spi: DUAL and QUAD support

fix the previous patch some mistake below:
1. DT in slave node, use "spi-tx-nbits = <1/2/4>" in place of using
   "spi-tx-dual, spi-tx-quad" directly, same to rx. So correct the
   previous way to get the property in @of_register_spi_devices().
2. Change the value of transfer bit macro(SPI_NBITS_SINGLE, SPI_NBITS_DUAL
   SPI_NBITS_QUAD) to 0x01, 0x02 and 0x04 to match the actual wires.
3. Add the following check
   (1)keep the tx_nbits and rx_nbits in spi_transfer is not beyond the
      single, dual and quad.
   (2)keep tx_nbits and rx_nbits are contained by @spi_device->mode
      example: if @spi_device->mode = DUAL, then tx/rx_nbits can not be set
               to QUAD(SPI_NBITS_QUAD)
   (3)if "@spi_device->mode & SPI_3WIRE", then tx/rx_nbits should be in
      single(SPI_NBITS_SINGLE)
Signed-off-by: wangyuhang <wangyuhang2014@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi.c

@@ -869,6 +869,51 @@ static void of_register_spi_devices(struct spi_master *master)
 		if (of_find_property(nc, "spi-3wire", NULL))
 			spi->mode |= SPI_3WIRE;
 
+		/* Device DUAL/QUAD mode */
+		prop = of_get_property(nc, "spi-tx-nbits", &len);
+		if (!prop || len < sizeof(*prop)) {
+			dev_err(&master->dev, "%s has no 'spi-tx-nbits' property\n",
+				nc->full_name);
+			spi_dev_put(spi);
+			continue;
+		}
+		switch (be32_to_cpup(prop)) {
+		case SPI_NBITS_SINGLE:
+			break;
+		case SPI_NBITS_DUAL:
+			spi->mode |= SPI_TX_DUAL;
+			break;
+		case SPI_NBITS_QUAD:
+			spi->mode |= SPI_TX_QUAD;
+			break;
+		default:
+			dev_err(&master->dev, "spi-tx-nbits value is not supported\n");
+			spi_dev_put(spi);
+			continue;
+		}
+
+		prop = of_get_property(nc, "spi-rx-nbits", &len);
+		if (!prop || len < sizeof(*prop)) {
+			dev_err(&master->dev, "%s has no 'spi-rx-nbits' property\n",
+				nc->full_name);
+			spi_dev_put(spi);
+			continue;
+		}
+		switch (be32_to_cpup(prop)) {
+		case SPI_NBITS_SINGLE:
+			break;
+		case SPI_NBITS_DUAL:
+			spi->mode |= SPI_RX_DUAL;
+			break;
+		case SPI_NBITS_QUAD:
+			spi->mode |= SPI_RX_QUAD;
+			break;
+		default:
+			dev_err(&master->dev, "spi-rx-nbits value is not supported\n");
+			spi_dev_put(spi);
+			continue;
+		}
+
 		/* Device speed */
 		prop = of_get_property(nc, "spi-max-frequency", &len);
 		if (!prop || len < sizeof(*prop)) {
@@ -1316,6 +1361,19 @@ int spi_setup(struct spi_device *spi)
 	unsigned	bad_bits;
 	int		status = 0;
 
+	/* check mode to prevent that DUAL and QUAD set at the same time
+	 */
+	if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
+		((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
+		dev_err(&spi->dev,
+		"setup: can not select dual and quad at the same time\n");
+		return -EINVAL;
+	}
+	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
+	 */
+	if ((spi->mode & SPI_3WIRE) && (spi->mode &
+		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
+		return -EINVAL;
 	/* help drivers fail *cleanly* when they need options
 	 * that aren't supported with their current master
 	 */
@@ -1378,6 +1436,8 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
 	/**
 	 * Set transfer bits_per_word and max speed as spi device default if
 	 * it is not set for this transfer.
+	 * Set transfer tx_nbits and rx_nbits as single transfer default
+	 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
 	 */
 	list_for_each_entry(xfer, &message->transfers, transfer_list) {
 		if (!xfer->bits_per_word)
@@ -1403,6 +1463,42 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
 			return -EINVAL;
 		if (xfer->speed_hz && master->max_speed_hz &&
 		    xfer->speed_hz > master->max_speed_hz)
+
+		if (xfer->tx_buf && !xfer->tx_nbits)
+			xfer->tx_nbits = SPI_NBITS_SINGLE;
+		if (xfer->rx_buf && !xfer->rx_nbits)
+			xfer->rx_nbits = SPI_NBITS_SINGLE;
+		/* check transfer tx/rx_nbits:
+		 * 1. keep the value is not out of single, dual and quad
+		 * 2. keep tx/rx_nbits is contained by mode in spi_device
+		 * 3. if SPI_3WIRE, tx/rx_nbits should be in single
+		 */
+		if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
+			xfer->tx_nbits != SPI_NBITS_DUAL &&
+			xfer->tx_nbits != SPI_NBITS_QUAD)
+			return -EINVAL;
+		if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
+			!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
+			return -EINVAL;
+		if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
+			!(spi->mode & SPI_TX_QUAD))
+			return -EINVAL;
+		if ((spi->mode & SPI_3WIRE) &&
+			(xfer->tx_nbits != SPI_NBITS_SINGLE))
+			return -EINVAL;
+		/* check transfer rx_nbits */
+		if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
+			xfer->rx_nbits != SPI_NBITS_DUAL &&
+			xfer->rx_nbits != SPI_NBITS_QUAD)
+			return -EINVAL;
+		if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
+			!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
+			return -EINVAL;
+		if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
+			!(spi->mode & SPI_RX_QUAD))
+			return -EINVAL;
+		if ((spi->mode & SPI_3WIRE) &&
+			(xfer->rx_nbits != SPI_NBITS_SINGLE))
 			return -EINVAL;
 	}
 

include/linux/spi/spi.h

@@ -74,7 +74,7 @@ struct spi_device {
 	struct spi_master	*master;
 	u32			max_speed_hz;
 	u8			chip_select;
-	u8			mode;
+	u16			mode;
 #define	SPI_CPHA	0x01			/* clock phase */
 #define	SPI_CPOL	0x02			/* clock polarity */
 #define	SPI_MODE_0	(0|0)			/* (original MicroWire) */
@@ -87,6 +87,10 @@ struct spi_device {
 #define	SPI_LOOP	0x20			/* loopback mode */
 #define	SPI_NO_CS	0x40			/* 1 dev/bus, no chipselect */
 #define	SPI_READY	0x80			/* slave pulls low to pause */
+#define	SPI_TX_DUAL	0x100			/* transmit with 2 wires */
+#define	SPI_TX_QUAD	0x200			/* transmit with 4 wires */
+#define	SPI_RX_DUAL	0x400			/* receive with 2 wires */
+#define	SPI_RX_QUAD	0x800			/* receive with 4 wires */
 	u8			bits_per_word;
 	int			irq;
 	void			*controller_state;
@@ -454,6 +458,10 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
  * @rx_buf: data to be read (dma-safe memory), or NULL
  * @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped
  * @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped
+ * @tx_nbits: number of bits used for writting. If 0 the default
+ *      (SPI_NBITS_SINGLE) is used.
+ * @rx_nbits: number of bits used for reading. If 0 the default
+ *      (SPI_NBITS_SINGLE) is used.
  * @len: size of rx and tx buffers (in bytes)
  * @speed_hz: Select a speed other than the device default for this
  *      transfer. If 0 the default (from @spi_device) is used.
@@ -508,6 +516,11 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
  * by the results of previous messages and where the whole transaction
  * ends when the chipselect goes intactive.
  *
+ * When SPI can transfer in 1x,2x or 4x. It can get this tranfer information
+ * from device through @tx_nbits and @rx_nbits. In Bi-direction, these
+ * two should both be set. User can set transfer mode with SPI_NBITS_SINGLE(1x)
+ * SPI_NBITS_DUAL(2x) and SPI_NBITS_QUAD(4x) to support these three transfer.
+ *
  * The code that submits an spi_message (and its spi_transfers)
  * to the lower layers is responsible for managing its memory.
  * Zero-initialize every field you don't set up explicitly, to
@@ -528,6 +541,11 @@ struct spi_transfer {
 	dma_addr_t	rx_dma;
 
 	unsigned	cs_change:1;
+	u8		tx_nbits;
+	u8		rx_nbits;
+#define	SPI_NBITS_SINGLE	0x01 /* 1bit transfer */
+#define	SPI_NBITS_DUAL		0x02 /* 2bits transfer */
+#define	SPI_NBITS_QUAD		0x04 /* 4bits transfer */
 	u8		bits_per_word;
 	u16		delay_usecs;
 	u32		speed_hz;
@@ -875,7 +893,7 @@ struct spi_board_info {
 	/* mode becomes spi_device.mode, and is essential for chips
 	 * where the default of SPI_CS_HIGH = 0 is wrong.
 	 */
-	u8		mode;
+	u16		mode;
 
 	/* ... may need additional spi_device chip config data here.
 	 * avoid stuff protocol drivers can set; but include stuff