From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Fri, 19 Apr 2013 16:40:31 +0200 Subject: [PATCH v3] ARM: default machine descriptor for multiplatform In-Reply-To: <201304191621.54681.arnd@arndb.de> References: <1365779468-116419-1-git-send-email-arnd@arndb.de> <20130419132848.GO14496@n2100.arm.linux.org.uk> <201304191621.54681.arnd@arndb.de> Message-ID: <201304191640.32139.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Since we now have default implementations for init_time and init_irq, the init_machine callback is the only one that is not yet optional, but since simple DT based platforms all have the same of_platform_populate function call in there, we can consolidate them as well, and then actually boot with a completely empty machine_desc. Unofortunately we cannot just default to an empty init_machine: We cannot call of_platform_populate before init_machine because that does not work in case of auxdata, and we cannot call it after init_machine either because the machine might need to run code after adding the devices. To take the final step, this adds support for booting without defining any machine_desc whatsoever. For the case that CONFIG_MULTIPLATFORM is enabled, it adds a global machine descriptor that never matches any machine but is used as a fallback if nothing else matches. We assume that without CONFIG_MULTIPLATFORM, we only want to boot on the systems that the kernel is built for, so we still retain the build-time warning for missing machine descriptors and the run-time warning when the platform does not match in that case. In the case that we run on a multiplatform kernel and the machine provides a fully populated device tree, we attempt to keep booting, hoping that no machine specific callbacks are necessary. Finally, this also removes the misguided "select ARCH_VEXPRESS" that was only added to avoid a build error for allnoconfig kernels. Signed-off-by: Arnd Bergmann Acked-by: Nicolas Pitre Acked-by: Olof Johansson Cc: "Russell King - ARM Linux" Cc: Rob Herring diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 1cacda4..e67d49d 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1014,7 +1014,6 @@ config ARCH_MULTI_V7 bool "ARMv7 based platforms (Cortex-A, PJ4, Scorpion, Krait)" default y select ARCH_MULTI_V6_V7 - select ARCH_VEXPRESS select CPU_V7 config ARCH_MULTI_V6_V7 diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c index 70f1bde..9038c9f 100644 --- a/arch/arm/kernel/devtree.c +++ b/arch/arm/kernel/devtree.c @@ -180,6 +180,13 @@ struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys) unsigned long dt_root; const char *model; + if (IS_ENABLED(CONFIG_ARCH_MULTIPLATFORM)) { + DT_MACHINE_START(GENERIC_DT, "Generic DT based system") + MACHINE_END + + mdesc_best = (struct machine_desc *)&__mach_desc_GENERIC_DT; + } + if (!dt_phys) return NULL; diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index d343a6c..9e0f43d 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -660,9 +661,17 @@ struct screen_info screen_info = { static int __init customize_machine(void) { - /* customizes platform devices, or adds new ones */ + /* + * customizes platform devices, or adds new ones + * On DT based machines, we fall back to populating the + * machine from the device tree, if no callback is provided, + * otherwise we would always need an init_machine callback. + */ if (machine_desc->init_machine) machine_desc->init_machine(); + else + of_platform_populate(NULL, of_default_bus_match_table, + NULL, NULL); return 0; } arch_initcall(customize_machine);