hd controller

[Peter Teoh]

at the lowest level, SCSI/IDE/SATA all shared a common command base
(perhaps with variations) - which is ATA command (because in
drivers/ata/*.c u can find the symbol ATA_XXX_CMD in all the three
different hardware architecture):

Below is a an example specified by standard body (these command are OS
agnostic):

https://github.com/gcastigl/SO2C2011TP2/blob/master/doc/ATA%20-%20ATAPI%20Command%20Set.pdf

Look at all the "ATA_CMD_*" command here:

https://github.com/Scorpiion/Renux_u-boot/blob/master/include/ata.h

So the drivers just literally concatenate these command into a string and
send it over to the device.

for example in drivers/ata/libata-core.c:

static int ata_read_native_max_address(struct ata_device *dev, u64
*max_sectors)
{
        unsigned int err_mask;
        struct ata_taskfile tf;
        int lba48 = ata_id_has_lba48(dev->id);

        ata_tf_init(dev, &tf);

        /* always clear all address registers */
        tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;

        if (lba48) {
                tf.command = ATA_CMD_READ_NATIVE_MAX_EXT;
                tf.flags |= ATA_TFLAG_LBA48;
        } else
                tf.command = ATA_CMD_READ_NATIVE_MAX;

the tf.command data within is ultimately send by port I/O operation.
BUT.....not sure of details, corrections welcome :-).

On Thu, Feb 7, 2013 at 4:19 PM, horseriver <horserivers at gmail.com> wrote:

> hi:)
>
>    I am curious about how hd controller work .
>    When user am reaing/writing hd ,it was implemented by sending command
>    to hd controller's special port.Then ,how does the controller know
>    a new command has received?
>
>    In this procedure , what work does the hd driver do ?
>
> thanks!
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>



-- 
Regards,
Peter Teoh
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20130208/87b049e2/attachment-0001.html