MIPS: BCM63xx: Fix SPI message control register handling for BCM6338/6348.

BCM6338 and BCM6348 have a message control register width of 8 bits, instead
of 16-bits like what the SPI driver assumes right now. Also the SPI message
type shift value of 14 is actually 6 for these SoCs.
This resulted in transmit FIFO corruption because we were writing 16-bits
to an 8-bits wide register, thus spanning on the first byte of the transmit
FIFO, which had already been filed in bcm63xx_spi_fill_txrx_fifo().

Fix this by passing the message control register width and message type
shift through platform data back to the SPI driver so that it can use
it properly.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: grant.likely@secretlab.ca
Cc: spi-devel-general@lists.sourceforge.net
Cc: jonas.gorski@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/3983/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/bcm63xx/dev-spi.c

@@ -106,11 +106,15 @@ int __init bcm63xx_spi_register(void)
 	if (BCMCPU_IS_6338() || BCMCPU_IS_6348()) {
 		spi_resources[0].end += BCM_6338_RSET_SPI_SIZE - 1;
 		spi_pdata.fifo_size = SPI_6338_MSG_DATA_SIZE;
+		spi_pdata.msg_type_shift = SPI_6338_MSG_TYPE_SHIFT;
+		spi_pdata.msg_ctl_width = SPI_6338_MSG_CTL_WIDTH;
 	}
 
 	if (BCMCPU_IS_6358() || BCMCPU_IS_6368()) {
 		spi_resources[0].end += BCM_6358_RSET_SPI_SIZE - 1;
 		spi_pdata.fifo_size = SPI_6358_MSG_DATA_SIZE;
+		spi_pdata.msg_type_shift = SPI_6358_MSG_TYPE_SHIFT;
+		spi_pdata.msg_ctl_width = SPI_6358_MSG_CTL_WIDTH;
 	}
 
 	bcm63xx_spi_regs_init();

arch/mips/include/asm/mach-bcm63xx/bcm63xx_dev_spi.h

@@ -9,6 +9,8 @@ int __init bcm63xx_spi_register(void);
 
 struct bcm63xx_spi_pdata {
 	unsigned int	fifo_size;
+	unsigned int	msg_type_shift;
+	unsigned int	msg_ctl_width;
 	int		bus_num;
 	int		num_chipselect;
 	u32		speed_hz;

arch/mips/include/asm/mach-bcm63xx/bcm63xx_regs.h

@@ -1054,7 +1054,8 @@
 #define SPI_6338_FILL_BYTE		0x07
 #define SPI_6338_MSG_TAIL		0x09
 #define SPI_6338_RX_TAIL		0x0b
-#define SPI_6338_MSG_CTL		0x40
+#define SPI_6338_MSG_CTL		0x40	/* 8-bits register */
+#define SPI_6338_MSG_CTL_WIDTH		8
 #define SPI_6338_MSG_DATA		0x41
 #define SPI_6338_MSG_DATA_SIZE		0x3f
 #define SPI_6338_RX_DATA		0x80
@@ -1070,7 +1071,8 @@
 #define SPI_6348_FILL_BYTE		0x07
 #define SPI_6348_MSG_TAIL		0x09
 #define SPI_6348_RX_TAIL		0x0b
-#define SPI_6348_MSG_CTL		0x40
+#define SPI_6348_MSG_CTL		0x40	/* 8-bits register */
+#define SPI_6348_MSG_CTL_WIDTH		8
 #define SPI_6348_MSG_DATA		0x41
 #define SPI_6348_MSG_DATA_SIZE		0x3f
 #define SPI_6348_RX_DATA		0x80
@@ -1078,6 +1080,7 @@
 
 /* BCM 6358 SPI core */
 #define SPI_6358_MSG_CTL		0x00	/* 16-bits register */
+#define SPI_6358_MSG_CTL_WIDTH		16
 #define SPI_6358_MSG_DATA		0x02
 #define SPI_6358_MSG_DATA_SIZE		0x21e
 #define SPI_6358_RX_DATA		0x400
@@ -1094,6 +1097,7 @@
 
 /* BCM 6358 SPI core */
 #define SPI_6368_MSG_CTL		0x00	/* 16-bits register */
+#define SPI_6368_MSG_CTL_WIDTH		16
 #define SPI_6368_MSG_DATA		0x02
 #define SPI_6368_MSG_DATA_SIZE		0x21e
 #define SPI_6368_RX_DATA		0x400
@@ -1115,7 +1119,10 @@
 #define SPI_HD_W			0x01
 #define SPI_HD_R			0x02
 #define SPI_BYTE_CNT_SHIFT		0
-#define SPI_MSG_TYPE_SHIFT		14
+#define SPI_6338_MSG_TYPE_SHIFT		6
+#define SPI_6348_MSG_TYPE_SHIFT		6
+#define SPI_6358_MSG_TYPE_SHIFT		14
+#define SPI_6368_MSG_TYPE_SHIFT		14
 
 /* Command */
 #define SPI_CMD_NOOP			0x00

drivers/spi/spi-bcm63xx.c

@@ -47,6 +47,8 @@ struct bcm63xx_spi {
 	/* Platform data */
 	u32			speed_hz;
 	unsigned		fifo_size;
+	unsigned int		msg_type_shift;
+	unsigned int		msg_ctl_width;
 
 	/* Data buffers */
 	const unsigned char	*tx_ptr;
@@ -221,13 +223,20 @@ static unsigned int bcm63xx_txrx_bufs(struct spi_device *spi,
 	msg_ctl = (t->len << SPI_BYTE_CNT_SHIFT);
 
 	if (t->rx_buf && t->tx_buf)
-		msg_ctl |= (SPI_FD_RW << SPI_MSG_TYPE_SHIFT);
+		msg_ctl |= (SPI_FD_RW << bs->msg_type_shift);
 	else if (t->rx_buf)
-		msg_ctl |= (SPI_HD_R << SPI_MSG_TYPE_SHIFT);
+		msg_ctl |= (SPI_HD_R << bs->msg_type_shift);
 	else if (t->tx_buf)
-		msg_ctl |= (SPI_HD_W << SPI_MSG_TYPE_SHIFT);
+		msg_ctl |= (SPI_HD_W << bs->msg_type_shift);
 
-	bcm_spi_writew(bs, msg_ctl, SPI_MSG_CTL);
+	switch (bs->msg_ctl_width) {
+	case 8:
+		bcm_spi_writeb(bs, msg_ctl, SPI_MSG_CTL);
+		break;
+	case 16:
+		bcm_spi_writew(bs, msg_ctl, SPI_MSG_CTL);
+		break;
+	}
 
 	/* Issue the transfer */
 	cmd = SPI_CMD_START_IMMEDIATE;
@@ -406,9 +415,21 @@ static int __devinit bcm63xx_spi_probe(struct platform_device *pdev)
 	master->transfer_one_message = bcm63xx_spi_transfer_one;
 	master->mode_bits = MODEBITS;
 	bs->speed_hz = pdata->speed_hz;
+	bs->msg_type_shift = pdata->msg_type_shift;
+	bs->msg_ctl_width = pdata->msg_ctl_width;
 	bs->tx_io = (u8 *)(bs->regs + bcm63xx_spireg(SPI_MSG_DATA));
 	bs->rx_io = (const u8 *)(bs->regs + bcm63xx_spireg(SPI_RX_DATA));
 
+	switch (bs->msg_ctl_width) {
+	case 8:
+	case 16:
+		break;
+	default:
+		dev_err(dev, "unsupported MSG_CTL width: %d\n",
+			 bs->msg_ctl_width);
+		goto out_clk_disable;
+	}
+
 	/* Initialize hardware */
 	clk_enable(bs->clk);
 	bcm_spi_writeb(bs, SPI_INTR_CLEAR_ALL, SPI_INT_STATUS);