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Message-ID: <c52865b2-8608-4a47-967a-6cf3e11b197a@arm.com>
Date: Wed, 6 Mar 2024 11:44:32 +0530
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Subject: Re: [PATCH V5 07/11] coresight: catu: Move ACPI support from AMBA
 driver to platform driver
Content-Language: en-US
To: Suzuki K Poulose <suzuki.poulose@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>
 <c43fcd3a-9813-4e1f-adb3-25cc32c54438@arm.com>
From: Anshuman Khandual <anshuman.khandual@arm.com>
In-Reply-To: <c43fcd3a-9813-4e1f-adb3-25cc32c54438@arm.com>
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On 3/5/24 23:02, Suzuki K Poulose wrote:
> 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 ?

Agreed, though it seems unnecessary, there is a small difference in there. In the platform
driver case i.e catu_platform_probe(), clk_put() is called on platform clock drvdata->pclk
(just enabled earlier) for cases when devm_ioremap_resource() fails.

To remove this redundancy, let's move devm_ioremap_resource() into it's AMBA caller i.e
catu_probe() thus dropping struct resource argument from __catu_probe(). Similar situation
is present in coresight-cpu-debug driver as well, will fix that.

But there are some other drivers in the series where coresight_get_enable_apb_pclk() called
on 'drvdata->pclk' and devm_ioremap_resource() is attempted inside the factored __xxx_probe()
function which is common for both AMBA and platform drivers.

Such drivers are ...

- tpiu
- tmc
- stm
- replicator

IMHO it would be better to follow same scheme for all drivers in the series. Please do let
me know which method will be preferred.

> 
>> +

>> +    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) ?

Agreed, although drvdata is derived in __xxx_remove() functions, a pre-check here is not
required - similar to the AMBA remove path. Sure, will drop them across drivers.

> 
> 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;
>