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/*
 *  acpi_ipmi.c - ACPI IPMI opregion
 *
 *  Copyright (C) 2010 Intel Corporation
 *  Copyright (C) 2010 Zhao Yakui <yakui.zhao@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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);