can: mcp251x: allow to read two registers in one spi transfer

This patch bases on work done earlier by David Jander.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: David Jander <david@protonic.nl>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>

diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
index fdea752f398fd23b94d02ed432552cc6be2a03aa..9b3466aed06d487db2d8d5a516782a006e0b9061 100644 (file)
--- a/drivers/net/can/mcp251x.c
+++ b/drivers/net/can/mcp251x.c
@@ -319,6 +319,20 @@ static u8 mcp251x_read_reg(struct spi_device *spi, uint8_t reg)
        return val;
 }
 
+static void mcp251x_read_2regs(struct spi_device *spi, uint8_t reg,
+               uint8_t *v1, uint8_t *v2)
+{
+       struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
+
+       priv->spi_tx_buf[0] = INSTRUCTION_READ;
+       priv->spi_tx_buf[1] = reg;
+
+       mcp251x_spi_trans(spi, 4);
+
+       *v1 = priv->spi_rx_buf[2];
+       *v2 = priv->spi_rx_buf[3];
+}
+
 static void mcp251x_write_reg(struct spi_device *spi, u8 reg, uint8_t val)
 {
        struct mcp251x_priv *priv = dev_get_drvdata(&spi->dev);
@@ -754,10 +768,11 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
        mutex_lock(&priv->mcp_lock);
        while (!priv->force_quit) {
                enum can_state new_state;
-               u8 intf = mcp251x_read_reg(spi, CANINTF);
-               u8 eflag;
+               u8 intf, eflag;
                int can_id = 0, data1 = 0;
 
+               mcp251x_read_2regs(spi, CANINTF, &intf, &eflag);
+
                if (intf & CANINTF_RX0IF) {
                        mcp251x_hw_rx(spi, 0);
                        /* Free one buffer ASAP */
@@ -770,7 +785,6 @@ static irqreturn_t mcp251x_can_ist(int irq, void *dev_id)
 
                mcp251x_write_bits(spi, CANINTF, intf, 0x00);
 
-               eflag = mcp251x_read_reg(spi, EFLG);
                mcp251x_write_reg(spi, EFLG, 0x00);
 
                /* Update can state */