scsi: define SCSI_DEVICE_MAX_LUN_COUNT to set a custom max lun count.

* virtio_scsi can have 16384 luns, though we cap at 256 as our scsi_ccb
only uses uchar as a type for target_lun and target_id members.
* minor code cleanup in scsi_scan_bus().

headers/os/drivers/bus/SCSI.h

@@ -288,6 +288,8 @@ typedef struct {
 
 // maximum targets on scsi bus
 #define SCSI_DEVICE_MAX_TARGET_COUNT "scsi/max_target_count"
+// maximum luns on scsi bus
+#define SCSI_DEVICE_MAX_LUN_COUNT "scsi/max_lun_count"
 
 // directory containing links to peripheral drivers
 #define SCSI_PERIPHERAL_DRIVERS_DIR "scsi"

src/add-ons/kernel/bus_managers/scsi/busses.cpp

@@ -101,6 +101,15 @@ scsi_create_bus(device_node *node, uint8 path_id)
 
 	if (pnp->get_attr_uint32(node, SCSI_DEVICE_MAX_TARGET_COUNT, &bus->max_target_count, true) != B_OK)
 		bus->max_target_count = MAX_TARGET_ID + 1;
+	if (pnp->get_attr_uint32(node, SCSI_DEVICE_MAX_LUN_COUNT, &bus->max_lun_count, true) != B_OK)
+		bus->max_lun_count = MAX_LUN_ID + 1;
+
+	// our scsi_ccb only has a uchar for target_id
+	if (bus->max_target_count > 256)
+		bus->max_target_count = 256;
+	// our scsi_ccb only has a uchar for target_lun
+	if (bus->max_lun_count > 256)
+		bus->max_lun_count = 256;
 
 	bus->node = node;
 	bus->lock_count = bus->blocked[0] = bus->blocked[1] = 0;

src/add-ons/kernel/bus_managers/scsi/device_scan.cpp

@@ -251,18 +251,16 @@ err:
 status_t
 scsi_scan_bus(scsi_bus_info *bus)
 {
-	int initiator_id, target_id;
 	scsi_path_inquiry inquiry;
-	uchar res;
 
 	SHOW_FLOW0( 3, "" );
 
 	// get ID of initiator (i.e. controller)
-	res = scsi_inquiry_path(bus, &inquiry);
+	uchar res = scsi_inquiry_path(bus, &inquiry);
 	if (res != SCSI_REQ_CMP)
 		return B_ERROR;
 
-	initiator_id = inquiry.initiator_id;
+	uint initiator_id = inquiry.initiator_id;
 
 	SHOW_FLOW(3, "initiator_id=%d", initiator_id);
 
@@ -270,9 +268,7 @@ scsi_scan_bus(scsi_bus_info *bus)
 	// as this function is optional for SIM, we ignore its result
 	bus->interface->scan_bus(bus->sim_cookie);
 
-	for (target_id = 0; target_id < (int)bus->max_target_count; ++target_id) {
-		int lun;
-
+	for (uint target_id = 0; target_id < bus->max_target_count; ++target_id) {
 		SHOW_FLOW(3, "target: %d", target_id);
 
 		if (target_id == initiator_id)
@@ -281,12 +277,10 @@ scsi_scan_bus(scsi_bus_info *bus)
 		// TODO: there are a lot of devices out there that go mad if you probe
 		// anything but LUN 0, so we should probably add a black-list
 		// or something
-		for (lun = 0; lun <= MAX_LUN_ID; ++lun) {
-			status_t status;
-
+		for (uint lun = 0; lun < bus->max_lun_count; ++lun) {
 			SHOW_FLOW(3, "lun: %d", lun);
 
-			status = scsi_scan_lun(bus, target_id, lun);
+			status_t status = scsi_scan_lun(bus, target_id, lun);
 
 			// if there is no device at lun 0, there's probably no device at all
 			if (lun == 0 && status != B_OK)

src/add-ons/kernel/bus_managers/scsi/scsi_internal.h

@@ -90,6 +90,7 @@ typedef struct scsi_bus_info {
 
 	uchar path_id;				// SCSI path id
 	uint32 max_target_count;	// maximum count of target_ids on the bus
+	uint32 max_lun_count;		// maximum count of lun_ids on the bus
 
 	thread_id service_thread;	// service thread
 	sem_id start_service;		// released whenever service thread has work to do

src/add-ons/kernel/busses/scsi/virtio/virtio_scsi.cpp

@@ -205,6 +205,7 @@ virtio_scsi_register_device(device_node *parent)
 		return status;
 
 	uint32 max_targets = config.max_target + 1;
+	uint32 max_luns = config.max_lun + 1;
 	uint32 max_blocks = 0x10000;
 	if (config.max_sectors != 0)
 		max_blocks = config.max_sectors;
@@ -212,6 +213,8 @@ virtio_scsi_register_device(device_node *parent)
 	device_attr attrs[] = {
 		{ SCSI_DEVICE_MAX_TARGET_COUNT, B_UINT32_TYPE,
 			{ ui32: max_targets }},
+		{ SCSI_DEVICE_MAX_LUN_COUNT, B_UINT32_TYPE,
+			{ ui32: max_luns }},
 		{ B_DEVICE_PRETTY_NAME, B_STRING_TYPE,
 			{ string: VIRTIO_SCSI_BRIDGE_PRETTY_NAME }},