firmware: qcom_scm: Allow qcom_scm driver to be loadable as a permenent module

Allow the qcom_scm driver to be loadable as a permenent module.

This still uses the "depends on QCOM_SCM || !QCOM_SCM" bit to
ensure that drivers that call into the qcom_scm driver are
also built as modules. While not ideal in some cases its the
only safe way I can find to avoid build errors without having
those drivers select QCOM_SCM and have to force it on (as
QCOM_SCM=n can be valid for those drivers).

Reviving this now that Saravana's fw_devlink defaults to on,
which should avoid loading troubles seen before.
Acked-by: NKalle Valo <kvalo@codeaurora.org>
Acked-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: NWill Deacon <will@kernel.org>
Reviewed-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Link: https://lore.kernel.org/r/20210707045320.529186-1-john.stultz@linaro.orgSigned-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

drivers/firmware/Kconfig

@@ -235,7 +235,7 @@ 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
 	depends on HAVE_ARM_SMCCC
 	select RESET_CONTROLLER

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

drivers/firmware/qcom_scm.c

@@ -1299,6 +1299,7 @@ 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 = {
@@ -1315,3 +1316,6 @@ 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");

drivers/iommu/Kconfig

@@ -253,6 +253,7 @@ config SPAPR_TCE_IOMMU
 config ARM_SMMU
 	tristate "ARM Ltd. System MMU (SMMU) Support"
 	depends on ARM64 || ARM || (COMPILE_TEST && !GENERIC_ATOMIC64)
+	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
@@ -382,6 +383,7 @@ 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

drivers/net/wireless/ath/ath10k/Kconfig

@@ -44,6 +44,7 @@ config ATH10K_SNOC
 	tristate "Qualcomm ath10k SNOC support"
 	depends on ATH10K
 	depends on ARCH_QCOM || COMPILE_TEST
+	depends on QCOM_SCM || !QCOM_SCM #if QCOM_SCM=m this can't be =y
 	select QCOM_QMI_HELPERS
 	help
 	  This module adds support for integrated WCN3990 chip connected