Re: [PATCH V5 07/11] coresight: catu: Move ACPI support from AMBA driver to platform driver

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 3/6/24 22:51, Suzuki K Poulose wrote:
> On 06/03/2024 06:14, Anshuman Khandual wrote:
>>
>>
>> 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.
> 
> Lets pass the "res" to the common probe and deal it there.

Sure, but then will have to deal with drvdata->pclk in the caller, where it was originally
acquired, when the __xxxx_probe() fails. For example - in case with the debug cpu driver,
following changes will be required.

diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
index 68d077174a6a..2d77f9a17692 100644
--- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
+++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
@@ -577,11 +577,11 @@ static int __debug_probe(struct device *dev, struct resource *res)
        }
 
        drvdata->dev = dev;
-
-       /* Validity for the resource is already checked by the AMBA core */
-       base = devm_ioremap_resource(dev, res);
-       if (IS_ERR(base))
-               return PTR_ERR(base);
+       if (res) {
+               base = devm_ioremap_resource(dev, res);
+               if (IS_ERR(base))
+                       return PTR_ERR(base);
+       }
 
        drvdata->base = base;
 
@@ -703,14 +703,6 @@ static int debug_platform_probe(struct platform_device *pdev)
        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);
@@ -720,6 +712,8 @@ static int debug_platform_probe(struct platform_device *pdev)
        if (ret) {
                pm_runtime_put_noidle(&pdev->dev);
                pm_runtime_disable(&pdev->dev);
+               if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
+                       clk_put(drvdata->pclk);
        }
        return ret;

>>
>>>
>>>> +
>>
>>>> +    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.
> 
> No, my point is : Is there a case where :
> 
> 1) drvdata == NULL, but we have a device to do some cleanup ?

NO, I don't believe there are any such cases.

> 2) If drvdata != NULL, but drvdata->csdev is not valid, because we failed to register the coresight device ?

I don't believe so. If drvdata->csdev is not valid because coresight_register() has failed,
that would have also failed driver' probe() as well. Hence driver remove() could not have
been called in such situations.

> 
> 
> Suzuki
> 
> 
>>
>>>
>>> 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;
>>>
>