[PATCH 0/2] coresight: tmc: Add support to configure AXI burst size

Add "arm,max-burst-size" optional property for TMC ETR.
If specified, this value indicates the maximum burst size
that can be initiated by TMC on the AXI bus.

Signed-off-by: Tanmay Jagdale <redacted>
---
 Documentation/devicetree/bindings/arm/coresight.txt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
index 7f9c1ca87487..7971f8dba2ee 100644
--- a/Documentation/devicetree/bindings/arm/coresight.txt
+++ b/Documentation/devicetree/bindings/arm/coresight.txt

@@ -127,6 +127,11 @@ its hardware characteristcs.
        * arm,scatter-gather: boolean. Indicates that the TMC-ETR can safely
          use the SG mode on this system.

+       * arm,max-burst-size: The maximum burst size initiated by TMC on the
+         AXI master interface. The burst size can be in the range [0..15],
+         the setting supports one data transfer per burst upto a maximum of
+         16 data transfers per burst.
+
 * Optional property for CATU :
        * interrupts : Exactly one SPI may be listed for reporting the address
          error
--

2.25.1

The current driver sets the write burst size initiated by TMC-ETR on
AXI bus to a fixed value of 16. Make this configurable by reading the
value specified in fwnode. If not specified, then default to 16.

Introduced a "max_burst_size" variable in tmc_drvdata structure to
facilitate this change.

Signed-off-by: Tanmay Jagdale <redacted>
---
 .../hwtracing/coresight/coresight-tmc-core.c  | 21 +++++++++++++++++--
 .../hwtracing/coresight/coresight-tmc-etr.c   |  3 ++-
 drivers/hwtracing/coresight/coresight-tmc.h   |  6 +++++-
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 74c6323d4d6a..d0276af82494 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c

@@ -432,6 +432,21 @@ static u32 tmc_etr_get_default_buffer_size(struct device *dev)
        return size;
 }

+static u32 tmc_etr_get_max_burst_size(struct device *dev)
+{
+       u32 burst_size;
+
+       if (fwnode_property_read_u32(dev->fwnode, "arm,max-burst-size",
+                                    &burst_size))
+               return TMC_AXICTL_WR_BURST_16;
+
+       /* Only permissible values are 0 to 15 */
+       if (burst_size > 0xF)
+               burst_size = TMC_AXICTL_WR_BURST_16;
+
+       return burst_size;
+}
+
 static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
 {
        int ret = 0;

@@ -469,10 +484,12 @@ static int tmc_probe(struct amba_device *adev, const struct amba_id *id)
        /* This device is not associated with a session */
        drvdata->pid = -1;

-       if (drvdata->config_type == TMC_CONFIG_TYPE_ETR)
+       if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
                drvdata->size = tmc_etr_get_default_buffer_size(dev);
-       else
+               drvdata->max_burst_size = tmc_etr_get_max_burst_size(dev);
+       } else {
                drvdata->size = readl_relaxed(drvdata->base + TMC_RSZ) * 4;
+       }

        desc.dev = dev;
        desc.groups = coresight_tmc_groups;

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index acdb59e0e661..0ac2a611110b 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -982,7 +982,8 @@ static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)

        axictl = readl_relaxed(drvdata->base + TMC_AXICTL);
        axictl &= ~TMC_AXICTL_CLEAR_MASK;
-       axictl |= (TMC_AXICTL_PROT_CTL_B1 | TMC_AXICTL_WR_BURST_16);
+       axictl |= TMC_AXICTL_PROT_CTL_B1;
+       axictl |= TMC_AXICTL_WR_BURST(drvdata->max_burst_size);
        axictl |= TMC_AXICTL_AXCACHE_OS;

        if (tmc_etr_has_cap(drvdata, TMC_ETR_AXI_ARCACHE)) {

diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index b91ec7dde7bc..6bec20a392b3 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h

@@ -70,7 +70,8 @@
 #define TMC_AXICTL_PROT_CTL_B0 BIT(0)
 #define TMC_AXICTL_PROT_CTL_B1 BIT(1)
 #define TMC_AXICTL_SCT_GAT_MODE        BIT(7)
-#define TMC_AXICTL_WR_BURST_16 0xF00
+#define TMC_AXICTL_WR_BURST(v) (((v) & 0xf) << 8)
+#define TMC_AXICTL_WR_BURST_16 0xf
 /* Write-back Read and Write-allocate */
 #define TMC_AXICTL_AXCACHE_OS  (0xf << 2)
 #define TMC_AXICTL_ARCACHE_OS  (0xf << 16)

@@ -174,6 +175,8 @@ struct etr_buf {
  * @etr_buf:   details of buffer used in TMC-ETR
  * @len:       size of the available trace for ETF/ETB.
  * @size:      trace buffer size for this TMC (common for all modes).
+ * @max_burst_size: The maximum burst size that can be initiated by
+ *             TMC-ETR on AXI bus.
  * @mode:      how this TMC is being used.
  * @config_type: TMC variant, must be of type @tmc_config_type.
  * @memwidth:  width of the memory interface databus, in bytes.

@@ -198,6 +201,7 @@ struct tmc_drvdata {
        };
        u32                     len;
        u32                     size;
+       u32                     max_burst_size;
        u32                     mode;
        enum tmc_config_type    config_type;
        enum tmc_mem_intf_width memwidth;
--

2.25.1