Re: [PATCH v6 23/26] coresight: etm4x: Add support for sysreg only devices

On Thu, Jan 07, 2021 at 12:38:56PM +0000, Suzuki K Poulose wrote:

Add support for devices with system instruction access only. They don't have a memory mapped interface and thus are not AMBA devices. System register access is not permitted to TRCPDCR and thus skip access to them.

Cc: Mike Leach mike.leach@linaro.org Cc: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Suzuki K Poulose suzuki.poulose@arm.com

---

Changes since v5:

• Rebased to accommodate check_arch_features(). Added comments to explain why we don't pass PID for system register based devices.

Changes since v4

• Add "remove" callback for platform_driver.
• Dropped Reviewed-by tag from Mathieu due to the above

Changes since v3

• Improve comment over "TRCPDCR" usage with sysreg
• Rename etm_xx => etm4_xx
• Update the compatible to "arm,coresight-etm4x-sysreg"

---

.../coresight/coresight-etm4x-core.c | 68 +++++++++++++++++-- 1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index f4fbb65b4cc1..34a6cdff75e7 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -27,6 +27,7 @@ #include <linux/seq_file.h> #include <linux/uaccess.h> #include <linux/perf_event.h> +#include <linux/platform_device.h> #include <linux/pm_runtime.h> #include <linux/property.h> @@ -1736,9 +1737,6 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) return -ENOMEM; }

• if (fwnode_property_present(dev_fwnode(dev), "qcom,skip-power-up"))

• drvdata->skip_power_up = true;
  

• drvdata->base = base;

spin_lock_init(&drvdata->spinlock); @@ -1762,6 +1760,11 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid) if (!drvdata->arch) return -EINVAL;

• /* TRCPDCR is not accessible with system instructions. */
• if (!desc.access.io_mem ||

•    fwnode_property_present(dev_fwnode(dev), "qcom,skip-power-up"))
  

• drvdata->skip_power_up = true;
  

• etm4_init_trace_id(drvdata); etm4_set_default(&drvdata->config);

@@ -1820,6 +1823,25 @@ static int etm4_probe_amba(struct amba_device *adev, const struct amba_id *id) return ret; } +static int etm4_probe_platform_dev(struct platform_device *pdev) +{

• int ret;
• pm_runtime_get_noresume(&pdev->dev);
• pm_runtime_set_active(&pdev->dev);
• pm_runtime_enable(&pdev->dev);
• /*

• * System register based devices could match the
  

• * HW by reading appropriate registers on the HW
  

• * and thus we could skip the PID.
  

• */
  

• ret = etm4_probe(&pdev->dev, NULL, 0);
• pm_runtime_put(&pdev->dev);
• return ret;

+}

static struct amba_cs_uci_id uci_id_etm4[] = { { /* ETMv4 UCI data */ @@ -1869,6 +1891,17 @@ static int __exit etm4_remove_amba(struct amba_device *adev) return 0; } +static int __exit etm4_remove_platform_dev(struct platform_device *pdev) +{

• int ret = 0;
• struct etmv4_drvdata *drvdata = dev_get_drvdata(&pdev->dev);
• if (drvdata)

• ret = etm4_remove_dev(drvdata);
  

• pm_runtime_disable(&pdev->dev);
• return ret;

+}

static const struct amba_id etm4_ids[] = { CS_AMBA_ID(0x000bb95d), /* Cortex-A53 */ CS_AMBA_ID(0x000bb95e), /* Cortex-A57 */ @@ -1901,6 +1934,21 @@ static struct amba_driver etm4x_amba_driver = { .id_table = etm4_ids, }; +static const struct of_device_id etm4_sysreg_match[] = {

• { .compatible = "arm,coresight-etm4x-sysreg" },
• {}

+};

+static struct platform_driver etm4_platform_driver = {

• .probe = etm4_probe_platform_dev,
• .remove = etm4_remove_platform_dev,
• .driver = {

• .name			= "coresight-etm4x",
  

• .of_match_table		= etm4_sysreg_match,
  

• .suppress_bind_attrs	= true,
  

• },

+};

static int __init etm4x_init(void) { int ret; @@ -1913,16 +1961,26 @@ static int __init etm4x_init(void) ret = amba_driver_register(&etm4x_amba_driver); if (ret) {

• pr_err("Error registering etm4x driver\n");
  

• etm4_pm_clear();
  

• pr_err("Error registering etm4x AMBA driver\n");
  

• goto clear_pm;
  

  }

• ret = platform_driver_register(&etm4_platform_driver);
• if (!ret)

• return 0;
  

• pr_err("Error registering etm4x platform driver\n");
• amba_driver_unregister(&etm4x_amba_driver);

+clear_pm:

• etm4_pm_clear(); return ret;

} static void __exit etm4x_exit(void) { amba_driver_unregister(&etm4x_amba_driver);

• platform_driver_unregister(&etm4_platform_driver);

Good catch.

Reviewed-by: Mathieu Poirier mathieu.poirier@linaro.org

etm4_pm_clear(); } -- 2.24.1