[PATCH 1/3] libsas: sgpio write support

[Dan Williams <dan.j.williams@intel.com>]

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

Cc: Artur Wojcik <artur.wojcik@intel.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/scsi/libsas/sas_host_smp.c |  103 +++++++++++++++++++++++++++++++++++-
 include/scsi/libsas.h              |   11 ++++
 include/scsi/sas.h                 |    8 +++
 3 files changed, 120 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/libsas/sas_host_smp.c b/drivers/scsi/libsas/sas_host_smp.c
index 04ad8dd..e1aa178 100644
--- a/drivers/scsi/libsas/sas_host_smp.c
+++ b/drivers/scsi/libsas/sas_host_smp.c
@@ -51,6 +51,91 @@ static void sas_host_smp_discover(struct sas_ha_struct *sas_ha, u8 *resp_data,
 	resp_data[15] = rphy->identify.target_port_protocols;
 }
 
+/**
+ * to_sas_gpio_gp_bit - given the gpio frame data find the byte/bit position of 'od'
+ * @od: od bit to find
+ * @data: incoming bitstream (from frame)
+ * @index: requested data register index (from frame)
+ * @count: total number of registers in the bitstream (from frame)
+ * @bit: bit position of 'od' in the returned byte
+ *
+ * returns NULL if 'od' is not in 'data'
+ *
+ * From SFF-8485 v0.7:
+ * "In GPIO_TX[1], bit 0 of byte 3 contains the first bit (i.e., OD0.0)
+ *  and bit 7 of byte 0 contains the 32nd bit (i.e., OD10.1).
+ *
+ *  In GPIO_TX[2], bit 0 of byte 3 contains the 33rd bit (i.e., OD10.2)
+ *  and bit 7 of byte 0 contains the 64th bit (i.e., OD21.0)."
+ *
+ * The general-purpose (raw-bitstream) RX registers have the same layout
+ * although 'od' is renamed 'id' for 'input data'.
+ *
+ * SFF-8489 defines the behavior of the LEDs in response to the 'od' values.
+ */
+static u8 *to_sas_gpio_gp_bit(unsigned int od, u8 *data, u8 index, u8 count, u8 *bit)
+{
+	unsigned int reg;
+	u8 byte;
+
+	/* gp registers start at index 1 */
+	if (index == 0)
+		return NULL;
+
+	index--; /* make index 0-based */
+	if (od < index * 32)
+		return NULL;
+
+	od -= index * 32;
+	reg = od >> 5;
+
+	if (reg >= count)
+		return NULL;
+
+	od &= (1 << 5) - 1;
+	byte = 3 - (od >> 3);
+	*bit = od & ((1 << 3) - 1);
+
+	return &data[reg * 4 + byte];
+}
+
+int try_test_sas_gpio_gp_bit(unsigned int od, u8 *data, u8 index, u8 count)
+{
+	u8 *byte;
+	u8 bit;
+
+	byte = to_sas_gpio_gp_bit(od, data, index, count, &bit);
+	if (!byte)
+		return -1;
+
+	return (*byte >> bit) & 1;
+}
+EXPORT_SYMBOL(try_test_sas_gpio_gp_bit);
+
+static int sas_host_smp_write_gpio(struct sas_ha_struct *sas_ha, u8 *resp_data,
+				   u8 reg_type, u8 reg_index, u8 reg_count,
+				   u8 *req_data)
+{
+	struct sas_internal *i = to_sas_internal(sas_ha->core.shost->transportt);
+	int written;
+
+	if (i->dft->lldd_write_gpio == NULL) {
+		resp_data[2] = SMP_RESP_FUNC_UNK;
+		return 0;
+	}
+
+	written = i->dft->lldd_write_gpio(sas_ha, reg_type, reg_index,
+					  reg_count, req_data);
+
+	if (written < 0) {
+		resp_data[2] = SMP_RESP_FUNC_FAILED;
+		written = 0;
+	} else
+		resp_data[2] = SMP_RESP_FUNC_ACC;
+
+	return written;
+}
+
 static void sas_report_phy_sata(struct sas_ha_struct *sas_ha, u8 *resp_data,
 				u8 phy_id)
 {
@@ -230,9 +315,23 @@ int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
 		/* Can't implement; hosts have no routes */
 		break;
 
-	case SMP_WRITE_GPIO_REG:
-		/* FIXME: need GPIO support in the transport class */
+	case SMP_WRITE_GPIO_REG: {
+		/* SFF-8485 v0.7 */
+		const int base_frame_size = 11;
+		int to_write = req_data[4];
+
+		if (blk_rq_bytes(req) < base_frame_size + to_write * 4 ||
+		    req->resid_len < base_frame_size + to_write * 4) {
+			resp_data[2] = SMP_RESP_INV_FRM_LEN;
+			break;
+		}
+
+		to_write = sas_host_smp_write_gpio(sas_ha, resp_data, req_data[2],
+						   req_data[3], to_write, &req_data[8]);
+		req->resid_len -= base_frame_size + to_write * 4;
+		rsp->resid_len -= 8;
 		break;
+	}
 
 	case SMP_CONF_ROUTE_INFO:
 		/* Can't implement; hosts have no routes */
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index ee86606..2d9ff0a 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 |
@@ -614,6 +621,10 @@ 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 e9fd022..a3001ad 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;