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// Copyright 2021 Canonical Ltd.
// Licensed under the LGPLv3 with static-linking exception.
// See LICENCE file for details.
package linux
import (
"errors"
"fmt"
"os"
"path/filepath"
efi "github.com/canonical/go-efilib"
)
func handleSATADevicePathNode(state *devicePathBuilderState) error {
if state.SysfsComponentsRemaining() < 6 {
return errors.New("invalid path: insufficient components")
}
state.AdvanceSysfsPath(6)
params, err := handleATAPath(state.SysfsPath())
if err != nil {
return err
}
// Each SATA device is represented in the SCSI layer by setting the
// channel to the port multiplier port number and the LUN as the LUN (see
// drivers/ata/libata-scsi.c:ata_scsi_scan_host).
pmp := params.channel
if pmp > 0x7fff {
return errors.New("invalid PMP")
}
// The target is always zero for SATA devices, as each port only has
// a single device.
if params.target != 0 {
return errors.New("invalid SCSI target")
}
// We need to determine if the device is connected via a port
// multiplier because we have to set the PMP address to 0xffff
// if it isn't. Unfortunately, it is zero indexed so checking
// that it is zero isn't sufficient.
//
// The kernel will expose a single host link%d device if there
// is no port multiplier, or one of more PMP link%d.%d devices
// if there is a port multiplier attached (see
// drivers/ata/libata-pmp.c:sata_pmp_init_links and
// drivers/ata/libata-transport.c:ata_tlink_add).
_, err = os.Stat(filepath.Join(state.SysfsPath(), "../../../../..", fmt.Sprintf("link%d.%d", params.printId, pmp)))
switch {
case os.IsNotExist(err):
// No port multiplier is connected.
pmp = 0xffff
case err != nil:
return err
default:
// A port multiplier is connected.
}
state.Path = append(state.Path, &efi.SATADevicePathNode{
// The kernel provides a one-indexed number and the firmware is zero-indexed.
HBAPortNumber: uint16(params.port) - 1,
PortMultiplierPortNumber: uint16(pmp),
LUN: uint16(params.lun)})
return nil
}
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