diff mbox series

[RFC,5/5] firmware: QCOM_SCM: Allow qcom_scm driver to be loadable as a permenent module

Message ID 20200616061338.109499-6-john.stultz@linaro.org
State New
Headers show
Series Allow for qcom-pdc, pinctrl-msm and qcom-scm drivers to be loadable as modules | expand

Commit Message

John Stultz June 16, 2020, 6:13 a.m. UTC
Allow the qcom_scm driver to be loadable as a
permenent module.

Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-arm-msm@vger.kernel.org
Cc: iommu@lists.linux-foundation.org
Cc: linux-gpio@vger.kernel.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 drivers/firmware/Kconfig    | 2 +-
 drivers/firmware/Makefile   | 3 ++-
 drivers/firmware/qcom_scm.c | 4 ++++
 drivers/iommu/Kconfig       | 2 ++
 4 files changed, 9 insertions(+), 2 deletions(-)

Comments

Will Deacon July 3, 2020, 12:23 p.m. UTC | #1
On Tue, Jun 16, 2020 at 01:52:32PM -0700, John Stultz wrote:
> On Tue, Jun 16, 2020 at 12:55 AM Marc Zyngier <maz@kernel.org> wrote:

> > On 2020-06-16 07:13, John Stultz wrote:

> > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig

> > > index b510f67dfa49..714893535dd2 100644

> > > --- a/drivers/iommu/Kconfig

> > > +++ b/drivers/iommu/Kconfig

> > > @@ -381,6 +381,7 @@ config SPAPR_TCE_IOMMU

> > >  config ARM_SMMU

> > >       tristate "ARM Ltd. System MMU (SMMU) Support"

> > >       depends on (ARM64 || ARM || (COMPILE_TEST && !GENERIC_ATOMIC64)) &&

> > > MMU

> > > +     depends on QCOM_SCM || !QCOM_SCM #if QCOM_SCM=m this can't be =y

> >

> > This looks a bit ugly. Could you explain why we need this at the SMMU

> > level? I'd have expected the dependency to flow the other way around...

> 

> Yea, so the arm-smmu-qcom.c file calls directly into the qcom-scm code

> via qcom_scm_qsmmu500_wait_safe_toggle()

>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iommu/arm-smmu-qcom.c?h=v5.8-rc1#n44

> 

> So if ARM_SMMU=y and QCOM_SCM=m we get:

> drivers/iommu/arm-smmu-qcom.o: In function `qcom_smmu500_reset':

> arm-smmu-qcom.c:(.text+0xb4): undefined reference to

> `qcom_scm_qsmmu500_wait_safe_toggle'

> 

> Do you have a suggestion for an alternative approach?


Can you use symbol_get() or something like that? How are module dependencies
handled by other drivers?

Will
Vinod Koul July 3, 2020, 12:49 p.m. UTC | #2
On 03-07-20, 13:23, Will Deacon wrote:
> On Tue, Jun 16, 2020 at 01:52:32PM -0700, John Stultz wrote:

> > On Tue, Jun 16, 2020 at 12:55 AM Marc Zyngier <maz@kernel.org> wrote:

> > > On 2020-06-16 07:13, John Stultz wrote:

> > > > diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig

> > > > index b510f67dfa49..714893535dd2 100644

> > > > --- a/drivers/iommu/Kconfig

> > > > +++ b/drivers/iommu/Kconfig

> > > > @@ -381,6 +381,7 @@ config SPAPR_TCE_IOMMU

> > > >  config ARM_SMMU

> > > >       tristate "ARM Ltd. System MMU (SMMU) Support"

> > > >       depends on (ARM64 || ARM || (COMPILE_TEST && !GENERIC_ATOMIC64)) &&

> > > > MMU

> > > > +     depends on QCOM_SCM || !QCOM_SCM #if QCOM_SCM=m this can't be =y

> > >

> > > This looks a bit ugly. Could you explain why we need this at the SMMU

> > > level? I'd have expected the dependency to flow the other way around...

> > 

> > Yea, so the arm-smmu-qcom.c file calls directly into the qcom-scm code

> > via qcom_scm_qsmmu500_wait_safe_toggle()

> >   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iommu/arm-smmu-qcom.c?h=v5.8-rc1#n44

> > 

> > So if ARM_SMMU=y and QCOM_SCM=m we get:

> > drivers/iommu/arm-smmu-qcom.o: In function `qcom_smmu500_reset':

> > arm-smmu-qcom.c:(.text+0xb4): undefined reference to

> > `qcom_scm_qsmmu500_wait_safe_toggle'

> > 

> > Do you have a suggestion for an alternative approach?

> 

> Can you use symbol_get() or something like that? How are module dependencies

> handled by other drivers?


So drivers deal with this by making rules in Kconfig which will prohibit
this case. QCOM_SCM depends on ARM_SMMU with the caveat that if ARM_SMMU
is a module, QCOM_SCM cant be inbuilt.

This can be done by adding below line in Kconfig for QCOM_SCM:

        depends on ARM_SMMU || !ARM_SMMU

This is quite prevalent is drivers to ensure dependency like this

Thanks
-- 
~Vinod
diff mbox series

Patch

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index fbd785dd0513..9e533a462bf4 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -236,7 +236,7 @@  config INTEL_STRATIX10_RSU
 	  Say Y here if you want Intel RSU support.
 
 config QCOM_SCM
-	bool
+	tristate "Qcom SCM driver"
 	depends on ARM || ARM64
 	select RESET_CONTROLLER
 
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 99510be9f5ed..cf24d674216b 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -17,7 +17,8 @@  obj-$(CONFIG_ISCSI_IBFT)	+= iscsi_ibft.o
 obj-$(CONFIG_FIRMWARE_MEMMAP)	+= memmap.o
 obj-$(CONFIG_RASPBERRYPI_FIRMWARE) += raspberrypi.o
 obj-$(CONFIG_FW_CFG_SYSFS)	+= qemu_fw_cfg.o
-obj-$(CONFIG_QCOM_SCM)		+= qcom_scm.o qcom_scm-smc.o qcom_scm-legacy.o
+obj-$(CONFIG_QCOM_SCM)		+= qcom-scm.o
+qcom-scm-objs += qcom_scm.o qcom_scm-smc.o qcom_scm-legacy.o
 obj-$(CONFIG_TI_SCI_PROTOCOL)	+= ti_sci.o
 obj-$(CONFIG_TRUSTED_FOUNDATIONS) += trusted_foundations.o
 obj-$(CONFIG_TURRIS_MOX_RWTM)	+= turris-mox-rwtm.o
diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 0e7233a20f34..b5e88bf66975 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -1155,6 +1155,7 @@  static const struct of_device_id qcom_scm_dt_match[] = {
 	{ .compatible = "qcom,scm" },
 	{}
 };
+MODULE_DEVICE_TABLE(of, qcom_scm_dt_match);
 
 static struct platform_driver qcom_scm_driver = {
 	.driver = {
@@ -1170,3 +1171,6 @@  static int __init qcom_scm_init(void)
 	return platform_driver_register(&qcom_scm_driver);
 }
 subsys_initcall(qcom_scm_init);
+
+MODULE_DESCRIPTION("Qualcomm Technologies, Inc. SCM driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index b510f67dfa49..714893535dd2 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -381,6 +381,7 @@  config SPAPR_TCE_IOMMU
 config ARM_SMMU
 	tristate "ARM Ltd. System MMU (SMMU) Support"
 	depends on (ARM64 || ARM || (COMPILE_TEST && !GENERIC_ATOMIC64)) && MMU
+	depends on QCOM_SCM || !QCOM_SCM #if QCOM_SCM=m this can't be =y
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select ARM_DMA_USE_IOMMU if ARM
@@ -500,6 +501,7 @@  config QCOM_IOMMU
 	# Note: iommu drivers cannot (yet?) be built as modules
 	bool "Qualcomm IOMMU Support"
 	depends on ARCH_QCOM || (COMPILE_TEST && !GENERIC_ATOMIC64)
+	depends on QCOM_SCM=y
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select ARM_DMA_USE_IOMMU