libata: make PMP support optional

Make PMP support optional by adding CONFIG_SATA_PMP and leaving out
libata-pmp.c if it isn't set.  PMP helpers return constant values if
PMP support is not enabled and PMP declarations alias non-PMP
counterparts.  This makes the compiler to leave out PMP related part
out and LLDs to use non-PMP counterparts automatically.

Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 48c8fc55391e..3eb6035b61b8 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -41,6 +41,12 @@ config ATA_ACPI
           You can disable this at kernel boot time by using the
           option libata.noacpi=1
 
+config SATA_PMP
+        bool "SATA Port Multiplier support"
+        default y
+        help
+          This option adds support for SATA Port Multipliers.
+
 config SATA_AHCI
         tristate "AHCI SATA support"
         depends on PCI