qcom_scm: hide Kconfig symbol

Now that SCM can be a loadable module, we have to add another
dependency to avoid link failures when ipa or adreno-gpu are
built-in:

aarch64-linux-ld: drivers/net/ipa/ipa_main.o: in function `ipa_probe':
ipa_main.c:(.text+0xfc4): undefined reference to `qcom_scm_is_available'

ld.lld: error: undefined symbol: qcom_scm_is_available
>>> referenced by adreno_gpu.c
>>>               gpu/drm/msm/adreno/adreno_gpu.o:(adreno_zap_shader_load) in archive drivers/built-in.a

This can happen when CONFIG_ARCH_QCOM is disabled and we don't select
QCOM_MDT_LOADER, but some other module selects QCOM_SCM. Ideally we'd
use a similar dependency here to what we have for QCOM_RPROC_COMMON,
but that causes dependency loops from other things selecting QCOM_SCM.

This appears to be an endless problem, so try something different this
time:

 - CONFIG_QCOM_SCM becomes a hidden symbol that nothing 'depends on'
   but that is simply selected by all of its users

 - All the stubs in include/linux/qcom_scm.h can go away

 - arm-smccc.h needs to provide a stub for __arm_smccc_smc() to
   allow compile-testing QCOM_SCM on all architectures.

 - To avoid a circular dependency chain involving RESET_CONTROLLER
   and PINCTRL_SUNXI, drop the 'select RESET_CONTROLLER' statement.
   According to my testing this still builds fine, and the QCOM
   platform selects this symbol already.
Acked-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Alex Elder <elder@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/firmware/Kconfig

@@ -203,10 +203,7 @@ config INTEL_STRATIX10_RSU
 	  Say Y here if you want Intel RSU support.
 
 config QCOM_SCM
-	tristate "Qcom SCM driver"
-	depends on ARM || ARM64
-	depends on HAVE_ARM_SMCCC
-	select RESET_CONTROLLER
+	tristate
 
 config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
 	bool "Qualcomm download mode enabled by default"

drivers/gpu/drm/msm/Kconfig

@@ -17,7 +17,7 @@ config DRM_MSM
 	select DRM_SCHED
 	select SHMEM
 	select TMPFS
-	select QCOM_SCM if ARCH_QCOM
+	select QCOM_SCM
 	select WANT_DEV_COREDUMP
 	select SND_SOC_HDMI_CODEC if SND_SOC
 	select SYNC_FILE
@@ -55,7 +55,7 @@ config DRM_MSM_GPU_SUDO
 
 config DRM_MSM_HDMI_HDCP
 	bool "Enable HDMI HDCP support in MSM DRM driver"
-	depends on DRM_MSM && QCOM_SCM
+	depends on DRM_MSM
 	default y
 	help
 	  Choose this option to enable HDCP state machine

drivers/iommu/Kconfig

@@ -308,7 +308,6 @@ config APPLE_DART
 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
@@ -438,7 +437,7 @@ 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 QCOM_SCM
 	select IOMMU_API
 	select IOMMU_IO_PGTABLE_LPAE
 	select ARM_DMA_USE_IOMMU

drivers/iommu/arm/arm-smmu/Makefile

 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o
 obj-$(CONFIG_ARM_SMMU) += arm_smmu.o
-arm_smmu-objs += arm-smmu.o arm-smmu-impl.o arm-smmu-nvidia.o arm-smmu-qcom.o
+arm_smmu-objs += arm-smmu.o arm-smmu-impl.o arm-smmu-nvidia.o
+arm_smmu-$(CONFIG_ARM_SMMU_QCOM) += arm-smmu-qcom.o

drivers/iommu/arm/arm-smmu/arm-smmu-impl.c

@@ -215,7 +215,8 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 	    of_device_is_compatible(np, "nvidia,tegra186-smmu"))
 		return nvidia_smmu_impl_init(smmu);
 
-	smmu = qcom_smmu_impl_init(smmu);
+	if (IS_ENABLED(CONFIG_ARM_SMMU_QCOM))
+		smmu = qcom_smmu_impl_init(smmu);
 
 	if (of_device_is_compatible(np, "marvell,ap806-smmu-500"))
 		smmu->impl = &mrvl_mmu500_impl;

drivers/media/platform/Kconfig

@@ -565,7 +565,7 @@ config VIDEO_QCOM_VENUS
 	depends on VIDEO_DEV && VIDEO_V4L2 && QCOM_SMEM
 	depends on (ARCH_QCOM && IOMMU_DMA) || COMPILE_TEST
 	select QCOM_MDT_LOADER if ARCH_QCOM
-	select QCOM_SCM if ARCH_QCOM
+	select QCOM_SCM
 	select VIDEOBUF2_DMA_CONTIG
 	select V4L2_MEM2MEM_DEV
 	help

drivers/mmc/host/Kconfig

@@ -547,7 +547,7 @@ config MMC_SDHCI_MSM
 	depends on MMC_SDHCI_PLTFM
 	select MMC_SDHCI_IO_ACCESSORS
 	select MMC_CQHCI
-	select QCOM_SCM if MMC_CRYPTO && ARCH_QCOM
+	select QCOM_SCM if MMC_CRYPTO
 	help
 	  This selects the Secure Digital Host Controller Interface (SDHCI)
 	  support present in Qualcomm SOCs. The controller supports

drivers/net/ipa/Kconfig

@@ -4,6 +4,7 @@ config QCOM_IPA
 	depends on ARCH_QCOM || COMPILE_TEST
 	depends on QCOM_RPROC_COMMON || (QCOM_RPROC_COMMON=n && COMPILE_TEST)
 	select QCOM_MDT_LOADER if ARCH_QCOM
+	select QCOM_SCM
 	select QCOM_QMI_HELPERS
 	help
 	  Choose Y or M here to include support for the Qualcomm

drivers/net/wireless/ath/ath10k/Kconfig

@@ -44,7 +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_SCM
 	select QCOM_QMI_HELPERS
 	help
 	  This module adds support for integrated WCN3990 chip connected

drivers/pinctrl/qcom/Kconfig

@@ -3,7 +3,8 @@ if (ARCH_QCOM || COMPILE_TEST)
 
 config PINCTRL_MSM
 	tristate "Qualcomm core pin controller driver"
-	depends on GPIOLIB && (QCOM_SCM || !QCOM_SCM) #if QCOM_SCM=m this can't be =y
+	depends on GPIOLIB
+	select QCOM_SCM
 	select PINMUX
 	select PINCONF
 	select GENERIC_PINCONF

include/linux/arm-smccc.h

@@ -321,10 +321,20 @@ asmlinkage unsigned long __arm_smccc_sve_check(unsigned long x0);
  * from register 0 to 3 on return from the SMC instruction.  An optional
  * quirk structure provides vendor specific behavior.
  */
+#ifdef CONFIG_HAVE_ARM_SMCCC
 asmlinkage void __arm_smccc_smc(unsigned long a0, unsigned long a1,
 			unsigned long a2, unsigned long a3, unsigned long a4,
 			unsigned long a5, unsigned long a6, unsigned long a7,
 			struct arm_smccc_res *res, struct arm_smccc_quirk *quirk);
+#else
+static inline void __arm_smccc_smc(unsigned long a0, unsigned long a1,
+			unsigned long a2, unsigned long a3, unsigned long a4,
+			unsigned long a5, unsigned long a6, unsigned long a7,
+			struct arm_smccc_res *res, struct arm_smccc_quirk *quirk)
+{
+	*res = (struct arm_smccc_res){};
+}
+#endif
 
 /**
  * __arm_smccc_hvc() - make HVC calls

include/linux/qcom_scm.h

@@ -61,7 +61,6 @@ enum qcom_scm_ice_cipher {
 #define QCOM_SCM_PERM_RW (QCOM_SCM_PERM_READ | QCOM_SCM_PERM_WRITE)
 #define QCOM_SCM_PERM_RWX (QCOM_SCM_PERM_RW | QCOM_SCM_PERM_EXEC)
 
-#if IS_ENABLED(CONFIG_QCOM_SCM)
 extern bool qcom_scm_is_available(void);
 
 extern int qcom_scm_set_cold_boot_addr(void *entry, const cpumask_t *cpus);
@@ -115,74 +114,4 @@ extern int qcom_scm_lmh_dcvsh(u32 payload_fn, u32 payload_reg, u32 payload_val,
 extern int qcom_scm_lmh_profile_change(u32 profile_id);
 extern bool qcom_scm_lmh_dcvsh_available(void);
 
-#else
-
-#include <linux/errno.h>
-
-static inline bool qcom_scm_is_available(void) { return false; }
-
-static inline int qcom_scm_set_cold_boot_addr(void *entry,
-		const cpumask_t *cpus) { return -ENODEV; }
-static inline int qcom_scm_set_warm_boot_addr(void *entry,
-		const cpumask_t *cpus) { return -ENODEV; }
-static inline void qcom_scm_cpu_power_down(u32 flags) {}
-static inline u32 qcom_scm_set_remote_state(u32 state,u32 id)
-		{ return -ENODEV; }
-
-static inline int qcom_scm_pas_init_image(u32 peripheral, const void *metadata,
-		size_t size) { return -ENODEV; }
-static inline int qcom_scm_pas_mem_setup(u32 peripheral, phys_addr_t addr,
-		phys_addr_t size) { return -ENODEV; }
-static inline int qcom_scm_pas_auth_and_reset(u32 peripheral)
-		{ return -ENODEV; }
-static inline int qcom_scm_pas_shutdown(u32 peripheral) { return -ENODEV; }
-static inline bool qcom_scm_pas_supported(u32 peripheral) { return false; }
-
-static inline int qcom_scm_io_readl(phys_addr_t addr, unsigned int *val)
-		{ return -ENODEV; }
-static inline int qcom_scm_io_writel(phys_addr_t addr, unsigned int val)
-		{ return -ENODEV; }
-
-static inline bool qcom_scm_restore_sec_cfg_available(void) { return false; }
-static inline int qcom_scm_restore_sec_cfg(u32 device_id, u32 spare)
-		{ return -ENODEV; }
-static inline int qcom_scm_iommu_secure_ptbl_size(u32 spare, size_t *size)
-		{ return -ENODEV; }
-static inline int qcom_scm_iommu_secure_ptbl_init(u64 addr, u32 size, u32 spare)
-		{ return -ENODEV; }
-extern inline int qcom_scm_mem_protect_video_var(u32 cp_start, u32 cp_size,
-						 u32 cp_nonpixel_start,
-						 u32 cp_nonpixel_size)
-		{ return -ENODEV; }
-static inline int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz,
-		unsigned int *src, const struct qcom_scm_vmperm *newvm,
-		unsigned int dest_cnt) { return -ENODEV; }
-
-static inline bool qcom_scm_ocmem_lock_available(void) { return false; }
-static inline int qcom_scm_ocmem_lock(enum qcom_scm_ocmem_client id, u32 offset,
-		u32 size, u32 mode) { return -ENODEV; }
-static inline int qcom_scm_ocmem_unlock(enum qcom_scm_ocmem_client id,
-		u32 offset, u32 size) { return -ENODEV; }
-
-static inline bool qcom_scm_ice_available(void) { return false; }
-static inline int qcom_scm_ice_invalidate_key(u32 index) { return -ENODEV; }
-static inline int qcom_scm_ice_set_key(u32 index, const u8 *key, u32 key_size,
-				       enum qcom_scm_ice_cipher cipher,
-				       u32 data_unit_size) { return -ENODEV; }
-
-static inline bool qcom_scm_hdcp_available(void) { return false; }
-static inline int qcom_scm_hdcp_req(struct qcom_scm_hdcp_req *req, u32 req_cnt,
-		u32 *resp) { return -ENODEV; }
-
-static inline int qcom_scm_qsmmu500_wait_safe_toggle(bool en)
-		{ return -ENODEV; }
-
-static inline int qcom_scm_lmh_dcvsh(u32 payload_fn, u32 payload_reg, u32 payload_val,
-				     u64 limit_node, u32 node_id, u64 version)
-		{ return -ENODEV; }
-
-static inline int qcom_scm_lmh_profile_change(u32 profile_id) { return -ENODEV; }
-
-static inline bool qcom_scm_lmh_dcvsh_available(void) { return -ENODEV; }
-#endif
 #endif