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>

1 files changed, 17 insertions, 3 deletions

diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c
index fdea752f398f..9b3466aed06d 100644
--- 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 */