can: mcp251x: add mcp251x_write_2regs() and make use of it

This patch introduces the function mcp251x_write_2regs() to write two
registers with one SPI transfer and converts the disabling of pending
interrupts in mcp251x_stop() to it.

Signed-off-by: Timo Schlüßler <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/spi/mcp251x.c

···
 	mcp251x_spi_trans(spi, 3);
 }
 
+static void mcp251x_write_2regs(struct spi_device *spi, u8 reg, u8 v1, u8 v2)
+{
+	struct mcp251x_priv *priv = spi_get_drvdata(spi);
+
+	priv->spi_tx_buf[0] = INSTRUCTION_WRITE;
+	priv->spi_tx_buf[1] = reg;
+	priv->spi_tx_buf[2] = v1;
+	priv->spi_tx_buf[3] = v2;
+
+	mcp251x_spi_trans(spi, 4);
+}
+
 static void mcp251x_write_bits(struct spi_device *spi, u8 reg,
 			       u8 mask, u8 val)
 {
···
 	mutex_lock(&priv->mcp_lock);
 
 	/* Disable and clear pending interrupts */
-	mcp251x_write_reg(spi, CANINTE, 0x00);
-	mcp251x_write_reg(spi, CANINTF, 0x00);
+	mcp251x_write_2regs(spi, CANINTE, 0x00, 0x00);
 
 	mcp251x_write_reg(spi, TXBCTRL(0), 0);
 	mcp251x_clean(net);