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    Subject[PATCH 5.10 441/530] i2c: rcar: protect against supurious interrupts on V3U
    Date
    From: Wolfram Sang <wsa+renesas@sang-engineering.com>

    [ Upstream commit 9c975c432bc0aa53a90438fc80b369cb35134a48 ]

    V3U creates spurious interrupts which we need to handle. This costs time
    until BUS_PHASE_DATA can be activated which is problematic for Gen2 SoCs
    and earlier. Because of this we introduce two interrupt handlers here
    which will call a generic main irq function once the timing critical
    stuff is done.

    Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
    Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
    Signed-off-by: Wolfram Sang <wsa@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/i2c/busses/i2c-rcar.c | 57 ++++++++++++++++++++++++++---------
    1 file changed, 43 insertions(+), 14 deletions(-)

    diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
    index 3c9c3a6f7ac8..12f6d452c0f7 100644
    --- a/drivers/i2c/busses/i2c-rcar.c
    +++ b/drivers/i2c/busses/i2c-rcar.c
    @@ -625,20 +625,11 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
    * generated. It turned out that taking a spinlock at the beginning of the ISR
    * was already causing repeated messages. Thus, this driver was converted to
    * the now lockless behaviour. Please keep this in mind when hacking the driver.
    + * R-Car Gen3 seems to have this fixed but earlier versions than R-Car Gen2 are
    + * likely affected. Therefore, we have different interrupt handler entries.
    */
    -static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
    +static irqreturn_t rcar_i2c_irq(int irq, struct rcar_i2c_priv *priv, u32 msr)
    {
    - struct rcar_i2c_priv *priv = ptr;
    - u32 msr;
    -
    - /* Clear START or STOP immediately, except for REPSTART after read */
    - if (likely(!(priv->flags & ID_P_REP_AFTER_RD)))
    - rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
    -
    - msr = rcar_i2c_read(priv, ICMSR);
    -
    - /* Only handle interrupts that are currently enabled */
    - msr &= rcar_i2c_read(priv, ICMIER);
    if (!msr) {
    if (rcar_i2c_slave_irq(priv))
    return IRQ_HANDLED;
    @@ -682,6 +673,41 @@ out:
    return IRQ_HANDLED;
    }

    +static irqreturn_t rcar_i2c_gen2_irq(int irq, void *ptr)
    +{
    + struct rcar_i2c_priv *priv = ptr;
    + u32 msr;
    +
    + /* Clear START or STOP immediately, except for REPSTART after read */
    + if (likely(!(priv->flags & ID_P_REP_AFTER_RD)))
    + rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
    +
    + /* Only handle interrupts that are currently enabled */
    + msr = rcar_i2c_read(priv, ICMSR);
    + msr &= rcar_i2c_read(priv, ICMIER);
    +
    + return rcar_i2c_irq(irq, priv, msr);
    +}
    +
    +static irqreturn_t rcar_i2c_gen3_irq(int irq, void *ptr)
    +{
    + struct rcar_i2c_priv *priv = ptr;
    + u32 msr;
    +
    + /* Only handle interrupts that are currently enabled */
    + msr = rcar_i2c_read(priv, ICMSR);
    + msr &= rcar_i2c_read(priv, ICMIER);
    +
    + /*
    + * Clear START or STOP immediately, except for REPSTART after read or
    + * if a spurious interrupt was detected.
    + */
    + if (likely(!(priv->flags & ID_P_REP_AFTER_RD) && msr))
    + rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
    +
    + return rcar_i2c_irq(irq, priv, msr);
    +}
    +
    static struct dma_chan *rcar_i2c_request_dma_chan(struct device *dev,
    enum dma_transfer_direction dir,
    dma_addr_t port_addr)
    @@ -929,6 +955,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
    struct i2c_adapter *adap;
    struct device *dev = &pdev->dev;
    unsigned long irqflags = 0;
    + irqreturn_t (*irqhandler)(int irq, void *ptr) = rcar_i2c_gen3_irq;
    int ret;

    /* Otherwise logic will break because some bytes must always use PIO */
    @@ -977,8 +1004,10 @@ static int rcar_i2c_probe(struct platform_device *pdev)

    rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */

    - if (priv->devtype < I2C_RCAR_GEN3)
    + if (priv->devtype < I2C_RCAR_GEN3) {
    irqflags |= IRQF_NO_THREAD;
    + irqhandler = rcar_i2c_gen2_irq;
    + }

    if (priv->devtype == I2C_RCAR_GEN3) {
    priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
    @@ -999,7 +1028,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
    priv->flags |= ID_P_HOST_NOTIFY;

    priv->irq = platform_get_irq(pdev, 0);
    - ret = devm_request_irq(dev, priv->irq, rcar_i2c_irq, irqflags, dev_name(dev), priv);
    + ret = devm_request_irq(dev, priv->irq, irqhandler, irqflags, dev_name(dev), priv);
    if (ret < 0) {
    dev_err(dev, "cannot get irq %d\n", priv->irq);
    goto out_pm_disable;
    --
    2.30.2


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