target/linux/octeontx/patches-5.4/0003-can-mcp251x-convert-to-half-duplex-SPI.patch

   1 From 097cc81ee5c15913ad330baffff2e3dea09bdad0 Mon Sep 17 00:00:00 2001
   2 From: Tim Harvey <tharvey@gateworks.com>
   3 Date: Thu, 30 Aug 2018 15:16:08 -0700
   4 Subject: [PATCH] can: mcp251x: convert driver to half-duplex SPI
   5
   6 Some SPI host controllers such as the Cavium Thunder TX do not support
   7 full-duplex SPI. Using half-duplex transfers allows the driver to work
   8 with those host controllers.
   9
  10 Signed-off-by: Tim Harvey <tharvey@gateworks.com>
  11 ---
  12  drivers/net/can/spi/mcp251x.c | 15 ++++++++-------
  13  1 file changed, 8 insertions(+), 7 deletions(-)
  14
  15 --- a/drivers/net/can/spi/mcp251x.c
  16 +++ b/drivers/net/can/spi/mcp251x.c
  17 @@ -291,23 +291,23 @@ static u8 mcp251x_read_reg(struct spi_de
  18         priv->spi_tx_buf[0] = INSTRUCTION_READ;
  19         priv->spi_tx_buf[1] = reg;
  20
  21 -       mcp251x_spi_trans(spi, 3);
  22 -       val = priv->spi_rx_buf[2];
  23 +       spi_write_then_read(spi, priv->spi_tx_buf, 2, &val, 1);
  24
  25         return val;
  26  }
  27
  28  static void mcp251x_read_2regs(struct spi_device *spi, u8 reg, u8 *v1, u8 *v2)
  29  {
  30 +       u8 val[4] = {0};
  31         struct mcp251x_priv *priv = spi_get_drvdata(spi);
  32
  33         priv->spi_tx_buf[0] = INSTRUCTION_READ;
  34         priv->spi_tx_buf[1] = reg;
  35
  36 -       mcp251x_spi_trans(spi, 4);
  37 +       spi_write_then_read(spi, priv->spi_tx_buf, 2, val, 2);
  38
  39 -       *v1 = priv->spi_rx_buf[2];
  40 -       *v2 = priv->spi_rx_buf[3];
  41 +       *v1 = val[0];
  42 +       *v2 = val[1];
  43  }
  44
  45  static void mcp251x_write_reg(struct spi_device *spi, u8 reg, u8 val)
  46 @@ -398,8 +398,9 @@ static void mcp251x_hw_rx_frame(struct s
  47                         buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
  48         } else {
  49                 priv->spi_tx_buf[RXBCTRL_OFF] = INSTRUCTION_READ_RXB(buf_idx);
  50 -               mcp251x_spi_trans(spi, SPI_TRANSFER_BUF_LEN);
  51 -               memcpy(buf, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN);
  52 +               spi_write_then_read(spi, priv->spi_tx_buf, 1, priv->spi_rx_buf,
  53 +                                   SPI_TRANSFER_BUF_LEN);
  54 +               memcpy(buf + 1, priv->spi_rx_buf, SPI_TRANSFER_BUF_LEN - 1);
  55         }
  56  }
  57