diff options
author | Len Brown <len.brown@intel.com> | 2011-01-12 05:03:13 -0500 |
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committer | Len Brown <len.brown@intel.com> | 2011-01-12 05:03:13 -0500 |
commit | 4b63bd35eb4e7959b0f7be17634689d34311524b (patch) | |
tree | 2dad174e4ef8cbe5ef86541a8496b5f97dcf35d1 /drivers | |
parent | 03b6e6e58d9dd5f3068288653810db3c15fde929 (diff) | |
parent | e92b297cc72ade7a58eaec7e01c906d856f8ab6e (diff) | |
download | op-kernel-dev-4b63bd35eb4e7959b0f7be17634689d34311524b.zip op-kernel-dev-4b63bd35eb4e7959b0f7be17634689d34311524b.tar.gz |
Merge branch 'ipmi' into release
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/acpi/Kconfig | 11 | ||||
-rw-r--r-- | drivers/acpi/Makefile | 1 | ||||
-rw-r--r-- | drivers/acpi/acpi_ipmi.c | 525 | ||||
-rw-r--r-- | drivers/char/ipmi/ipmi_msghandler.c | 27 | ||||
-rw-r--r-- | drivers/char/ipmi/ipmi_si_intf.c | 20 |
5 files changed, 580 insertions, 4 deletions
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 788e88e..865fcb3 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -207,6 +207,17 @@ config ACPI_PROCESSOR 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 diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index 9cc9f2c..d113fa5 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -69,5 +69,6 @@ processor-y += processor_idle.o processor_thermal.o 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/ diff --git a/drivers/acpi/acpi_ipmi.c b/drivers/acpi/acpi_ipmi.c new file mode 100644 index 0000000..f40acef --- /dev/null +++ b/drivers/acpi/acpi_ipmi.c @@ -0,0 +1,525 @@ +/* + * 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); diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c index 2fe72f8..38223e9 100644 --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -970,6 +970,33 @@ out_kfree: } EXPORT_SYMBOL(ipmi_create_user); +int ipmi_get_smi_info(int if_num, struct ipmi_smi_info *data) +{ + int rv = 0; + ipmi_smi_t intf; + struct ipmi_smi_handlers *handlers; + + mutex_lock(&ipmi_interfaces_mutex); + list_for_each_entry_rcu(intf, &ipmi_interfaces, link) { + if (intf->intf_num == if_num) + goto found; + } + /* Not found, return an error */ + rv = -EINVAL; + mutex_unlock(&ipmi_interfaces_mutex); + return rv; + +found: + handlers = intf->handlers; + rv = -ENOSYS; + if (handlers->get_smi_info) + rv = handlers->get_smi_info(intf->send_info, data); + mutex_unlock(&ipmi_interfaces_mutex); + + return rv; +} +EXPORT_SYMBOL(ipmi_get_smi_info); + static void free_user(struct kref *ref) { ipmi_user_t user = container_of(ref, struct ipmi_user, refcount); diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c index c4bacc6..3a3643c 100644 --- a/drivers/char/ipmi/ipmi_si_intf.c +++ b/drivers/char/ipmi/ipmi_si_intf.c @@ -57,6 +57,7 @@ #include <asm/irq.h> #include <linux/interrupt.h> #include <linux/rcupdate.h> +#include <linux/ipmi.h> #include <linux/ipmi_smi.h> #include <asm/io.h> #include "ipmi_si_sm.h" @@ -107,10 +108,6 @@ enum si_type { }; static char *si_to_str[] = { "kcs", "smic", "bt" }; -enum ipmi_addr_src { - SI_INVALID = 0, SI_HOTMOD, SI_HARDCODED, SI_SPMI, SI_ACPI, SI_SMBIOS, - SI_PCI, SI_DEVICETREE, SI_DEFAULT -}; static char *ipmi_addr_src_to_str[] = { NULL, "hotmod", "hardcoded", "SPMI", "ACPI", "SMBIOS", "PCI", "device-tree", "default" }; @@ -291,6 +288,7 @@ struct smi_info { struct task_struct *thread; struct list_head link; + union ipmi_smi_info_union addr_info; }; #define smi_inc_stat(smi, stat) \ @@ -1186,6 +1184,18 @@ static int smi_start_processing(void *send_info, return 0; } +static int get_smi_info(void *send_info, struct ipmi_smi_info *data) +{ + struct smi_info *smi = send_info; + + data->addr_src = smi->addr_source; + data->dev = smi->dev; + data->addr_info = smi->addr_info; + get_device(smi->dev); + + return 0; +} + static void set_maintenance_mode(void *send_info, int enable) { struct smi_info *smi_info = send_info; @@ -1197,6 +1207,7 @@ static void set_maintenance_mode(void *send_info, int enable) static struct ipmi_smi_handlers handlers = { .owner = THIS_MODULE, .start_processing = smi_start_processing, + .get_smi_info = get_smi_info, .sender = sender, .request_events = request_events, .set_maintenance_mode = set_maintenance_mode, @@ -2157,6 +2168,7 @@ static int __devinit ipmi_pnp_probe(struct pnp_dev *dev, printk(KERN_INFO PFX "probing via ACPI\n"); handle = acpi_dev->handle; + info->addr_info.acpi_info.acpi_handle = handle; /* _IFT tells us the interface type: KCS, BT, etc */ status = acpi_evaluate_integer(handle, "_IFT", NULL, &tmp); |