coresight: tmc: re-implementing tmc_read_prepare/unprepare() functions

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit b1789b793eb4627928f55a6acea8da7c25e5c6b4)

diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
index 66fa7736d12f519edf4956fd5fda5a9987a8eedf..d211aeec49f8dc7f08065c3ee5b52e71cc164ec6 100644 (file)
--- 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)