diff mbox

[RFC] spi: spidev: Add support for Dual/Quad SPI Transfers

Message ID 1392999293-5015-1-git-send-email-geert@linux-m68k.org (mailing list archive)
State Changes Requested
Headers show

Commit Message

Geert Uytterhoeven Feb. 21, 2014, 4:14 p.m. UTC 
From: Geert Uytterhoeven <geert+renesas@linux-m68k.org>

Add support for Dual/Quad SPI Transfers to the spidev API, and the
spidev_test test program.

This requires enlarging the mode from 8 to 16 bits.
Note that this does break binary compatibility with userspace.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
---
The Kconfig entry for SPI_SPIDEV states:

    Note that this application programming interface is EXPERIMENTAL
    and hence SUBJECT TO CHANGE WITHOUT NOTICE while it stabilizes.

So it's OK to break binary compatibility?
Or should we introduce PI_IOC_RD_MODE16 and SPI_IOC_WR_MODE16 instead?
---
 Documentation/spi/spidev_test.c |   39 +++++++++++++++++++++++++++++++++++----
 drivers/spi/spidev.c            |   17 ++++++++++-------
 include/uapi/linux/spi/spidev.h |   12 +++++++++---
 3 files changed, 54 insertions(+), 14 deletions(-)

Comments

Mark Brown Feb. 24, 2014, 1:35 a.m. UTC | #1 
On Fri, Feb 21, 2014 at 05:14:53PM +0100, Geert Uytterhoeven wrote:

> The Kconfig entry for SPI_SPIDEV states:

>     Note that this application programming interface is EXPERIMENTAL
>     and hence SUBJECT TO CHANGE WITHOUT NOTICE while it stabilizes.

> So it's OK to break binary compatibility?
> Or should we introduce PI_IOC_RD_MODE16 and SPI_IOC_WR_MODE16 instead?

I think it's been experimental for so long that it has become a stable
interface I'm afraid - the new calls would be better.  Why not go for 32
bits instead of 16 bits for the new calls, that way it'll take longer to
fill up again?
diff mbox

Patch

diff --git a/Documentation/spi/spidev_test.c b/Documentation/spi/spidev_test.c
index efd7385e907f..68c705b1326c 100644
--- a/Documentation/spi/spidev_test.c
+++ b/Documentation/spi/spidev_test.c
@@ -30,7 +30,7 @@  static void pabort(const char *s)
 }
 
 static const char *device = "/dev/spidev1.1";
-static uint8_t mode;
+static uint16_t mode;
 static uint8_t bits = 8;
 static uint32_t speed = 500000;
 static uint16_t delay;
@@ -57,6 +57,21 @@  static void transfer(int fd)
 		.bits_per_word = bits,
 	};
 
+	if (mode & SPI_TX_QUAD)
+		tr.tx_nbits = 4;
+	else if (mode & SPI_TX_DUAL)
+		tr.tx_nbits = 2;
+	if (mode & SPI_RX_QUAD)
+		tr.rx_nbits = 4;
+	else if (mode & SPI_RX_DUAL)
+		tr.rx_nbits = 2;
+	if (!(mode & SPI_LOOP)) {
+		if (mode & (SPI_TX_QUAD | SPI_TX_DUAL))
+			tr.rx_buf = 0;
+		else if (mode & (SPI_RX_QUAD | SPI_RX_DUAL))
+			tr.tx_buf = 0;
+	}
+
 	ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
 	if (ret < 1)
 		pabort("can't send spi message");
@@ -83,7 +98,9 @@  static void print_usage(const char *prog)
 	     "  -C --cs-high  chip select active high\n"
 	     "  -3 --3wire    SI/SO signals shared\n"
 	     "  -N --no-cs    no chip select\n"
-	     "  -R --ready    slave pulls low to pause\n");
+	     "  -R --ready    slave pulls low to pause\n"
+	     "  -2 --dual     dual transfer\n"
+	     "  -4 --quad     quad transfer\n");
 	exit(1);
 }
 
@@ -103,11 +120,13 @@  static void parse_opts(int argc, char *argv[])
 			{ "3wire",   0, 0, '3' },
 			{ "no-cs",   0, 0, 'N' },
 			{ "ready",   0, 0, 'R' },
+			{ "dual",    0, 0, '2' },
+			{ "quad",    0, 0, '4' },
 			{ NULL, 0, 0, 0 },
 		};
 		int c;
 
-		c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);
+		c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR24", lopts, NULL);
 
 		if (c == -1)
 			break;
@@ -149,11 +168,23 @@  static void parse_opts(int argc, char *argv[])
 		case 'R':
 			mode |= SPI_READY;
 			break;
+		case '2':
+			mode |= SPI_TX_DUAL;
+			break;
+		case '4':
+			mode |= SPI_TX_QUAD;
+			break;
 		default:
 			print_usage(argv[0]);
 			break;
 		}
 	}
+	if (mode & SPI_LOOP) {
+		if (mode & SPI_TX_DUAL)
+			mode |= SPI_RX_DUAL;
+		if (mode & SPI_TX_QUAD)
+			mode |= SPI_RX_QUAD;
+	}
 }
 
 int main(int argc, char *argv[])
@@ -200,7 +231,7 @@  int main(int argc, char *argv[])
 	if (ret == -1)
 		pabort("can't get max speed hz");
 
-	printf("spi mode: %d\n", mode);
+	printf("spi mode: %x\n", mode);
 	printf("bits per word: %d\n", bits);
 	printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);
 
diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c
index d7c6e36021e8..e490e01db192 100644
--- a/drivers/spi/spidev.c
+++ b/drivers/spi/spidev.c
@@ -73,7 +73,8 @@  static DECLARE_BITMAP(minors, N_SPI_MINORS);
  */
 #define SPI_MODE_MASK		(SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
 				| SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
-				| SPI_NO_CS | SPI_READY)
+				| SPI_NO_CS | SPI_READY | SPI_TX_DUAL \
+				| SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)
 
 struct spidev_data {
 	dev_t			devt;
@@ -265,6 +266,8 @@  static int spidev_message(struct spidev_data *spidev,
 		buf += k_tmp->len;
 
 		k_tmp->cs_change = !!u_tmp->cs_change;
+		k_tmp->tx_nbits = u_tmp->tx_nbits;
+		k_tmp->rx_nbits = u_tmp->rx_nbits;
 		k_tmp->bits_per_word = u_tmp->bits_per_word;
 		k_tmp->delay_usecs = u_tmp->delay_usecs;
 		k_tmp->speed_hz = u_tmp->speed_hz;
@@ -357,7 +360,7 @@  spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	/* read requests */
 	case SPI_IOC_RD_MODE:
 		retval = __put_user(spi->mode & SPI_MODE_MASK,
-					(__u8 __user *)arg);
+					(__u16 __user *)arg);
 		break;
 	case SPI_IOC_RD_LSB_FIRST:
 		retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
@@ -372,9 +375,9 @@  spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 	/* write requests */
 	case SPI_IOC_WR_MODE:
-		retval = __get_user(tmp, (u8 __user *)arg);
+		retval = __get_user(tmp, (u16 __user *)arg);
 		if (retval == 0) {
-			u8	save = spi->mode;
+			u16	save = spi->mode;
 
 			if (tmp & ~SPI_MODE_MASK) {
 				retval = -EINVAL;
@@ -382,18 +385,18 @@  spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 			}
 
 			tmp |= spi->mode & ~SPI_MODE_MASK;
-			spi->mode = (u8)tmp;
+			spi->mode = (u16)tmp;
 			retval = spi_setup(spi);
 			if (retval < 0)
 				spi->mode = save;
 			else
-				dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
+				dev_dbg(&spi->dev, "spi mode %04x\n", tmp);
 		}
 		break;
 	case SPI_IOC_WR_LSB_FIRST:
 		retval = __get_user(tmp, (__u8 __user *)arg);
 		if (retval == 0) {
-			u8	save = spi->mode;
+			u16	save = spi->mode;
 
 			if (tmp)
 				spi->mode |= SPI_LSB_FIRST;
diff --git a/include/uapi/linux/spi/spidev.h b/include/uapi/linux/spi/spidev.h
index 52d9ed01855f..50e8aef0e7ca 100644
--- a/include/uapi/linux/spi/spidev.h
+++ b/include/uapi/linux/spi/spidev.h
@@ -42,6 +42,10 @@ 
 #define SPI_LOOP		0x20
 #define SPI_NO_CS		0x40
 #define SPI_READY		0x80
+#define SPI_TX_DUAL		0x100
+#define SPI_TX_QUAD		0x200
+#define SPI_RX_DUAL		0x400
+#define SPI_RX_QUAD		0x800
 
 /*---------------------------------------------------------------------------*/
 
@@ -92,7 +96,9 @@  struct spi_ioc_transfer {
 	__u16		delay_usecs;
 	__u8		bits_per_word;
 	__u8		cs_change;
-	__u32		pad;
+	__u8		tx_nbits;
+	__u8		rx_nbits;
+	__u16		pad;
 
 	/* If the contents of 'struct spi_ioc_transfer' ever change
 	 * incompatibly, then the ioctl number (currently 0) must change;
@@ -111,8 +117,8 @@  struct spi_ioc_transfer {
 
 
 /* Read / Write of SPI mode (SPI_MODE_0..SPI_MODE_3) */
-#define SPI_IOC_RD_MODE			_IOR(SPI_IOC_MAGIC, 1, __u8)
-#define SPI_IOC_WR_MODE			_IOW(SPI_IOC_MAGIC, 1, __u8)
+#define SPI_IOC_RD_MODE			_IOR(SPI_IOC_MAGIC, 1, __u16)
+#define SPI_IOC_WR_MODE			_IOW(SPI_IOC_MAGIC, 1, __u16)
 
 /* Read / Write SPI bit justification */
 #define SPI_IOC_RD_LSB_FIRST		_IOR(SPI_IOC_MAGIC, 2, __u8)