,9 @@ unsigned int ipmi_addr_length(int addr_type)
 			|| (addr_type == IPMI_IPMB_BROADCAST_ADDR_TYPE))
 		return sizeof(struct ipmi_ipmb_addr);
 
+	if (addr_type == IPMI_IPMB_DIRECT_ADDR_TYPE)
+		return sizeof(struct ipmi_ipmb_direct_addr);
+
 	if (addr_type == IPMI_LAN_ADDR_TYPE)
 		return sizeof(struct ipmi_lan_addr);
 
@@ -2052,6 +2088,58 @@ static int i_ipmi_req_ipmb(struct ipmi_smi        *intf,
 	return rv;
 }
 
+static int i_ipmi_req_ipmb_direct(struct ipmi_smi        *intf,
+				  struct ipmi_addr       *addr,
+				  long			 msgid,
+				  struct kernel_ipmi_msg *msg,
+				  struct ipmi_smi_msg    *smi_msg,
+				  struct ipmi_recv_msg   *recv_msg,
+				  unsigned char          source_lun)
+{
+	struct ipmi_ipmb_direct_addr *daddr;
+	bool is_cmd = !(recv_msg->msg.netfn & 0x1);
+
+	if (!(intf->handlers->flags & IPMI_SMI_CAN_HANDLE_IPMB_DIRECT))
+		return -EAFNOSUPPORT;
+
+	/* Responses must have a completion code. */
+	if (!is_cmd && msg->data_len < 1) {
+		ipmi_inc_stat(intf, sent_invalid_commands);
+		return -EINVAL;
+	}
+
+	if ((msg->data_len + 4) > IPMI_MAX_MSG_LENGTH) {
+		ipmi_inc_stat(intf, sent_invalid_commands);
+		return -EMSGSIZE;
+	}
+
+	daddr = (struct ipmi_ipmb_direct_addr *) addr;
+	if (daddr->rq_lun > 3 || daddr->rs_lun > 3) {
+		ipmi_inc_stat(intf, sent_invalid_commands);
+		return -EINVAL;
+	}
+
+	smi_msg->type = IPMI_SMI_MSG_TYPE_IPMB_DIRECT;
+	smi_msg->msgid = msgid;
+
+	if (is_cmd) {
+		smi_msg->data[0] = msg->netfn << 2 | daddr->rs_lun;
+		smi_msg->data[2] = recv_msg->msgid << 2 | daddr->rq_lun;
+	} else {
+		smi_msg->data[0] = msg->netfn << 2 | daddr->rq_lun;
+		smi_msg->data[2] = recv_msg->msgid << 2 | daddr->rs_lun;
+	}
+	smi_msg->data[1] = daddr->slave_addr;
+	smi_msg->data[3] = msg->cmd;
+
+	memcpy(smi_msg->data + 4, msg->data, msg->data_len);
+	smi_msg->data_size = msg->data_len + 4;
+
+	smi_msg->user_data = recv_msg;
+
+	return 0;
+}
+
 static int i_ipmi_req_lan(struct ipmi_smi        *intf,
 			  struct ipmi_addr       *addr,
 			  long                   msgid,
@@ -2241,6 +2329,9 @@ static int i_ipmi_request(struct ipmi_user     *user,
 		rv = i_ipmi_req_ipmb(intf, addr, msgid, msg, smi_msg, recv_msg,
 				     source_address, source_lun,
 				     retries, retry_time_ms);
+	} else if (is_ipmb_direct_addr(addr)) {
+		rv = i_ipmi_req_ipmb_direct(intf, addr, msgid, msg, smi_msg,
+					    recv_msg, source_lun);
 	} else if (is_lan_addr(addr)) {
 		rv = i_ipmi_req_lan(intf, addr, msgid, msg, smi_msg, recv_msg,
 				    source_lun, retries, retry_time_ms);
@@ -3802,6 +3893,123 @@ static int handle_ipmb_get_msg_cmd(struct ipmi_smi *intf,
 	return rv;
 }
 
+static int handle_ipmb_direct_rcv_cmd(struct ipmi_smi *intf,
+				      struct ipmi_smi_msg *msg)
+{
+	struct cmd_rcvr          *rcvr;
+	int                      rv = 0;
+	struct ipmi_user         *user = NULL;
+	struct ipmi_ipmb_direct_addr *daddr;
+	struct ipmi_recv_msg     *recv_msg;
+	unsigned char netfn = msg->rsp[0] >> 2;
+	unsigned char cmd = msg->rsp[3];
+
+	rcu_read_lock();
+	/* We always use channel 0 for direct messages. */
+	rcvr = find_cmd_rcvr(intf, netfn, cmd, 0);
+	if (rcvr) {
+		user = rcvr->user;
+		kref_get(&user->refcount);
+	} else
+		user = NULL;
+	rcu_read_unlock();
+
+	if (user == NULL) {
+		/* We didn't find a user, deliver an error response. */
+		ipmi_inc_stat(intf, unhandled_commands);
+
+		msg->data[0] = ((netfn + 1) << 2) | (msg->rsp[4] & 0x3);
+		msg->data[1] = msg->rsp[2];
+		msg->data[2] = msg->rsp[4] & ~0x3;
+		msg->data[3] = cmd;
+		msg->data[4] = IPMI_INVALID_CMD_COMPLETION_CODE;
+		msg->data_size = 5;
+
+		rcu_read_lock();
+		if (!intf->in_shutdown) {
+			smi_send(intf, intf->handlers, msg, 0);
+			/*
+			 * We used the message, so return the value
+			 * that causes it to not be freed or
+			 * queued.
+			 */
+			rv = -1;
+		}
+		rcu_read_unlock();
+	} else {
+		recv_msg = ipmi_alloc_recv_msg();
+		if (!recv_msg) {
+			/*
+			 * We couldn't allocate memory for the
+			 * message, so requeue it for handling
+			 * later.
+			 */
+			rv = 1;
+			kref_put(&user->refcount, free_user);
+		} else {
+			/* Extract the source address from the data. */
+			daddr = (struct ipmi_ipmb_direct_addr *)&recv_msg->addr;
+			daddr->addr_type = IPMI_IPMB_DIRECT_ADDR_TYPE;
+			daddr->channel = 0;
+			daddr->slave_addr = msg->rsp[1];
+			daddr->rs_lun = msg->rsp[0] & 3;
+			daddr->rq_lun = msg->rsp[2] & 3;
+
+			/*
+			 * Extract the rest of the message information
+			 * from the IPMB header.
+			 */
+			recv_msg->user = user;
+			recv_msg->recv_type = IPMI_CMD_RECV_TYPE;
+			recv_msg->msgid = (msg->rsp[2] >> 2);
+			recv_msg->msg.netfn = msg->rsp[0] >> 2;
+			recv_msg->msg.cmd = msg->rsp[3];
+			recv_msg->msg.data = recv_msg->msg_data;
+
+			recv_msg->msg.data_len = msg->rsp_size - 4;
+			memcpy(recv_msg->msg_data, msg->rsp + 4,
+			       msg->rsp_size - 4);
+			if (deliver_response(intf, recv_msg))
+				ipmi_inc_stat(intf, unhandled_commands);
+			else
+				ipmi_inc_stat(intf, handled_commands);
+		}
+	}
+
+	return rv;
+}
+
+static int handle_ipmb_direct_rcv_rsp(struct ipmi_smi *intf,
+				      struct ipmi_smi_msg *msg)
+{
+	struct ipmi_recv_msg *recv_msg;
+	struct ipmi_ipmb_direct_addr *daddr;
+
+	recv_msg = (struct ipmi_recv_msg *) msg->user_data;
+	if (recv_msg == NULL) {
+		dev_warn(intf->si_dev,
+			 "IPMI message received with no owner. This could be because of a malformed message, or because of a hardware error.  Contact your hardware vendor for assistance.\n");
+		return 0;
+	}
+
+	recv_msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
+	recv_msg->msgid = msg->msgid;
+	daddr = (struct ipmi_ipmb_direct_addr *) &recv_msg->addr;
+	daddr->addr_type = IPMI_IPMB_DIRECT_ADDR_TYPE;
+	daddr->channel = 0;
+	daddr->slave_addr = msg->rsp[1];
+	daddr->rq_lun = msg->rsp[0] & 3;
+	daddr->rs_lun = msg->rsp[2] & 3;
+	recv_msg->msg.netfn = msg->rsp[0] >> 2;
+	recv_msg->msg.cmd = msg->rsp[3];
+	memcpy(recv_msg->msg_data, &msg->rsp[4], msg->rsp_size - 4);
+	recv_msg->msg.data = recv_msg->msg_data;
+	recv_msg->msg.data_len = msg->rsp_size - 4;
+	deliver_local_response(intf, recv_msg);
+
+	return 0;
+}
+
 static int handle_lan_get_msg_rsp(struct ipmi_smi *intf,
 				  struct ipmi_smi_msg *msg)
 {
@@ -4227,18 +4435,40 @@ static int handle_bmc_rsp(struct ipmi_smi *intf,
 static int handle_one_recv_msg(struct ipmi_smi *intf,
 			       struct ipmi_smi_msg *msg)
 {
-	int requeue;
+	int requeue = 0;
 	int chan;
+	unsigned char cc;
+	bool is_cmd = !((msg->rsp[0] >> 2) & 1);
 
 	pr_debug("Recv: %*ph\n", msg->rsp_size, msg->rsp);
 
-	if ((msg->data_size >= 2)
+	if (msg->rsp_size < 2) {
+		/* Message is too small to be correct. */
+		dev_warn(intf->si_dev,
+			 "BMC returned too small a message for netfn %x cmd %x, got %d bytes\n",
+			 (msg->data[0] >> 2) | 1, msg->data[1], msg->rsp_size);
+
+return_unspecified:
+		/* Generate an error response for the message. */
+		msg->rsp[0] = msg->data[0] | (1 << 2);
+		msg->rsp[1] = msg->data[1];
+		msg->rsp[2] = IPMI_ERR_UNSPECIFIED;
+		msg->rsp_size = 3;
+	} else if (msg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
+		/* commands must have at least 3 bytes, responses 4. */
+		if (is_cmd && (msg->rsp_size < 3)) {
+			ipmi_inc_stat(intf, invalid_commands);
+			goto out;
+		}
+		if (!is_cmd && (msg->rsp_size < 4))
+			goto return_unspecified;
+	} else if ((msg->data_size >= 2)
 	    && (msg->data[0] == (IPMI_NETFN_APP_REQUEST << 2))
 	    && (msg->data[1] == IPMI_SEND_MSG_CMD)
 	    && (msg->user_data == NULL)) {
 
 		if (intf->in_shutdown)
-			goto free_msg;
+			goto out;
 
 		/*
 		 * This is the local response to a command send, start
@@ -4273,21 +4503,6 @@ static int handle_one_recv_msg(struct ipmi_smi *intf,
 		} else
 			/* The message was sent, start the timer. */
 			intf_start_seq_timer(intf, msg->msgid);
-free_msg:
-		requeue = 0;
-		goto out;
-
-	} else if (msg->rsp_size < 2) {
-		/* Message is too small to be correct. */
-		dev_warn(intf->si_dev,
-			 "BMC returned too small a message for netfn %x cmd %x, got %d bytes\n",
-			 (msg->data[0] >> 2) | 1, msg->data[1], msg->rsp_size);
-
-		/* Generate an error response for the message. */
-		msg->rsp[0] = msg->data[0] | (1 << 2);
-		msg->rsp[1] = msg->data[1];
-		msg->rsp[2] = IPMI_ERR_UNSPECIFIED;
-		msg->rsp_size = 3;
 	} else if (((msg->rsp[0] >> 2) != ((msg->data[0] >> 2) | 1))
 		   || (msg->rsp[1] != msg->data[1])) {
 		/*
@@ -4299,39 +4514,46 @@ static int handle_one_recv_msg(struct ipmi_smi *intf,
 			 (msg->data[0] >> 2) | 1, msg->data[1],
 			 msg->rsp[0] >> 2, msg->rsp[1]);
 
-		/* Generate an error response for the message. */
-		msg->rsp[0] = msg->data[0] | (1 << 2);
-		msg->rsp[1] = msg->data[1];
-		msg->rsp[2] = IPMI_ERR_UNSPECIFIED;
-		msg->rsp_size = 3;
+		goto return_unspecified;
 	}
 
-	if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
-	    && (msg->rsp[1] == IPMI_SEND_MSG_CMD)
-	    && (msg->user_data != NULL)) {
+	if (msg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
+		if ((msg->data[0] >> 2) & 1) {
+			/* It's a response to a sent response. */
+			chan = 0;
+			cc = msg->rsp[4];
+			goto process_response_response;
+		}
+		if (is_cmd)
+			requeue = handle_ipmb_direct_rcv_cmd(intf, msg);
+		else
+			requeue = handle_ipmb_direct_rcv_rsp(intf, msg);
+	} else if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
+		   && (msg->rsp[1] == IPMI_SEND_MSG_CMD)
+		   && (msg->user_data != NULL)) {
 		/*
 		 * It's a response to a response we sent.  For this we
 		 * deliver a send message response to the user.
 		 */
-		struct ipmi_recv_msg *recv_msg = msg->user_data;
-
-		requeue = 0;
-		if (msg->rsp_size < 2)
-			/* Message is too small to be correct. */
-			goto out;
+		struct ipmi_recv_msg *recv_msg;
 
 		chan = msg->data[2] & 0x0f;
 		if (chan >= IPMI_MAX_CHANNELS)
 			/* Invalid channel number */
 			goto out;
+		cc = msg->rsp[2];
 
+process_response_response:
+		recv_msg = msg->user_data;
+
+		requeue = 0;
 		if (!recv_msg)
 			goto out;
 
 		recv_msg->recv_type = IPMI_RESPONSE_RESPONSE_TYPE;
 		recv_msg->msg.data = recv_msg->msg_data;
+		recv_msg->msg_data[0] = cc;
 		recv_msg->msg.data_len = 1;
-		recv_msg->msg_data[0] = msg->rsp[2];
 		deliver_local_response(intf, recv_msg);
 	} else if ((msg->rsp[0] == ((IPMI_NETFN_APP_REQUEST|1) << 2))
 		   && (msg->rsp[1] == IPMI_GET_MSG_CMD)) {
diff --git a/include/linux/ipmi_smi.h b/include/linux/ipmi_smi.h
index deec18b8944a..9277d21c2690 100644
--- a/include/linux/ipmi_smi.h
+++ b/include/linux/ipmi_smi.h
@@ -38,6 +38,59 @@ struct ipmi_smi;
 #define IPMI_WATCH_MASK_CHECK_WATCHDOG	(1 << 1)
 #define IPMI_WATCH_MASK_CHECK_COMMANDS	(1 << 2)
 
+/*
+ * SMI messages
+ *
+ * When communicating with an SMI, messages come in two formats:
+ *
+ * * Normal (to a BMC over a BMC interface)
+ *
+ * * IPMB (over a IPMB to another MC)
+ *
+ * When normal, commands are sent using the format defined by a
+ * standard message over KCS (NetFn must be even):
+ *
+ *   +-----------+-----+------+
+ *   | NetFn/LUN | Cmd | Data |
+ *   +-----------+-----+------+
+ *
+ * And responses, similarly, with an completion code added (NetFn must
+ * be odd):
+ *
+ *   +-----------+-----+------+------+
+ *   | NetFn/LUN | Cmd | CC   | Data |
+ *   +-----------+-----+------+------+
+ *
+ * With normal messages, only commands are sent and only responses are
+ * received.
+ *
+ * In IPMB mode, we are acting as an IPMB device. Commands will be in
+ * the following format (NetFn must be even):
+ *
+ *   +-------------+------+-------------+-----+------+
+ *   | NetFn/rsLUN | Addr | rqSeq/rqLUN | Cmd | Data |
+ *   +-------------+------+-------------+-----+------+
+ *
+ * Responses will using the following format:
+ *
+ *   +-------------+------+-------------+-----+------+------+
+ *   | NetFn/rqLUN | Addr | rqSeq/rsLUN | Cmd | CC   | Data |
+ *   +-------------+------+-------------+-----+------+------+
+ *
+ * This is similar to the format defined in the IPMB manual section
+ * 2.11.1 with the checksums and the first address removed.  Also, the
+ * address is always the remote address.
+ *
+ * IPMB messages can be commands and responses in both directions.
+ * Received commands are handled as received commands from the message
+ * queue.
+ */
+
+enum ipmi_smi_msg_type {
+	IPMI_SMI_MSG_TYPE_NORMAL = 0,
+	IPMI_SMI_MSG_TYPE_IPMB_DIRECT
+};
+
 /*
  * Messages to/from the lower layer.  The smi interface will take one
  * of these to send. After the send has occurred and a response has
@@ -54,6 +107,8 @@ struct ipmi_smi;
 struct ipmi_smi_msg {
 	struct list_head link;
 
+	enum ipmi_smi_msg_type type;
+
 	long    msgid;
 	void    *user_data;
 
@@ -73,6 +128,10 @@ struct ipmi_smi_msg {
 struct ipmi_smi_handlers {
 	struct module *owner;
 
+	/* Capabilities of the SMI. */
+#define IPMI_SMI_CAN_HANDLE_IPMB_DIRECT		(1 << 0)
+	unsigned int flags;
+
 	/*
 	 * The low-level interface cannot start sending messages to
 	 * the upper layer until this function is called.  This may
diff --git a/include/uapi/linux/ipmi.h b/include/uapi/linux/ipmi.h
index 007e65f9243b..966c3070959b 100644
--- a/include/uapi/linux/ipmi.h
+++ b/include/uapi/linux/ipmi.h
@@ -80,6 +80,20 @@ struct ipmi_ipmb_addr {
 	unsigned char lun;
 };
 
+/*
+ * Used for messages received directly from an IPMB that have not gone
+ * through a MC.  This is for systems that sit right on an IPMB so
+ * they can receive commands and respond to them.
+ */
+#define IPMI_IPMB_DIRECT_ADDR_TYPE	0x81
+struct ipmi_ipmb_direct_addr {
+	int           addr_type;
+	short         channel;
+	unsigned char slave_addr;
+	unsigned char rs_lun;
+	unsigned char rq_lun;
+};
+
 /*
  * A LAN Address.  This is an address to/from a LAN interface bridged
  * by the BMC, not an address actually out on the LAN.
-- 
2.25.1

[PATCH 3/5] ipmi:ipmb: Add initial support for IPMI over IPMB

[minyard]

From: Corey Minyard <cminyard@mvista.com>

This provides access to the management controllers on an IPMB bus to a
device sitting on the IPMB bus.  It also provides slave capability to
respond to received messages on the bus.

Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
---
 drivers/char/ipmi/Kconfig     |   9 +
 drivers/char/ipmi/Makefile    |   1 +
 drivers/char/ipmi/ipmi_ipmb.c | 510 ++++++++++++++++++++++++++++++++++
 3 files changed, 520 insertions(+)
 create mode 100644 drivers/char/ipmi/ipmi_ipmb.c

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 249b31197eea..1c92209f023b 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -75,6 +75,15 @@ config IPMI_SSIF
 	  have a driver that must be accessed over an I2C bus instead of a
 	  standard interface.  This module requires I2C support.
 
+config IPMI_IPMB
+       tristate 'IPMI IPMB interface'
+       select I2C
+       help
+	 Provides a driver for a system running right on the IPMB bus.
+	 It supports normal system interface messages to a BMC on the IPMB
+	 bus, and it also supports direct messaging on the bus using
+	 IPMB direct messages.  This module requires I2C support.
+
 config IPMI_POWERNV
 	depends on PPC_POWERNV
 	tristate 'POWERNV (OPAL firmware) IPMI interface'
diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile
index 84f47d18007f..7ce790efad92 100644
--- a/drivers/char/ipmi/Makefile
+++ b/drivers/char/ipmi/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_IPMI_SI) += ipmi_si.o
 obj-$(CONFIG_IPMI_DMI_DECODE) += ipmi_dmi.o
 obj-$(CONFIG_IPMI_PLAT_DATA) += ipmi_plat_data.o
 obj-$(CONFIG_IPMI_SSIF) += ipmi_ssif.o
+obj-$(CONFIG_IPMI_IPMB) += ipmi_ipmb.o
 obj-$(CONFIG_IPMI_POWERNV) += ipmi_powernv.o
 obj-$(CONFIG_IPMI_WATCHDOG) += ipmi_watchdog.o
 obj-$(CONFIG_IPMI_POWEROFF) += ipmi_poweroff.o
diff --git a/drivers/char/ipmi/ipmi_ipmb.c b/drivers/char/ipmi/ipmi_ipmb.c
new file mode 100644
index 000000000000..b10a1fd9c563
--- /dev/null
+++ b/drivers/char/ipmi/ipmi_ipmb.c
@@ -0,0 +1,510 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Driver to talk to a remote management controller on IPMB.
+ */
+
+#include <linux/acpi.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/semaphore.h>
+#include <linux/kthread.h>
+#include <linux/wait.h>
+#include <linux/ipmi_msgdefs.h>
+#include <linux/ipmi_smi.h>
+
+#define DEVICE_NAME "ipmi-ipmb"
+
+static int bmcaddr = 0x20;
+module_param(bmcaddr, int, 0644);
+MODULE_PARM_DESC(bmcaddr, "Address to use for BMC.");
+
+static unsigned int retry_time_ms = 250;
+module_param(retry_time_ms, uint, 0644);
+MODULE_PARM_DESC(max_retries, "Timeout time between retries, in milliseconds.");
+
+static unsigned int max_retries = 1;
+module_param(max_retries, uint, 0644);
+MODULE_PARM_DESC(max_retries, "Max resends of a command before timing out.");
+
+/* Add room for the two slave addresses, two checksums, and rqSeq. */
+#define IPMB_MAX_MSG_LEN (IPMI_MAX_MSG_LENGTH + 5)
+
+struct ipmi_ipmb_dev {
+	struct ipmi_smi *intf;
+	struct i2c_client *client;
+
+	struct ipmi_smi_handlers handlers;
+
+	bool ready;
+
+	u8 bmcaddr;
+
+	u8 curr_seq;
+
+	struct ipmi_smi_msg *next_msg;
+	struct ipmi_smi_msg *working_msg;
+
+	/* Transmit thread. */
+	struct task_struct *thread;
+	struct semaphore wake_thread;
+	struct semaphore got_rsp;
+	spinlock_t lock;
+	bool stopping;
+
+	u8 xmitmsg[IPMB_MAX_MSG_LEN];
+	unsigned int xmitlen;
+
+	u8 rcvmsg[IPMB_MAX_MSG_LEN];
+	unsigned int rcvlen;
+	bool overrun;
+};
+
+static bool valid_ipmb(struct ipmi_ipmb_dev *iidev)
+{
+	u8 *msg = iidev->rcvmsg;
+	u8 netfn;
+
+	if (iidev->overrun)
+		return false;
+
+	/* Minimum message size. */
+	if (iidev->rcvlen < 7)
+		return false;
+
+	/* Is it a response? */
+	netfn = msg[1] >> 2;
+	if (netfn & 1) {
+		/* Response messages have an added completion code. */
+		if (iidev->rcvlen < 8)
+			return false;
+	}
+
+	if (ipmb_checksum(msg, 3) != 0)
+		return false;
+	if (ipmb_checksum(msg + 3, iidev->rcvlen - 3) != 0)
+		return false;
+
+	return true;
+}
+
+static void ipmi_ipmb_check_msg_done(struct ipmi_ipmb_dev *iidev)
+{
+	struct ipmi_smi_msg *imsg = NULL;
+	u8 *msg = iidev->rcvmsg;
+	bool is_cmd;
+	unsigned long flags;
+
+	if (iidev->rcvlen == 0)
+		return;
+	if (!valid_ipmb(iidev))
+		goto done;
+
+	is_cmd = ((msg[1] >> 2) & 1) == 0;
+
+	if (is_cmd) {
+		/* Ignore commands until we are up. */
+		if (!iidev->ready)
+			goto done;
+
+		/* It's a command, allocate a message for it. */
+		imsg = ipmi_alloc_smi_msg();
+		if (!imsg)
+			goto done;
+		imsg->type = IPMI_SMI_MSG_TYPE_IPMB_DIRECT;
+		imsg->data_size = 0;
+	} else {
+		spin_lock_irqsave(&iidev->lock, flags);
+		if (iidev->working_msg) {
+			u8 seq = msg[4] >> 2;
+			bool xmit_rsp = (iidev->working_msg->data[0] >> 2) & 1;
+
+			/*
+			 * Responses should carry the sequence we sent
+			 * them with.  If it's a transmitted response,
+			 * ignore it.  And if the message hasn't been
+			 * transmitted, ignore it.
+			 */
+			if (!xmit_rsp && seq == iidev->curr_seq) {
+				iidev->curr_seq = (iidev->curr_seq + 1) & 0x3f;
+
+				imsg = iidev->working_msg;
+				iidev->working_msg = NULL;
+			}
+		}
+		spin_unlock_irqrestore(&iidev->lock, flags);
+	}
+
+	if (!imsg)
+		goto done;
+
+	if (imsg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
+		imsg->rsp[0] = msg[1]; /* NetFn/LUN */
+		/*
+		 * Keep the source address, rqSeq.  Drop the trailing
+		 * checksum.
+		 */
+		memcpy(imsg->rsp + 1, msg + 3, iidev->rcvlen - 4);
+		imsg->rsp_size = iidev->rcvlen - 3;
+	} else {
+		imsg->rsp[0] = msg[1]; /* NetFn/LUN */
+		/*
+		 * Skip the source address, rqSeq.  Drop the trailing
+		 * checksum.
+		 */
+		memcpy(imsg->rsp + 1, msg + 5, iidev->rcvlen - 6);
+		imsg->rsp_size = iidev->rcvlen - 5;
+	}
+	ipmi_smi_msg_received(iidev->intf, imsg);
+	if (!is_cmd)
+		up(&iidev->got_rsp);
+
+done:
+	iidev->overrun = false;
+	iidev->rcvlen = 0;
+}
+
+/*
+ * The IPMB protocol only supports i2c writes so there is no need to
+ * support I2C_SLAVE_READ* events, except to know if the other end has
+ * issued a read without going to stop mode.
+ */
+static int ipmi_ipmb_slave_cb(struct i2c_client *client,
+			      enum i2c_slave_event event, u8 *val)
+{
+	struct ipmi_ipmb_dev *iidev = i2c_get_clientdata(client);
+
+	switch (event) {
+	case I2C_SLAVE_WRITE_REQUESTED:
+		ipmi_ipmb_check_msg_done(iidev);
+		/*
+		 * First byte is the slave address, to ease the checksum
+		 * calculation.
+		 */
+		iidev->rcvmsg[0] = client->addr << 1;
+		iidev->rcvlen = 1;
+		break;
+
+	case I2C_SLAVE_WRITE_RECEIVED:
+		if (iidev->rcvlen > sizeof(iidev->rcvmsg))
+			iidev->overrun = true;
+		else
+			iidev->rcvmsg[iidev->rcvlen++] = *val;
+		break;
+
+	case I2C_SLAVE_READ_REQUESTED:
+	case I2C_SLAVE_STOP:
+		ipmi_ipmb_check_msg_done(iidev);
+		break;
+
+	case I2C_SLAVE_READ_PROCESSED:
+		break;
+	}
+
+	return 0;
+}
+
+static void ipmi_ipmb_send_response(struct ipmi_ipmb_dev *iidev,
+				    struct ipmi_smi_msg *msg, u8 cc)
+{
+	if ((msg->data[0] >> 2) & 1) {
+		/*
+		 * It's a response being sent, we needto return a
+		 * response response.  Fake a send msg command
+		 * response with channel 0.  This will always be ipmb
+		 * direct.
+		 */
+		msg->data[0] = (IPMI_NETFN_APP_REQUEST | 1) << 2;
+		msg->data[3] = IPMI_SEND_MSG_CMD;
+		msg->data[4] = cc;
+		msg->data_size = 5;
+	}
+	msg->rsp[0] = msg->data[0] | (1 << 2);
+	if (msg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
+		msg->rsp[1] = msg->data[1];
+		msg->rsp[2] = msg->data[2];
+		msg->rsp[3] = msg->data[3];
+		msg->rsp[4] = cc;
+		msg->rsp_size = 5;
+	} else {
+		msg->rsp[1] = msg->data[1];
+		msg->rsp[2] = cc;
+		msg->rsp_size = 3;
+	}
+	ipmi_smi_msg_received(iidev->intf, msg);
+}
+
+static void ipmi_ipmb_format_for_xmit(struct ipmi_ipmb_dev *iidev,
+				      struct ipmi_smi_msg *msg)
+{
+	if (msg->type == IPMI_SMI_MSG_TYPE_IPMB_DIRECT) {
+		iidev->xmitmsg[0] = msg->data[1];
+		iidev->xmitmsg[1] = msg->data[0];
+		memcpy(iidev->xmitmsg + 4, msg->data + 2, msg->data_size - 2);
+		iidev->xmitlen = msg->data_size + 2;
+	} else {
+		iidev->xmitmsg[0] = iidev->bmcaddr;
+		iidev->xmitmsg[1] = msg->data[0];
+		iidev->xmitmsg[4] = 0;
+		memcpy(iidev->xmitmsg + 5, msg->data + 1, msg->data_size - 1);
+		iidev->xmitlen = msg->data_size + 4;
+	}
+	iidev->xmitmsg[3] = iidev->client->addr << 1;
+	if (((msg->data[0] >> 2) & 1) == 0)
+		/* If it's a command, put in our own sequence number. */
+		iidev->xmitmsg[4] = ((iidev->xmitmsg[4] & 0x03) |
+				     (iidev->curr_seq << 2));
+
+	/* Now add on the final checksums. */
+	iidev->xmitmsg[2] = ipmb_checksum(iidev->xmitmsg, 2);
+	iidev->xmitmsg[iidev->xmitlen] =
+		ipmb_checksum(iidev->xmitmsg + 3, iidev->xmitlen - 3);
+	iidev->xmitlen++;
+}
+
+static int ipmi_ipmb_thread(void *data)
+{
+	struct ipmi_ipmb_dev *iidev = data;
+
+	while (!kthread_should_stop()) {
+		long ret;
+		struct i2c_msg i2c_msg;
+		struct ipmi_smi_msg *msg = NULL;
+		unsigned long flags;
+		unsigned int retries = 0;
+
+		/* Wait for a message to send */
+		ret = down_interruptible(&iidev->wake_thread);
+		if (iidev->stopping)
+			break;
+		if (ret)
+			continue;
+
+		spin_lock_irqsave(&iidev->lock, flags);
+		if (iidev->next_msg) {
+			msg = iidev->next_msg;
+			iidev->next_msg = NULL;
+		}
+		spin_unlock_irqrestore(&iidev->lock, flags);
+		if (!msg)
+			continue;
+
+		ipmi_ipmb_format_for_xmit(iidev, msg);
+
+retry:
+		i2c_msg.len = iidev->xmitlen - 1;
+		if (i2c_msg.len > 32) {
+			ipmi_ipmb_send_response(iidev, msg,
+						IPMI_REQ_LEN_EXCEEDED_ERR);
+			continue;
+		}
+
+		i2c_msg.addr = iidev->xmitmsg[0] >> 1;
+		i2c_msg.flags = 0;
+		i2c_msg.buf = iidev->xmitmsg + 1;
+
+		/* Rely on i2c_transfer for a barrier. */
+		iidev->working_msg = msg;
+
+		ret = i2c_transfer(iidev->client->adapter, &i2c_msg, 1);
+
+		if ((msg->data[0] >> 2) & 1) {
+			/*
+			 * It's a response, nothing will be returned
+			 * by the other end.
+			 */
+
+			iidev->working_msg = NULL;
+			ipmi_ipmb_send_response(iidev, msg,
+						ret < 0 ? IPMI_BUS_ERR : 0);
+			continue;
+		}
+		if (ret < 0) {
+			iidev->working_msg = NULL;
+			ipmi_ipmb_send_response(iidev, msg, IPMI_BUS_ERR);
+			continue;
+		}
+
+		/* A command was sent, wait for its response. */
+		ret = down_timeout(&iidev->got_rsp,
+				   msecs_to_jiffies(retry_time_ms));
+
+		/*
+		 * Grab the message if we can.  If the handler hasn't
+		 * already handled it, the message will still be there.
+		 */
+		spin_lock_irqsave(&iidev->lock, flags);
+		msg = iidev->working_msg;
+		iidev->working_msg = NULL;
+		spin_unlock_irqrestore(&iidev->lock, flags);
+
+		if (!msg && ret) {
+			/*
+			 * If working_msg is not set and we timed out,
+			 * that means the message grabbed by
+			 * check_msg_done before we could grab it
+			 * here.  Wait again for check_msg_done to up
+			 * the semaphore.
+			 */
+			down(&iidev->got_rsp);
+		} else if (msg && ++retries <= max_retries) {
+			spin_lock_irqsave(&iidev->lock, flags);
+			iidev->working_msg = msg;
+			spin_unlock_irqrestore(&iidev->lock, flags);
+			goto retry;
+		}
+
+		if (msg)
+			ipmi_ipmb_send_response(iidev, msg, IPMI_TIMEOUT_ERR);
+	}
+
+	if (iidev->next_msg)
+		/* Return an unspecified error. */
+		ipmi_ipmb_send_response(iidev, iidev->next_msg, 0xff);
+
+	return 0;
+}
+
+static int ipmi_ipmb_start_processing(void            *send_info,
+				      struct ipmi_smi *new_intf)
+{
+	struct ipmi_ipmb_dev *iidev = send_info;
+
+	iidev->intf = new_intf;
+	iidev->ready = true;
+	return 0;
+}
+
+static void ipmi_ipmb_stop_thread(struct ipmi_ipmb_dev *iidev)
+{
+	if (iidev->thread) {
+		struct task_struct *t = iidev->thread;
+
+		iidev->thread = NULL;
+		iidev->stopping = true;
+		up(&iidev->wake_thread);
+		up(&iidev->got_rsp);
+		kthread_stop(t);
+	}
+}
+
+static void ipmi_ipmb_shutdown(void *send_info)
+{
+	struct ipmi_ipmb_dev *iidev = send_info;
+
+	ipmi_ipmb_stop_thread(iidev);
+}
+
+static void ipmi_ipmb_sender(void                *send_info,
+			     struct ipmi_smi_msg *msg)
+{
+	struct ipmi_ipmb_dev *iidev = send_info;
+	unsigned long flags;
+
+	spin_lock_irqsave(&iidev->lock, flags);
+	BUG_ON(iidev->next_msg);
+
+	iidev->next_msg = msg;
+	spin_unlock_irqrestore(&iidev->lock, flags);
+
+	up(&iidev->wake_thread);
+}
+
+static void ipmi_ipmb_request_events(void *send_info)
+{
+	/* We don't fetch events here. */
+}
+
+static int ipmi_ipmb_remove(struct i2c_client *client)
+{
+	struct ipmi_ipmb_dev *iidev = i2c_get_clientdata(client);
+
+	if (iidev->client) {
+		iidev->client = NULL;
+		i2c_slave_unregister(client);
+	}
+	ipmi_ipmb_stop_thread(iidev);
+
+	return 0;
+}
+
+static int ipmi_ipmb_probe(struct i2c_client *client,
+			   const struct i2c_device_id *id)
+{
+	struct ipmi_ipmb_dev *iidev;
+	int rv;
+
+	iidev = devm_kzalloc(&client->dev, sizeof(*iidev), GFP_KERNEL);
+	if (!iidev)
+		return -ENOMEM;
+
+	iidev->bmcaddr = bmcaddr;
+
+	i2c_set_clientdata(client, iidev);
+	client->flags |= I2C_CLIENT_SLAVE;
+
+	rv = i2c_slave_register(client, ipmi_ipmb_slave_cb);
+	if (rv)
+		return rv;
+
+	iidev->client = client;
+
+	iidev->handlers.flags = IPMI_SMI_CAN_HANDLE_IPMB_DIRECT;
+	iidev->handlers.start_processing = ipmi_ipmb_start_processing;
+	iidev->handlers.shutdown = ipmi_ipmb_shutdown;
+	iidev->handlers.sender = ipmi_ipmb_sender;
+	iidev->handlers.request_events = ipmi_ipmb_request_events;
+
+	spin_lock_init(&iidev->lock);
+	sema_init(&iidev->wake_thread, 0);
+	sema_init(&iidev->got_rsp, 0);
+
+	iidev->thread = kthread_run(ipmi_ipmb_thread, iidev,
+				    "kipmb%4.4x", client->addr);
+	if (IS_ERR(iidev->thread)) {
+		rv = PTR_ERR(iidev->thread);
+		dev_notice(&client->dev,
+			   "Could not start kernel thread: error %d\n", rv);
+		goto out_err;
+	}
+
+	rv = ipmi_register_smi(&iidev->handlers,
+			       iidev,
+			       &client->dev,
+			       iidev->bmcaddr);
+	if (rv)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	ipmi_ipmb_remove(client);
+	return rv;
+}
+
+static const struct i2c_device_id ipmi_ipmb_id[] = {
+	{ DEVICE_NAME, 0 },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, ipmi_ipmb_id);
+
+static struct i2c_driver ipmi_ipmb_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name = DEVICE_NAME,
+	},
+	.probe		= ipmi_ipmb_probe,
+	.remove		= ipmi_ipmb_remove,
+	.id_table	= ipmi_ipmb_id,
+};
+module_i2c_driver(ipmi_ipmb_driver);
+
+MODULE_AUTHOR("Corey Minyard");
+MODULE_DESCRIPTION("IPMI IPMB driver");
+MODULE_LICENSE("GPL v2");
-- 
2.25.1

Re: [PATCH 3/5] ipmi:ipmb: Add initial support for IPMI over IPMB

[Randy Dunlap]

Hi,

On 10/4/21 5:40 PM, minyard@acm.org wrote:
> From: Corey Minyard <cminyard@mvista.com>
> 
> This provides access to the management controllers on an IPMB bus to a
> device sitting on the IPMB bus.  It also provides slave capability to
> respond to received messages on the bus.
> 
> Signed-off-by: Corey Minyard <minyard@acm.org>
> Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
> Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
> ---
>   drivers/char/ipmi/Kconfig     |   9 +
>   drivers/char/ipmi/Makefile    |   1 +
>   drivers/char/ipmi/ipmi_ipmb.c | 510 ++++++++++++++++++++++++++++++++++
>   3 files changed, 520 insertions(+)
>   create mode 100644 drivers/char/ipmi/ipmi_ipmb.c
> 
> diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
> index 249b31197eea..1c92209f023b 100644
> --- a/drivers/char/ipmi/Kconfig
> +++ b/drivers/char/ipmi/Kconfig
> @@ -75,6 +75,15 @@ config IPMI_SSIF
>   	  have a driver that must be accessed over an I2C bus instead of a
>   	  standard interface.  This module requires I2C support.
>   
> +config IPMI_IPMB
> +       tristate 'IPMI IPMB interface'
> +       select I2C

How can this select I2C unconditionally? At this point we don't
even know if this platform has/supports I2C.

Ditto for IPMI_SSIF in the current Kconfig file, while
IPMB_DEVICE_INTERFACE depends on I2C (as it should IMO).



> +       help
> +	 Provides a driver for a system running right on the IPMB bus.
> +	 It supports normal system interface messages to a BMC on the IPMB
> +	 bus, and it also supports direct messaging on the bus using
> +	 IPMB direct messages.  This module requires I2C support.

<form-letter-bot>

Please follow coding-style for Kconfig files:

(from Documentation/process/coding-style.rst, section 10):

For all of the Kconfig* configuration files throughout the source tree,
the indentation is somewhat different.  Lines under a ``config`` definition
are indented with one tab, while help text is indented an additional two
spaces.

> +
>   config IPMI_POWERNV
>   	depends on PPC_POWERNV
>   	tristate 'POWERNV (OPAL firmware) IPMI interface'


> diff --git a/drivers/char/ipmi/ipmi_ipmb.c b/drivers/char/ipmi/ipmi_ipmb.c
> new file mode 100644
> index 000000000000..b10a1fd9c563
> --- /dev/null
> +++ b/drivers/char/ipmi/ipmi_ipmb.c
> @@ -0,0 +1,510 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Driver to talk to a remote management controller on IPMB.
> + */
> +

[...]

> +
> +static int ipmi_ipmb_start_processing(void            *send_info,

Odd spacing/formatting above.

> +				      struct ipmi_smi *new_intf)
> +{
> +	struct ipmi_ipmb_dev *iidev = send_info;
> +
> +	iidev->intf = new_intf;
> +	iidev->ready = true;
> +	return 0;
> +}
> +
> +
> +static void ipmi_ipmb_sender(void                *send_info,

Ditto.

> +			     struct ipmi_smi_msg *msg)
> +{


-- 
~Randy

Re: [PATCH 3/5] ipmi:ipmb: Add initial support for IPMI over IPMB

[Corey Minyard]

On Mon, Oct 04, 2021 at 06:27:34PM -0700, Randy Dunlap wrote:
> Hi,

Thanks, all issues addressed.

-corey

> 
> On 10/4/21 5:40 PM, minyard@acm.org wrote:
> > From: Corey Minyard <cminyard@mvista.com>
> > 
> > This provides access to the management controllers on an IPMB bus to a
> > device sitting on the IPMB bus.  It also provides slave capability to
> > respond to received messages on the bus.
> > 
> > Signed-off-by: Corey Minyard <minyard@acm.org>
> > Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
> > Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
> > ---
> >   drivers/char/ipmi/Kconfig     |   9 +
> >   drivers/char/ipmi/Makefile    |   1 +
> >   drivers/char/ipmi/ipmi_ipmb.c | 510 ++++++++++++++++++++++++++++++++++
> >   3 files changed, 520 insertions(+)
> >   create mode 100644 drivers/char/ipmi/ipmi_ipmb.c
> > 
> > diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
> > index 249b31197eea..1c92209f023b 100644
> > --- a/drivers/char/ipmi/Kconfig
> > +++ b/drivers/char/ipmi/Kconfig
> > @@ -75,6 +75,15 @@ config IPMI_SSIF
> >   	  have a driver that must be accessed over an I2C bus instead of a
> >   	  standard interface.  This module requires I2C support.
> > +config IPMI_IPMB
> > +       tristate 'IPMI IPMB interface'
> > +       select I2C
> 
> How can this select I2C unconditionally? At this point we don't
> even know if this platform has/supports I2C.
> 
> Ditto for IPMI_SSIF in the current Kconfig file, while
> IPMB_DEVICE_INTERFACE depends on I2C (as it should IMO).
> 
> 
> 
> > +       help
> > +	 Provides a driver for a system running right on the IPMB bus.
> > +	 It supports normal system interface messages to a BMC on the IPMB
> > +	 bus, and it also supports direct messaging on the bus using
> > +	 IPMB direct messages.  This module requires I2C support.
> 
> <form-letter-bot>
> 
> Please follow coding-style for Kconfig files:
> 
> (from Documentation/process/coding-style.rst, section 10):
> 
> For all of the Kconfig* configuration files throughout the source tree,
> the indentation is somewhat different.  Lines under a ``config`` definition
> are indented with one tab, while help text is indented an additional two
> spaces.
> 
> > +
> >   config IPMI_POWERNV
> >   	depends on PPC_POWERNV
> >   	tristate 'POWERNV (OPAL firmware) IPMI interface'
> 
> 
> > diff --git a/drivers/char/ipmi/ipmi_ipmb.c b/drivers/char/ipmi/ipmi_ipmb.c
> > new file mode 100644
> > index 000000000000..b10a1fd9c563
> > --- /dev/null
> > +++ b/drivers/char/ipmi/ipmi_ipmb.c
> > @@ -0,0 +1,510 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +/*
> > + * Driver to talk to a remote management controller on IPMB.
> > + */
> > +
> 
> [...]
> 
> > +
> > +static int ipmi_ipmb_start_processing(void            *send_info,
> 
> Odd spacing/formatting above.
> 
> > +				      struct ipmi_smi *new_intf)
> > +{
> > +	struct ipmi_ipmb_dev *iidev = send_info;
> > +
> > +	iidev->intf = new_intf;
> > +	iidev->ready = true;
> > +	return 0;
> > +}
> > +
> > +
> > +static void ipmi_ipmb_sender(void                *send_info,
> 
> Ditto.
> 
> > +			     struct ipmi_smi_msg *msg)
> > +{
> 
> 
> -- 
> ~Randy

[PATCH 4/5] ipmi: Add docs for IPMB direct addressing

[minyard]

From: Corey Minyard <cminyard@mvista.com>

Describe the addressing mechanism and how to use it.

Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
---
 Documentation/driver-api/ipmi.rst | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/Documentation/driver-api/ipmi.rst b/Documentation/driver-api/ipmi.rst
index bc281f10ce4b..c9cb5669bc4c 100644
--- a/Documentation/driver-api/ipmi.rst
+++ b/Documentation/driver-api/ipmi.rst
@@ -166,8 +166,8 @@ and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE.  This is used for talking
 straight to the BMC on the current card.  The channel must be
 IPMI_BMC_CHANNEL.
 
-Messages that are destined to go out on the IPMB bus use the
-IPMI_IPMB_ADDR_TYPE address type.  The format is::
+Messages that are destined to go out on the IPMB bus going through the
+BMC use the IPMI_IPMB_ADDR_TYPE address type.  The format is::
 
   struct ipmi_ipmb_addr
   {
@@ -181,6 +181,23 @@ The "channel" here is generally zero, but some devices support more
 than one channel, it corresponds to the channel as defined in the IPMI
 spec.
 
+There is also an IPMB direct address for a situation where the sender
+is directly on an IPMB bus and doesn't have to go through the BMC.
+You can send messages to a specific management controller (MC) on the
+IPMB using the IPMI_IPMB_DIRECT_ADDR_TYPE with the following format::
+
+  struct ipmi_ipmb_direct_addr
+  {
+	int           addr_type;
+	short         channel;
+	unsigned char slave_addr;
+	unsigned char rq_lun;
+	unsigned char rs_lun;
+  };
+
+The channel is always zero.  You can also receive commands from other
+MCs that you have registered to handle and respond to them, so you can
+use this to implement a management controller on a bus..
 
 Messages
 --------
@@ -348,6 +365,10 @@ user may be registered for each netfn/cmd/channel, but different users
 may register for different commands, or the same command if the
 channel bitmasks do not overlap.
 
+To respond to a received command, set the response bit in the returned
+netfn, use the address from the received message, and use the same
+msgid that you got in the receive message.
+
 From userland, equivalent IOCTLs are provided to do these functions.
 
 
-- 
2.25.1

[PATCH 5/5] ipmi: Add docs for the IPMI IPMB driver

[minyard]

From: Corey Minyard <cminyard@mvista.com>

Describe how to use the IPMI IPMB driver, including it's quirks.

Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
---
 Documentation/driver-api/ipmi.rst | 39 +++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/Documentation/driver-api/ipmi.rst b/Documentation/driver-api/ipmi.rst
index c9cb5669bc4c..e224e47b6b09 100644
--- a/Documentation/driver-api/ipmi.rst
+++ b/Documentation/driver-api/ipmi.rst
@@ -591,6 +591,45 @@ web page.
 The driver supports a hot add and remove of interfaces through the I2C
 sysfs interface.
 
+The IPMI IPMB Driver
+--------------------
+
+This driver is for supporting a system that sits on an IPMB bus; it
+allows the interface to look like a normal IPMI interface.  Sending
+system interface addressed messages to it will cause the message to go
+to the registered BMC on the system (default at IPMI address 0x20).
+
+It also allows you to directly address other MCs on the bus using the
+ipmb direct addressing.  You can receive commands from other MCs on
+the bus and they will be handled through the normal received command
+mechanism described above.
+
+Parameters are::
+
+  ipmi_ipmb.bmcaddr=<address to use for system interface addresses messages>
+	ipmi_ipmb.retry_time_ms=<Time between retries on IPMB>
+	ipmi_ipmb.max_retries=<Number of times to retry a message>
+
+Loading the module will not result in the driver automatcially
+starting unless there is device tree information setting it up.  If
+you want to instantiate one of these by hand, do::
+
+  echo ipmi-ipmb <addr> > /sys/class/i2c-dev/i2c-<n>/device/new_device
+
+Note that the address you give here is the I2C address, not the IPMI
+address.  So if you want your MC address to be 0x60, you put 0x30
+here.  See the I2C driver info for more details.
+
+Command bridging to other IPMB busses through this interface does not
+work.  The receive message queue is not implemented, by design.  There
+is only one receive message queue on a BMC, and that is meant for the
+host drivers, not something on the IPMB bus.
+
+A BMC may have multiple IPMB busses, which bus your device sits on
+depends on how the system is wired.  You can fetch the channels with
+"ipmitool channel info <n>" where <n> is the channel, with the
+channels being 0-7 and try the IPMB channels.
+
 Other Pieces
 ------------
 
-- 
2.25.1