[10/14] soc: qcom: Add RPM processor/subsystem driver

  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.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
 drivers/soc/qcom/Makefile   |  2 +-
 drivers/soc/qcom/rpm-proc.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+), 1 deletion(-)
  

On 5.06.2023 09:08, 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.
> 
> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> ---
>  drivers/soc/qcom/Makefile   |  2 +-
>  drivers/soc/qcom/rpm-proc.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 77 insertions(+), 1 deletion(-)
> 
> 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..0652be7f7895
> --- /dev/null
> +++ b/drivers/soc/qcom/rpm-proc.c
> @@ -0,0 +1,76 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright (c) 2021-2023, Stephan Gerhold <stephan@gerhold.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);
> +		if (IS_ERR(edge))
> +			return dev_err_probe(dev, PTR_ERR(edge),
> +					     "Failed to register smd-edge\n");
Need of_node_put in both success and IS_ERR paths

> +	}
> +
> +	ret = devm_of_platform_populate(dev);
> +	if (ret) {
> +		dev_err(dev, "Failed to populate children devices: %d\n", ret);
I may be having a brain lag moment but I think it should be "child"
singular, otherwise it sounds like they're devices for children!

> +		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);
Maybe we can go as early as core...

Konrad
> +
> +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@gerhold.net>");
> +MODULE_LICENSE("GPL");
>
  

On Mon, Jun 05, 2023 at 09:06:54PM +0200, Konrad Dybcio wrote:
> 
> 
> On 5.06.2023 09:08, 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.
> > 
> > Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
> > ---
> >  drivers/soc/qcom/Makefile   |  2 +-
> >  drivers/soc/qcom/rpm-proc.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 77 insertions(+), 1 deletion(-)
> > 
> > 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..0652be7f7895
> > --- /dev/null
> > +++ b/drivers/soc/qcom/rpm-proc.c
> > @@ -0,0 +1,76 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/* Copyright (c) 2021-2023, Stephan Gerhold <stephan@gerhold.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);
> > +		if (IS_ERR(edge))
> > +			return dev_err_probe(dev, PTR_ERR(edge),
> > +					     "Failed to register smd-edge\n");
> Need of_node_put in both success and IS_ERR paths
> 

Oops. :/

> > +	}
> > +
> > +	ret = devm_of_platform_populate(dev);
> > +	if (ret) {
> > +		dev_err(dev, "Failed to populate children devices: %d\n", ret);
> I may be having a brain lag moment but I think it should be "child"
> singular, otherwise it sounds like they're devices for children!
> 

Uh somehow both sounds fine to me so I'll just change it in v2. :)

> > +		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);
> Maybe we can go as early as core...
> 

SMEM is arch_initcall() so at least for the SMD case it can never
succeed probing in core_initcall() and would likely just cause
unnecessary probe deferrals. That's why I chose arch_initcall().

Are you sure anything will really benefit from core_initcall() here?

I'd just like to avoid making things worse by using a random way too
early initcall level. We have some really weird examples in the tree
currently, e.g.:
  - rpmpd: core_initcall()
  - smd-rpm: arch_initcall()
  - glink-rpm: subsys_initcall()
But they actually need to be loaded in opposite order...

Thanks,
Stephan
  

On 5.06.2023 21:51, Stephan Gerhold wrote:
> On Mon, Jun 05, 2023 at 09:06:54PM +0200, Konrad Dybcio wrote:
>>
>>
>> On 5.06.2023 09:08, 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.
>>>
>>> Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
>>> ---
[...]

> SMEM is arch_initcall() so at least for the SMD case it can never
> succeed probing in core_initcall() and would likely just cause
> unnecessary probe deferrals. That's why I chose arch_initcall().
> 
> Are you sure anything will really benefit from core_initcall() here?
> 
> I'd just like to avoid making things worse by using a random way too
> early initcall level. We have some really weird examples in the tree
> currently, e.g.:
>   - rpmpd: core_initcall()
>   - smd-rpm: arch_initcall()
>   - glink-rpm: subsys_initcall()
> But they actually need to be loaded in opposite order...
Yes, we should make some sort of dep graph and clean it up..

Konrad
> 
> Thanks,
> Stephan
  

Hi Stephan,

kernel test robot noticed the following build errors:

[auto build test ERROR on 8d5a57ea6a0b1722725170e32e511701ca7c454c]

url:    https://github.com/intel-lab-lkp/linux/commits/Stephan-Gerhold/dt-bindings-soc-qcom-smd-rpm-Fix-sort-order/20230605-151438
base:   8d5a57ea6a0b1722725170e32e511701ca7c454c
patch link:    https://lore.kernel.org/r/20230531-rpm-rproc-v1-10-e0a3b6de1f14%40gerhold.net
patch subject: [PATCH 10/14] soc: qcom: Add RPM processor/subsystem driver
config: m68k-randconfig-r023-20230605 (https://download.01.org/0day-ci/archive/20230606/202306060446.CAOHuKLm-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 12.3.0
reproduce (this is a W=1 build):
        mkdir -p ~/bin
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/e08a6ffdb1d65902d0c4fed40968ff2e4d83a476
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Stephan-Gerhold/dt-bindings-soc-qcom-smd-rpm-Fix-sort-order/20230605-151438
        git checkout e08a6ffdb1d65902d0c4fed40968ff2e4d83a476
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.3.0 ~/bin/make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306060446.CAOHuKLm-lkp@intel.com/

All errors (new ones prefixed by >>):

   m68k-linux-ld: drivers/soc/qcom/rpm-proc.o: in function `rpm_proc_remove':
>> rpm-proc.c:(.text+0x12): undefined reference to `qcom_smd_unregister_edge'