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Date:   Tue, 2 Feb 2021 11:56:39 -0700
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, coresight@...ts.linaro.org,
        suzuki.poulose@....com, mike.leach@...aro.org,
        lcherian@...vell.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 05/14] coresight: ete: Add support for ETE tracing

On Wed, Jan 27, 2021 at 02:25:29PM +0530, Anshuman Khandual wrote:
> From: Suzuki K Poulose <suzuki.poulose@....com>
> 
> Add ETE as one of the supported device types we support
> with ETM4x driver. The devices are named following the
> existing convention as ete<N>.
> 
> ETE mandates that the trace resource status register is programmed
> before the tracing is turned on. For the moment simply write to
> it indicating TraceActive.
> 
> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
> Cc: Mike Leach <mike.leach@...aro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>  drivers/hwtracing/coresight/Kconfig                | 10 ++--
>  drivers/hwtracing/coresight/coresight-etm4x-core.c | 56 +++++++++++++++++-----
>  .../hwtracing/coresight/coresight-etm4x-sysfs.c    | 19 ++++++--
>  drivers/hwtracing/coresight/coresight-etm4x.h      | 16 ++++++-
>  4 files changed, 79 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index 7b44ba2..f154ae7 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -97,15 +97,15 @@ config CORESIGHT_SOURCE_ETM3X
>  	  module will be called coresight-etm3x.
>  
>  config CORESIGHT_SOURCE_ETM4X
> -	tristate "CoreSight Embedded Trace Macrocell 4.x driver"
> +	tristate "CoreSight ETMv4.x / ETE driver"
>  	depends on ARM64
>  	select CORESIGHT_LINKS_AND_SINKS
>  	select PID_IN_CONTEXTIDR
>  	help
> -	  This driver provides support for the ETM4.x tracer module, tracing the
> -	  instructions that a processor is executing. This is primarily useful
> -	  for instruction level tracing. Depending on the implemented version
> -	  data tracing may also be available.
> +	  This driver provides support for the CoreSight Embedded Trace Macrocell
> +	  version 4.x and the Embedded Trace Extensions (ETE). Both are CPU tracer
> +	  modules, tracing the instructions that a processor is executing. This is
> +	  primarily useful for instruction level tracing.
>  
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called coresight-etm4x.
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 9e92d2a..b40e3c2 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -431,6 +431,13 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
>  		etm4x_relaxed_write32(csa, trcpdcr | TRCPDCR_PU, TRCPDCR);
>  	}
>  
> +	/*
> +	 * ETE mandates that the TRCRSR is written to before
> +	 * enabling it.
> +	 */
> +	if (etm4x_is_ete(drvdata))
> +		etm4x_relaxed_write32(csa, TRCRSR_TA, TRCRSR);
> +
>  	/* Enable the trace unit */
>  	etm4x_relaxed_write32(csa, 1, TRCPRGCTLR);
>  
> @@ -864,13 +871,24 @@ static bool etm4_init_sysreg_access(struct etmv4_drvdata *drvdata,
>  	 * ETMs implementing sysreg access must implement TRCDEVARCH.
>  	 */
>  	devarch = read_etm4x_sysreg_const_offset(TRCDEVARCH);
> -	if ((devarch & ETM_DEVARCH_ID_MASK) != ETM_DEVARCH_ETMv4x_ARCH)
> +	switch (devarch & ETM_DEVARCH_ID_MASK) {
> +	case ETM_DEVARCH_ETMv4x_ARCH:
> +		*csa = (struct csdev_access) {
> +			.io_mem	= false,
> +			.read	= etm4x_sysreg_read,
> +			.write	= etm4x_sysreg_write,
> +		};
> +		break;
> +	case ETM_DEVARCH_ETE_ARCH:
> +		*csa = (struct csdev_access) {
> +			.io_mem	= false,
> +			.read	= ete_sysreg_read,
> +			.write	= ete_sysreg_write,
> +		};
> +		break;
> +	default:
>  		return false;
> -	*csa = (struct csdev_access) {
> -		.io_mem	= false,
> -		.read	= etm4x_sysreg_read,
> -		.write	= etm4x_sysreg_write,
> -	};
> +	}
>  
>  	drvdata->arch = etm_devarch_to_arch(devarch);
>  	return true;
> @@ -1808,6 +1826,8 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>  	struct etmv4_drvdata *drvdata;
>  	struct coresight_desc desc = { 0 };
>  	struct etm4_init_arg init_arg = { 0 };
> +	u8 major, minor;
> +	char *type_name;
>  
>  	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
>  	if (!drvdata)
> @@ -1834,10 +1854,6 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>  	if (drvdata->cpu < 0)
>  		return drvdata->cpu;
>  
> -	desc.name = devm_kasprintf(dev, GFP_KERNEL, "etm%d", drvdata->cpu);
> -	if (!desc.name)
> -		return -ENOMEM;
> -
>  	init_arg.drvdata = drvdata;
>  	init_arg.csa = &desc.access;
>  	init_arg.pid = etm_pid;
> @@ -1853,6 +1869,20 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>  	if (!desc.access.io_mem ||
>  	    fwnode_property_present(dev_fwnode(dev), "qcom,skip-power-up"))
>  		drvdata->skip_power_up = true;

Add a space here...

> +	major = ETM_ARCH_MAJOR_VERSION(drvdata->arch);
> +	minor = ETM_ARCH_MINOR_VERSION(drvdata->arch);

And here too.  Othersiwe it makes a big blob in the middle of the function.

> +	if (etm4x_is_ete(drvdata)) {
> +		type_name = "ete";
> +		/* ETE v1 has major version == 5. Adjust this for logging.*/
> +		major -= 4;

I don't have the documentation for the ETE but I would not adjust @major.  I
would simply leave it to what the HW gives us since regardless of the name, the
major revision of the IP block is 5.

> +	} else {
> +		type_name = "etm";
> +	}
> +
> +	desc.name = devm_kasprintf(dev, GFP_KERNEL,
> +				   "%s%d", type_name, drvdata->cpu);
> +	if (!desc.name)
> +		return -ENOMEM;
>  
>  	etm4_init_trace_id(drvdata);
>  	etm4_set_default(&drvdata->config);
> @@ -1881,9 +1911,8 @@ static int etm4_probe(struct device *dev, void __iomem *base, u32 etm_pid)
>  
>  	etmdrvdata[drvdata->cpu] = drvdata;
>  
> -	dev_info(&drvdata->csdev->dev, "CPU%d: ETM v%d.%d initialized\n",
> -		 drvdata->cpu, ETM_ARCH_MAJOR_VERSION(drvdata->arch),
> -		 ETM_ARCH_MINOR_VERSION(drvdata->arch));
> +	dev_info(&drvdata->csdev->dev, "CPU%d: %s v%d.%d initialized\n",
> +		 drvdata->cpu, type_name, major, minor);
>  
>  	if (boot_enable) {
>  		coresight_enable(drvdata->csdev);
> @@ -2027,6 +2056,7 @@ static struct amba_driver etm4x_amba_driver = {
>  
>  static const struct of_device_id etm4_sysreg_match[] = {
>  	{ .compatible	= "arm,coresight-etm4x-sysreg" },
> +	{ .compatible	= "arm,embedded-trace-extension" },
>  	{}
>  };
>  
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> index b646d53..1c490bc 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> @@ -2374,12 +2374,20 @@ static inline bool
>  etm4x_register_implemented(struct etmv4_drvdata *drvdata, u32 offset)
>  {
>  	switch (offset) {
> -	ETM4x_SYSREG_LIST_CASES
> +	ETM_COMMON_SYSREG_LIST_CASES
>  		/*
> -		 * Registers accessible via system instructions are always
> -		 * implemented.
> +		 * Common registers to ETE & ETM4x accessible via system
> +		 * instructions are always implemented.
>  		 */
>  		return true;
> +
> +	ETM4x_ONLY_SYSREG_LIST_CASES
> +		/*
> +		 * We only support etm4x and ete. So if the device is not
> +		 * ETE, it must be ETMv4x.
> +		 */
> +		return !etm4x_is_ete(drvdata);
> +
>  	ETM4x_MMAP_LIST_CASES
>  		/*
>  		 * Registers accessible only via memory-mapped registers
> @@ -2389,8 +2397,13 @@ etm4x_register_implemented(struct etmv4_drvdata *drvdata, u32 offset)
>  		 * coresight_register() and the csdev is not initialized
>  		 * until that is done. So rely on the drvdata->base to
>  		 * detect if we have a memory mapped access.
> +		 * Also ETE doesn't implement memory mapped access, thus
> +		 * it is sufficient to check that we are using mmio.
>  		 */
>  		return !!drvdata->base;
> +
> +	ETE_ONLY_SYSREG_LIST_CASES
> +		return etm4x_is_ete(drvdata);
>  	}
>  
>  	return false;
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
> index ca24ac5..8b90de5 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.h
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.h
> @@ -128,6 +128,8 @@
>  #define TRCCIDR2			0xFF8
>  #define TRCCIDR3			0xFFC
>  
> +#define TRCRSR_TA			BIT(12)
> +
>  /*
>   * System instructions to access ETM registers.
>   * See ETMv4.4 spec ARM IHI0064F section 4.3.6 System instructions
> @@ -390,6 +392,9 @@
>  #define ETM_COMMON_SYSREG_LIST_CASES		\
>  	ETM_COMMON_SYSREG_LIST(NOP, __unused)
>  
> +#define ETM4x_ONLY_SYSREG_LIST_CASES		\
> +	ETM4x_ONLY_SYSREG_LIST(NOP, __unused)
> +
>  #define ETM4x_SYSREG_LIST_CASES			\
>  	ETM_COMMON_SYSREG_LIST_CASES		\
>  	ETM4x_ONLY_SYSREG_LIST(NOP, __unused)
> @@ -406,7 +411,6 @@
>  	ETE_ONLY_SYSREG_LIST(WRITE, (val))
>  
>  #define ETE_ONLY_SYSREG_LIST_CASES		\
> -	ETM_COMMON_SYSREG_LIST_CASES		\

This goes in patch 04.

With the above:

Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>

>  	ETE_ONLY_SYSREG_LIST(NOP, __unused)
>  
>  #define read_etm4x_sysreg_offset(offset, _64bit)				\
> @@ -589,11 +593,14 @@
>  	((ETM_DEVARCH_MAKE_ARCHID_ARCH_VER(major)) | ETM_DEVARCH_ARCHID_ARCH_PART(0xA13))
>  
>  #define ETM_DEVARCH_ARCHID_ETMv4x		ETM_DEVARCH_MAKE_ARCHID(0x4)
> +#define ETM_DEVARCH_ARCHID_ETE			ETM_DEVARCH_MAKE_ARCHID(0x5)
>  
>  #define ETM_DEVARCH_ID_MASK						\
>  	(ETM_DEVARCH_ARCHITECT_MASK | ETM_DEVARCH_ARCHID_MASK | ETM_DEVARCH_PRESENT)
>  #define ETM_DEVARCH_ETMv4x_ARCH						\
>  	(ETM_DEVARCH_ARCHITECT_ARM | ETM_DEVARCH_ARCHID_ETMv4x | ETM_DEVARCH_PRESENT)
> +#define ETM_DEVARCH_ETE_ARCH						\
> +	(ETM_DEVARCH_ARCHITECT_ARM | ETM_DEVARCH_ARCHID_ETE | ETM_DEVARCH_PRESENT)
>  
>  #define TRCSTATR_IDLE_BIT		0
>  #define TRCSTATR_PMSTABLE_BIT		1
> @@ -683,6 +690,8 @@
>  #define ETM_ARCH_MINOR_VERSION(arch)	((arch) & 0xfU)
>  
>  #define ETM_ARCH_V4	ETM_ARCH_VERSION(4, 0)
> +#define ETM_ARCH_ETE	ETM_ARCH_VERSION(5, 0)
> +
>  /* Interpretation of resource numbers change at ETM v4.3 architecture */
>  #define ETM_ARCH_V4_3	ETM_ARCH_VERSION(4, 3)
>  
> @@ -989,4 +998,9 @@ void etm4_config_trace_mode(struct etmv4_config *config);
>  
>  u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit);
>  void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit);
> +
> +static inline bool etm4x_is_ete(struct etmv4_drvdata *drvdata)
> +{
> +	return drvdata->arch >= ETM_ARCH_ETE;
> +}
>  #endif
> -- 
> 2.7.4
> 

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