NetBSD/share/man/man9/wdc.9

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.Dd October 18, 1998
.Dt wdc 9
.Os NetBSD
.Sh NAME
.Nm wdc
.Nd machine-indepedant IDE/ATAPI driver
.Sh SYNOPSIS
.Fd #include <dev/ata/atavar.h>
.Fd #include <sys/dev/ic/wdcvar.h>
.Ft int
.Fn wdcprobe "struct channel_softc * chp"
.Ft void
.Fn wdcattach "struct channel_softc * chp"
.Sh description
The
.Nm
driver provides the machine independant core functions for driving IDE
devices. IDE devices-specific drivers (
.Nm wd
or
.Nm atapibus )
will use services provided by
.Nm wdc .
.Pp
The machine-dependant bus front-end provides informations to
.Nm
vith the 
.Va wdc_softc
and
.Va channel_softc
structures. The first one defines global controller properties, and the second
contain per-channel informations.
.Nm
returns informations about the attached devices in the
.Va ata_drive_datas
structure.
.Bd -literal
struct wdc_softc { /* Per controller state */
        struct device sc_dev;
        int           cap;
#define WDC_CAPABILITY_DATA16 0x0001    
#define WDC_CAPABILITY_DATA32 0x0002    
#define WDC_CAPABILITY_MODE   0x0004    
#define WDC_CAPABILITY_DMA    0x0008    
#define WDC_CAPABILITY_UDMA   0x0010    
#define WDC_CAPABILITY_HWLOCK 0x0020    
#define WDC_CAPABILITY_ATA_NOSTREAM 0x0040 
#define WDC_CAPABILITY_ATAPI_NOSTREAM 0x0080 
#define WDC_CAPABILITY_NO_EXTRA_RESETS 0x0100 
        u_int8_t      pio_mode; 
        u_int8_t      dma_mode; 
        int nchannels;  
        struct channel_softc *channels;

        void            *dma_arg;
        int            (*dma_init) __P((void *, int, int, void *, size_t,
        void           (*dma_start) __P((void *, int, int, int));
        int            (*dma_finish) __P((void *, int, int, int));
#define WDC_DMA_READ 0x01
#define WDC_DMA_POLL 0x02

        int            (*claim_hw) __P((void *, int));
        void            (*free_hw) __P((void *));
};

struct channel_softc { /* Per channel data */
        int channel;
        struct wdc_softc *wdc;
        bus_space_tag_t       cmd_iot;
        bus_space_handle_t    cmd_ioh;
        bus_space_tag_t       ctl_iot;
        bus_space_handle_t    ctl_ioh;
        bus_space_tag_t       data32iot;
        bus_space_handle_t    data32ioh;
        int ch_flags;
#define WDCF_ACTIVE   0x01      
#define WDCF_IRQ_WAIT 0x10      
        u_int8_t ch_status;
        u_int8_t ch_error; 
        struct ata_drive_datas ch_drive[2];
        struct channel_queue *ch_queue;
};

struct ata_drive_datas {
    u_int8_t drive;
    u_int8_t drive_flags;
#define DRIVE_ATA   0x01
#define DRIVE_ATAPI 0x02
#define DRIVE (DRIVE_ATA|DRIVE_ATAPI)
#define DRIVE_CAP32 0x04
#define DRIVE_DMA   0x08
#define DRIVE_UDMA  0x10
#define DRIVE_MODE 0x20
    u_int8_t PIO_mode;
    u_int8_t DMA_mode;
    u_int8_t UDMA_mode;
    u_int8_t state;

    struct device *drv_softc;
    void* chnl_softc;
};

.Ed

The bus front-end needs to fill in the following elements of
.Va wdc_softc :
.Bl -tag -compact -width "dma_finish" -offset "xxxx"
.It cap
supports one or more of the WDC_CAPABILITY flags
.It nchannels
number of  channels supported by this controller
.It channels
array of
.Va struct channel_softc
of size
.Va nchannels
properly initialised
.El
The following elements are optional:
.Bl -tag -compact -width "dma_finish" -offset "xxxx"
.It pio_mode
.It dma_mode
.It dma_arg
.It dma_init
.It dma_start
.It dma_finish
.It claim_hw
.It free_hw
.El
.Pp
The
.Va WDC_CAPABILITY_DATA16
and
.Va WDC_CAPABILITY_DATA32
flags informs
.Nm
wether the controller supports 16 and 32 bits I/O accesses on the data port.
If both are set, a test will be done for each drive using the ATA or
ATAPI IDENTIFY command, to automatically select the working mode.
.Pp
The
.Va WDC_CAPABILITY_DMA
and
.Va WDC_CAPABILITY_UDMA
flags are set for controllers supporting the DMA and Utra-DMA modes.
The bus front-end needs to provide the
.Va dma_init ,
.Va dma_start
and
.Va dma_finish
functions.
.Va dma_init
is called just before issuing a DMA command to the IDE device. The arguments
are, respectively:
.Va dma_arg ,
the channel number, the drive number on this channel,
the virtual address of the DMA buffer, the size of the transfert, and the
.Va WDC_DMA
flags.
.Va dma_start
is called just after issuing a DMA command to the IDE device. The arguments
are, respectively:
.Va dma_arg ,
the channel number, the drive number on this channel, and the
.Va WDC_DMA
flags.
.Va dma_finish
is called once the transfert is complete. The arguments are, respectively:
.Va dma_arg ,
the channel number, the drive number on this channel, and the
.Va WDC_DMA
flags.
.Va WDC_DMA_READ
indicates the direction of the data transfert, and
.Va WDC_DMA_POLL
indicates if the transfert will use (or used) interrupts.
.Pp
The
.Va WDC_CAPABILITY_MODE
flag means that the bus front-end can program the PIO and DMA modes, so
.Nm
needs to provide back the supported modes for each drives, and set the drives
modes. The
.Va pio_mode
and
.Va dma_mode
needs to be set to the hightest PIO and DMA mode supported. If
.Va WDC_CAPABILITY_UDMA
is set, then
.Va dma_mode 
must be set to the hightest Ultra-DMA mode supported. If
.Va WDC_CAPABILITY_MODE
is not set,
.Nm
will not attempt to change the current drives settings, assuming the host's
firmware has done it rigth.
.Pp
The
.Va WDC_CAPABILITY_HWLOCK
flag is set for controllers needing hardware looking before access to the
I/O ports. If this flag is set, the bus front-end needs to provide the
.Va claim_hw
and
.Va free_hw
functions. 
.Va claim_hw
will be called when the driver wants to access the controller ports.
The second parameter is set to 1 when it is possible to sleep wainting
for the lock, 0 otherwise. It should return 1 when access has been granted,
0 otherwise. When access has not been granted and sleep is not allowed,
the bus front-end shall call
.Va wdcrestart()
with the first argument passed to
.Va claim_hw
as argument. This arguments will also be the one passed to 
.Va free_hw.
This function is called once the transfert is complete, so that the lock can
be released.
.Pp
Access to the data port are done by using the bus_space stream functions,
unless the
.Va WDC_CAPABILITY_ATA_NOSTREAM
or
.Va WDC_CAPABILITY_ATAPI_NOSTREAM
flags are set. This should not be used, unless the data bus is not wired
properly (which seems common on big-endian systems), and byte-order needs
to be preserved for compatibility with the host's firmware. Also note that
the IDE bus is a little-endian bus, so the bus_space functions used
for the bus_space tag passed in the 
.Va channel_softc
have to do the apropriate byte-swapping for big-endian systems.
.Pp
.Va WDC_CAPABILITY_NO_EXTRA_RESETS
avoid the controller reset at the end of the disks probe. This reset is needed
for some controllers, and cause problems with some others.
.Pp
The bus front-end needs to fill in the following
elements of
.Va channel_softc :
.Bl -tag -compact -width "dma_finish" -offset "xxxx"
.It channel
The channel number on the controller
.It wdc
A pointer to the controller's wdc_softc
.It cmd_iot, cmd_ioh
Bus-space tag and handle for access to the command block registers (which
includes the 16-bit data port)
.It ctl_iot, ctl_ioh
Bus-space tag and handle for access to the control block registers
.It ch_queue
A pointer to a
.Va struct channel_queue .
This will hold the queues of outstanding commands for this controller.
.El
The following elements are optional:
.Bl -tag -compact -width "dma_finish" -offset "xxxx"
.It data32iot, data32ioh
Bus-space tag and handle for 32-bit data accesses. Only needed if
.Va WDC_CAPABILITY_DATA32
is set in the controller's
.Va wdc_softc .
.El
.Pp
.Va ch_queue
can point to a common
.Va struct channel_queue
if the controller doesn't support concurent access to his different channels.
If each channels are independant, it his recommended that each channel have
his own
.Va ch_queue .
Better performances will result.
.Pp
The bus-specific front-end can use the
.Va wdcprobe()
function, with a properly inithialised
.Va struct channel_softc
as argument (
.Va wdc
can be set to NULL. This allows
.Va wdcprobe
to be easily used in bus front-end probe functions). This function will return
an integer where bit 0
will be set if the master device has been found, and 1 if the slave
device has been found.
.Pp
The bus-specific's attach function has to call
.Va wdcattach()
for each channels, with a pointer to a properly initialised
.Va channel softc
as argument. This will probe devices attached to the IDE channel and attach
them. Once this function returns, the
.Va ch_drive
array of the
.Va channel_softc
will contains the drive's capabilities. This can be used to properly
initialise the controller's mode, or disable a channel without drives.
.Pp
The elements of interest in
.Va ata_drive_datas
for a bus front-end are:
.Bl -tag -compact -width "dma_finish" -offset "xxxx"
.It drive
The drive number
.It drive_flags
Flags indicating the drive capabilities. A null
.Va drive_flags
indicate either that no drive are here, or that no driver was
found for this device.
.It PIO_mode, DMA_mode, UDMA_mode
the hightest supported modes for this drive compatible with the controller's
capabilities. Needs to be reset to the mode to use by the drive, if known.
.It drv_softc
A pointer to the drive's softc. Can be used to print the drive's name.
.El
.Pp
.Va drive_flags
handles the following flags:
.Bl -tag -compact -width "dma_finish" -offset "xxxx"
.It DRIVE_ATA, DRIVE_ATAPI
Gives the drive type, if any. The shortcut DRIVE can be used to just test
the presence/absence of a drive.
.It DRIVE_CAP32
This drive works with 32-bit data I/O.
.It DRIVE_DMA
This drive supports DMA
.It DRIVE_UDMA
This drive supports Ultra-DMA
.It DRIVE_MODE
This drive properly reported its PIO and DMA mode.
.El
.Pp
Once the controller has been initialised, it has to reset the
.Va DRIVE_DMA
and
.Va DRIVE_UDMA ,
as well as the values of
.Va PIO_mode ,
.Va DMA_mode
and
.Va  UDMA_mode
if the modes to be used are not hightest ones supported by the drive.
.Sh SEE ALSO
.Xr wdc 4
.Xr bus_space 9
.Sh CODE REFERENCES
The wdc core functions are implemented in
.Pa sys/dev/ic/wdc.c .
Low-level ATA and ATAPI support is provided by
.Pa sys/dev/ata_wdc.c
and
.Pa sys/dev/scsipi/atapi_wdc.c
respectively.
.Pp
An example of simple bus front-end can be found in
.Pa sys/dev/isapnp/wdc_isapnp.c .
A more complex one, with multiple channels and bus-master DMA support is
.Pa sys/dev/pci/pciide.c .
.Pa sys/arch/atari/dev/wdc_mb.c
makes use of hardware locking, and also provides an example of bus-front
end for a big-endian system, which needs byte-swapping bus_space functions.