xref: /linux/drivers/misc/mei/mei_dev.h (revision e58e871becec2d3b04ed91c0c16fe8deac9c9dfa)
1 /*
2  *
3  * Intel Management Engine Interface (Intel MEI) Linux driver
4  * Copyright (c) 2003-2012, Intel Corporation.
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms and conditions of the GNU General Public License,
8  * version 2, as published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope it will be useful, but WITHOUT
11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
13  * more details.
14  *
15  */
16 
17 #ifndef _MEI_DEV_H_
18 #define _MEI_DEV_H_
19 
20 #include <linux/types.h>
21 #include <linux/cdev.h>
22 #include <linux/poll.h>
23 #include <linux/mei.h>
24 #include <linux/mei_cl_bus.h>
25 
26 #include "hw.h"
27 #include "hbm.h"
28 
29 #define MEI_RD_MSG_BUF_SIZE           (128 * sizeof(u32))
30 
31 /*
32  * Number of Maximum MEI Clients
33  */
34 #define MEI_CLIENTS_MAX 256
35 
36 /*
37  * maximum number of consecutive resets
38  */
39 #define MEI_MAX_CONSEC_RESET  3
40 
41 /*
42  * Number of File descriptors/handles
43  * that can be opened to the driver.
44  *
45  * Limit to 255: 256 Total Clients
46  * minus internal client for MEI Bus Messages
47  */
48 #define  MEI_MAX_OPEN_HANDLE_COUNT (MEI_CLIENTS_MAX - 1)
49 
50 /* File state */
51 enum file_state {
52 	MEI_FILE_UNINITIALIZED = 0,
53 	MEI_FILE_INITIALIZING,
54 	MEI_FILE_CONNECTING,
55 	MEI_FILE_CONNECTED,
56 	MEI_FILE_DISCONNECTING,
57 	MEI_FILE_DISCONNECT_REPLY,
58 	MEI_FILE_DISCONNECT_REQUIRED,
59 	MEI_FILE_DISCONNECTED,
60 };
61 
62 /* MEI device states */
63 enum mei_dev_state {
64 	MEI_DEV_INITIALIZING = 0,
65 	MEI_DEV_INIT_CLIENTS,
66 	MEI_DEV_ENABLED,
67 	MEI_DEV_RESETTING,
68 	MEI_DEV_DISABLED,
69 	MEI_DEV_POWER_DOWN,
70 	MEI_DEV_POWER_UP
71 };
72 
73 const char *mei_dev_state_str(int state);
74 
75 enum mei_file_transaction_states {
76 	MEI_IDLE,
77 	MEI_WRITING,
78 	MEI_WRITE_COMPLETE,
79 };
80 
81 /**
82  * enum mei_cb_file_ops  - file operation associated with the callback
83  * @MEI_FOP_READ:       read
84  * @MEI_FOP_WRITE:      write
85  * @MEI_FOP_CONNECT:    connect
86  * @MEI_FOP_DISCONNECT: disconnect
87  * @MEI_FOP_DISCONNECT_RSP: disconnect response
88  * @MEI_FOP_NOTIFY_START:   start notification
89  * @MEI_FOP_NOTIFY_STOP:    stop notification
90  */
91 enum mei_cb_file_ops {
92 	MEI_FOP_READ = 0,
93 	MEI_FOP_WRITE,
94 	MEI_FOP_CONNECT,
95 	MEI_FOP_DISCONNECT,
96 	MEI_FOP_DISCONNECT_RSP,
97 	MEI_FOP_NOTIFY_START,
98 	MEI_FOP_NOTIFY_STOP,
99 };
100 
101 /**
102  * enum mei_cl_io_mode - io mode between driver and fw
103  *
104  * @MEI_CL_IO_TX_BLOCKING: send is blocking
105  * @MEI_CL_IO_TX_INTERNAL: internal communication between driver and FW
106  *
107  * @MEI_CL_IO_RX_NONBLOCK: recv is non-blocking
108  */
109 enum mei_cl_io_mode {
110 	MEI_CL_IO_TX_BLOCKING = BIT(0),
111 	MEI_CL_IO_TX_INTERNAL = BIT(1),
112 
113 	MEI_CL_IO_RX_NONBLOCK = BIT(2),
114 };
115 
116 /*
117  * Intel MEI message data struct
118  */
119 struct mei_msg_data {
120 	size_t size;
121 	unsigned char *data;
122 };
123 
124 /* Maximum number of processed FW status registers */
125 #define MEI_FW_STATUS_MAX 6
126 /* Minimal  buffer for FW status string (8 bytes in dw + space or '\0') */
127 #define MEI_FW_STATUS_STR_SZ (MEI_FW_STATUS_MAX * (8 + 1))
128 
129 
130 /*
131  * struct mei_fw_status - storage of FW status data
132  *
133  * @count: number of actually available elements in array
134  * @status: FW status registers
135  */
136 struct mei_fw_status {
137 	int count;
138 	u32 status[MEI_FW_STATUS_MAX];
139 };
140 
141 /**
142  * struct mei_me_client - representation of me (fw) client
143  *
144  * @list: link in me client list
145  * @refcnt: struct reference count
146  * @props: client properties
147  * @client_id: me client id
148  * @tx_flow_ctrl_creds: flow control credits
149  * @connect_count: number connections to this client
150  * @bus_added: added to bus
151  */
152 struct mei_me_client {
153 	struct list_head list;
154 	struct kref refcnt;
155 	struct mei_client_properties props;
156 	u8 client_id;
157 	u8 tx_flow_ctrl_creds;
158 	u8 connect_count;
159 	u8 bus_added;
160 };
161 
162 
163 struct mei_cl;
164 
165 /**
166  * struct mei_cl_cb - file operation callback structure
167  *
168  * @list: link in callback queue
169  * @cl: file client who is running this operation
170  * @fop_type: file operation type
171  * @buf: buffer for data associated with the callback
172  * @buf_idx: last read index
173  * @fp: pointer to file structure
174  * @status: io status of the cb
175  * @internal: communication between driver and FW flag
176  * @blocking: transmission blocking mode
177  * @completed: the transfer or reception has completed
178  */
179 struct mei_cl_cb {
180 	struct list_head list;
181 	struct mei_cl *cl;
182 	enum mei_cb_file_ops fop_type;
183 	struct mei_msg_data buf;
184 	size_t buf_idx;
185 	const struct file *fp;
186 	int status;
187 	u32 internal:1;
188 	u32 blocking:1;
189 	u32 completed:1;
190 };
191 
192 /**
193  * struct mei_cl - me client host representation
194  *    carried in file->private_data
195  *
196  * @link: link in the clients list
197  * @dev: mei parent device
198  * @state: file operation state
199  * @tx_wait: wait queue for tx completion
200  * @rx_wait: wait queue for rx completion
201  * @wait:  wait queue for management operation
202  * @ev_wait: notification wait queue
203  * @ev_async: event async notification
204  * @status: connection status
205  * @me_cl: fw client connected
206  * @fp: file associated with client
207  * @host_client_id: host id
208  * @tx_flow_ctrl_creds: transmit flow credentials
209  * @rx_flow_ctrl_creds: receive flow credentials
210  * @timer_count:  watchdog timer for operation completion
211  * @notify_en: notification - enabled/disabled
212  * @notify_ev: pending notification event
213  * @writing_state: state of the tx
214  * @rd_pending: pending read credits
215  * @rd_completed: completed read
216  *
217  * @cldev: device on the mei client bus
218  */
219 struct mei_cl {
220 	struct list_head link;
221 	struct mei_device *dev;
222 	enum file_state state;
223 	wait_queue_head_t tx_wait;
224 	wait_queue_head_t rx_wait;
225 	wait_queue_head_t wait;
226 	wait_queue_head_t ev_wait;
227 	struct fasync_struct *ev_async;
228 	int status;
229 	struct mei_me_client *me_cl;
230 	const struct file *fp;
231 	u8 host_client_id;
232 	u8 tx_flow_ctrl_creds;
233 	u8 rx_flow_ctrl_creds;
234 	u8 timer_count;
235 	u8 notify_en;
236 	u8 notify_ev;
237 	enum mei_file_transaction_states writing_state;
238 	struct list_head rd_pending;
239 	struct list_head rd_completed;
240 
241 	struct mei_cl_device *cldev;
242 };
243 
244 /**
245  * struct mei_hw_ops - hw specific ops
246  *
247  * @host_is_ready    : query for host readiness
248  *
249  * @hw_is_ready      : query if hw is ready
250  * @hw_reset         : reset hw
251  * @hw_start         : start hw after reset
252  * @hw_config        : configure hw
253  *
254  * @fw_status        : get fw status registers
255  * @pg_state         : power gating state of the device
256  * @pg_in_transition : is device now in pg transition
257  * @pg_is_enabled    : is power gating enabled
258  *
259  * @intr_clear       : clear pending interrupts
260  * @intr_enable      : enable interrupts
261  * @intr_disable     : disable interrupts
262  * @synchronize_irq  : synchronize irqs
263  *
264  * @hbuf_free_slots  : query for write buffer empty slots
265  * @hbuf_is_ready    : query if write buffer is empty
266  * @hbuf_max_len     : query for write buffer max len
267  *
268  * @write            : write a message to FW
269  *
270  * @rdbuf_full_slots : query how many slots are filled
271  *
272  * @read_hdr         : get first 4 bytes (header)
273  * @read             : read a buffer from the FW
274  */
275 struct mei_hw_ops {
276 
277 	bool (*host_is_ready)(struct mei_device *dev);
278 
279 	bool (*hw_is_ready)(struct mei_device *dev);
280 	int (*hw_reset)(struct mei_device *dev, bool enable);
281 	int (*hw_start)(struct mei_device *dev);
282 	void (*hw_config)(struct mei_device *dev);
283 
284 	int (*fw_status)(struct mei_device *dev, struct mei_fw_status *fw_sts);
285 	enum mei_pg_state (*pg_state)(struct mei_device *dev);
286 	bool (*pg_in_transition)(struct mei_device *dev);
287 	bool (*pg_is_enabled)(struct mei_device *dev);
288 
289 	void (*intr_clear)(struct mei_device *dev);
290 	void (*intr_enable)(struct mei_device *dev);
291 	void (*intr_disable)(struct mei_device *dev);
292 	void (*synchronize_irq)(struct mei_device *dev);
293 
294 	int (*hbuf_free_slots)(struct mei_device *dev);
295 	bool (*hbuf_is_ready)(struct mei_device *dev);
296 	size_t (*hbuf_max_len)(const struct mei_device *dev);
297 	int (*write)(struct mei_device *dev,
298 		     struct mei_msg_hdr *hdr,
299 		     const unsigned char *buf);
300 
301 	int (*rdbuf_full_slots)(struct mei_device *dev);
302 
303 	u32 (*read_hdr)(const struct mei_device *dev);
304 	int (*read)(struct mei_device *dev,
305 		     unsigned char *buf, unsigned long len);
306 };
307 
308 /* MEI bus API*/
309 void mei_cl_bus_rescan(struct mei_device *bus);
310 void mei_cl_bus_rescan_work(struct work_struct *work);
311 void mei_cl_bus_dev_fixup(struct mei_cl_device *dev);
312 ssize_t __mei_cl_send(struct mei_cl *cl, u8 *buf, size_t length,
313 		      unsigned int mode);
314 ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length,
315 		      unsigned int mode);
316 bool mei_cl_bus_rx_event(struct mei_cl *cl);
317 bool mei_cl_bus_notify_event(struct mei_cl *cl);
318 void mei_cl_bus_remove_devices(struct mei_device *bus);
319 bool mei_cl_bus_module_get(struct mei_cl *cl);
320 void mei_cl_bus_module_put(struct mei_cl *cl);
321 int mei_cl_bus_init(void);
322 void mei_cl_bus_exit(void);
323 
324 /**
325  * enum mei_pg_event - power gating transition events
326  *
327  * @MEI_PG_EVENT_IDLE: the driver is not in power gating transition
328  * @MEI_PG_EVENT_WAIT: the driver is waiting for a pg event to complete
329  * @MEI_PG_EVENT_RECEIVED: the driver received pg event
330  * @MEI_PG_EVENT_INTR_WAIT: the driver is waiting for a pg event interrupt
331  * @MEI_PG_EVENT_INTR_RECEIVED: the driver received pg event interrupt
332  */
333 enum mei_pg_event {
334 	MEI_PG_EVENT_IDLE,
335 	MEI_PG_EVENT_WAIT,
336 	MEI_PG_EVENT_RECEIVED,
337 	MEI_PG_EVENT_INTR_WAIT,
338 	MEI_PG_EVENT_INTR_RECEIVED,
339 };
340 
341 /**
342  * enum mei_pg_state - device internal power gating state
343  *
344  * @MEI_PG_OFF: device is not power gated - it is active
345  * @MEI_PG_ON:  device is power gated - it is in lower power state
346  */
347 enum mei_pg_state {
348 	MEI_PG_OFF = 0,
349 	MEI_PG_ON =  1,
350 };
351 
352 const char *mei_pg_state_str(enum mei_pg_state state);
353 
354 /**
355  * struct mei_device -  MEI private device struct
356  *
357  * @dev         : device on a bus
358  * @cdev        : character device
359  * @minor       : minor number allocated for device
360  *
361  * @write_list  : write pending list
362  * @write_waiting_list : write completion list
363  * @ctrl_wr_list : pending control write list
364  * @ctrl_rd_list : pending control read list
365  *
366  * @file_list   : list of opened handles
367  * @open_handle_count: number of opened handles
368  *
369  * @device_lock : big device lock
370  * @timer_work  : MEI timer delayed work (timeouts)
371  *
372  * @recvd_hw_ready : hw ready message received flag
373  *
374  * @wait_hw_ready : wait queue for receive HW ready message form FW
375  * @wait_pg     : wait queue for receive PG message from FW
376  * @wait_hbm_start : wait queue for receive HBM start message from FW
377  *
378  * @reset_count : number of consecutive resets
379  * @dev_state   : device state
380  * @hbm_state   : state of host bus message protocol
381  * @init_clients_timer : HBM init handshake timeout
382  *
383  * @pg_event    : power gating event
384  * @pg_domain   : runtime PM domain
385  *
386  * @rd_msg_buf  : control messages buffer
387  * @rd_msg_hdr  : read message header storage
388  *
389  * @hbuf_depth  : depth of hardware host/write buffer is slots
390  * @hbuf_is_ready : query if the host host/write buffer is ready
391  *
392  * @version     : HBM protocol version in use
393  * @hbm_f_pg_supported  : hbm feature pgi protocol
394  * @hbm_f_dc_supported  : hbm feature dynamic clients
395  * @hbm_f_dot_supported : hbm feature disconnect on timeout
396  * @hbm_f_ev_supported  : hbm feature event notification
397  * @hbm_f_fa_supported  : hbm feature fixed address client
398  * @hbm_f_ie_supported  : hbm feature immediate reply to enum request
399  * @hbm_f_os_supported  : hbm feature support OS ver message
400  *
401  * @me_clients_rwsem: rw lock over me_clients list
402  * @me_clients  : list of FW clients
403  * @me_clients_map : FW clients bit map
404  * @host_clients_map : host clients id pool
405  *
406  * @allow_fixed_address: allow user space to connect a fixed client
407  * @override_fixed_address: force allow fixed address behavior
408  *
409  * @reset_work  : work item for the device reset
410  * @bus_rescan_work : work item for the bus rescan
411  *
412  * @device_list : mei client bus list
413  * @cl_bus_lock : client bus list lock
414  *
415  * @dbgfs_dir   : debugfs mei root directory
416  *
417  * @ops:        : hw specific operations
418  * @hw          : hw specific data
419  */
420 struct mei_device {
421 	struct device *dev;
422 	struct cdev cdev;
423 	int minor;
424 
425 	struct list_head write_list;
426 	struct list_head write_waiting_list;
427 	struct list_head ctrl_wr_list;
428 	struct list_head ctrl_rd_list;
429 
430 	struct list_head file_list;
431 	long open_handle_count;
432 
433 	struct mutex device_lock;
434 	struct delayed_work timer_work;
435 
436 	bool recvd_hw_ready;
437 	/*
438 	 * waiting queue for receive message from FW
439 	 */
440 	wait_queue_head_t wait_hw_ready;
441 	wait_queue_head_t wait_pg;
442 	wait_queue_head_t wait_hbm_start;
443 
444 	/*
445 	 * mei device  states
446 	 */
447 	unsigned long reset_count;
448 	enum mei_dev_state dev_state;
449 	enum mei_hbm_state hbm_state;
450 	u16 init_clients_timer;
451 
452 	/*
453 	 * Power Gating support
454 	 */
455 	enum mei_pg_event pg_event;
456 #ifdef CONFIG_PM
457 	struct dev_pm_domain pg_domain;
458 #endif /* CONFIG_PM */
459 
460 	unsigned char rd_msg_buf[MEI_RD_MSG_BUF_SIZE];
461 	u32 rd_msg_hdr;
462 
463 	/* write buffer */
464 	u8 hbuf_depth;
465 	bool hbuf_is_ready;
466 
467 	struct hbm_version version;
468 	unsigned int hbm_f_pg_supported:1;
469 	unsigned int hbm_f_dc_supported:1;
470 	unsigned int hbm_f_dot_supported:1;
471 	unsigned int hbm_f_ev_supported:1;
472 	unsigned int hbm_f_fa_supported:1;
473 	unsigned int hbm_f_ie_supported:1;
474 	unsigned int hbm_f_os_supported:1;
475 
476 	struct rw_semaphore me_clients_rwsem;
477 	struct list_head me_clients;
478 	DECLARE_BITMAP(me_clients_map, MEI_CLIENTS_MAX);
479 	DECLARE_BITMAP(host_clients_map, MEI_CLIENTS_MAX);
480 
481 	bool allow_fixed_address;
482 	bool override_fixed_address;
483 
484 	struct work_struct reset_work;
485 	struct work_struct bus_rescan_work;
486 
487 	/* List of bus devices */
488 	struct list_head device_list;
489 	struct mutex cl_bus_lock;
490 
491 #if IS_ENABLED(CONFIG_DEBUG_FS)
492 	struct dentry *dbgfs_dir;
493 #endif /* CONFIG_DEBUG_FS */
494 
495 
496 	const struct mei_hw_ops *ops;
497 	char hw[0] __aligned(sizeof(void *));
498 };
499 
500 static inline unsigned long mei_secs_to_jiffies(unsigned long sec)
501 {
502 	return msecs_to_jiffies(sec * MSEC_PER_SEC);
503 }
504 
505 /**
506  * mei_data2slots - get slots - number of (dwords) from a message length
507  *	+ size of the mei header
508  *
509  * @length: size of the messages in bytes
510  *
511  * Return: number of slots
512  */
513 static inline u32 mei_data2slots(size_t length)
514 {
515 	return DIV_ROUND_UP(sizeof(struct mei_msg_hdr) + length, 4);
516 }
517 
518 /**
519  * mei_slots2data - get data in slots - bytes from slots
520  *
521  * @slots: number of available slots
522  *
523  * Return: number of bytes in slots
524  */
525 static inline u32 mei_slots2data(int slots)
526 {
527 	return slots * 4;
528 }
529 
530 /*
531  * mei init function prototypes
532  */
533 void mei_device_init(struct mei_device *dev,
534 		     struct device *device,
535 		     const struct mei_hw_ops *hw_ops);
536 int mei_reset(struct mei_device *dev);
537 int mei_start(struct mei_device *dev);
538 int mei_restart(struct mei_device *dev);
539 void mei_stop(struct mei_device *dev);
540 void mei_cancel_work(struct mei_device *dev);
541 
542 /*
543  *  MEI interrupt functions prototype
544  */
545 
546 void mei_timer(struct work_struct *work);
547 void mei_schedule_stall_timer(struct mei_device *dev);
548 int mei_irq_read_handler(struct mei_device *dev,
549 			 struct list_head *cmpl_list, s32 *slots);
550 
551 int mei_irq_write_handler(struct mei_device *dev, struct list_head *cmpl_list);
552 void mei_irq_compl_handler(struct mei_device *dev, struct list_head *cmpl_list);
553 
554 /*
555  * Register Access Function
556  */
557 
558 
559 static inline void mei_hw_config(struct mei_device *dev)
560 {
561 	dev->ops->hw_config(dev);
562 }
563 
564 static inline enum mei_pg_state mei_pg_state(struct mei_device *dev)
565 {
566 	return dev->ops->pg_state(dev);
567 }
568 
569 static inline bool mei_pg_in_transition(struct mei_device *dev)
570 {
571 	return dev->ops->pg_in_transition(dev);
572 }
573 
574 static inline bool mei_pg_is_enabled(struct mei_device *dev)
575 {
576 	return dev->ops->pg_is_enabled(dev);
577 }
578 
579 static inline int mei_hw_reset(struct mei_device *dev, bool enable)
580 {
581 	return dev->ops->hw_reset(dev, enable);
582 }
583 
584 static inline int mei_hw_start(struct mei_device *dev)
585 {
586 	return dev->ops->hw_start(dev);
587 }
588 
589 static inline void mei_clear_interrupts(struct mei_device *dev)
590 {
591 	dev->ops->intr_clear(dev);
592 }
593 
594 static inline void mei_enable_interrupts(struct mei_device *dev)
595 {
596 	dev->ops->intr_enable(dev);
597 }
598 
599 static inline void mei_disable_interrupts(struct mei_device *dev)
600 {
601 	dev->ops->intr_disable(dev);
602 }
603 
604 static inline void mei_synchronize_irq(struct mei_device *dev)
605 {
606 	dev->ops->synchronize_irq(dev);
607 }
608 
609 static inline bool mei_host_is_ready(struct mei_device *dev)
610 {
611 	return dev->ops->host_is_ready(dev);
612 }
613 static inline bool mei_hw_is_ready(struct mei_device *dev)
614 {
615 	return dev->ops->hw_is_ready(dev);
616 }
617 
618 static inline bool mei_hbuf_is_ready(struct mei_device *dev)
619 {
620 	return dev->ops->hbuf_is_ready(dev);
621 }
622 
623 static inline int mei_hbuf_empty_slots(struct mei_device *dev)
624 {
625 	return dev->ops->hbuf_free_slots(dev);
626 }
627 
628 static inline size_t mei_hbuf_max_len(const struct mei_device *dev)
629 {
630 	return dev->ops->hbuf_max_len(dev);
631 }
632 
633 static inline int mei_write_message(struct mei_device *dev,
634 				    struct mei_msg_hdr *hdr, const void *buf)
635 {
636 	return dev->ops->write(dev, hdr, buf);
637 }
638 
639 static inline u32 mei_read_hdr(const struct mei_device *dev)
640 {
641 	return dev->ops->read_hdr(dev);
642 }
643 
644 static inline void mei_read_slots(struct mei_device *dev,
645 		     unsigned char *buf, unsigned long len)
646 {
647 	dev->ops->read(dev, buf, len);
648 }
649 
650 static inline int mei_count_full_read_slots(struct mei_device *dev)
651 {
652 	return dev->ops->rdbuf_full_slots(dev);
653 }
654 
655 static inline int mei_fw_status(struct mei_device *dev,
656 				struct mei_fw_status *fw_status)
657 {
658 	return dev->ops->fw_status(dev, fw_status);
659 }
660 
661 bool mei_hbuf_acquire(struct mei_device *dev);
662 
663 bool mei_write_is_idle(struct mei_device *dev);
664 
665 #if IS_ENABLED(CONFIG_DEBUG_FS)
666 int mei_dbgfs_register(struct mei_device *dev, const char *name);
667 void mei_dbgfs_deregister(struct mei_device *dev);
668 #else
669 static inline int mei_dbgfs_register(struct mei_device *dev, const char *name)
670 {
671 	return 0;
672 }
673 static inline void mei_dbgfs_deregister(struct mei_device *dev) {}
674 #endif /* CONFIG_DEBUG_FS */
675 
676 int mei_register(struct mei_device *dev, struct device *parent);
677 void mei_deregister(struct mei_device *dev);
678 
679 #define MEI_HDR_FMT "hdr:host=%02d me=%02d len=%d internal=%1d comp=%1d"
680 #define MEI_HDR_PRM(hdr)                  \
681 	(hdr)->host_addr, (hdr)->me_addr, \
682 	(hdr)->length, (hdr)->internal, (hdr)->msg_complete
683 
684 ssize_t mei_fw_status2str(struct mei_fw_status *fw_sts, char *buf, size_t len);
685 /**
686  * mei_fw_status_str - fetch and convert fw status registers to printable string
687  *
688  * @dev: the device structure
689  * @buf: string buffer at minimal size MEI_FW_STATUS_STR_SZ
690  * @len: buffer len must be >= MEI_FW_STATUS_STR_SZ
691  *
692  * Return: number of bytes written or < 0 on failure
693  */
694 static inline ssize_t mei_fw_status_str(struct mei_device *dev,
695 					char *buf, size_t len)
696 {
697 	struct mei_fw_status fw_status;
698 	int ret;
699 
700 	buf[0] = '\0';
701 
702 	ret = mei_fw_status(dev, &fw_status);
703 	if (ret)
704 		return ret;
705 
706 	ret = mei_fw_status2str(&fw_status, buf, MEI_FW_STATUS_STR_SZ);
707 
708 	return ret;
709 }
710 
711 
712 #endif
713