[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>

2 files changed, 19 insertions, 0 deletions

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 2517254b8403..af0a1deac930 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -405,6 +405,13 @@ static inline void sas_phy_disconnected(struct asd_sas_phy *phy)
         phy->linkrate = SAS_LINK_RATE_UNKNOWN;
 }
 
+static inline unsigned int to_sas_gpio_od(int device, int bit)
+{
+        return 3 * device + bit;
+}
+
+int try_test_sas_gpio_gp_bit(unsigned int od, u8 *data, u8 index, u8 count);
+
 /* ---------- Tasks ---------- */
 /*
       service_response |  SAS_TASK_COMPLETE  |  SAS_TASK_UNDELIVERED |
@@ -592,6 +599,10 @@ struct sas_domain_function_template {
 
         /* Phy management */
         int (*lldd_control_phy)(struct asd_sas_phy *, enum phy_func, void *);
+
+        /* GPIO support */
+        int (*lldd_write_gpio)(struct sas_ha_struct *, u8 reg_type,
+                               u8 reg_index, u8 reg_count, u8 *write_data);
 };
 
 extern int sas_register_ha(struct sas_ha_struct *);
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;