xref: /openbmc/linux/arch/powerpc/include/asm/smu.h (revision 842ed298)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _SMU_H
3 #define _SMU_H
4 
5 /*
6  * Definitions for talking to the SMU chip in newer G5 PowerMacs
7  */
8 #ifdef __KERNEL__
9 #include <linux/list.h>
10 #endif
11 #include <linux/types.h>
12 
13 /*
14  * Known SMU commands
15  *
16  * Most of what is below comes from looking at the Open Firmware driver,
17  * though this is still incomplete and could use better documentation here
18  * or there...
19  */
20 
21 
22 /*
23  * Partition info commands
24  *
25  * These commands are used to retrieve the sdb-partition-XX datas from
26  * the SMU. The length is always 2. First byte is the subcommand code
27  * and second byte is the partition ID.
28  *
29  * The reply is 6 bytes:
30  *
31  *  - 0..1 : partition address
32  *  - 2    : a byte containing the partition ID
33  *  - 3    : length (maybe other bits are rest of header ?)
34  *
35  * The data must then be obtained with calls to another command:
36  * SMU_CMD_MISC_ee_GET_DATABLOCK_REC (described below).
37  */
38 #define SMU_CMD_PARTITION_COMMAND		0x3e
39 #define   SMU_CMD_PARTITION_LATEST		0x01
40 #define   SMU_CMD_PARTITION_BASE		0x02
41 #define   SMU_CMD_PARTITION_UPDATE		0x03
42 
43 
44 /*
45  * Fan control
46  *
47  * This is a "mux" for fan control commands. The command seem to
48  * act differently based on the number of arguments. With 1 byte
49  * of argument, this seem to be queries for fans status, setpoint,
50  * etc..., while with 0xe arguments, we will set the fans speeds.
51  *
52  * Queries (1 byte arg):
53  * ---------------------
54  *
55  * arg=0x01: read RPM fans status
56  * arg=0x02: read RPM fans setpoint
57  * arg=0x11: read PWM fans status
58  * arg=0x12: read PWM fans setpoint
59  *
60  * the "status" queries return the current speed while the "setpoint" ones
61  * return the programmed/target speed. It _seems_ that the result is a bit
62  * mask in the first byte of active/available fans, followed by 6 words (16
63  * bits) containing the requested speed.
64  *
65  * Setpoint (14 bytes arg):
66  * ------------------------
67  *
68  * first arg byte is 0 for RPM fans and 0x10 for PWM. Second arg byte is the
69  * mask of fans affected by the command. Followed by 6 words containing the
70  * setpoint value for selected fans in the mask (or 0 if mask value is 0)
71  */
72 #define SMU_CMD_FAN_COMMAND			0x4a
73 
74 
75 /*
76  * Battery access
77  *
78  * Same command number as the PMU, could it be same syntax ?
79  */
80 #define SMU_CMD_BATTERY_COMMAND			0x6f
81 #define   SMU_CMD_GET_BATTERY_INFO		0x00
82 
83 /*
84  * Real time clock control
85  *
86  * This is a "mux", first data byte contains the "sub" command.
87  * The "RTC" part of the SMU controls the date, time, powerup
88  * timer, but also a PRAM
89  *
90  * Dates are in BCD format on 7 bytes:
91  * [sec] [min] [hour] [weekday] [month day] [month] [year]
92  * with month being 1 based and year minus 100
93  */
94 #define SMU_CMD_RTC_COMMAND			0x8e
95 #define   SMU_CMD_RTC_SET_PWRUP_TIMER		0x00 /* i: 7 bytes date */
96 #define   SMU_CMD_RTC_GET_PWRUP_TIMER		0x01 /* o: 7 bytes date */
97 #define   SMU_CMD_RTC_STOP_PWRUP_TIMER		0x02
98 #define   SMU_CMD_RTC_SET_PRAM_BYTE_ACC		0x20 /* i: 1 byte (address?) */
99 #define   SMU_CMD_RTC_SET_PRAM_AUTOINC		0x21 /* i: 1 byte (data?) */
100 #define   SMU_CMD_RTC_SET_PRAM_LO_BYTES 	0x22 /* i: 10 bytes */
101 #define   SMU_CMD_RTC_SET_PRAM_HI_BYTES 	0x23 /* i: 10 bytes */
102 #define   SMU_CMD_RTC_GET_PRAM_BYTE		0x28 /* i: 1 bytes (address?) */
103 #define   SMU_CMD_RTC_GET_PRAM_LO_BYTES 	0x29 /* o: 10 bytes */
104 #define   SMU_CMD_RTC_GET_PRAM_HI_BYTES 	0x2a /* o: 10 bytes */
105 #define	  SMU_CMD_RTC_SET_DATETIME		0x80 /* i: 7 bytes date */
106 #define   SMU_CMD_RTC_GET_DATETIME		0x81 /* o: 7 bytes date */
107 
108  /*
109   * i2c commands
110   *
111   * To issue an i2c command, first is to send a parameter block to
112   * the SMU. This is a command of type 0x9a with 9 bytes of header
113   * eventually followed by data for a write:
114   *
115   * 0: bus number (from device-tree usually, SMU has lots of busses !)
116   * 1: transfer type/format (see below)
117   * 2: device address. For combined and combined4 type transfers, this
118   *    is the "write" version of the address (bit 0x01 cleared)
119   * 3: subaddress length (0..3)
120   * 4: subaddress byte 0 (or only byte for subaddress length 1)
121   * 5: subaddress byte 1
122   * 6: subaddress byte 2
123   * 7: combined address (device address for combined mode data phase)
124   * 8: data length
125   *
126   * The transfer types are the same good old Apple ones it seems,
127   * that is:
128   *   - 0x00: Simple transfer
129   *   - 0x01: Subaddress transfer (addr write + data tx, no restart)
130   *   - 0x02: Combined transfer (addr write + restart + data tx)
131   *
132   * This is then followed by actual data for a write.
133   *
134   * At this point, the OF driver seems to have a limitation on transfer
135   * sizes of 0xd bytes on reads and 0x5 bytes on writes. I do not know
136   * whether this is just an OF limit due to some temporary buffer size
137   * or if this is an SMU imposed limit. This driver has the same limitation
138   * for now as I use a 0x10 bytes temporary buffer as well
139   *
140   * Once that is completed, a response is expected from the SMU. This is
141   * obtained via a command of type 0x9a with a length of 1 byte containing
142   * 0 as the data byte. OF also fills the rest of the data buffer with 0xff's
143   * though I can't tell yet if this is actually necessary. Once this command
144   * is complete, at this point, all I can tell is what OF does. OF tests
145   * byte 0 of the reply:
146   *   - on read, 0xfe or 0xfc : bus is busy, wait (see below) or nak ?
147   *   - on read, 0x00 or 0x01 : reply is in buffer (after the byte 0)
148   *   - on write, < 0 -> failure (immediate exit)
149   *   - else, OF just exists (without error, weird)
150   *
151   * So on read, there is this wait-for-busy thing when getting a 0xfc or
152   * 0xfe result. OF does a loop of up to 64 retries, waiting 20ms and
153   * doing the above again until either the retries expire or the result
154   * is no longer 0xfe or 0xfc
155   *
156   * The Darwin I2C driver is less subtle though. On any non-success status
157   * from the response command, it waits 5ms and tries again up to 20 times,
158   * it doesn't differentiate between fatal errors or "busy" status.
159   *
160   * This driver provides an asynchronous paramblock based i2c command
161   * interface to be used either directly by low level code or by a higher
162   * level driver interfacing to the linux i2c layer. The current
163   * implementation of this relies on working timers & timer interrupts
164   * though, so be careful of calling context for now. This may be "fixed"
165   * in the future by adding a polling facility.
166   */
167 #define SMU_CMD_I2C_COMMAND			0x9a
168           /* transfer types */
169 #define   SMU_I2C_TRANSFER_SIMPLE	0x00
170 #define   SMU_I2C_TRANSFER_STDSUB	0x01
171 #define   SMU_I2C_TRANSFER_COMBINED	0x02
172 
173 /*
174  * Power supply control
175  *
176  * The "sub" command is an ASCII string in the data, the
177  * data length is that of the string.
178  *
179  * The VSLEW command can be used to get or set the voltage slewing.
180  *  - length 5 (only "VSLEW") : it returns "DONE" and 3 bytes of
181  *    reply at data offset 6, 7 and 8.
182  *  - length 8 ("VSLEWxyz") has 3 additional bytes appended, and is
183  *    used to set the voltage slewing point. The SMU replies with "DONE"
184  * I yet have to figure out their exact meaning of those 3 bytes in
185  * both cases. They seem to be:
186  *  x = processor mask
187  *  y = op. point index
188  *  z = processor freq. step index
189  * I haven't yet deciphered result codes
190  *
191  */
192 #define SMU_CMD_POWER_COMMAND			0xaa
193 #define   SMU_CMD_POWER_RESTART		       	"RESTART"
194 #define   SMU_CMD_POWER_SHUTDOWN		"SHUTDOWN"
195 #define   SMU_CMD_POWER_VOLTAGE_SLEW		"VSLEW"
196 
197 /*
198  * Read ADC sensors
199  *
200  * This command takes one byte of parameter: the sensor ID (or "reg"
201  * value in the device-tree) and returns a 16 bits value
202  */
203 #define SMU_CMD_READ_ADC			0xd8
204 
205 
206 /* Misc commands
207  *
208  * This command seem to be a grab bag of various things
209  *
210  * Parameters:
211  *   1: subcommand
212  */
213 #define SMU_CMD_MISC_df_COMMAND			0xdf
214 
215 /*
216  * Sets "system ready" status
217  *
218  * I did not yet understand how it exactly works or what it does.
219  *
220  * Guessing from OF code, 0x02 activates the display backlight. Apple uses/used
221  * the same codebase for all OF versions. On PowerBooks, this command would
222  * enable the backlight. For the G5s, it only activates the front LED. However,
223  * don't take this for granted.
224  *
225  * Parameters:
226  *   2: status [0x00, 0x01 or 0x02]
227  */
228 #define   SMU_CMD_MISC_df_SET_DISPLAY_LIT	0x02
229 
230 /*
231  * Sets mode of power switch.
232  *
233  * What this actually does is not yet known. Maybe it enables some interrupt.
234  *
235  * Parameters:
236  *   2: enable power switch? [0x00 or 0x01]
237  *   3 (optional): enable nmi? [0x00 or 0x01]
238  *
239  * Returns:
240  *   If parameter 2 is 0x00 and parameter 3 is not specified, returns whether
241  *   NMI is enabled. Otherwise unknown.
242  */
243 #define   SMU_CMD_MISC_df_NMI_OPTION		0x04
244 
245 /* Sets LED dimm offset.
246  *
247  * The front LED dimms itself during sleep. Its brightness (or, well, the PWM
248  * frequency) depends on current time. Therefore, the SMU needs to know the
249  * timezone.
250  *
251  * Parameters:
252  *   2-8: unknown (BCD coding)
253  */
254 #define   SMU_CMD_MISC_df_DIMM_OFFSET		0x99
255 
256 
257 /*
258  * Version info commands
259  *
260  * Parameters:
261  *   1 (optional): Specifies version part to retrieve
262  *
263  * Returns:
264  *   Version value
265  */
266 #define SMU_CMD_VERSION_COMMAND			0xea
267 #define   SMU_VERSION_RUNNING			0x00
268 #define   SMU_VERSION_BASE			0x01
269 #define   SMU_VERSION_UPDATE			0x02
270 
271 
272 /*
273  * Switches
274  *
275  * These are switches whose status seems to be known to the SMU.
276  *
277  * Parameters:
278  *   none
279  *
280  * Result:
281  *   Switch bits (ORed, see below)
282  */
283 #define SMU_CMD_SWITCHES			0xdc
284 
285 /* Switches bits */
286 #define SMU_SWITCH_CASE_CLOSED			0x01
287 #define SMU_SWITCH_AC_POWER			0x04
288 #define SMU_SWITCH_POWER_SWITCH			0x08
289 
290 
291 /*
292  * Misc commands
293  *
294  * This command seem to be a grab bag of various things
295  *
296  * SMU_CMD_MISC_ee_GET_DATABLOCK_REC is used, among others, to
297  * transfer blocks of data from the SMU. So far, I've decrypted it's
298  * usage to retrieve partition data. In order to do that, you have to
299  * break your transfer in "chunks" since that command cannot transfer
300  * more than a chunk at a time. The chunk size used by OF is 0xe bytes,
301  * but it seems that the darwin driver will let you do 0x1e bytes if
302  * your "PMU" version is >= 0x30. You can get the "PMU" version apparently
303  * either in the last 16 bits of property "smu-version-pmu" or as the 16
304  * bytes at offset 1 of "smu-version-info"
305  *
306  * For each chunk, the command takes 7 bytes of arguments:
307  *  byte 0: subcommand code (0x02)
308  *  byte 1: 0x04 (always, I don't know what it means, maybe the address
309  *                space to use or some other nicety. It's hard coded in OF)
310  *  byte 2..5: SMU address of the chunk (big endian 32 bits)
311  *  byte 6: size to transfer (up to max chunk size)
312  *
313  * The data is returned directly
314  */
315 #define SMU_CMD_MISC_ee_COMMAND			0xee
316 #define   SMU_CMD_MISC_ee_GET_DATABLOCK_REC	0x02
317 
318 /* Retrieves currently used watts.
319  *
320  * Parameters:
321  *   1: 0x03 (Meaning unknown)
322  */
323 #define   SMU_CMD_MISC_ee_GET_WATTS		0x03
324 
325 #define   SMU_CMD_MISC_ee_LEDS_CTRL		0x04 /* i: 00 (00,01) [00] */
326 #define   SMU_CMD_MISC_ee_GET_DATA		0x05 /* i: 00 , o: ?? */
327 
328 
329 /*
330  * Power related commands
331  *
332  * Parameters:
333  *   1: subcommand
334  */
335 #define SMU_CMD_POWER_EVENTS_COMMAND		0x8f
336 
337 /* SMU_POWER_EVENTS subcommands */
338 enum {
339 	SMU_PWR_GET_POWERUP_EVENTS      = 0x00,
340 	SMU_PWR_SET_POWERUP_EVENTS      = 0x01,
341 	SMU_PWR_CLR_POWERUP_EVENTS      = 0x02,
342 	SMU_PWR_GET_WAKEUP_EVENTS       = 0x03,
343 	SMU_PWR_SET_WAKEUP_EVENTS       = 0x04,
344 	SMU_PWR_CLR_WAKEUP_EVENTS       = 0x05,
345 
346 	/*
347 	 * Get last shutdown cause
348 	 *
349 	 * Returns:
350 	 *   1 byte (signed char): Last shutdown cause. Exact meaning unknown.
351 	 */
352 	SMU_PWR_LAST_SHUTDOWN_CAUSE	= 0x07,
353 
354 	/*
355 	 * Sets or gets server ID. Meaning or use is unknown.
356 	 *
357 	 * Parameters:
358 	 *   2 (optional): Set server ID (1 byte)
359 	 *
360 	 * Returns:
361 	 *   1 byte (server ID?)
362 	 */
363 	SMU_PWR_SERVER_ID		= 0x08,
364 };
365 
366 /* Power events wakeup bits */
367 enum {
368 	SMU_PWR_WAKEUP_KEY              = 0x01, /* Wake on key press */
369 	SMU_PWR_WAKEUP_AC_INSERT        = 0x02, /* Wake on AC adapter plug */
370 	SMU_PWR_WAKEUP_AC_CHANGE        = 0x04,
371 	SMU_PWR_WAKEUP_LID_OPEN         = 0x08,
372 	SMU_PWR_WAKEUP_RING             = 0x10,
373 };
374 
375 
376 /*
377  * - Kernel side interface -
378  */
379 
380 #ifdef __KERNEL__
381 
382 /*
383  * Asynchronous SMU commands
384  *
385  * Fill up this structure and submit it via smu_queue_command(),
386  * and get notified by the optional done() callback, or because
387  * status becomes != 1
388  */
389 
390 struct smu_cmd;
391 
392 struct smu_cmd
393 {
394 	/* public */
395 	u8			cmd;		/* command */
396 	int			data_len;	/* data len */
397 	int			reply_len;	/* reply len */
398 	void			*data_buf;	/* data buffer */
399 	void			*reply_buf;	/* reply buffer */
400 	int			status;		/* command status */
401 	void			(*done)(struct smu_cmd *cmd, void *misc);
402 	void			*misc;
403 
404 	/* private */
405 	struct list_head	link;
406 };
407 
408 /*
409  * Queues an SMU command, all fields have to be initialized
410  */
411 extern int smu_queue_cmd(struct smu_cmd *cmd);
412 
413 /*
414  * Simple command wrapper. This structure embeds a small buffer
415  * to ease sending simple SMU commands from the stack
416  */
417 struct smu_simple_cmd
418 {
419 	struct smu_cmd	cmd;
420 	u8	       	buffer[16];
421 };
422 
423 /*
424  * Queues a simple command. All fields will be initialized by that
425  * function
426  */
427 extern int smu_queue_simple(struct smu_simple_cmd *scmd, u8 command,
428 			    unsigned int data_len,
429 			    void (*done)(struct smu_cmd *cmd, void *misc),
430 			    void *misc,
431 			    ...);
432 
433 /*
434  * Completion helper. Pass it to smu_queue_simple or as 'done'
435  * member to smu_queue_cmd, it will call complete() on the struct
436  * completion passed in the "misc" argument
437  */
438 extern void smu_done_complete(struct smu_cmd *cmd, void *misc);
439 
440 /*
441  * Synchronous helpers. Will spin-wait for completion of a command
442  */
443 extern void smu_spinwait_cmd(struct smu_cmd *cmd);
444 
445 static inline void smu_spinwait_simple(struct smu_simple_cmd *scmd)
446 {
447 	smu_spinwait_cmd(&scmd->cmd);
448 }
449 
450 /*
451  * Poll routine to call if blocked with irqs off
452  */
453 extern void smu_poll(void);
454 
455 
456 /*
457  * Init routine, presence check....
458  */
459 extern int smu_init(void);
460 extern int smu_present(void);
461 struct platform_device;
462 extern struct platform_device *smu_get_ofdev(void);
463 
464 
465 /*
466  * Common command wrappers
467  */
468 extern void smu_shutdown(void);
469 extern void smu_restart(void);
470 struct rtc_time;
471 extern int smu_get_rtc_time(struct rtc_time *time, int spinwait);
472 extern int smu_set_rtc_time(struct rtc_time *time, int spinwait);
473 
474 /*
475  * Kernel asynchronous i2c interface
476  */
477 
478 #define SMU_I2C_READ_MAX	0x1d
479 #define SMU_I2C_WRITE_MAX	0x15
480 
481 /* SMU i2c header, exactly matches i2c header on wire */
482 struct smu_i2c_param
483 {
484 	u8	bus;		/* SMU bus ID (from device tree) */
485 	u8	type;		/* i2c transfer type */
486 	u8	devaddr;	/* device address (includes direction) */
487 	u8	sublen;		/* subaddress length */
488 	u8	subaddr[3];	/* subaddress */
489 	u8	caddr;		/* combined address, filled by SMU driver */
490 	u8	datalen;	/* length of transfer */
491 	u8	data[SMU_I2C_READ_MAX];	/* data */
492 };
493 
494 struct smu_i2c_cmd
495 {
496 	/* public */
497 	struct smu_i2c_param	info;
498 	void			(*done)(struct smu_i2c_cmd *cmd, void *misc);
499 	void			*misc;
500 	int			status; /* 1 = pending, 0 = ok, <0 = fail */
501 
502 	/* private */
503 	struct smu_cmd		scmd;
504 	int			read;
505 	int			stage;
506 	int			retries;
507 	u8			pdata[32];
508 	struct list_head	link;
509 };
510 
511 /*
512  * Call this to queue an i2c command to the SMU. You must fill info,
513  * including info.data for a write, done and misc.
514  * For now, no polling interface is provided so you have to use completion
515  * callback.
516  */
517 extern int smu_queue_i2c(struct smu_i2c_cmd *cmd);
518 
519 
520 #endif /* __KERNEL__ */
521 
522 
523 /*
524  * - SMU "sdb" partitions informations -
525  */
526 
527 
528 /*
529  * Partition header format
530  */
531 struct smu_sdbp_header {
532 	__u8	id;
533 	__u8	len;
534 	__u8	version;
535 	__u8	flags;
536 };
537 
538 
539  /*
540  * demangle 16 and 32 bits integer in some SMU partitions
541  * (currently, afaik, this concerns only the FVT partition
542  * (0x12)
543  */
544 #define SMU_U16_MIX(x)	le16_to_cpu(x)
545 #define SMU_U32_MIX(x)  ((((x) & 0xff00ff00u) >> 8)|(((x) & 0x00ff00ffu) << 8))
546 
547 
548 /* This is the definition of the SMU sdb-partition-0x12 table (called
549  * CPU F/V/T operating points in Darwin). The definition for all those
550  * SMU tables should be moved to some separate file
551  */
552 #define SMU_SDB_FVT_ID			0x12
553 
554 struct smu_sdbp_fvt {
555 	__u32	sysclk;			/* Base SysClk frequency in Hz for
556 					 * this operating point. Value need to
557 					 * be unmixed with SMU_U32_MIX()
558 					 */
559 	__u8	pad;
560 	__u8	maxtemp;		/* Max temp. supported by this
561 					 * operating point
562 					 */
563 
564 	__u16	volts[3];		/* CPU core voltage for the 3
565 					 * PowerTune modes, a mode with
566 					 * 0V = not supported. Value need
567 					 * to be unmixed with SMU_U16_MIX()
568 					 */
569 };
570 
571 /* This partition contains voltage & current sensor calibration
572  * informations
573  */
574 #define SMU_SDB_CPUVCP_ID		0x21
575 
576 struct smu_sdbp_cpuvcp {
577 	__u16	volt_scale;		/* u4.12 fixed point */
578 	__s16	volt_offset;		/* s4.12 fixed point */
579 	__u16	curr_scale;		/* u4.12 fixed point */
580 	__s16	curr_offset;		/* s4.12 fixed point */
581 	__s32	power_quads[3];		/* s4.28 fixed point */
582 };
583 
584 /* This partition contains CPU thermal diode calibration
585  */
586 #define SMU_SDB_CPUDIODE_ID		0x18
587 
588 struct smu_sdbp_cpudiode {
589 	__u16	m_value;		/* u1.15 fixed point */
590 	__s16	b_value;		/* s10.6 fixed point */
591 
592 };
593 
594 /* This partition contains Slots power calibration
595  */
596 #define SMU_SDB_SLOTSPOW_ID		0x78
597 
598 struct smu_sdbp_slotspow {
599 	__u16	pow_scale;		/* u4.12 fixed point */
600 	__s16	pow_offset;		/* s4.12 fixed point */
601 };
602 
603 /* This partition contains machine specific version information about
604  * the sensor/control layout
605  */
606 #define SMU_SDB_SENSORTREE_ID		0x25
607 
608 struct smu_sdbp_sensortree {
609 	__u8	model_id;
610 	__u8	unknown[3];
611 };
612 
613 /* This partition contains CPU thermal control PID informations. So far
614  * only single CPU machines have been seen with an SMU, so we assume this
615  * carries only informations for those
616  */
617 #define SMU_SDB_CPUPIDDATA_ID		0x17
618 
619 struct smu_sdbp_cpupiddata {
620 	__u8	unknown1;
621 	__u8	target_temp_delta;
622 	__u8	unknown2;
623 	__u8	history_len;
624 	__s16	power_adj;
625 	__u16	max_power;
626 	__s32	gp,gr,gd;
627 };
628 
629 
630 /* Other partitions without known structures */
631 #define SMU_SDB_DEBUG_SWITCHES_ID	0x05
632 
633 #ifdef __KERNEL__
634 /*
635  * This returns the pointer to an SMU "sdb" partition data or NULL
636  * if not found. The data format is described below
637  */
638 extern const struct smu_sdbp_header *smu_get_sdb_partition(int id,
639 					unsigned int *size);
640 
641 /* Get "sdb" partition data from an SMU satellite */
642 extern struct smu_sdbp_header *smu_sat_get_sdb_partition(unsigned int sat_id,
643 					int id, unsigned int *size);
644 
645 
646 #endif /* __KERNEL__ */
647 
648 
649 /*
650  * - Userland interface -
651  */
652 
653 /*
654  * A given instance of the device can be configured for 2 different
655  * things at the moment:
656  *
657  *  - sending SMU commands (default at open() time)
658  *  - receiving SMU events (not yet implemented)
659  *
660  * Commands are written with write() of a command block. They can be
661  * "driver" commands (for example to switch to event reception mode)
662  * or real SMU commands. They are made of a header followed by command
663  * data if any.
664  *
665  * For SMU commands (not for driver commands), you can then read() back
666  * a reply. The reader will be blocked or not depending on how the device
667  * file is opened. poll() isn't implemented yet. The reply will consist
668  * of a header as well, followed by the reply data if any. You should
669  * always provide a buffer large enough for the maximum reply data, I
670  * recommand one page.
671  *
672  * It is illegal to send SMU commands through a file descriptor configured
673  * for events reception
674  *
675  */
676 struct smu_user_cmd_hdr
677 {
678 	__u32		cmdtype;
679 #define SMU_CMDTYPE_SMU			0	/* SMU command */
680 #define SMU_CMDTYPE_WANTS_EVENTS	1	/* switch fd to events mode */
681 #define SMU_CMDTYPE_GET_PARTITION	2	/* retrieve an sdb partition */
682 
683 	__u8		cmd;			/* SMU command byte */
684 	__u8		pad[3];			/* padding */
685 	__u32		data_len;		/* Length of data following */
686 };
687 
688 struct smu_user_reply_hdr
689 {
690 	__u32		status;			/* Command status */
691 	__u32		reply_len;		/* Length of data follwing */
692 };
693 
694 #endif /*  _SMU_H */
695