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@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!

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--
Regards,
Peter Teoh