[SCSI] libsas: sgpio write support

Add SFF-8485 v0.7 / SAS-1 smp-write-gpio register support to libsas.
Defer SAS-2 support unless/until it defines an sgpio interface.

Minimum implementation needed to get the lights blinking.
try_test_sas_gpio_gp_bit() provides a common method to parse the
incoming write data (raw bitstream), and the to_sas_gpio_gp_bit() helper
routine can be used as a basis for the set/clear operations for the
'read' implementation.  Host implementations parse as many bits
(ODx.[012]) as are locally supported and report the number of registers
successfully written.  If the submitted data overruns the internal
number of registers available report the write as a success with the
number of bytes remaining reported in ->resid_len.

Example (assuming an active backplane) set the "identify" pattern for
the first 21 devices:

smp_write_gpio --count=2 --data=92,49,24,92,24,92,49,24 -t 4 --index=1 /dev/bsg/sas_hostX

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/scsi/sas.h b/include/scsi/sas.h
index e9fd02281381..a3001add0c66 100644
--- a/include/scsi/sas.h
+++ b/include/scsi/sas.h
@@ -195,6 +195,14 @@ enum sas_open_rej_reason {
 	SAS_OREJ_RSVD_RETRY = 18,
 };
 
+enum sas_gpio_reg_type {
+	SAS_GPIO_REG_CFG   = 0,
+	SAS_GPIO_REG_RX    = 1,
+	SAS_GPIO_REG_RX_GP = 2,
+	SAS_GPIO_REG_TX    = 3,
+	SAS_GPIO_REG_TX_GP = 4,
+};
+
 struct  dev_to_host_fis {
 	u8     fis_type;	  /* 0x34 */
 	u8     flags;