[PATCH 1/6] scsi: Add INQUIRY data field definitions and accessor helpers

[Brian Bunker <brian@purestorage.com>]

Add well-documented inline functions and macros to parse INQUIRY data
fields according to SPC-6 section 6.7.2. These helpers provide a
consistent interface for extracting:

- Peripheral qualifier and device type from byte 0
- Removable media bit from byte 1
- Response data format from byte 3
- Capability flags (WBUS16, SYNC, CMDQUE, SFTRE) from byte 7
- Vendor, product, and revision strings

This is preparatory work for adding INQUIRY data update support during
device rescan operations.

Signed-off-by: Brian Bunker <brian@purestorage.com>
Signed-off-by: Krishna Kant <krishna.kant@purestorage.com>
---
 include/scsi/scsi.h | 171 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 171 insertions(+)

diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 08ac3200b4a4b..8f38d9a884f91 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -172,6 +172,177 @@ enum scsi_qc_status {
 #define SCSI_INQ_PQ_NOT_CON     0x01
 #define SCSI_INQ_PQ_NOT_CAP     0x03
 
+/*
+ * INQUIRY data field offsets and lengths
+ */
+#define SCSI_INQ_STD_LEN		36	/* Min standard INQ len */
+#define SCSI_INQ_VENDOR_OFFSET		8
+#define SCSI_INQ_VENDOR_LEN		8
+#define SCSI_INQ_PRODUCT_OFFSET		16
+#define SCSI_INQ_PRODUCT_LEN		16
+#define SCSI_INQ_REVISION_OFFSET	32
+#define SCSI_INQ_REVISION_LEN		4
+
+/*
+ * INQUIRY data byte 0 bit masks
+ */
+#define SCSI_INQ_PERIPH_QUAL_MASK	0xe0	/* bits 5-7 */
+#define SCSI_INQ_PERIPH_QUAL_SHIFT	5
+#define SCSI_INQ_DEVICE_TYPE_MASK	0x1f	/* bits 0-4 */
+
+/*
+ * INQUIRY data byte 1 bit masks
+ */
+#define SCSI_INQ_RMB_MASK		0x80	/* bit 7 */
+
+/*
+ * INQUIRY data byte 3 bit masks
+ */
+#define SCSI_INQ_RESP_DATA_FMT_MASK	0x0f	/* bits 0-3 */
+
+/*
+ * INQUIRY data byte 7 bit masks
+ */
+#define SCSI_INQ_WBUS16			0x20	/* Wide Bus 16 (bit 5) */
+#define SCSI_INQ_SYNC			0x10	/* Synchronous (bit 4) */
+#define SCSI_INQ_CMDQUE			0x02	/* Command Queuing (bit 1) */
+#define SCSI_INQ_SFTRE			0x01	/* Soft Reset (bit 0) */
+
+/**
+ * scsi_inq_periph_qual - Extract peripheral qualifier from byte 0
+ * @inq_byte0: INQUIRY data byte 0
+ *
+ * Returns: Peripheral Qualifier (0-7)
+ */
+static inline unsigned char scsi_inq_periph_qual(unsigned char inq_byte0)
+{
+	return (inq_byte0 & SCSI_INQ_PERIPH_QUAL_MASK) >>
+		SCSI_INQ_PERIPH_QUAL_SHIFT;
+}
+
+/**
+ * scsi_inq_device_type - Extract device type from byte 0
+ * @inq_byte0: INQUIRY data byte 0
+ * @lun: Logical Unit Number
+ *
+ * Extracts the peripheral device type. For well-known logical units
+ * (W-LUNs), corrects the type to TYPE_WLUN if device reports wrong type.
+ *
+ * Returns: Peripheral Device Type (0-31)
+ */
+static inline unsigned char scsi_inq_device_type(unsigned char inq_byte0,
+						 u64 lun)
+{
+	unsigned char type = inq_byte0 & SCSI_INQ_DEVICE_TYPE_MASK;
+
+	/*
+	 * Some devices respond with wrong type for well-known logical
+	 * units. Force well-known type to enumerate them correctly.
+	 */
+	if (scsi_is_wlun(lun) && type != TYPE_WLUN)
+		type = TYPE_WLUN;
+
+	return type;
+}
+
+/**
+ * scsi_inq_removable - Extract removable media bit from byte 1
+ * @inq_byte1: INQUIRY data byte 1
+ *
+ * Returns: true if removable, false if not
+ */
+static inline bool scsi_inq_removable(unsigned char inq_byte1)
+{
+	return inq_byte1 & SCSI_INQ_RMB_MASK;
+}
+
+/**
+ * scsi_inq_resp_data_fmt - Extract response data format from byte 3
+ * @inq_byte3: INQUIRY data byte 3
+ *
+ * Returns: Response Data Format (0-15)
+ */
+static inline unsigned char scsi_inq_resp_data_fmt(unsigned char inq_byte3)
+{
+	return inq_byte3 & SCSI_INQ_RESP_DATA_FMT_MASK;
+}
+
+/**
+ * scsi_inq_wbus16 - Check wide bus support from byte 7
+ * @inq_byte7: INQUIRY data byte 7
+ *
+ * Returns: true if 16-bit wide bus supported, false if not
+ */
+static inline bool scsi_inq_wbus16(unsigned char inq_byte7)
+{
+	return inq_byte7 & SCSI_INQ_WBUS16;
+}
+
+/**
+ * scsi_inq_sync - Check synchronous transfer support from byte 7
+ * @inq_byte7: INQUIRY data byte 7
+ *
+ * Returns: true if synchronous transfers supported, false if not
+ */
+static inline bool scsi_inq_sync(unsigned char inq_byte7)
+{
+	return inq_byte7 & SCSI_INQ_SYNC;
+}
+
+/**
+ * scsi_inq_cmdque - Check command queuing support from byte 7
+ * @inq_byte7: INQUIRY data byte 7
+ *
+ * Returns: true if command queuing supported, false if not
+ */
+static inline bool scsi_inq_cmdque(unsigned char inq_byte7)
+{
+	return inq_byte7 & SCSI_INQ_CMDQUE;
+}
+
+/**
+ * scsi_inq_sftre - Check soft reset support from byte 7
+ * @inq_byte7: INQUIRY data byte 7
+ *
+ * Returns: true if soft reset supported, false if not
+ */
+static inline bool scsi_inq_sftre(unsigned char inq_byte7)
+{
+	return inq_byte7 & SCSI_INQ_SFTRE;
+}
+
+/**
+ * scsi_inq_vendor - Get pointer to vendor string
+ * @inq_data: Pointer to INQUIRY data buffer
+ *
+ * Returns: Pointer to 8-byte vendor string (not null-terminated)
+ */
+static inline const char *scsi_inq_vendor(const unsigned char *inq_data)
+{
+	return (const char *)(inq_data + SCSI_INQ_VENDOR_OFFSET);
+}
+
+/**
+ * scsi_inq_product - Get pointer to product string
+ * @inq_data: Pointer to INQUIRY data buffer
+ *
+ * Returns: Pointer to 16-byte product string (not null-terminated)
+ */
+static inline const char *scsi_inq_product(const unsigned char *inq_data)
+{
+	return (const char *)(inq_data + SCSI_INQ_PRODUCT_OFFSET);
+}
+
+/**
+ * scsi_inq_revision - Get pointer to revision string
+ * @inq_data: Pointer to INQUIRY data buffer
+ *
+ * Returns: Pointer to 4-byte revision string (not null-terminated)
+ */
+static inline const char *scsi_inq_revision(const unsigned char *inq_data)
+{
+	return (const char *)(inq_data + SCSI_INQ_REVISION_OFFSET);
+}
 
 /*
  * Here are some scsi specific ioctl commands which are sometimes useful.
-- 
2.50.1 (Apple Git-155)