linux-kernel - Re: [PATCH v2 08/12] soc: qcom: Add RPM processor/subsystem driver

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Message-ID: <cf296298-f122-a316-b8ed-118990374b71@linaro.org>
Date:   Fri, 9 Jun 2023 17:24:49 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Stephan Gerhold <stephan@...hold.net>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-remoteproc@...r.kernel.org
Subject: Re: [PATCH v2 08/12] soc: qcom: Add RPM processor/subsystem driver



On 8.06.2023 09:10, Stephan Gerhold wrote:
> Add a simple driver for the qcom,rpm-proc compatible that registers the
> "smd-edge" and populates other children defined in the device tree.
> 
> Note that the DT schema belongs to the remoteproc subsystem while this
> driver is added inside soc/qcom. I argue that the RPM *is* a remoteproc,
> but as an implementation detail in Linux it can currently not benefit
> from anything provided by the remoteproc subsystem. The RPM firmware is
> usually already loaded and started by earlier components in the boot
> chain and is not meant to be ever restarted.
> 
> To avoid breaking existing kernel configurations the driver is always
> built when smd-rpm.c is also built. They belong closely together anyway.
> To avoid build errors CONFIG_RPMSG_QCOM_SMD must be also built-in if
> rpm-proc is.
> 
> Signed-off-by: Stephan Gerhold <stephan@...hold.net>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad
>  drivers/soc/qcom/Kconfig    |  1 +
>  drivers/soc/qcom/Makefile   |  2 +-
>  drivers/soc/qcom/rpm-proc.c | 77 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 79 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
> index e597799e8121..715348869d04 100644
> --- a/drivers/soc/qcom/Kconfig
> +++ b/drivers/soc/qcom/Kconfig
> @@ -191,6 +191,7 @@ config QCOM_SMD_RPM
>  	tristate "Qualcomm Resource Power Manager (RPM) over SMD"
>  	depends on ARCH_QCOM || COMPILE_TEST
>  	depends on RPMSG
> +	depends on RPMSG_QCOM_SMD || RPMSG_QCOM_SMD=n
>  	help
>  	  If you say yes to this option, support will be included for the
>  	  Resource Power Manager system found in the Qualcomm 8974 based
> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> index 99114c71092b..113b9ff2ad43 100644
> --- a/drivers/soc/qcom/Makefile
> +++ b/drivers/soc/qcom/Makefile
> @@ -18,7 +18,7 @@ obj-$(CONFIG_QCOM_RPM_MASTER_STATS)	+= rpm_master_stats.o
>  obj-$(CONFIG_QCOM_RPMH)		+= qcom_rpmh.o
>  qcom_rpmh-y			+= rpmh-rsc.o
>  qcom_rpmh-y			+= rpmh.o
> -obj-$(CONFIG_QCOM_SMD_RPM)	+= smd-rpm.o
> +obj-$(CONFIG_QCOM_SMD_RPM)	+= rpm-proc.o smd-rpm.o
>  obj-$(CONFIG_QCOM_SMEM) +=	smem.o
>  obj-$(CONFIG_QCOM_SMEM_STATE) += smem_state.o
>  obj-$(CONFIG_QCOM_SMP2P)	+= smp2p.o
> diff --git a/drivers/soc/qcom/rpm-proc.c b/drivers/soc/qcom/rpm-proc.c
> new file mode 100644
> index 000000000000..2995d9b90190
> --- /dev/null
> +++ b/drivers/soc/qcom/rpm-proc.c
> @@ -0,0 +1,77 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2021-2023, Stephan Gerhold <stephan@...hold.net> */
> +
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/rpmsg/qcom_smd.h>
> +
> +static int rpm_proc_probe(struct platform_device *pdev)
> +{
> +	struct qcom_smd_edge *edge = NULL;
> +	struct device *dev = &pdev->dev;
> +	struct device_node *edge_node;
> +	int ret;
> +
> +	edge_node = of_get_child_by_name(dev->of_node, "smd-edge");
> +	if (edge_node) {
> +		edge = qcom_smd_register_edge(dev, edge_node);
> +		of_node_put(edge_node);
> +		if (IS_ERR(edge))
> +			return dev_err_probe(dev, PTR_ERR(edge),
> +					     "Failed to register smd-edge\n");
> +	}
> +
> +	ret = devm_of_platform_populate(dev);
> +	if (ret) {
> +		dev_err(dev, "Failed to populate child devices: %d\n", ret);
> +		goto err;
> +	}
> +
> +	platform_set_drvdata(pdev, edge);
> +	return 0;
> +err:
> +	if (edge)
> +		qcom_smd_unregister_edge(edge);
> +	return ret;
> +}
> +
> +static void rpm_proc_remove(struct platform_device *pdev)
> +{
> +	struct qcom_smd_edge *edge = platform_get_drvdata(pdev);
> +
> +	if (edge)
> +		qcom_smd_unregister_edge(edge);
> +}
> +
> +static const struct of_device_id rpm_proc_of_match[] = {
> +	{ .compatible = "qcom,rpm-proc", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, rpm_proc_of_match);
> +
> +static struct platform_driver rpm_proc_driver = {
> +	.probe = rpm_proc_probe,
> +	.remove_new = rpm_proc_remove,
> +	.driver = {
> +		.name = "qcom-rpm-proc",
> +		.of_match_table = rpm_proc_of_match,
> +	},
> +};
> +
> +static int __init rpm_proc_init(void)
> +{
> +	return platform_driver_register(&rpm_proc_driver);
> +}
> +arch_initcall(rpm_proc_init);
> +
> +static void __exit rpm_proc_exit(void)
> +{
> +	platform_driver_unregister(&rpm_proc_driver);
> +}
> +module_exit(rpm_proc_exit);
> +
> +MODULE_DESCRIPTION("Qualcomm RPM processor/subsystem driver");
> +MODULE_AUTHOR("Stephan Gerhold <stephan@...hold.net>");
> +MODULE_LICENSE("GPL");
>