platform/x86: dell-smbios: Link all dell-smbios-* modules together

Some race conditions were raised due to dell-smbios and its backends
not being ready by the time that a consumer would call one of the
exported methods.

To avoid this problem, guarantee that all initialization has been
done by linking them all together and running init for them all.

As part of this change the Kconfig needs to be adjusted so that
CONFIG_DELL_SMBIOS_SMM and CONFIG_DELL_SMBIOS_WMI are boolean
rather than modules.

CONFIG_DELL_SMBIOS is a visually selectable option again and both
CONFIG_DELL_SMBIOS_WMI and CONFIG_DELL_SMBIOS_SMM are optional.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
[dvhart: Update prompt and help text for DELL_SMBIOS_* backends]
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/Kconfig

@@ -106,30 +106,35 @@ config ASUS_LAPTOP
 	  If you have an ACPI-compatible ASUS laptop, say Y or M here.
 
 config DELL_SMBIOS
-	tristate
+	tristate "Dell SMBIOS driver"
+	---help---
+	This provides support for the Dell SMBIOS calling interface.
+	If you have a Dell computer you should enable this option.
+
+	Be sure to select at least one backend for it to work properly.
 
 config DELL_SMBIOS_WMI
-	tristate "Dell SMBIOS calling interface (WMI implementation)"
+	bool "Dell SMBIOS driver WMI backend"
 	depends on ACPI_WMI
 	select DELL_WMI_DESCRIPTOR
 	select DELL_SMBIOS
 	---help---
 	This provides an implementation for the Dell SMBIOS calling interface
 	communicated over ACPI-WMI.
 
-	If you have a Dell computer from >2007 you should say Y or M here.
+	If you have a Dell computer from >2007 you should say Y here.
 	If you aren't sure and this module doesn't work for your computer
 	it just won't load.
 
 config DELL_SMBIOS_SMM
-	tristate "Dell SMBIOS calling interface (SMM implementation)"
+	bool "Dell SMBIOS driver SMM backend"
 	depends on DCDBAS
 	select DELL_SMBIOS
 	---help---
 	This provides an implementation for the Dell SMBIOS calling interface
 	communicated over SMI/SMM.
 
-	If you have a Dell computer from <=2017 you should say Y or M here.
+	If you have a Dell computer from <=2017 you should say Y here.
 	If you aren't sure and this module doesn't work for your computer
 	it just won't load.
 

drivers/platform/x86/Makefile

@@ -14,8 +14,8 @@ obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o
 obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
 obj-$(CONFIG_DELL_SMBIOS)	+= dell-smbios.o
 dell-smbios-objs		:= dell-smbios-base.o
-obj-$(CONFIG_DELL_SMBIOS_WMI)	+= dell-smbios-wmi.o
-obj-$(CONFIG_DELL_SMBIOS_SMM)	+= dell-smbios-smm.o
+dell-smbios-$(CONFIG_DELL_SMBIOS_WMI)	+= dell-smbios-wmi.o
+dell-smbios-$(CONFIG_DELL_SMBIOS_SMM)	+= dell-smbios-smm.o
 obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
 obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
 obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o

drivers/platform/x86/dell-smbios-base.c

@@ -556,7 +556,7 @@ static void free_group(struct platform_device *pdev)
 static int __init dell_smbios_init(void)
 {
 	const struct dmi_device *valid;
-	int ret;
+	int ret, wmi, smm;
 
 	valid = dmi_find_device(DMI_DEV_TYPE_OEM_STRING, "Dell System", NULL);
 	if (!valid) {
@@ -591,8 +591,24 @@ static int __init dell_smbios_init(void)
 	if (ret)
 		goto fail_create_group;
 
+	/* register backends */
+	wmi = init_dell_smbios_wmi();
+	if (wmi)
+		pr_debug("Failed to initialize WMI backend: %d\n", wmi);
+	smm = init_dell_smbios_smm();
+	if (smm)
+		pr_debug("Failed to initialize SMM backend: %d\n", smm);
+	if (wmi && smm) {
+		pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
+			wmi, smm);
+		goto fail_sysfs;
+	}
+
 	return 0;
 
+fail_sysfs:
+	free_group(platform_device);
+
 fail_create_group:
 	platform_device_del(platform_device);
 
@@ -609,6 +625,8 @@ static int __init dell_smbios_init(void)
 
 static void __exit dell_smbios_exit(void)
 {
+	exit_dell_smbios_wmi();
+	exit_dell_smbios_smm();
 	mutex_lock(&smbios_mutex);
 	if (platform_device) {
 		free_group(platform_device);
@@ -625,5 +643,6 @@ module_exit(dell_smbios_exit);
 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
 MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
+MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
 MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
 MODULE_LICENSE("GPL");

drivers/platform/x86/dell-smbios-smm.c

@@ -58,7 +58,7 @@ static const struct dmi_system_id dell_device_table[] __initconst = {
 };
 MODULE_DEVICE_TABLE(dmi, dell_device_table);
 
-static void __init parse_da_table(const struct dmi_header *dm)
+static void parse_da_table(const struct dmi_header *dm)
 {
 	struct calling_interface_structure *table =
 		container_of(dm, struct calling_interface_structure, header);
@@ -73,7 +73,7 @@ static void __init parse_da_table(const struct dmi_header *dm)
 	da_command_code = table->cmdIOCode;
 }
 
-static void __init find_cmd_address(const struct dmi_header *dm, void *dummy)
+static void find_cmd_address(const struct dmi_header *dm, void *dummy)
 {
 	switch (dm->type) {
 	case 0xda: /* Calling interface */
@@ -128,7 +128,7 @@ static bool test_wsmt_enabled(void)
 	return false;
 }
 
-static int __init dell_smbios_smm_init(void)
+int init_dell_smbios_smm(void)
 {
 	int ret;
 	/*
@@ -176,21 +176,11 @@ static int __init dell_smbios_smm_init(void)
 	return ret;
 }
 
-static void __exit dell_smbios_smm_exit(void)
+void exit_dell_smbios_smm(void)
 {
 	if (platform_device) {
 		dell_smbios_unregister_device(&platform_device->dev);
 		platform_device_unregister(platform_device);
 		free_page((unsigned long)buffer);
 	}
 }
-
-subsys_initcall(dell_smbios_smm_init);
-module_exit(dell_smbios_smm_exit);
-
-MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
-MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
-MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
-MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
-MODULE_DESCRIPTION("Dell SMBIOS communications over SMI");
-MODULE_LICENSE("GPL");

drivers/platform/x86/dell-smbios-wmi.c

@@ -228,7 +228,7 @@ static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
 	{ },
 };
 
-static void __init parse_b1_table(const struct dmi_header *dm)
+static void parse_b1_table(const struct dmi_header *dm)
 {
 	struct misc_bios_flags_structure *flags =
 	container_of(dm, struct misc_bios_flags_structure, header);
@@ -242,7 +242,7 @@ static void __init parse_b1_table(const struct dmi_header *dm)
 		wmi_supported = 1;
 }
 
-static void __init find_b1(const struct dmi_header *dm, void *dummy)
+static void find_b1(const struct dmi_header *dm, void *dummy)
 {
 	switch (dm->type) {
 	case 0xb1: /* misc bios flags */
@@ -261,7 +261,7 @@ static struct wmi_driver dell_smbios_wmi_driver = {
 	.filter_callback = dell_smbios_wmi_filter,
 };
 
-static int __init init_dell_smbios_wmi(void)
+int init_dell_smbios_wmi(void)
 {
 	dmi_walk(find_b1, NULL);
 
@@ -271,15 +271,9 @@ static int __init init_dell_smbios_wmi(void)
 	return wmi_driver_register(&dell_smbios_wmi_driver);
 }
 
-static void __exit exit_dell_smbios_wmi(void)
+void exit_dell_smbios_wmi(void)
 {
 	wmi_driver_unregister(&dell_smbios_wmi_driver);
 }
 
-module_init(init_dell_smbios_wmi);
-module_exit(exit_dell_smbios_wmi);
-
 MODULE_ALIAS("wmi:" DELL_WMI_SMBIOS_GUID);
-MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
-MODULE_DESCRIPTION("Dell SMBIOS communications over WMI");
-MODULE_LICENSE("GPL");

drivers/platform/x86/dell-smbios.h

@@ -75,4 +75,29 @@ int dell_laptop_register_notifier(struct notifier_block *nb);
 int dell_laptop_unregister_notifier(struct notifier_block *nb);
 void dell_laptop_call_notifier(unsigned long action, void *data);
 
-#endif
+/* for the supported backends */
+#ifdef CONFIG_DELL_SMBIOS_WMI
+int init_dell_smbios_wmi(void);
+void exit_dell_smbios_wmi(void);
+#else /* CONFIG_DELL_SMBIOS_WMI */
+static inline int init_dell_smbios_wmi(void)
+{
+	return -ENODEV;
+}
+static inline void exit_dell_smbios_wmi(void)
+{}
+#endif /* CONFIG_DELL_SMBIOS_WMI */
+
+#ifdef CONFIG_DELL_SMBIOS_SMM
+int init_dell_smbios_smm(void);
+void exit_dell_smbios_smm(void);
+#else /* CONFIG_DELL_SMBIOS_SMM */
+static inline int init_dell_smbios_smm(void)
+{
+	return -ENODEV;
+}
+static inline void exit_dell_smbios_smm(void)
+{}
+#endif /* CONFIG_DELL_SMBIOS_SMM */
+
+#endif /* _DELL_SMBIOS_H_ */