Re: [PATCH V3 4/6] coresight: etm4x: Change etm4_platform_driver driver for MMIO devices

Suzuki K Poulose
2023-05-19T12:45:04Z

On 19/05/2023 06:21, 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@linaro.org>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: Leo Yan <leo.yan@linaro.org>
> Cc: coresight@lists.linaro.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> .../coresight/coresight-etm4x-core.c | 62 +++++++++++++++++--
> drivers/hwtracing/coresight/coresight-etm4x.h | 4 ++
> include/linux/coresight.h | 47 ++++++++++++++
> 3 files changed, 109 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 914ef6eb85d1..807b3a5a0eda 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);
> + 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,
> }
> };
>
> @@ -2246,6 +2269,10 @@ static int __exit etm4_remove_platform_dev(struct platform_device *pdev)
>
> if (drvdata)
> ret = etm4_remove_dev(drvdata);
> +
> + if (drvdata->pclk)
> + clk_put(drvdata->pclk);
> +

Shouldn't this be done *after* pm_runtime_disable() below ?

> pm_runtime_disable(&pdev->dev);

> return ret;
> }
> @@ -2286,7 +2313,33 @@ static struct amba_driver etm4x_amba_driver = {
> .id_table = etm4_ids,
> };
>
> -static const struct of_device_id etm4_sysreg_match[] = {
> +#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);
> +
> + return 0;
> +}
> +
> +static int etm4_runtime_resume(struct device *dev)
> +{
> + struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
> +
> + if (!IS_ERR(drvdata->pclk))
> + 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_match[] = {

minor nit: This is still only for the system instruction based
etms, so this renaming is going to confuse. Please leave it
unchanged.

Suzuki