summaryrefslogtreecommitdiffstats
path: root/include/scsi/libsas.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/scsi/libsas.h')
-rw-r--r--include/scsi/libsas.h721
1 files changed, 721 insertions, 0 deletions
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
new file mode 100644
index 000000000..3de3b10da
--- /dev/null
+++ b/include/scsi/libsas.h
@@ -0,0 +1,721 @@
+/*
+ * SAS host prototypes and structures header file
+ *
+ * Copyright (C) 2005 Adaptec, Inc. All rights reserved.
+ * Copyright (C) 2005 Luben Tuikov <luben_tuikov@adaptec.com>
+ *
+ * This file is licensed under GPLv2.
+ *
+ * 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
+ *
+ */
+
+#ifndef _LIBSAS_H_
+#define _LIBSAS_H_
+
+
+#include <linux/timer.h>
+#include <linux/pci.h>
+#include <scsi/sas.h>
+#include <linux/libata.h>
+#include <linux/list.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_transport_sas.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+
+struct block_device;
+
+enum sas_class {
+ SAS,
+ EXPANDER
+};
+
+enum sas_phy_role {
+ PHY_ROLE_NONE = 0,
+ PHY_ROLE_TARGET = 0x40,
+ PHY_ROLE_INITIATOR = 0x80,
+};
+
+enum sas_phy_type {
+ PHY_TYPE_PHYSICAL,
+ PHY_TYPE_VIRTUAL
+};
+
+/* The events are mnemonically described in sas_dump.c
+ * so when updating/adding events here, please also
+ * update the other file too.
+ */
+enum port_event {
+ PORTE_BYTES_DMAED = 0U,
+ PORTE_BROADCAST_RCVD,
+ PORTE_LINK_RESET_ERR,
+ PORTE_TIMER_EVENT,
+ PORTE_HARD_RESET,
+ PORT_NUM_EVENTS,
+};
+
+enum phy_event {
+ PHYE_LOSS_OF_SIGNAL = 0U,
+ PHYE_OOB_DONE,
+ PHYE_OOB_ERROR,
+ PHYE_SPINUP_HOLD, /* hot plug SATA, no COMWAKE sent */
+ PHYE_RESUME_TIMEOUT,
+ PHYE_SHUTDOWN,
+ PHY_NUM_EVENTS,
+};
+
+enum discover_event {
+ DISCE_DISCOVER_DOMAIN = 0U,
+ DISCE_REVALIDATE_DOMAIN,
+ DISCE_SUSPEND,
+ DISCE_RESUME,
+ DISC_NUM_EVENTS,
+};
+
+/* ---------- Expander Devices ---------- */
+
+#define to_dom_device(_obj) container_of(_obj, struct domain_device, dev_obj)
+#define to_dev_attr(_attr) container_of(_attr, struct domain_dev_attribute,\
+ attr)
+
+enum routing_attribute {
+ DIRECT_ROUTING,
+ SUBTRACTIVE_ROUTING,
+ TABLE_ROUTING,
+};
+
+enum ex_phy_state {
+ PHY_EMPTY,
+ PHY_VACANT,
+ PHY_NOT_PRESENT,
+ PHY_DEVICE_DISCOVERED
+};
+
+struct ex_phy {
+ int phy_id;
+
+ enum ex_phy_state phy_state;
+
+ enum sas_device_type attached_dev_type;
+ enum sas_linkrate linkrate;
+
+ u8 attached_sata_host:1;
+ u8 attached_sata_dev:1;
+ u8 attached_sata_ps:1;
+
+ enum sas_protocol attached_tproto;
+ enum sas_protocol attached_iproto;
+
+ u8 attached_sas_addr[SAS_ADDR_SIZE];
+ u8 attached_phy_id;
+
+ int phy_change_count;
+ enum routing_attribute routing_attr;
+ u8 virtual:1;
+
+ int last_da_index;
+
+ struct sas_phy *phy;
+ struct sas_port *port;
+};
+
+struct expander_device {
+ struct list_head children;
+
+ int ex_change_count;
+ u16 max_route_indexes;
+ u8 num_phys;
+
+ u8 t2t_supp:1;
+ u8 configuring:1;
+ u8 conf_route_table:1;
+
+ u8 enclosure_logical_id[8];
+
+ struct ex_phy *ex_phy;
+ struct sas_port *parent_port;
+
+ struct mutex cmd_mutex;
+};
+
+/* ---------- SATA device ---------- */
+#define ATA_RESP_FIS_SIZE 24
+
+struct sata_device {
+ unsigned int class;
+ u8 port_no; /* port number, if this is a PM (Port) */
+
+ struct ata_port *ap;
+ struct ata_host *ata_host;
+ struct smp_resp rps_resp ____cacheline_aligned; /* report_phy_sata_resp */
+ u8 fis[ATA_RESP_FIS_SIZE];
+};
+
+struct ssp_device {
+ struct list_head eh_list_node; /* pending a user requested eh action */
+ struct scsi_lun reset_lun;
+};
+
+enum {
+ SAS_DEV_GONE,
+ SAS_DEV_FOUND, /* device notified to lldd */
+ SAS_DEV_DESTROY,
+ SAS_DEV_EH_PENDING,
+ SAS_DEV_LU_RESET,
+ SAS_DEV_RESET,
+};
+
+struct domain_device {
+ spinlock_t done_lock;
+ enum sas_device_type dev_type;
+
+ enum sas_linkrate linkrate;
+ enum sas_linkrate min_linkrate;
+ enum sas_linkrate max_linkrate;
+
+ int pathways;
+
+ struct domain_device *parent;
+ struct list_head siblings; /* devices on the same level */
+ struct asd_sas_port *port; /* shortcut to root of the tree */
+ struct sas_phy *phy;
+
+ struct list_head dev_list_node;
+ struct list_head disco_list_node; /* awaiting probe or destruct */
+
+ enum sas_protocol iproto;
+ enum sas_protocol tproto;
+
+ struct sas_rphy *rphy;
+
+ u8 sas_addr[SAS_ADDR_SIZE];
+ u8 hashed_sas_addr[HASHED_SAS_ADDR_SIZE];
+
+ u8 frame_rcvd[32];
+
+ union {
+ struct expander_device ex_dev;
+ struct sata_device sata_dev; /* STP & directly attached */
+ struct ssp_device ssp_dev;
+ };
+
+ void *lldd_dev;
+ unsigned long state;
+ struct kref kref;
+};
+
+struct sas_work {
+ struct list_head drain_node;
+ struct work_struct work;
+};
+
+static inline void INIT_SAS_WORK(struct sas_work *sw, void (*fn)(struct work_struct *))
+{
+ INIT_WORK(&sw->work, fn);
+ INIT_LIST_HEAD(&sw->drain_node);
+}
+
+struct sas_discovery_event {
+ struct sas_work work;
+ struct asd_sas_port *port;
+};
+
+static inline struct sas_discovery_event *to_sas_discovery_event(struct work_struct *work)
+{
+ struct sas_discovery_event *ev = container_of(work, typeof(*ev), work.work);
+
+ return ev;
+}
+
+struct sas_discovery {
+ struct sas_discovery_event disc_work[DISC_NUM_EVENTS];
+ unsigned long pending;
+ u8 fanout_sas_addr[8];
+ u8 eeds_a[8];
+ u8 eeds_b[8];
+ int max_level;
+};
+
+/* The port struct is Class:RW, driver:RO */
+struct asd_sas_port {
+/* private: */
+ struct sas_discovery disc;
+ struct domain_device *port_dev;
+ spinlock_t dev_list_lock;
+ struct list_head dev_list;
+ struct list_head disco_list;
+ struct list_head destroy_list;
+ struct list_head sas_port_del_list;
+ enum sas_linkrate linkrate;
+
+ struct sas_work work;
+ int suspended;
+
+/* public: */
+ int id;
+
+ enum sas_class class;
+ u8 sas_addr[SAS_ADDR_SIZE];
+ u8 attached_sas_addr[SAS_ADDR_SIZE];
+ enum sas_protocol iproto;
+ enum sas_protocol tproto;
+
+ enum sas_oob_mode oob_mode;
+
+ spinlock_t phy_list_lock;
+ struct list_head phy_list;
+ int num_phys;
+ u32 phy_mask;
+
+ struct sas_ha_struct *ha;
+
+ struct sas_port *port;
+
+ void *lldd_port; /* not touched by the sas class code */
+};
+
+struct asd_sas_event {
+ struct sas_work work;
+ struct asd_sas_phy *phy;
+ int event;
+};
+
+static inline struct asd_sas_event *to_asd_sas_event(struct work_struct *work)
+{
+ struct asd_sas_event *ev = container_of(work, typeof(*ev), work.work);
+
+ return ev;
+}
+
+static inline void INIT_SAS_EVENT(struct asd_sas_event *ev,
+ void (*fn)(struct work_struct *),
+ struct asd_sas_phy *phy, int event)
+{
+ INIT_SAS_WORK(&ev->work, fn);
+ ev->phy = phy;
+ ev->event = event;
+}
+
+#define SAS_PHY_SHUTDOWN_THRES 1024
+
+/* The phy pretty much is controlled by the LLDD.
+ * The class only reads those fields.
+ */
+struct asd_sas_phy {
+/* private: */
+ atomic_t event_nr;
+ int in_shutdown;
+ int error;
+ int suspended;
+
+ struct sas_phy *phy;
+
+/* public: */
+ /* The following are class:RO, driver:R/W */
+ int enabled; /* must be set */
+
+ int id; /* must be set */
+ enum sas_class class;
+ enum sas_protocol iproto;
+ enum sas_protocol tproto;
+
+ enum sas_phy_type type;
+ enum sas_phy_role role;
+ enum sas_oob_mode oob_mode;
+ enum sas_linkrate linkrate;
+
+ u8 *sas_addr; /* must be set */
+ u8 attached_sas_addr[SAS_ADDR_SIZE]; /* class:RO, driver: R/W */
+
+ spinlock_t frame_rcvd_lock;
+ u8 *frame_rcvd; /* must be set */
+ int frame_rcvd_size;
+
+ spinlock_t sas_prim_lock;
+ u32 sas_prim;
+
+ struct list_head port_phy_el; /* driver:RO */
+ struct asd_sas_port *port; /* Class:RW, driver: RO */
+
+ struct sas_ha_struct *ha; /* may be set; the class sets it anyway */
+
+ void *lldd_phy; /* not touched by the sas_class_code */
+};
+
+struct scsi_core {
+ struct Scsi_Host *shost;
+
+};
+
+enum sas_ha_state {
+ SAS_HA_REGISTERED,
+ SAS_HA_DRAINING,
+ SAS_HA_ATA_EH_ACTIVE,
+ SAS_HA_FROZEN,
+};
+
+struct sas_ha_struct {
+/* private: */
+ struct list_head defer_q; /* work queued while draining */
+ struct mutex drain_mutex;
+ unsigned long state;
+ spinlock_t lock;
+ int eh_active;
+ wait_queue_head_t eh_wait_q;
+ struct list_head eh_dev_q;
+
+ struct mutex disco_mutex;
+
+ struct scsi_core core;
+
+/* public: */
+ char *sas_ha_name;
+ struct device *dev; /* should be set */
+ struct module *lldd_module; /* should be set */
+
+ struct workqueue_struct *event_q;
+ struct workqueue_struct *disco_q;
+
+ u8 *sas_addr; /* must be set */
+ u8 hashed_sas_addr[HASHED_SAS_ADDR_SIZE];
+
+ spinlock_t phy_port_lock;
+ struct asd_sas_phy **sas_phy; /* array of valid pointers, must be set */
+ struct asd_sas_port **sas_port; /* array of valid pointers, must be set */
+ int num_phys; /* must be set, gt 0, static */
+
+ int strict_wide_ports; /* both sas_addr and attached_sas_addr must match
+ * their siblings when forming wide ports */
+
+ /* LLDD calls these to notify the class of an event. */
+ int (*notify_port_event)(struct asd_sas_phy *, enum port_event);
+ int (*notify_phy_event)(struct asd_sas_phy *, enum phy_event);
+
+ void *lldd_ha; /* not touched by sas class code */
+
+ struct list_head eh_done_q; /* complete via scsi_eh_flush_done_q */
+ struct list_head eh_ata_q; /* scmds to promote from sas to ata eh */
+
+ int event_thres;
+};
+
+#define SHOST_TO_SAS_HA(_shost) (*(struct sas_ha_struct **)(_shost)->hostdata)
+
+static inline struct domain_device *
+starget_to_domain_dev(struct scsi_target *starget) {
+ return starget->hostdata;
+}
+
+static inline struct domain_device *
+sdev_to_domain_dev(struct scsi_device *sdev) {
+ return starget_to_domain_dev(sdev->sdev_target);
+}
+
+static inline struct ata_device *sas_to_ata_dev(struct domain_device *dev)
+{
+ return &dev->sata_dev.ap->link.device[0];
+}
+
+static inline struct domain_device *
+cmd_to_domain_dev(struct scsi_cmnd *cmd)
+{
+ return sdev_to_domain_dev(cmd->device);
+}
+
+void sas_hash_addr(u8 *hashed, const u8 *sas_addr);
+
+/* Before calling a notify event, LLDD should use this function
+ * when the link is severed (possibly from its tasklet).
+ * The idea is that the Class only reads those, while the LLDD,
+ * can R/W these (thus avoiding a race).
+ */
+static inline void sas_phy_disconnected(struct asd_sas_phy *phy)
+{
+ phy->oob_mode = OOB_NOT_CONNECTED;
+ phy->linkrate = SAS_LINK_RATE_UNKNOWN;
+}
+
+static inline unsigned int to_sas_gpio_od(int device, int bit)
+{
+ return 3 * device + bit;
+}
+
+static inline void sas_put_local_phy(struct sas_phy *phy)
+{
+ put_device(&phy->dev);
+}
+
+#ifdef CONFIG_SCSI_SAS_HOST_SMP
+int try_test_sas_gpio_gp_bit(unsigned int od, u8 *data, u8 index, u8 count);
+#else
+static inline int try_test_sas_gpio_gp_bit(unsigned int od, u8 *data, u8 index, u8 count)
+{
+ return -1;
+}
+#endif
+
+/* ---------- Tasks ---------- */
+/*
+ service_response | SAS_TASK_COMPLETE | SAS_TASK_UNDELIVERED |
+ exec_status | | |
+ ---------------------+---------------------+-----------------------+
+ SAM_... | X | |
+ DEV_NO_RESPONSE | X | X |
+ INTERRUPTED | X | |
+ QUEUE_FULL | | X |
+ DEVICE_UNKNOWN | | X |
+ SG_ERR | | X |
+ ---------------------+---------------------+-----------------------+
+ */
+
+enum service_response {
+ SAS_TASK_COMPLETE,
+ SAS_TASK_UNDELIVERED = -1,
+};
+
+enum exec_status {
+ /* The SAM_STAT_.. codes fit in the lower 6 bits, alias some of
+ * them here to silence 'case value not in enumerated type' warnings
+ */
+ __SAM_STAT_CHECK_CONDITION = SAM_STAT_CHECK_CONDITION,
+
+ SAS_DEV_NO_RESPONSE = 0x80,
+ SAS_DATA_UNDERRUN,
+ SAS_DATA_OVERRUN,
+ SAS_INTERRUPTED,
+ SAS_QUEUE_FULL,
+ SAS_DEVICE_UNKNOWN,
+ SAS_SG_ERR,
+ SAS_OPEN_REJECT,
+ SAS_OPEN_TO,
+ SAS_PROTO_RESPONSE,
+ SAS_PHY_DOWN,
+ SAS_NAK_R_ERR,
+ SAS_PENDING,
+ SAS_ABORTED_TASK,
+};
+
+/* When a task finishes with a response, the LLDD examines the
+ * response:
+ * - For an ATA task task_status_struct::stat is set to
+ * SAS_PROTO_RESPONSE, and the task_status_struct::buf is set to the
+ * contents of struct ata_task_resp.
+ * - For SSP tasks, if no data is present or status/TMF response
+ * is valid, task_status_struct::stat is set. If data is present
+ * (SENSE data), the LLDD copies up to SAS_STATUS_BUF_SIZE, sets
+ * task_status_struct::buf_valid_size, and task_status_struct::stat is
+ * set to SAM_CHECK_COND.
+ *
+ * "buf" has format SCSI Sense for SSP task, or struct ata_task_resp
+ * for ATA task.
+ *
+ * "frame_len" is the total frame length, which could be more or less
+ * than actually copied.
+ *
+ * Tasks ending with response, always set the residual field.
+ */
+struct ata_task_resp {
+ u16 frame_len;
+ u8 ending_fis[ATA_RESP_FIS_SIZE]; /* dev to host or data-in */
+};
+
+#define SAS_STATUS_BUF_SIZE 96
+
+struct task_status_struct {
+ enum service_response resp;
+ enum exec_status stat;
+ int buf_valid_size;
+
+ u8 buf[SAS_STATUS_BUF_SIZE];
+
+ u32 residual;
+ enum sas_open_rej_reason open_rej_reason;
+};
+
+/* ATA and ATAPI task queuable to a SAS LLDD.
+ */
+struct sas_ata_task {
+ struct host_to_dev_fis fis;
+ u8 atapi_packet[16]; /* 0 if not ATAPI task */
+
+ u8 retry_count; /* hardware retry, should be > 0 */
+
+ u8 dma_xfer:1; /* PIO:0 or DMA:1 */
+ u8 use_ncq:1;
+ u8 set_affil_pol:1;
+ u8 stp_affil_pol:1;
+
+ u8 device_control_reg_update:1;
+};
+
+struct sas_smp_task {
+ struct scatterlist smp_req;
+ struct scatterlist smp_resp;
+};
+
+enum task_attribute {
+ TASK_ATTR_SIMPLE = 0,
+ TASK_ATTR_HOQ = 1,
+ TASK_ATTR_ORDERED= 2,
+ TASK_ATTR_ACA = 4,
+};
+
+struct sas_ssp_task {
+ u8 retry_count; /* hardware retry, should be > 0 */
+
+ u8 LUN[8];
+ u8 enable_first_burst:1;
+ enum task_attribute task_attr;
+ u8 task_prio;
+ struct scsi_cmnd *cmd;
+};
+
+struct sas_task {
+ struct domain_device *dev;
+
+ spinlock_t task_state_lock;
+ unsigned task_state_flags;
+
+ enum sas_protocol task_proto;
+
+ union {
+ struct sas_ata_task ata_task;
+ struct sas_smp_task smp_task;
+ struct sas_ssp_task ssp_task;
+ };
+
+ struct scatterlist *scatter;
+ int num_scatter;
+ u32 total_xfer_len;
+ u8 data_dir:2; /* Use PCI_DMA_... */
+
+ struct task_status_struct task_status;
+ void (*task_done)(struct sas_task *);
+
+ void *lldd_task; /* for use by LLDDs */
+ void *uldd_task;
+ struct sas_task_slow *slow_task;
+};
+
+struct sas_task_slow {
+ /* standard/extra infrastructure for slow path commands (SMP and
+ * internal lldd commands
+ */
+ struct timer_list timer;
+ struct completion completion;
+ struct sas_task *task;
+};
+
+#define SAS_TASK_STATE_PENDING 1
+#define SAS_TASK_STATE_DONE 2
+#define SAS_TASK_STATE_ABORTED 4
+#define SAS_TASK_NEED_DEV_RESET 8
+#define SAS_TASK_AT_INITIATOR 16
+
+extern struct sas_task *sas_alloc_task(gfp_t flags);
+extern struct sas_task *sas_alloc_slow_task(gfp_t flags);
+extern void sas_free_task(struct sas_task *task);
+
+struct sas_domain_function_template {
+ /* The class calls these to notify the LLDD of an event. */
+ void (*lldd_port_formed)(struct asd_sas_phy *);
+ void (*lldd_port_deformed)(struct asd_sas_phy *);
+
+ /* The class calls these when a device is found or gone. */
+ int (*lldd_dev_found)(struct domain_device *);
+ void (*lldd_dev_gone)(struct domain_device *);
+
+ int (*lldd_execute_task)(struct sas_task *, gfp_t gfp_flags);
+
+ /* Task Management Functions. Must be called from process context. */
+ int (*lldd_abort_task)(struct sas_task *);
+ int (*lldd_abort_task_set)(struct domain_device *, u8 *lun);
+ int (*lldd_clear_aca)(struct domain_device *, u8 *lun);
+ int (*lldd_clear_task_set)(struct domain_device *, u8 *lun);
+ int (*lldd_I_T_nexus_reset)(struct domain_device *);
+ int (*lldd_ata_check_ready)(struct domain_device *);
+ void (*lldd_ata_set_dmamode)(struct domain_device *);
+ int (*lldd_lu_reset)(struct domain_device *, u8 *lun);
+ int (*lldd_query_task)(struct sas_task *);
+
+ /* Port and Adapter management */
+ int (*lldd_clear_nexus_port)(struct asd_sas_port *);
+ int (*lldd_clear_nexus_ha)(struct sas_ha_struct *);
+
+ /* Phy management */
+ int (*lldd_control_phy)(struct asd_sas_phy *, enum phy_func, void *);
+
+ /* GPIO support */
+ int (*lldd_write_gpio)(struct sas_ha_struct *, u8 reg_type,
+ u8 reg_index, u8 reg_count, u8 *write_data);
+};
+
+extern int sas_register_ha(struct sas_ha_struct *);
+extern int sas_unregister_ha(struct sas_ha_struct *);
+extern void sas_prep_resume_ha(struct sas_ha_struct *sas_ha);
+extern void sas_resume_ha(struct sas_ha_struct *sas_ha);
+extern void sas_suspend_ha(struct sas_ha_struct *sas_ha);
+
+int sas_set_phy_speed(struct sas_phy *phy,
+ struct sas_phy_linkrates *rates);
+int sas_phy_reset(struct sas_phy *phy, int hard_reset);
+extern int sas_queuecommand(struct Scsi_Host * ,struct scsi_cmnd *);
+extern int sas_target_alloc(struct scsi_target *);
+extern int sas_slave_configure(struct scsi_device *);
+extern int sas_change_queue_depth(struct scsi_device *, int new_depth);
+extern int sas_bios_param(struct scsi_device *,
+ struct block_device *,
+ sector_t capacity, int *hsc);
+extern struct scsi_transport_template *
+sas_domain_attach_transport(struct sas_domain_function_template *);
+extern struct device_attribute dev_attr_phy_event_threshold;
+
+int sas_discover_root_expander(struct domain_device *);
+
+void sas_init_ex_attr(void);
+
+int sas_ex_revalidate_domain(struct domain_device *);
+
+void sas_unregister_domain_devices(struct asd_sas_port *port, int gone);
+void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *);
+int sas_discover_event(struct asd_sas_port *, enum discover_event ev);
+
+int sas_discover_sata(struct domain_device *);
+int sas_discover_end_dev(struct domain_device *);
+
+void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *);
+
+void sas_init_dev(struct domain_device *);
+
+void sas_task_abort(struct sas_task *);
+int sas_eh_abort_handler(struct scsi_cmnd *cmd);
+int sas_eh_device_reset_handler(struct scsi_cmnd *cmd);
+int sas_eh_target_reset_handler(struct scsi_cmnd *cmd);
+
+extern void sas_target_destroy(struct scsi_target *);
+extern int sas_slave_alloc(struct scsi_device *);
+extern int sas_ioctl(struct scsi_device *sdev, int cmd, void __user *arg);
+extern int sas_drain_work(struct sas_ha_struct *ha);
+
+extern void sas_ssp_task_response(struct device *dev, struct sas_task *task,
+ struct ssp_response_iu *iu);
+struct sas_phy *sas_get_local_phy(struct domain_device *dev);
+
+int sas_request_addr(struct Scsi_Host *shost, u8 *addr);
+
+#endif /* _SASLIB_H_ */