Re: [PATCH V2 4/5] coresight: etm4x: Change etm4_platform_driver driver for MMIO devices

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On 27/03/2023 06:05, Anshuman Khandual wrote:
Add support for handling MMIO based devices via platform driver. We need to
make sure that :

1) The APB clock, if present is enabled at probe and via runtime_pm ops
2) Use the ETM4x architecture or CoreSight architecture registers to
    identify a device as CoreSight ETM4x, instead of relying a white list of
    "Peripheral IDs"

The driver doesn't get to handle the devices yet, until we wire the ACPI
changes to move the devices to be handled via platform driver than the
etm4_amba driver.

Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Leo Yan <leo.yan@xxxxxxxxxx>
Cc: coresight@xxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
  .../coresight/coresight-etm4x-core.c          | 62 +++++++++++++++++--
  drivers/hwtracing/coresight/coresight-etm4x.h |  4 ++
  include/linux/coresight.h                     | 47 ++++++++++++++
  3 files changed, 109 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 3521838ab4fb..bef205023bbe 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -30,6 +30,7 @@
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
  #include <linux/property.h>
+#include <linux/clk/clk-conf.h>
#include <asm/barrier.h>
  #include <asm/sections.h>
@@ -1067,12 +1068,22 @@ static bool etm4_init_sysreg_access(struct etmv4_drvdata *drvdata,
  	return true;
  }
+static bool is_etm4x_devtype(void __iomem *base)
+{
+	u32 devtype = readl(base + TRCDEVTYPE);
+
+	return (devtype == ETM_DEVTYPE_ETMv4x_ARCH);
+}
+
  static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
  				   struct csdev_access *csa)
  {
  	u32 devarch = readl_relaxed(drvdata->base + TRCDEVARCH);
  	u32 idr1 = readl_relaxed(drvdata->base + TRCIDR1);
+ if (!is_coresight_device(drvdata->base) || !is_etm4x_devtype(drvdata->base))
+		return false;
+
  	/*
  	 * All ETMs must implement TRCDEVARCH to indicate that
  	 * the component is an ETMv4. To support any broken
@@ -2133,6 +2144,7 @@ static int etm4_probe_amba(struct amba_device *adev, const struct amba_id *id)
static int etm4_probe_platform_dev(struct platform_device *pdev)
  {
+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	struct etmv4_drvdata *drvdata;
  	int ret;
@@ -2140,7 +2152,18 @@ static int etm4_probe_platform_dev(struct platform_device *pdev)
  	if (!drvdata)
  		return -ENOMEM;
- drvdata->base = NULL;
+	drvdata->pclk = coresight_get_enable_apb_pclk(&pdev->dev);
+	if (IS_ERR(drvdata->pclk))
+		return -ENODEV;
+
+	if (res) {
+		drvdata->base = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(drvdata->base)) {
+			clk_put(drvdata->pclk);
+			return PTR_ERR(drvdata->base);
+		}
+	}
+
  	dev_set_drvdata(&pdev->dev, drvdata);
  	pm_runtime_get_noresume(&pdev->dev);
  	pm_runtime_set_active(&pdev->dev);
@@ -2186,7 +2209,7 @@ static struct amba_cs_uci_id uci_id_etm4[] = {
  		/*  ETMv4 UCI data */
  		.devarch	= ETM_DEVARCH_ETMv4x_ARCH,
  		.devarch_mask	= ETM_DEVARCH_ID_MASK,
-		.devtype	= 0x00000013,
+		.devtype	= ETM_DEVTYPE_ETMv4x_ARCH,
  	}
  };
@@ -2244,6 +2267,10 @@ static int __exit etm4_remove_platform_dev(struct platform_device *pdev) if (drvdata)
  		ret = etm4_remove_dev(drvdata);
+
+	if (drvdata->pclk)
+		clk_put(drvdata->pclk);
+
  	pm_runtime_disable(&pdev->dev);
  	return ret;
  }
@@ -2284,7 +2311,33 @@ static struct amba_driver etm4x_amba_driver = {
  	.id_table	= etm4_ids,
  };
-static const struct of_device_id etm4_sysreg_match[] = {
+#ifdef CONFIG_PM
+static int etm4_runtime_suspend(struct device *dev)
+{
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (!IS_ERR(drvdata->pclk))
+		clk_disable_unprepare(drvdata->pclk);
+
+	return 0;
+}
+
+static int etm4_runtime_resume(struct device *dev)
+{
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (!IS_ERR(drvdata->pclk))
+		clk_prepare_enable(drvdata->pclk);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops etm4_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(etm4_runtime_suspend, etm4_runtime_resume, NULL)
+};
+
+static const struct of_device_id etm4_match[] = {
  	{ .compatible	= "arm,coresight-etm4x-sysreg" },
  	{ .compatible	= "arm,embedded-trace-extension" },
  	{}
@@ -2295,8 +2348,9 @@ static struct platform_driver etm4_platform_driver = {
  	.remove		= etm4_remove_platform_dev,
  	.driver			= {
  		.name			= "coresight-etm4x",
-		.of_match_table		= etm4_sysreg_match,
+		.of_match_table		= etm4_match,
  		.suppress_bind_attrs	= true,
+		.pm			= &etm4_dev_pm_ops,
  	},
  };
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 434f4e95ee17..78dfe7949548 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -701,6 +701,8 @@
  #define ETM_DEVARCH_ETE_ARCH						\
  	(ETM_DEVARCH_ARCHITECT_ARM | ETM_DEVARCH_ARCHID_ETE | ETM_DEVARCH_PRESENT)
+#define ETM_DEVTYPE_ETMv4x_ARCH 0x00000013

This has nothing to do with ETMv4 ARCH. This indicates :

[3:0] == 0x3 -> Indicates CoreSight Source
[7:4] == 0x1 -> Generates PE trace

So, we could call it : CS_DEVTYPE_PE_TRACE, but not ETMv4x

Rest looks good to me.

Suzuki




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