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Date: Tue, 5 Mar 2024 17:32:54 +0000
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From: Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH V5 07/11] coresight: catu: Move ACPI support from AMBA
 driver to platform driver
To: Anshuman Khandual <anshuman.khandual@arm.com>,
 linux-arm-kernel@lists.infradead.org
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>,
 Sudeep Holla <sudeep.holla@arm.com>, Mike Leach <mike.leach@linaro.org>,
 James Clark <james.clark@arm.com>,
 Maxime Coquelin <mcoquelin.stm32@gmail.com>,
 Alexandre Torgue <alexandre.torgue@foss.st.com>, linux-acpi@vger.kernel.org,
 linux-kernel@vger.kernel.org, coresight@lists.linaro.org,
 linux-stm32@st-md-mailman.stormreply.com
References: <20240222082142.3663983-1-anshuman.khandual@arm.com>
 <20240222082142.3663983-8-anshuman.khandual@arm.com>
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On 22/02/2024 08:21, Anshuman Khandual wrote:
> Add support for the catu devices in a new platform driver, which can then
> be used on ACPI based platforms. This change would now allow runtime power
> management for ACPI based systems. The driver would try to enable the APB
> clock if available. But first this renames and then refactors catu_probe()
> and catu_remove(), making sure it can be used both for platform and AMBA
> drivers. This also moves pm_runtime_put() from catu_probe() to the callers.
> 
> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: James Clark <james.clark@arm.com>
> Cc: linux-acpi@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Cc: coresight@lists.linaro.org
> Acked-by: Sudeep Holla <sudeep.holla@arm.com> # For ACPI related changes
> Reviewed-by: James Clark <james.clark@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> Changes in V5:
> 
> - Updated commit message regarding catu_probe/remove() refactoring and renaming
> 
>   drivers/acpi/arm64/amba.c                    |   1 -
>   drivers/hwtracing/coresight/coresight-catu.c | 142 ++++++++++++++++---
>   drivers/hwtracing/coresight/coresight-catu.h |   1 +
>   3 files changed, 124 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/amba.c b/drivers/acpi/arm64/amba.c
> index afb6afb66967..587061b0fd2f 100644
> --- a/drivers/acpi/arm64/amba.c
> +++ b/drivers/acpi/arm64/amba.c
> @@ -27,7 +27,6 @@ static const struct acpi_device_id amba_id_list[] = {
>   	{"ARMHC503", 0}, /* ARM CoreSight Debug */
>   	{"ARMHC979", 0}, /* ARM CoreSight TPIU */
>   	{"ARMHC97C", 0}, /* ARM CoreSight SoC-400 TMC, SoC-600 ETF/ETB */
> -	{"ARMHC9CA", 0}, /* ARM CoreSight CATU */
>   	{"", 0},
>   };
>   
> diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c
> index 3949ded0d4fa..a3ea46b53898 100644
> --- a/drivers/hwtracing/coresight/coresight-catu.c
> +++ b/drivers/hwtracing/coresight/coresight-catu.c
> @@ -7,6 +7,8 @@
>    * Author: Suzuki K Poulose <suzuki.poulose@arm.com>
>    */
>   
> +#include <linux/platform_device.h>
> +#include <linux/acpi.h>
>   #include <linux/amba/bus.h>
>   #include <linux/device.h>
>   #include <linux/dma-mapping.h>
> @@ -502,28 +504,20 @@ static const struct coresight_ops catu_ops = {
>   	.helper_ops = &catu_helper_ops,
>   };
>   
> -static int catu_probe(struct amba_device *adev, const struct amba_id *id)
> +static int __catu_probe(struct device *dev, struct resource *res)
>   {
>   	int ret = 0;
>   	u32 dma_mask;
> -	struct catu_drvdata *drvdata;
> +	struct catu_drvdata *drvdata = dev_get_drvdata(dev);
>   	struct coresight_desc catu_desc;
>   	struct coresight_platform_data *pdata = NULL;
> -	struct device *dev = &adev->dev;
>   	void __iomem *base;
>   
>   	catu_desc.name = coresight_alloc_device_name(&catu_devs, dev);
>   	if (!catu_desc.name)
>   		return -ENOMEM;
>   
> -	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> -	if (!drvdata) {
> -		ret = -ENOMEM;
> -		goto out;
> -	}
> -
> -	dev_set_drvdata(dev, drvdata);
> -	base = devm_ioremap_resource(dev, &adev->res);
> +	base = devm_ioremap_resource(dev, res);
>   	if (IS_ERR(base)) {
>   		ret = PTR_ERR(base);
>   		goto out;
> @@ -567,19 +561,39 @@ static int catu_probe(struct amba_device *adev, const struct amba_id *id)
>   	drvdata->csdev = coresight_register(&catu_desc);
>   	if (IS_ERR(drvdata->csdev))
>   		ret = PTR_ERR(drvdata->csdev);
> -	else
> -		pm_runtime_put(&adev->dev);
>   out:
>   	return ret;
>   }
>   
> -static void catu_remove(struct amba_device *adev)
> +static int catu_probe(struct amba_device *adev, const struct amba_id *id)
>   {
> -	struct catu_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> +	struct catu_drvdata *drvdata;
> +	int ret;
> +
> +	drvdata = devm_kzalloc(&adev->dev, sizeof(*drvdata), GFP_KERNEL);
> +	if (!drvdata)
> +		return -ENOMEM;
> +
> +	amba_set_drvdata(adev, drvdata);
> +	ret = __catu_probe(&adev->dev, &adev->res);
> +	if (!ret)
> +		pm_runtime_put(&adev->dev);
> +
> +	return ret;
> +}
> +
> +static void __catu_remove(struct device *dev)
> +{
> +	struct catu_drvdata *drvdata = dev_get_drvdata(dev);
>   
>   	coresight_unregister(drvdata->csdev);
>   }
>   
> +static void catu_remove(struct amba_device *adev)
> +{
> +	__catu_remove(&adev->dev);
> +}
> +
>   static struct amba_id catu_ids[] = {
>   	CS_AMBA_ID(0x000bb9ee),
>   	{},
> @@ -598,13 +612,103 @@ static struct amba_driver catu_driver = {
>   	.id_table			= catu_ids,
>   };
>   
> +static int catu_platform_probe(struct platform_device *pdev)
> +{
> +	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	struct catu_drvdata *drvdata;
> +	int ret = 0;
> +
> +	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
> +	if (!drvdata)
> +		return -ENOMEM;
> +
> +	drvdata->pclk = coresight_get_enable_apb_pclk(&pdev->dev);
> +	if (IS_ERR(drvdata->pclk))
> +		return -ENODEV;


---8>---

> +
> +	if (res) {
> +		drvdata->base = devm_ioremap_resource(&pdev->dev, res);
> +		if (IS_ERR(drvdata->base)) {
> +			clk_put(drvdata->pclk);
> +			return PTR_ERR(drvdata->base);
> +		}
> +	}

---<8---

The above section seems unncessary as we already try to map the base in 
__catu_probe ?

> +
> +	pm_runtime_get_noresume(&pdev->dev);
> +	pm_runtime_set_active(&pdev->dev);
> +	pm_runtime_enable(&pdev->dev);
> +
> +	dev_set_drvdata(&pdev->dev, drvdata);
> +	ret = __catu_probe(&pdev->dev, res);
> +	pm_runtime_put(&pdev->dev);
> +	if (ret)
> +		pm_runtime_disable(&pdev->dev);
> +
> +	return ret;
> +}
> +
> +static int catu_platform_remove(struct platform_device *pdev)
> +{
> +	struct catu_drvdata *drvdata = dev_get_drvdata(&pdev->dev);
> +
> +	if (drvdata)
> +		__catu_remove(&pdev->dev);

I don't understand the need for if () check here (and on all the other 
drivers). Even if we have a drvdata != NULL, what guarantees that
the drvdata->csdev is valid (which is used in xx_remove) ?

Suzuki

> +
> +	pm_runtime_disable(&pdev->dev);
> +	if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> +		clk_put(drvdata->pclk);
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int catu_runtime_suspend(struct device *dev)
> +{
> +	struct catu_drvdata *drvdata = dev_get_drvdata(dev);
> +
> +	if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> +		clk_disable_unprepare(drvdata->pclk);
> +	return 0;
> +}
> +
> +static int catu_runtime_resume(struct device *dev)
> +{
> +	struct catu_drvdata *drvdata = dev_get_drvdata(dev);
> +
> +	if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> +		clk_prepare_enable(drvdata->pclk);
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops catu_dev_pm_ops = {
> +	SET_RUNTIME_PM_OPS(catu_runtime_suspend, catu_runtime_resume, NULL)
> +};
> +
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id catu_acpi_ids[] = {
> +	{"ARMHC9CA", 0}, /* ARM CoreSight CATU */
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(acpi, catu_acpi_ids);
> +#endif
> +
> +static struct platform_driver catu_platform_driver = {
> +	.probe	= catu_platform_probe,
> +	.remove	= catu_platform_remove,
> +	.driver	= {
> +		.name			= "coresight-catu-platform",
> +		.acpi_match_table	= ACPI_PTR(catu_acpi_ids),
> +		.suppress_bind_attrs	= true,
> +		.pm			= &catu_dev_pm_ops,
> +	},
> +};
> +
>   static int __init catu_init(void)
>   {
>   	int ret;
>   
> -	ret = amba_driver_register(&catu_driver);
> -	if (ret)
> -		pr_info("Error registering catu driver\n");
> +	ret = coresight_init_driver("catu", &catu_driver, &catu_platform_driver);
>   	tmc_etr_set_catu_ops(&etr_catu_buf_ops);
>   	return ret;
>   }
> @@ -612,7 +716,7 @@ static int __init catu_init(void)
>   static void __exit catu_exit(void)
>   {
>   	tmc_etr_remove_catu_ops();
> -	amba_driver_unregister(&catu_driver);
> +	coresight_remove_driver(&catu_driver, &catu_platform_driver);
>   }
>   
>   module_init(catu_init);
> diff --git a/drivers/hwtracing/coresight/coresight-catu.h b/drivers/hwtracing/coresight/coresight-catu.h
> index 442e034bbfba..141feac1c14b 100644
> --- a/drivers/hwtracing/coresight/coresight-catu.h
> +++ b/drivers/hwtracing/coresight/coresight-catu.h
> @@ -61,6 +61,7 @@
>   #define CATU_IRQEN_OFF		0x0
>   
>   struct catu_drvdata {
> +	struct clk *pclk;
>   	void __iomem *base;
>   	struct coresight_device *csdev;
>   	int irq;