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    Subject[PATCH 4.9 008/125] can: c_can: D_CAN: c_can_chip_config(): perform a sofware reset on open
    Date
    From: Jeroen Hofstee <jhofstee@victronenergy.com>

    [ Upstream commit 23c5a9488f076bab336177cd1d1a366bd8ddf087 ]

    When the CAN interface is closed it the hardwre is put in power down
    mode, but does not reset the error counters / state. Reset the D_CAN on
    open, so the reported state and the actual state match.

    According to [1], the C_CAN module doesn't have the software reset.

    [1] http://www.bosch-semiconductors.com/media/ip_modules/pdf_2/c_can_fd8/users_manual_c_can_fd8_r210_1.pdf

    Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>
    Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/can/c_can/c_can.c | 26 ++++++++++++++++++++++++++
    1 file changed, 26 insertions(+)

    diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
    index 7d35f6737499c..4ead5a18b7940 100644
    --- a/drivers/net/can/c_can/c_can.c
    +++ b/drivers/net/can/c_can/c_can.c
    @@ -52,6 +52,7 @@
    #define CONTROL_EX_PDR BIT(8)

    /* control register */
    +#define CONTROL_SWR BIT(15)
    #define CONTROL_TEST BIT(7)
    #define CONTROL_CCE BIT(6)
    #define CONTROL_DISABLE_AR BIT(5)
    @@ -572,6 +573,26 @@ static void c_can_configure_msg_objects(struct net_device *dev)
    IF_MCONT_RCV_EOB);
    }

    +static int c_can_software_reset(struct net_device *dev)
    +{
    + struct c_can_priv *priv = netdev_priv(dev);
    + int retry = 0;
    +
    + if (priv->type != BOSCH_D_CAN)
    + return 0;
    +
    + priv->write_reg(priv, C_CAN_CTRL_REG, CONTROL_SWR | CONTROL_INIT);
    + while (priv->read_reg(priv, C_CAN_CTRL_REG) & CONTROL_SWR) {
    + msleep(20);
    + if (retry++ > 100) {
    + netdev_err(dev, "CCTRL: software reset failed\n");
    + return -EIO;
    + }
    + }
    +
    + return 0;
    +}
    +
    /*
    * Configure C_CAN chip:
    * - enable/disable auto-retransmission
    @@ -581,6 +602,11 @@ static void c_can_configure_msg_objects(struct net_device *dev)
    static int c_can_chip_config(struct net_device *dev)
    {
    struct c_can_priv *priv = netdev_priv(dev);
    + int err;
    +
    + err = c_can_software_reset(dev);
    + if (err)
    + return err;

    /* enable automatic retransmission */
    priv->write_reg(priv, C_CAN_CTRL_REG, CONTROL_ENABLE_AR);
    --
    2.20.1


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