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    Subject[PATCH V4 03/18] coresight: tmc: re-implementing tmc_read_prepare/unprepare() functions
    Date
    In their current implementation the tmc_read_prepare/unprepare()
    are a lump of if/else that is difficult to read. This patch is
    alleviating that by using a switch statement. The latter also
    allows for a better control on the error path.

    Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
    Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    ---
    drivers/hwtracing/coresight/coresight-tmc.c | 56 ++++++++++++++++++-----------
    1 file changed, 36 insertions(+), 20 deletions(-)

    diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
    index 66fa7736d12f..d211aeec49f8 100644
    --- a/drivers/hwtracing/coresight/coresight-tmc.c
    +++ b/drivers/hwtracing/coresight/coresight-tmc.c
    @@ -431,7 +431,7 @@ static const struct coresight_ops tmc_etf_cs_ops = {

    static int tmc_read_prepare(struct tmc_drvdata *drvdata)
    {
    - int ret;
    + int ret = 0;
    unsigned long flags;
    enum tmc_mode mode;

    @@ -439,25 +439,31 @@ static int tmc_read_prepare(struct tmc_drvdata *drvdata)
    if (!drvdata->enable)
    goto out;

    - if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
    + switch (drvdata->config_type) {
    + case TMC_CONFIG_TYPE_ETB:
    tmc_etb_disable_hw(drvdata);
    - } else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
    - tmc_etr_disable_hw(drvdata);
    - } else {
    + break;
    + case TMC_CONFIG_TYPE_ETF:
    + /* There is no point in reading a TMC in HW FIFO mode */
    mode = readl_relaxed(drvdata->base + TMC_MODE);
    - if (mode == TMC_MODE_CIRCULAR_BUFFER) {
    - tmc_etb_disable_hw(drvdata);
    - } else {
    - ret = -ENODEV;
    + if (mode != TMC_MODE_CIRCULAR_BUFFER) {
    + ret = -EINVAL;
    goto err;
    }
    +
    + tmc_etb_disable_hw(drvdata);
    + break;
    + case TMC_CONFIG_TYPE_ETR:
    + tmc_etr_disable_hw(drvdata);
    + break;
    + default:
    + ret = -EINVAL;
    + goto err;
    }
    +
    out:
    drvdata->reading = true;
    - spin_unlock_irqrestore(&drvdata->spinlock, flags);
    -
    dev_info(drvdata->dev, "TMC read start\n");
    - return 0;
    err:
    spin_unlock_irqrestore(&drvdata->spinlock, flags);
    return ret;
    @@ -472,20 +478,30 @@ static void tmc_read_unprepare(struct tmc_drvdata *drvdata)
    if (!drvdata->enable)
    goto out;

    - if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
    + switch (drvdata->config_type) {
    + case TMC_CONFIG_TYPE_ETB:
    tmc_etb_enable_hw(drvdata);
    - } else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
    - tmc_etr_enable_hw(drvdata);
    - } else {
    + break;
    + case TMC_CONFIG_TYPE_ETF:
    + /* Make sure we don't re-enable a TMC in HW FIFO mode */
    mode = readl_relaxed(drvdata->base + TMC_MODE);
    - if (mode == TMC_MODE_CIRCULAR_BUFFER)
    - tmc_etb_enable_hw(drvdata);
    + if (mode != TMC_MODE_CIRCULAR_BUFFER)
    + goto err;
    +
    + tmc_etb_enable_hw(drvdata);
    + break;
    + case TMC_CONFIG_TYPE_ETR:
    + tmc_etr_disable_hw(drvdata);
    + break;
    + default:
    + goto err;
    }
    +
    out:
    drvdata->reading = false;
    - spin_unlock_irqrestore(&drvdata->spinlock, flags);
    -
    dev_info(drvdata->dev, "TMC read end\n");
    +err:
    + spin_unlock_irqrestore(&drvdata->spinlock, flags);
    }

    static int tmc_open(struct inode *inode, struct file *file)
    --
    2.5.0
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