greybus: spi: add device_type field to device config

Add device_type field in device config operation to get the type of
device and try to expose less the kernel internal over greybus.
This include the spidev, spi-nor will fetch the correct nor id over
jede and a modalias that will have the previous behavior (name will set
the driver to be loaded).

As at it, fix a trivial error path and return immediately.

Tested: using gbsim and confirming that a spidev and mtd device were
created.
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/greybus_protocols.h

@@ -737,6 +737,10 @@ struct gb_spi_device_config_response {
 	__le16	mode;
 	__u8	bits_per_word;
 	__le32	max_speed_hz;
+	__u8	device_type;
+#define GB_SPI_SPI_DEV		0x00
+#define GB_SPI_SPI_NOR		0x01
+#define GB_SPI_SPI_MODALIAS	0x02
 	__u8	name[32];
 } __packed;
 

drivers/staging/greybus/kernel_ver.h

@@ -305,4 +305,12 @@ static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev)
 #define PSY_HAVE_PUT
 #endif
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(3, 16, 0)
+#define SPI_DEV_MODALIAS "spidev"
+#define SPI_NOR_MODALIAS "spi-nor"
+#else
+#define SPI_DEV_MODALIAS "spidev"
+#define SPI_NOR_MODALIAS "m25p80"
+#endif
+
 #endif	/* __GREYBUS_KERNEL_VER_H */

drivers/staging/greybus/spi.c

@@ -285,6 +285,7 @@ static int gb_spi_setup_device(struct gb_spi *spi, u8 cs)
 	struct spi_board_info spi_board = { {0} };
 	struct spi_device *spidev;
 	int ret;
+	u8 dev_type;
 
 	request.chip_select = cs;
 
@@ -294,7 +295,20 @@ static int gb_spi_setup_device(struct gb_spi *spi, u8 cs)
 	if (ret < 0)
 		return ret;
 
-	memcpy(spi_board.modalias, response.name, sizeof(spi_board.modalias));
+	dev_type = response.device_type;
+
+	if (dev_type == GB_SPI_SPI_DEV)
+		strlcpy(spi_board.modalias, SPI_DEV_MODALIAS,
+			sizeof(spi_board.modalias));
+	else if (dev_type == GB_SPI_SPI_NOR)
+		strlcpy(spi_board.modalias, SPI_NOR_MODALIAS,
+			sizeof(spi_board.modalias));
+	else if (dev_type == GB_SPI_SPI_MODALIAS)
+		memcpy(spi_board.modalias, response.name,
+		       sizeof(spi_board.modalias));
+	else
+		return -EINVAL;
+
 	spi_board.mode		= le16_to_cpu(response.mode);
 	spi_board.bus_num	= master->bus_num;
 	spi_board.chip_select	= cs;
@@ -302,7 +316,7 @@ static int gb_spi_setup_device(struct gb_spi *spi, u8 cs)
 
 	spidev = spi_new_device(master, &spi_board);
 	if (!spidev)
-		ret = -EINVAL;
+		return -EINVAL;
 
 	return 0;
 }