IPMI/ACPI: Add the IPMI opregion driver to enable ACPI to access BMC controller

ACPI 4.0 spec adds the ACPI IPMI opregion, which means that the ACPI AML
code can also communicate with the BMC controller. This is to install
the ACPI IPMI opregion and enable the ACPI to access the BMC controller
through the IPMI message.

It will create IPMI user interface for every IPMI device detected
in ACPI namespace and install the corresponding IPMI opregion space handler.
Then it can enable ACPI to access the BMC controller through the IPMI
message.

The following describes how to process the IPMI request in IPMI space handler:
1. format the IPMI message based on the request in AML code.
IPMI system address. Now the address type is SYSTEM_INTERFACE_ADDR_TYPE
IPMI net function & command
IPMI message payload
2. send the IPMI message by using the function of ipmi_request_settime
3. wait for the completion of IPMI message. It can be done in different
routes: One is in handled in IPMI user recv callback function. Another is
handled in timeout function.
4. format the IPMI response and return it to ACPI AML code.

At the same time it also addes the module dependency. The ACPI IPMI opregion
will depend on the IPMI subsystem.

Signed-off-by: Zhao Yakui <[e-mail]>
cc: Bjorn Helgaas <[e-mail]>
Signed-off-by: Corey Minyard <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>

drivers/acpi/Kconfig

···
 
 	  To compile this driver as a module, choose M here:
 	  the module will be called processor.
+config ACPI_IPMI
+	tristate "IPMI"
+	depends on EXPERIMENTAL && IPMI_SI && IPMI_HANDLER
+	default n
+	help
+	  This driver enables the ACPI to access the BMC controller. And it
+	  uses the IPMI request/response message to communicate with BMC
+	  controller, which can be found on on the server.
+
+	  To compile this driver as a module, choose M here:
+	  the module will be called as acpi_ipmi.
 
 config ACPI_HOTPLUG_CPU
 	bool

drivers/acpi/Makefile

···
 processor-$(CONFIG_CPU_FREQ)	+= processor_perflib.o
 
 obj-$(CONFIG_ACPI_PROCESSOR_AGGREGATOR) += acpi_pad.o
+obj-$(CONFIG_ACPI_IPMI)		+= acpi_ipmi.o
 
 obj-$(CONFIG_ACPI_APEI)		+= apei/

drivers/acpi/acpi_ipmi.c

···
+/*
+ *  acpi_ipmi.c - ACPI IPMI opregion
+ *
+ *  Copyright (C) 2010 Intel Corporation
+ *  Copyright (C) 2010 Zhao Yakui <[e-mail]>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or (at
+ *  your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/io.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+#include <linux/ipmi.h>
+#include <linux/device.h>
+#include <linux/pnp.h>
+
+MODULE_AUTHOR("Zhao Yakui");
+MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
+MODULE_LICENSE("GPL");
+
+#define IPMI_FLAGS_HANDLER_INSTALL	0
+
+#define ACPI_IPMI_OK			0
+#define ACPI_IPMI_TIMEOUT		0x10
+#define ACPI_IPMI_UNKNOWN		0x07
+/* the IPMI timeout is 5s */
+#define IPMI_TIMEOUT			(5 * HZ)
+
+struct acpi_ipmi_device {
+	/* the device list attached to driver_data.ipmi_devices */
+	struct list_head head;
+	/* the IPMI request message list */
+	struct list_head tx_msg_list;
+	struct mutex	tx_msg_lock;
+	acpi_handle handle;
+	struct pnp_dev *pnp_dev;
+	ipmi_user_t	user_interface;
+	int ipmi_ifnum; /* IPMI interface number */
+	long curr_msgid;
+	unsigned long flags;
+	struct ipmi_smi_info smi_data;
+};
+
+struct ipmi_driver_data {
+	struct list_head	ipmi_devices;
+	struct ipmi_smi_watcher	bmc_events;
+	struct ipmi_user_hndl	ipmi_hndlrs;
+	struct mutex		ipmi_lock;
+};
+
+struct acpi_ipmi_msg {
+	struct list_head head;
+	/*
+	 * General speaking the addr type should be SI_ADDR_TYPE. And
+	 * the addr channel should be BMC.
+	 * In fact it can also be IPMB type. But we will have to
+	 * parse it from the Netfn command buffer. It is so complex
+	 * that it is skipped.
+	 */
+	struct ipmi_addr addr;
+	long tx_msgid;
+	/* it is used to track whether the IPMI message is finished */
+	struct completion tx_complete;
+	struct kernel_ipmi_msg tx_message;
+	int	msg_done;
+	/* tx data . And copy it from ACPI object buffer */
+	u8	tx_data[64];
+	int	tx_len;
+	u8	rx_data[64];
+	int	rx_len;
+	struct acpi_ipmi_device *device;
+};
+
+/* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
+struct acpi_ipmi_buffer {
+	u8 status;
+	u8 length;
+	u8 data[64];
+};
+
+static void ipmi_register_bmc(int iface, struct device *dev);
+static void ipmi_bmc_gone(int iface);
+static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
+static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device);
+static void acpi_remove_ipmi_device(struct acpi_ipmi_device *ipmi_device);
+
+static struct ipmi_driver_data driver_data = {
+	.ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
+	.bmc_events = {
+		.owner = THIS_MODULE,
+		.new_smi = ipmi_register_bmc,
+		.smi_gone = ipmi_bmc_gone,
+	},
+	.ipmi_hndlrs = {
+		.ipmi_recv_hndl = ipmi_msg_handler,
+	},
+};
+
+static struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi)
+{
+	struct acpi_ipmi_msg *ipmi_msg;
+	struct pnp_dev *pnp_dev = ipmi->pnp_dev;
+
+	ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
+	if (!ipmi_msg)	{
+		dev_warn(&pnp_dev->dev, "Can't allocate memory for ipmi_msg\n");
+		return NULL;
+	}
+	init_completion(&ipmi_msg->tx_complete);
+	INIT_LIST_HEAD(&ipmi_msg->head);
+	ipmi_msg->device = ipmi;
+	return ipmi_msg;
+}
+
+#define		IPMI_OP_RGN_NETFN(offset)	((offset >> 8) & 0xff)
+#define		IPMI_OP_RGN_CMD(offset)		(offset & 0xff)
+static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
+				acpi_physical_address address,
+				acpi_integer *value)
+{
+	struct kernel_ipmi_msg *msg;
+	struct acpi_ipmi_buffer *buffer;
+	struct acpi_ipmi_device *device;
+
+	msg = &tx_msg->tx_message;
+	/*
+	 * IPMI network function and command are encoded in the address
+	 * within the IPMI OpRegion; see ACPI 4.0, sec 5.5.2.4.3.
+	 */
+	msg->netfn = IPMI_OP_RGN_NETFN(address);
+	msg->cmd = IPMI_OP_RGN_CMD(address);
+	msg->data = tx_msg->tx_data;
+	/*
+	 * value is the parameter passed by the IPMI opregion space handler.
+	 * It points to the IPMI request message buffer
+	 */
+	buffer = (struct acpi_ipmi_buffer *)value;
+	/* copy the tx message data */
+	msg->data_len = buffer->length;
+	memcpy(tx_msg->tx_data, buffer->data, msg->data_len);
+	/*
+	 * now the default type is SYSTEM_INTERFACE and channel type is BMC.
+	 * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
+	 * the addr type should be changed to IPMB. Then we will have to parse
+	 * the IPMI request message buffer to get the IPMB address.
+	 * If so, please fix me.
+	 */
+	tx_msg->addr.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
+	tx_msg->addr.channel = IPMI_BMC_CHANNEL;
+	tx_msg->addr.data[0] = 0;
+
+	/* Get the msgid */
+	device = tx_msg->device;
+	mutex_lock(&device->tx_msg_lock);
+	device->curr_msgid++;
+	tx_msg->tx_msgid = device->curr_msgid;
+	mutex_unlock(&device->tx_msg_lock);
+}
+
+static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
+		acpi_integer *value, int rem_time)
+{
+	struct acpi_ipmi_buffer *buffer;
+
+	/*
+	 * value is also used as output parameter. It represents the response
+	 * IPMI message returned by IPMI command.
+	 */
+	buffer = (struct acpi_ipmi_buffer *)value;
+	if (!rem_time && !msg->msg_done) {
+		buffer->status = ACPI_IPMI_TIMEOUT;
+		return;
+	}
+	/*
+	 * If the flag of msg_done is not set or the recv length is zero, it
+	 * means that the IPMI command is not executed correctly.
+	 * The status code will be ACPI_IPMI_UNKNOWN.
+	 */
+	if (!msg->msg_done || !msg->rx_len) {
+		buffer->status = ACPI_IPMI_UNKNOWN;
+		return;
+	}
+	/*
+	 * If the IPMI response message is obtained correctly, the status code
+	 * will be ACPI_IPMI_OK
+	 */
+	buffer->status = ACPI_IPMI_OK;
+	buffer->length = msg->rx_len;
+	memcpy(buffer->data, msg->rx_data, msg->rx_len);
+}
+
+static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
+{
+	struct acpi_ipmi_msg *tx_msg, *temp;
+	int count = HZ / 10;
+	struct pnp_dev *pnp_dev = ipmi->pnp_dev;
+
+	list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
+		/* wake up the sleep thread on the Tx msg */
+		complete(&tx_msg->tx_complete);
+	}
+
+	/* wait for about 100ms to flush the tx message list */
+	while (count--) {
+		if (list_empty(&ipmi->tx_msg_list))
+			break;
+		schedule_timeout(1);
+	}
+	if (!list_empty(&ipmi->tx_msg_list))
+		dev_warn(&pnp_dev->dev, "tx msg list is not NULL\n");
+}
+
+static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
+{
+	struct acpi_ipmi_device *ipmi_device = user_msg_data;
+	int msg_found = 0;
+	struct acpi_ipmi_msg *tx_msg;
+	struct pnp_dev *pnp_dev = ipmi_device->pnp_dev;
+
+	if (msg->user != ipmi_device->user_interface) {
+		dev_warn(&pnp_dev->dev, "Unexpected response is returned. "
+			"returned user %p, expected user %p\n",
+			msg->user, ipmi_device->user_interface);
+		ipmi_free_recv_msg(msg);
+		return;
+	}
+	mutex_lock(&ipmi_device->tx_msg_lock);
+	list_for_each_entry(tx_msg, &ipmi_device->tx_msg_list, head) {
+		if (msg->msgid == tx_msg->tx_msgid) {
+			msg_found = 1;
+			break;
+		}
+	}
+
+	mutex_unlock(&ipmi_device->tx_msg_lock);
+	if (!msg_found) {
+		dev_warn(&pnp_dev->dev, "Unexpected response (msg id %ld) is "
+			"returned.\n", msg->msgid);
+		ipmi_free_recv_msg(msg);
+		return;
+	}
+
+	if (msg->msg.data_len) {
+		/* copy the response data to Rx_data buffer */
+		memcpy(tx_msg->rx_data, msg->msg_data, msg->msg.data_len);
+		tx_msg->rx_len = msg->msg.data_len;
+		tx_msg->msg_done = 1;
+	}
+	complete(&tx_msg->tx_complete);
+	ipmi_free_recv_msg(msg);
+};
+
+static void ipmi_register_bmc(int iface, struct device *dev)
+{
+	struct acpi_ipmi_device *ipmi_device, *temp;
+	struct pnp_dev *pnp_dev;
+	ipmi_user_t		user;
+	int err;
+	struct ipmi_smi_info smi_data;
+	acpi_handle handle;
+
+	err = ipmi_get_smi_info(iface, &smi_data);
+
+	if (err)
+		return;
+
+	if (smi_data.addr_src != SI_ACPI) {
+		put_device(smi_data.dev);
+		return;
+	}
+
+	handle = smi_data.addr_info.acpi_info.acpi_handle;
+
+	mutex_lock(&driver_data.ipmi_lock);
+	list_for_each_entry(temp, &driver_data.ipmi_devices, head) {
+		/*
+		 * if the corresponding ACPI handle is already added
+		 * to the device list, don't add it again.
+		 */
+		if (temp->handle == handle)
+			goto out;
+	}
+
+	ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);
+
+	if (!ipmi_device)
+		goto out;
+
+	pnp_dev = to_pnp_dev(smi_data.dev);
+	ipmi_device->handle = handle;
+	ipmi_device->pnp_dev = pnp_dev;
+
+	err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
+					ipmi_device, &user);
+	if (err) {
+		dev_warn(&pnp_dev->dev, "Can't create IPMI user interface\n");
+		kfree(ipmi_device);
+		goto out;
+	}
+	acpi_add_ipmi_device(ipmi_device);
+	ipmi_device->user_interface = user;
+	ipmi_device->ipmi_ifnum = iface;
+	mutex_unlock(&driver_data.ipmi_lock);
+	memcpy(&ipmi_device->smi_data, &smi_data, sizeof(struct ipmi_smi_info));
+	return;
+
+out:
+	mutex_unlock(&driver_data.ipmi_lock);
+	put_device(smi_data.dev);
+	return;
+}
+
+static void ipmi_bmc_gone(int iface)
+{
+	struct acpi_ipmi_device *ipmi_device, *temp;
+
+	mutex_lock(&driver_data.ipmi_lock);
+	list_for_each_entry_safe(ipmi_device, temp,
+				&driver_data.ipmi_devices, head) {
+		if (ipmi_device->ipmi_ifnum != iface)
+			continue;
+
+		acpi_remove_ipmi_device(ipmi_device);
+		put_device(ipmi_device->smi_data.dev);
+		kfree(ipmi_device);
+		break;
+	}
+	mutex_unlock(&driver_data.ipmi_lock);
+}
+/* --------------------------------------------------------------------------
+ *			Address Space Management
+ * -------------------------------------------------------------------------- */
+/*
+ * This is the IPMI opregion space handler.
+ * @function: indicates the read/write. In fact as the IPMI message is driven
+ * by command, only write is meaningful.
+ * @address: This contains the netfn/command of IPMI request message.
+ * @bits   : not used.
+ * @value  : it is an in/out parameter. It points to the IPMI message buffer.
+ *	     Before the IPMI message is sent, it represents the actual request
+ *	     IPMI message. After the IPMI message is finished, it represents
+ *	     the response IPMI message returned by IPMI command.
+ * @handler_context: IPMI device context.
+ */
+
+static acpi_status
+acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
+		      u32 bits, acpi_integer *value,
+		      void *handler_context, void *region_context)
+{
+	struct acpi_ipmi_msg *tx_msg;
+	struct acpi_ipmi_device *ipmi_device = handler_context;
+	int err, rem_time;
+	acpi_status status;
+	/*
+	 * IPMI opregion message.
+	 * IPMI message is firstly written to the BMC and system software
+	 * can get the respsonse. So it is unmeaningful for the read access
+	 * of IPMI opregion.
+	 */
+	if ((function & ACPI_IO_MASK) == ACPI_READ)
+		return AE_TYPE;
+
+	if (!ipmi_device->user_interface)
+		return AE_NOT_EXIST;
+
+	tx_msg = acpi_alloc_ipmi_msg(ipmi_device);
+	if (!tx_msg)
+		return AE_NO_MEMORY;
+
+	acpi_format_ipmi_msg(tx_msg, address, value);
+	mutex_lock(&ipmi_device->tx_msg_lock);
+	list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
+	mutex_unlock(&ipmi_device->tx_msg_lock);
+	err = ipmi_request_settime(ipmi_device->user_interface,
+					&tx_msg->addr,
+					tx_msg->tx_msgid,
+					&tx_msg->tx_message,
+					NULL, 0, 0, 0);
+	if (err) {
+		status = AE_ERROR;
+		goto end_label;
+	}
+	rem_time = wait_for_completion_timeout(&tx_msg->tx_complete,
+					IPMI_TIMEOUT);
+	acpi_format_ipmi_response(tx_msg, value, rem_time);
+	status = AE_OK;
+
+end_label:
+	mutex_lock(&ipmi_device->tx_msg_lock);
+	list_del(&tx_msg->head);
+	mutex_unlock(&ipmi_device->tx_msg_lock);
+	kfree(tx_msg);
+	return status;
+}
+
+static void ipmi_remove_space_handler(struct acpi_ipmi_device *ipmi)
+{
+	if (!test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
+		return;
+
+	acpi_remove_address_space_handler(ipmi->handle,
+				ACPI_ADR_SPACE_IPMI, &acpi_ipmi_space_handler);
+
+	clear_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
+}
+
+static int ipmi_install_space_handler(struct acpi_ipmi_device *ipmi)
+{
+	acpi_status status;
+
+	if (test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
+		return 0;
+
+	status = acpi_install_address_space_handler(ipmi->handle,
+						    ACPI_ADR_SPACE_IPMI,
+						    &acpi_ipmi_space_handler,
+						    NULL, ipmi);
+	if (ACPI_FAILURE(status)) {
+		struct pnp_dev *pnp_dev = ipmi->pnp_dev;
+		dev_warn(&pnp_dev->dev, "Can't register IPMI opregion space "
+			"handle\n");
+		return -EINVAL;
+	}
+	set_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
+	return 0;
+}
+
+static void acpi_add_ipmi_device(struct acpi_ipmi_device *ipmi_device)
+{
+
+	INIT_LIST_HEAD(&ipmi_device->head);
+
+	mutex_init(&ipmi_device->tx_msg_lock);
+	INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
+	ipmi_install_space_handler(ipmi_device);
+
+	list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
+}
+
+static void acpi_remove_ipmi_device(struct acpi_ipmi_device *ipmi_device)
+{
+	/*
+	 * If the IPMI user interface is created, it should be
+	 * destroyed.
+	 */
+	if (ipmi_device->user_interface) {
+		ipmi_destroy_user(ipmi_device->user_interface);
+		ipmi_device->user_interface = NULL;
+	}
+	/* flush the Tx_msg list */
+	if (!list_empty(&ipmi_device->tx_msg_list))
+		ipmi_flush_tx_msg(ipmi_device);
+
+	list_del(&ipmi_device->head);
+	ipmi_remove_space_handler(ipmi_device);
+}
+
+static int __init acpi_ipmi_init(void)
+{
+	int result = 0;
+
+	if (acpi_disabled)
+		return result;
+
+	mutex_init(&driver_data.ipmi_lock);
+
+	result = ipmi_smi_watcher_register(&driver_data.bmc_events);
+
+	return result;
+}
+
+static void __exit acpi_ipmi_exit(void)
+{
+	struct acpi_ipmi_device *ipmi_device, *temp;
+
+	if (acpi_disabled)
+		return;
+
+	ipmi_smi_watcher_unregister(&driver_data.bmc_events);
+
+	/*
+	 * When one smi_watcher is unregistered, it is only deleted
+	 * from the smi_watcher list. But the smi_gone callback function
+	 * is not called. So explicitly uninstall the ACPI IPMI oregion
+	 * handler and free it.
+	 */
+	mutex_lock(&driver_data.ipmi_lock);
+	list_for_each_entry_safe(ipmi_device, temp,
+				&driver_data.ipmi_devices, head) {
+		acpi_remove_ipmi_device(ipmi_device);
+		put_device(ipmi_device->smi_data.dev);
+		kfree(ipmi_device);
+	}
+	mutex_unlock(&driver_data.ipmi_lock);
+}
+
+module_init(acpi_ipmi_init);
+module_exit(acpi_ipmi_exit);