[SCSI] libsas: add SAS management protocol handler

This patch adds support for SAS Management Protocol (SMP) passthrough
support via bsg. aic94xx can use this.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libsas/sas_expander.c

@@ -23,6 +23,7 @@
  */
 
 #include <linux/scatterlist.h>
+#include <linux/blkdev.h>
 
 #include "sas_internal.h"
 
@@ -1972,3 +1973,50 @@ out:
 	return res;
 }
 #endif
+
+int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
+		    struct request *req)
+{
+	struct domain_device *dev;
+	int ret, type = rphy->identify.device_type;
+	struct request *rsp = req->next_rq;
+
+	if (!rsp) {
+		printk("%s: space for a smp response is missing\n",
+		       __FUNCTION__);
+		return -EINVAL;
+	}
+
+	/* seems aic94xx doesn't support */
+	if (!rphy) {
+		printk("%s: can we send a smp request to a host?\n",
+		       __FUNCTION__);
+		return -EINVAL;
+	}
+
+	if (type != SAS_EDGE_EXPANDER_DEVICE &&
+	    type != SAS_FANOUT_EXPANDER_DEVICE) {
+		printk("%s: can we send a smp request to a device?\n",
+		       __FUNCTION__);
+		return -EINVAL;
+	}
+
+	dev = sas_find_dev_by_rphy(rphy);
+	if (!dev) {
+		printk("%s: fail to find a domain_device?\n", __FUNCTION__);
+		return -EINVAL;
+	}
+
+	/* do we need to support multiple segments? */
+	if (req->bio->bi_vcnt > 1 || rsp->bio->bi_vcnt > 1) {
+		printk("%s: multiple segments req %u %u, rsp %u %u\n",
+		       __FUNCTION__, req->bio->bi_vcnt, req->data_len,
+		       rsp->bio->bi_vcnt, rsp->data_len);
+		return -EINVAL;
+	}
+
+	ret = smp_execute_task(dev, bio_data(req->bio), req->data_len,
+			       bio_data(rsp->bio), rsp->data_len);
+
+	return ret;
+}

drivers/scsi/libsas/sas_init.c

@@ -259,6 +259,7 @@ static struct sas_function_template sft = {
 	.phy_reset = sas_phy_reset,
 	.set_phy_speed = sas_set_phy_speed,
 	.get_linkerrors = sas_get_linkerrors,
+	.smp_handler = sas_smp_handler,
 };
 
 struct scsi_transport_template *

include/scsi/libsas.h

@@ -674,4 +674,6 @@ extern void sas_target_destroy(struct scsi_target *);
 extern int sas_slave_alloc(struct scsi_device *);
 extern int sas_ioctl(struct scsi_device *sdev, int cmd, void __user *arg);
 
+extern int sas_smp_handler(struct Scsi_Host *shost, struct sas_rphy *rphy,
+			   struct request *req);
 #endif /* _SASLIB_H_ */