|  | #ifndef _SMU_H | 
|  | #define _SMU_H | 
|  |  | 
|  | /* | 
|  | * Definitions for talking to the SMU chip in newer G5 PowerMacs | 
|  | */ | 
|  | #ifdef __KERNEL__ | 
|  | #include <linux/list.h> | 
|  | #endif | 
|  | #include <linux/types.h> | 
|  |  | 
|  | /* | 
|  | * Known SMU commands | 
|  | * | 
|  | * Most of what is below comes from looking at the Open Firmware driver, | 
|  | * though this is still incomplete and could use better documentation here | 
|  | * or there... | 
|  | */ | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Partition info commands | 
|  | * | 
|  | * These commands are used to retrieve the sdb-partition-XX datas from | 
|  | * the SMU. The lenght is always 2. First byte is the subcommand code | 
|  | * and second byte is the partition ID. | 
|  | * | 
|  | * The reply is 6 bytes: | 
|  | * | 
|  | *  - 0..1 : partition address | 
|  | *  - 2    : a byte containing the partition ID | 
|  | *  - 3    : length (maybe other bits are rest of header ?) | 
|  | * | 
|  | * The data must then be obtained with calls to another command: | 
|  | * SMU_CMD_MISC_ee_GET_DATABLOCK_REC (described below). | 
|  | */ | 
|  | #define SMU_CMD_PARTITION_COMMAND		0x3e | 
|  | #define   SMU_CMD_PARTITION_LATEST		0x01 | 
|  | #define   SMU_CMD_PARTITION_BASE		0x02 | 
|  | #define   SMU_CMD_PARTITION_UPDATE		0x03 | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Fan control | 
|  | * | 
|  | * This is a "mux" for fan control commands. The command seem to | 
|  | * act differently based on the number of arguments. With 1 byte | 
|  | * of argument, this seem to be queries for fans status, setpoint, | 
|  | * etc..., while with 0xe arguments, we will set the fans speeds. | 
|  | * | 
|  | * Queries (1 byte arg): | 
|  | * --------------------- | 
|  | * | 
|  | * arg=0x01: read RPM fans status | 
|  | * arg=0x02: read RPM fans setpoint | 
|  | * arg=0x11: read PWM fans status | 
|  | * arg=0x12: read PWM fans setpoint | 
|  | * | 
|  | * the "status" queries return the current speed while the "setpoint" ones | 
|  | * return the programmed/target speed. It _seems_ that the result is a bit | 
|  | * mask in the first byte of active/available fans, followed by 6 words (16 | 
|  | * bits) containing the requested speed. | 
|  | * | 
|  | * Setpoint (14 bytes arg): | 
|  | * ------------------------ | 
|  | * | 
|  | * first arg byte is 0 for RPM fans and 0x10 for PWM. Second arg byte is the | 
|  | * mask of fans affected by the command. Followed by 6 words containing the | 
|  | * setpoint value for selected fans in the mask (or 0 if mask value is 0) | 
|  | */ | 
|  | #define SMU_CMD_FAN_COMMAND			0x4a | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Battery access | 
|  | * | 
|  | * Same command number as the PMU, could it be same syntax ? | 
|  | */ | 
|  | #define SMU_CMD_BATTERY_COMMAND			0x6f | 
|  | #define   SMU_CMD_GET_BATTERY_INFO		0x00 | 
|  |  | 
|  | /* | 
|  | * Real time clock control | 
|  | * | 
|  | * This is a "mux", first data byte contains the "sub" command. | 
|  | * The "RTC" part of the SMU controls the date, time, powerup | 
|  | * timer, but also a PRAM | 
|  | * | 
|  | * Dates are in BCD format on 7 bytes: | 
|  | * [sec] [min] [hour] [weekday] [month day] [month] [year] | 
|  | * with month being 1 based and year minus 100 | 
|  | */ | 
|  | #define SMU_CMD_RTC_COMMAND			0x8e | 
|  | #define   SMU_CMD_RTC_SET_PWRUP_TIMER		0x00 /* i: 7 bytes date */ | 
|  | #define   SMU_CMD_RTC_GET_PWRUP_TIMER		0x01 /* o: 7 bytes date */ | 
|  | #define   SMU_CMD_RTC_STOP_PWRUP_TIMER		0x02 | 
|  | #define   SMU_CMD_RTC_SET_PRAM_BYTE_ACC		0x20 /* i: 1 byte (address?) */ | 
|  | #define   SMU_CMD_RTC_SET_PRAM_AUTOINC		0x21 /* i: 1 byte (data?) */ | 
|  | #define   SMU_CMD_RTC_SET_PRAM_LO_BYTES 	0x22 /* i: 10 bytes */ | 
|  | #define   SMU_CMD_RTC_SET_PRAM_HI_BYTES 	0x23 /* i: 10 bytes */ | 
|  | #define   SMU_CMD_RTC_GET_PRAM_BYTE		0x28 /* i: 1 bytes (address?) */ | 
|  | #define   SMU_CMD_RTC_GET_PRAM_LO_BYTES 	0x29 /* o: 10 bytes */ | 
|  | #define   SMU_CMD_RTC_GET_PRAM_HI_BYTES 	0x2a /* o: 10 bytes */ | 
|  | #define	  SMU_CMD_RTC_SET_DATETIME		0x80 /* i: 7 bytes date */ | 
|  | #define   SMU_CMD_RTC_GET_DATETIME		0x81 /* o: 7 bytes date */ | 
|  |  | 
|  | /* | 
|  | * i2c commands | 
|  | * | 
|  | * To issue an i2c command, first is to send a parameter block to the | 
|  | * the SMU. This is a command of type 0x9a with 9 bytes of header | 
|  | * eventually followed by data for a write: | 
|  | * | 
|  | * 0: bus number (from device-tree usually, SMU has lots of busses !) | 
|  | * 1: transfer type/format (see below) | 
|  | * 2: device address. For combined and combined4 type transfers, this | 
|  | *    is the "write" version of the address (bit 0x01 cleared) | 
|  | * 3: subaddress length (0..3) | 
|  | * 4: subaddress byte 0 (or only byte for subaddress length 1) | 
|  | * 5: subaddress byte 1 | 
|  | * 6: subaddress byte 2 | 
|  | * 7: combined address (device address for combined mode data phase) | 
|  | * 8: data length | 
|  | * | 
|  | * The transfer types are the same good old Apple ones it seems, | 
|  | * that is: | 
|  | *   - 0x00: Simple transfer | 
|  | *   - 0x01: Subaddress transfer (addr write + data tx, no restart) | 
|  | *   - 0x02: Combined transfer (addr write + restart + data tx) | 
|  | * | 
|  | * This is then followed by actual data for a write. | 
|  | * | 
|  | * At this point, the OF driver seems to have a limitation on transfer | 
|  | * sizes of 0xd bytes on reads and 0x5 bytes on writes. I do not know | 
|  | * wether this is just an OF limit due to some temporary buffer size | 
|  | * or if this is an SMU imposed limit. This driver has the same limitation | 
|  | * for now as I use a 0x10 bytes temporary buffer as well | 
|  | * | 
|  | * Once that is completed, a response is expected from the SMU. This is | 
|  | * obtained via a command of type 0x9a with a length of 1 byte containing | 
|  | * 0 as the data byte. OF also fills the rest of the data buffer with 0xff's | 
|  | * though I can't tell yet if this is actually necessary. Once this command | 
|  | * is complete, at this point, all I can tell is what OF does. OF tests | 
|  | * byte 0 of the reply: | 
|  | *   - on read, 0xfe or 0xfc : bus is busy, wait (see below) or nak ? | 
|  | *   - on read, 0x00 or 0x01 : reply is in buffer (after the byte 0) | 
|  | *   - on write, < 0 -> failure (immediate exit) | 
|  | *   - else, OF just exists (without error, weird) | 
|  | * | 
|  | * So on read, there is this wait-for-busy thing when getting a 0xfc or | 
|  | * 0xfe result. OF does a loop of up to 64 retries, waiting 20ms and | 
|  | * doing the above again until either the retries expire or the result | 
|  | * is no longer 0xfe or 0xfc | 
|  | * | 
|  | * The Darwin I2C driver is less subtle though. On any non-success status | 
|  | * from the response command, it waits 5ms and tries again up to 20 times, | 
|  | * it doesn't differenciate between fatal errors or "busy" status. | 
|  | * | 
|  | * This driver provides an asynchronous paramblock based i2c command | 
|  | * interface to be used either directly by low level code or by a higher | 
|  | * level driver interfacing to the linux i2c layer. The current | 
|  | * implementation of this relies on working timers & timer interrupts | 
|  | * though, so be careful of calling context for now. This may be "fixed" | 
|  | * in the future by adding a polling facility. | 
|  | */ | 
|  | #define SMU_CMD_I2C_COMMAND			0x9a | 
|  | /* transfer types */ | 
|  | #define   SMU_I2C_TRANSFER_SIMPLE	0x00 | 
|  | #define   SMU_I2C_TRANSFER_STDSUB	0x01 | 
|  | #define   SMU_I2C_TRANSFER_COMBINED	0x02 | 
|  |  | 
|  | /* | 
|  | * Power supply control | 
|  | * | 
|  | * The "sub" command is an ASCII string in the data, the | 
|  | * data lenght is that of the string. | 
|  | * | 
|  | * The VSLEW command can be used to get or set the voltage slewing. | 
|  | *  - lenght 5 (only "VSLEW") : it returns "DONE" and 3 bytes of | 
|  | *    reply at data offset 6, 7 and 8. | 
|  | *  - lenght 8 ("VSLEWxyz") has 3 additional bytes appended, and is | 
|  | *    used to set the voltage slewing point. The SMU replies with "DONE" | 
|  | * I yet have to figure out their exact meaning of those 3 bytes in | 
|  | * both cases. They seem to be: | 
|  | *  x = processor mask | 
|  | *  y = op. point index | 
|  | *  z = processor freq. step index | 
|  | * I haven't yet decyphered result codes | 
|  | * | 
|  | */ | 
|  | #define SMU_CMD_POWER_COMMAND			0xaa | 
|  | #define   SMU_CMD_POWER_RESTART		       	"RESTART" | 
|  | #define   SMU_CMD_POWER_SHUTDOWN		"SHUTDOWN" | 
|  | #define   SMU_CMD_POWER_VOLTAGE_SLEW		"VSLEW" | 
|  |  | 
|  | /* | 
|  | * Read ADC sensors | 
|  | * | 
|  | * This command takes one byte of parameter: the sensor ID (or "reg" | 
|  | * value in the device-tree) and returns a 16 bits value | 
|  | */ | 
|  | #define SMU_CMD_READ_ADC			0xd8 | 
|  |  | 
|  | /* Misc commands | 
|  | * | 
|  | * This command seem to be a grab bag of various things | 
|  | */ | 
|  | #define SMU_CMD_MISC_df_COMMAND			0xdf | 
|  | #define   SMU_CMD_MISC_df_SET_DISPLAY_LIT	0x02 /* i: 1 byte */ | 
|  | #define   SMU_CMD_MISC_df_NMI_OPTION		0x04 | 
|  |  | 
|  | /* | 
|  | * Version info commands | 
|  | * | 
|  | * I haven't quite tried to figure out how these work | 
|  | */ | 
|  | #define SMU_CMD_VERSION_COMMAND			0xea | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Misc commands | 
|  | * | 
|  | * This command seem to be a grab bag of various things | 
|  | * | 
|  | * SMU_CMD_MISC_ee_GET_DATABLOCK_REC is used, among others, to | 
|  | * transfer blocks of data from the SMU. So far, I've decrypted it's | 
|  | * usage to retrieve partition data. In order to do that, you have to | 
|  | * break your transfer in "chunks" since that command cannot transfer | 
|  | * more than a chunk at a time. The chunk size used by OF is 0xe bytes, | 
|  | * but it seems that the darwin driver will let you do 0x1e bytes if | 
|  | * your "PMU" version is >= 0x30. You can get the "PMU" version apparently | 
|  | * either in the last 16 bits of property "smu-version-pmu" or as the 16 | 
|  | * bytes at offset 1 of "smu-version-info" | 
|  | * | 
|  | * For each chunk, the command takes 7 bytes of arguments: | 
|  | *  byte 0: subcommand code (0x02) | 
|  | *  byte 1: 0x04 (always, I don't know what it means, maybe the address | 
|  | *                space to use or some other nicety. It's hard coded in OF) | 
|  | *  byte 2..5: SMU address of the chunk (big endian 32 bits) | 
|  | *  byte 6: size to transfer (up to max chunk size) | 
|  | * | 
|  | * The data is returned directly | 
|  | */ | 
|  | #define SMU_CMD_MISC_ee_COMMAND			0xee | 
|  | #define   SMU_CMD_MISC_ee_GET_DATABLOCK_REC	0x02 | 
|  | #define	  SMU_CMD_MISC_ee_LEDS_CTRL		0x04 /* i: 00 (00,01) [00] */ | 
|  | #define   SMU_CMD_MISC_ee_GET_DATA		0x05 /* i: 00 , o: ?? */ | 
|  |  | 
|  |  | 
|  |  | 
|  | /* | 
|  | * - Kernel side interface - | 
|  | */ | 
|  |  | 
|  | #ifdef __KERNEL__ | 
|  |  | 
|  | /* | 
|  | * Asynchronous SMU commands | 
|  | * | 
|  | * Fill up this structure and submit it via smu_queue_command(), | 
|  | * and get notified by the optional done() callback, or because | 
|  | * status becomes != 1 | 
|  | */ | 
|  |  | 
|  | struct smu_cmd; | 
|  |  | 
|  | struct smu_cmd | 
|  | { | 
|  | /* public */ | 
|  | u8			cmd;		/* command */ | 
|  | int			data_len;	/* data len */ | 
|  | int			reply_len;	/* reply len */ | 
|  | void			*data_buf;	/* data buffer */ | 
|  | void			*reply_buf;	/* reply buffer */ | 
|  | int			status;		/* command status */ | 
|  | void			(*done)(struct smu_cmd *cmd, void *misc); | 
|  | void			*misc; | 
|  |  | 
|  | /* private */ | 
|  | struct list_head	link; | 
|  | }; | 
|  |  | 
|  | /* | 
|  | * Queues an SMU command, all fields have to be initialized | 
|  | */ | 
|  | extern int smu_queue_cmd(struct smu_cmd *cmd); | 
|  |  | 
|  | /* | 
|  | * Simple command wrapper. This structure embeds a small buffer | 
|  | * to ease sending simple SMU commands from the stack | 
|  | */ | 
|  | struct smu_simple_cmd | 
|  | { | 
|  | struct smu_cmd	cmd; | 
|  | u8	       	buffer[16]; | 
|  | }; | 
|  |  | 
|  | /* | 
|  | * Queues a simple command. All fields will be initialized by that | 
|  | * function | 
|  | */ | 
|  | extern int smu_queue_simple(struct smu_simple_cmd *scmd, u8 command, | 
|  | unsigned int data_len, | 
|  | void (*done)(struct smu_cmd *cmd, void *misc), | 
|  | void *misc, | 
|  | ...); | 
|  |  | 
|  | /* | 
|  | * Completion helper. Pass it to smu_queue_simple or as 'done' | 
|  | * member to smu_queue_cmd, it will call complete() on the struct | 
|  | * completion passed in the "misc" argument | 
|  | */ | 
|  | extern void smu_done_complete(struct smu_cmd *cmd, void *misc); | 
|  |  | 
|  | /* | 
|  | * Synchronous helpers. Will spin-wait for completion of a command | 
|  | */ | 
|  | extern void smu_spinwait_cmd(struct smu_cmd *cmd); | 
|  |  | 
|  | static inline void smu_spinwait_simple(struct smu_simple_cmd *scmd) | 
|  | { | 
|  | smu_spinwait_cmd(&scmd->cmd); | 
|  | } | 
|  |  | 
|  | /* | 
|  | * Poll routine to call if blocked with irqs off | 
|  | */ | 
|  | extern void smu_poll(void); | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Init routine, presence check.... | 
|  | */ | 
|  | extern int smu_init(void); | 
|  | extern int smu_present(void); | 
|  | struct of_device; | 
|  | extern struct of_device *smu_get_ofdev(void); | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Common command wrappers | 
|  | */ | 
|  | extern void smu_shutdown(void); | 
|  | extern void smu_restart(void); | 
|  | struct rtc_time; | 
|  | extern int smu_get_rtc_time(struct rtc_time *time, int spinwait); | 
|  | extern int smu_set_rtc_time(struct rtc_time *time, int spinwait); | 
|  |  | 
|  | /* | 
|  | * SMU command buffer absolute address, exported by pmac_setup, | 
|  | * this is allocated very early during boot. | 
|  | */ | 
|  | extern unsigned long smu_cmdbuf_abs; | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Kenrel asynchronous i2c interface | 
|  | */ | 
|  |  | 
|  | #define SMU_I2C_READ_MAX	0x1d | 
|  | #define SMU_I2C_WRITE_MAX	0x15 | 
|  |  | 
|  | /* SMU i2c header, exactly matches i2c header on wire */ | 
|  | struct smu_i2c_param | 
|  | { | 
|  | u8	bus;		/* SMU bus ID (from device tree) */ | 
|  | u8	type;		/* i2c transfer type */ | 
|  | u8	devaddr;	/* device address (includes direction) */ | 
|  | u8	sublen;		/* subaddress length */ | 
|  | u8	subaddr[3];	/* subaddress */ | 
|  | u8	caddr;		/* combined address, filled by SMU driver */ | 
|  | u8	datalen;	/* length of transfer */ | 
|  | u8	data[SMU_I2C_READ_MAX];	/* data */ | 
|  | }; | 
|  |  | 
|  | struct smu_i2c_cmd | 
|  | { | 
|  | /* public */ | 
|  | struct smu_i2c_param	info; | 
|  | void			(*done)(struct smu_i2c_cmd *cmd, void *misc); | 
|  | void			*misc; | 
|  | int			status; /* 1 = pending, 0 = ok, <0 = fail */ | 
|  |  | 
|  | /* private */ | 
|  | struct smu_cmd		scmd; | 
|  | int			read; | 
|  | int			stage; | 
|  | int			retries; | 
|  | u8			pdata[32]; | 
|  | struct list_head	link; | 
|  | }; | 
|  |  | 
|  | /* | 
|  | * Call this to queue an i2c command to the SMU. You must fill info, | 
|  | * including info.data for a write, done and misc. | 
|  | * For now, no polling interface is provided so you have to use completion | 
|  | * callback. | 
|  | */ | 
|  | extern int smu_queue_i2c(struct smu_i2c_cmd *cmd); | 
|  |  | 
|  |  | 
|  | #endif /* __KERNEL__ */ | 
|  |  | 
|  |  | 
|  | /* | 
|  | * - SMU "sdb" partitions informations - | 
|  | */ | 
|  |  | 
|  |  | 
|  | /* | 
|  | * Partition header format | 
|  | */ | 
|  | struct smu_sdbp_header { | 
|  | __u8	id; | 
|  | __u8	len; | 
|  | __u8	version; | 
|  | __u8	flags; | 
|  | }; | 
|  |  | 
|  |  | 
|  | /* | 
|  | * demangle 16 and 32 bits integer in some SMU partitions | 
|  | * (currently, afaik, this concerns only the FVT partition | 
|  | * (0x12) | 
|  | */ | 
|  | #define SMU_U16_MIX(x)	le16_to_cpu(x); | 
|  | #define SMU_U32_MIX(x)  ((((x) & 0xff00ff00u) >> 8)|(((x) & 0x00ff00ffu) << 8)) | 
|  |  | 
|  |  | 
|  | /* This is the definition of the SMU sdb-partition-0x12 table (called | 
|  | * CPU F/V/T operating points in Darwin). The definition for all those | 
|  | * SMU tables should be moved to some separate file | 
|  | */ | 
|  | #define SMU_SDB_FVT_ID			0x12 | 
|  |  | 
|  | struct smu_sdbp_fvt { | 
|  | __u32	sysclk;			/* Base SysClk frequency in Hz for | 
|  | * this operating point. Value need to | 
|  | * be unmixed with SMU_U32_MIX() | 
|  | */ | 
|  | __u8	pad; | 
|  | __u8	maxtemp;		/* Max temp. supported by this | 
|  | * operating point | 
|  | */ | 
|  |  | 
|  | __u16	volts[3];		/* CPU core voltage for the 3 | 
|  | * PowerTune modes, a mode with | 
|  | * 0V = not supported. Value need | 
|  | * to be unmixed with SMU_U16_MIX() | 
|  | */ | 
|  | }; | 
|  |  | 
|  | /* This partition contains voltage & current sensor calibration | 
|  | * informations | 
|  | */ | 
|  | #define SMU_SDB_CPUVCP_ID		0x21 | 
|  |  | 
|  | struct smu_sdbp_cpuvcp { | 
|  | __u16	volt_scale;		/* u4.12 fixed point */ | 
|  | __s16	volt_offset;		/* s4.12 fixed point */ | 
|  | __u16	curr_scale;		/* u4.12 fixed point */ | 
|  | __s16	curr_offset;		/* s4.12 fixed point */ | 
|  | __s32	power_quads[3];		/* s4.28 fixed point */ | 
|  | }; | 
|  |  | 
|  | /* This partition contains CPU thermal diode calibration | 
|  | */ | 
|  | #define SMU_SDB_CPUDIODE_ID		0x18 | 
|  |  | 
|  | struct smu_sdbp_cpudiode { | 
|  | __u16	m_value;		/* u1.15 fixed point */ | 
|  | __s16	b_value;		/* s10.6 fixed point */ | 
|  |  | 
|  | }; | 
|  |  | 
|  | /* This partition contains Slots power calibration | 
|  | */ | 
|  | #define SMU_SDB_SLOTSPOW_ID		0x78 | 
|  |  | 
|  | struct smu_sdbp_slotspow { | 
|  | __u16	pow_scale;		/* u4.12 fixed point */ | 
|  | __s16	pow_offset;		/* s4.12 fixed point */ | 
|  | }; | 
|  |  | 
|  | /* This partition contains machine specific version information about | 
|  | * the sensor/control layout | 
|  | */ | 
|  | #define SMU_SDB_SENSORTREE_ID		0x25 | 
|  |  | 
|  | struct smu_sdbp_sensortree { | 
|  | __u8	model_id; | 
|  | __u8	unknown[3]; | 
|  | }; | 
|  |  | 
|  | /* This partition contains CPU thermal control PID informations. So far | 
|  | * only single CPU machines have been seen with an SMU, so we assume this | 
|  | * carries only informations for those | 
|  | */ | 
|  | #define SMU_SDB_CPUPIDDATA_ID		0x17 | 
|  |  | 
|  | struct smu_sdbp_cpupiddata { | 
|  | __u8	unknown1; | 
|  | __u8	target_temp_delta; | 
|  | __u8	unknown2; | 
|  | __u8	history_len; | 
|  | __s16	power_adj; | 
|  | __u16	max_power; | 
|  | __s32	gp,gr,gd; | 
|  | }; | 
|  |  | 
|  |  | 
|  | /* Other partitions without known structures */ | 
|  | #define SMU_SDB_DEBUG_SWITCHES_ID	0x05 | 
|  |  | 
|  | #ifdef __KERNEL__ | 
|  | /* | 
|  | * This returns the pointer to an SMU "sdb" partition data or NULL | 
|  | * if not found. The data format is described below | 
|  | */ | 
|  | extern const struct smu_sdbp_header *smu_get_sdb_partition(int id, | 
|  | unsigned int *size); | 
|  |  | 
|  | /* Get "sdb" partition data from an SMU satellite */ | 
|  | extern struct smu_sdbp_header *smu_sat_get_sdb_partition(unsigned int sat_id, | 
|  | int id, unsigned int *size); | 
|  |  | 
|  |  | 
|  | #endif /* __KERNEL__ */ | 
|  |  | 
|  |  | 
|  | /* | 
|  | * - Userland interface - | 
|  | */ | 
|  |  | 
|  | /* | 
|  | * A given instance of the device can be configured for 2 different | 
|  | * things at the moment: | 
|  | * | 
|  | *  - sending SMU commands (default at open() time) | 
|  | *  - receiving SMU events (not yet implemented) | 
|  | * | 
|  | * Commands are written with write() of a command block. They can be | 
|  | * "driver" commands (for example to switch to event reception mode) | 
|  | * or real SMU commands. They are made of a header followed by command | 
|  | * data if any. | 
|  | * | 
|  | * For SMU commands (not for driver commands), you can then read() back | 
|  | * a reply. The reader will be blocked or not depending on how the device | 
|  | * file is opened. poll() isn't implemented yet. The reply will consist | 
|  | * of a header as well, followed by the reply data if any. You should | 
|  | * always provide a buffer large enough for the maximum reply data, I | 
|  | * recommand one page. | 
|  | * | 
|  | * It is illegal to send SMU commands through a file descriptor configured | 
|  | * for events reception | 
|  | * | 
|  | */ | 
|  | struct smu_user_cmd_hdr | 
|  | { | 
|  | __u32		cmdtype; | 
|  | #define SMU_CMDTYPE_SMU			0	/* SMU command */ | 
|  | #define SMU_CMDTYPE_WANTS_EVENTS	1	/* switch fd to events mode */ | 
|  | #define SMU_CMDTYPE_GET_PARTITION	2	/* retrieve an sdb partition */ | 
|  |  | 
|  | __u8		cmd;			/* SMU command byte */ | 
|  | __u8		pad[3];			/* padding */ | 
|  | __u32		data_len;		/* Lenght of data following */ | 
|  | }; | 
|  |  | 
|  | struct smu_user_reply_hdr | 
|  | { | 
|  | __u32		status;			/* Command status */ | 
|  | __u32		reply_len;		/* Lenght of data follwing */ | 
|  | }; | 
|  |  | 
|  | #endif /*  _SMU_H */ |