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Message-ID: <6862ce69-e316-be85-7725-c4471c905556@arm.com>
Date: Mon, 29 May 2023 08:20:04 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
coresight@...ts.linaro.org
Cc: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
Steve Clevenger <scclevenger@...amperecomputing.com>,
Rob Herring <robh+dt@...nel.org>,
Frank Rowand <frowand.list@...il.com>,
Russell King <linux@...linux.org.uk>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Len Brown <lenb@...nel.org>,
Sudeep Holla <sudeep.holla@....com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...aro.org>, devicetree@...r.kernel.org,
linux-acpi@...r.kernel.org
Subject: Re: [PATCH V4 4/6] coresight: etm4x: Change etm4_platform_driver
driver for MMIO devices
On 5/26/23 02:53, Suzuki K Poulose wrote:
> Hi Anshuman
>
> Please find a minor issue with the clock handling below.
>
> On 23/05/2023 05:45, 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@...aro.org>
>> Cc: Suzuki K Poulose <suzuki.poulose@....com>
>> Cc: Mike Leach <mike.leach@...aro.org>
>> Cc: Leo Yan <leo.yan@...aro.org>
>> Cc: coresight@...ts.linaro.org
>> Cc: linux-arm-kernel@...ts.infradead.org
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
>> ---
>> .../coresight/coresight-etm4x-core.c | 57 ++++++++++++++++++-
>> drivers/hwtracing/coresight/coresight-etm4x.h | 4 ++
>> include/linux/coresight.h | 47 +++++++++++++++
>> 3 files changed, 106 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
>> index 57a7181017bd..c9e2219ee6b6 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>
>> @@ -1073,11 +1074,21 @@ static bool etm4_init_sysreg_access(struct etmv4_drvdata *drvdata,
>> return true;
>> }
>> +static bool is_devtype_cpu_trace(void __iomem *base)
>> +{
>> + u32 devtype = readl(base + TRCDEVTYPE);
>> +
>> + return (devtype == CS_DEVTYPE_PE_TRACE);
>> +}
>> +
>> static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
>> struct csdev_access *csa)
>> {
>> u32 devarch = readl_relaxed(drvdata->base + TRCDEVARCH);
>> + if (!is_coresight_device(drvdata->base) || !is_devtype_cpu_trace(drvdata->base))
>> + return false;
>> +
>> /*
>> * All ETMs must implement TRCDEVARCH to indicate that
>> * the component is an ETMv4. Even though TRCIDR1 also
>> @@ -2135,6 +2146,7 @@ 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;
>> @@ -2142,7 +2154,18 @@ 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);
>
> clk_put() can handle drvdata->pclk == NULL and bail out early. So calling this without the != NULL check is fine.
>
>> + return PTR_ERR(drvdata->base);
>> + }
>> + }
>> +
>> dev_set_drvdata(&pdev->dev, drvdata);
>> pm_runtime_get_noresume(&pdev->dev);
>> pm_runtime_set_active(&pdev->dev);
>> @@ -2188,7 +2211,7 @@ 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 = CS_DEVTYPE_PE_TRACE,
>> }
>> };
>> @@ -2247,6 +2270,9 @@ static int __exit etm4_remove_platform_dev(struct platform_device *pdev)
>> if (drvdata)
>> ret = etm4_remove_dev(drvdata);
>> pm_runtime_disable(&pdev->dev);
>> +
>> + if (drvdata->pclk)
>> + clk_put(drvdata->pclk);
>> return ret;
>> }
>> @@ -2286,6 +2312,32 @@ static struct amba_driver etm4x_amba_driver = {
>> .id_table = etm4_ids,
>> };
>> +#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);
>
> However this seems to be inconsistent. Should we not use:
>
> if (drvdata->pclk)
> ...
This makes sense, will update the condition check as follows.
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -2318,7 +2318,7 @@ static int etm4_runtime_suspend(struct device *dev)
{
struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
- if (!IS_ERR(drvdata->pclk))
+ if (drvdata->pclk && !IS_ERR(drvdata->pclk))
clk_disable_unprepare(drvdata->pclk);
return 0;
@@ -2328,7 +2328,7 @@ static int etm4_runtime_resume(struct device *dev)
{
struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
- if (!IS_ERR(drvdata->pclk))
+ if (drvdata->pclk && !IS_ERR(drvdata->pclk))
clk_prepare_enable(drvdata->pclk);
return 0;
>
>> +
>> + return 0;
>> +}
>> +
>> +static int etm4_runtime_resume(struct device *dev)
>> +{
>> + struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
>> +
>> + if (!IS_ERR(drvdata->pclk))
>
> same as above ?
>
>> + 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_sysreg_match[] = {
>> { .compatible = "arm,coresight-etm4x-sysreg" },
>> { .compatible = "arm,embedded-trace-extension" },
>> @@ -2299,6 +2351,7 @@ static struct platform_driver etm4_platform_driver = {
>> .name = "coresight-etm4x",
>> .of_match_table = etm4_sysreg_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 27c8a9901868..0ff0bd2cd504 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 CS_DEVTYPE_PE_TRACE 0x00000013
>> +
>> #define TRCSTATR_IDLE_BIT 0
>> #define TRCSTATR_PMSTABLE_BIT 1
>> #define ETM_DEFAULT_ADDR_COMP 0
>> @@ -944,6 +946,7 @@ struct etmv4_save_state {
>> /**
>> * struct etm4_drvdata - specifics associated to an ETM component
>> + * @pclk APB clock for this component
>
> Might be worth adding the comment here :
>
> * @pclk: APB clock if present, otherwise NULL
Sure, will update this comment above.
>
> Rest looks fine to me
>
> Suzuki
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