| Message ID | 201304191640.32139.arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/19/2013 09:40 AM, Arnd Bergmann wrote: > 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 <arnd@arndb.de> > Acked-by: Nicolas Pitre <nico@linaro.org> > Acked-by: Olof Johansson <olof@lixom.net> > Cc: "Russell King - ARM Linux" <linux@arm.linux.org.uk> [...] > if (machine_desc->init_machine) > machine_desc->init_machine(); > + else > + of_platform_populate(NULL, of_default_bus_match_table, This will fail to build for !OF. of_platform.h needs this: #define of_default_bus_match_table NULL You may need some struct forward declarations, but this commit in my tree for 3.10 should fix those: commit d450f445f9a654080a6be4094376c2192d9a1f36 Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Date: Tue Feb 19 02:58:25 2013 +0300 <linux/of_platform.h>: fix compilation warnings with DT disabled Rob > + NULL, NULL); > return 0; > } > arch_initcall(customize_machine); >
On Friday 19 April 2013, Rob Herring wrote: > This will fail to build for !OF. of_platform.h needs this: > > #define of_default_bus_match_table NULL > > You may need some struct forward declarations, but this commit in my > tree for 3.10 should fix those: > > commit d450f445f9a654080a6be4094376c2192d9a1f36 > Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> > Date: Tue Feb 19 02:58:25 2013 +0300 > > <linux/of_platform.h>: fix compilation warnings with DT disabled > Ok. I've actually stumbled over missing declarations from of_platform.h and related files a number of times. Could we please not hide any declarations inside of #ifdef when there is no #else alternative? If we just show the of_default_bus_match_table declaration in the header file, there is no need to provide the silly NULL macro, since the of_platform_populate alternative will just ignore it. I'll just put the code in an #ifdef for now, but I'd really prefer to clean up this and many other locations that currently have to do #ifdef CONFIG_OF when they really don't need to. Arnd
On 04/19/2013 04:54 PM, Arnd Bergmann wrote: > On Friday 19 April 2013, Rob Herring wrote: >> This will fail to build for !OF. of_platform.h needs this: >> >> #define of_default_bus_match_table NULL >> >> You may need some struct forward declarations, but this commit in my >> tree for 3.10 should fix those: >> >> commit d450f445f9a654080a6be4094376c2192d9a1f36 >> Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> >> Date: Tue Feb 19 02:58:25 2013 +0300 >> >> <linux/of_platform.h>: fix compilation warnings with DT disabled >> > > Ok. I've actually stumbled over missing declarations from of_platform.h > and related files a number of times. Could we please not hide any > declarations inside of #ifdef when there is no #else alternative? > > If we just show the of_default_bus_match_table declaration in the > header file, there is no need to provide the silly NULL macro, > since the of_platform_populate alternative will just ignore it. > > I'll just put the code in an #ifdef for now, but I'd really prefer > to clean up this and many other locations that currently have > to do #ifdef CONFIG_OF when they really don't need to. I think we can kill off CONFIG_OF_DEVICE completely. It is always enabled when OF is (even for the oddball Sparc). The only remaining user of of_platform_driver is ibmebus and 2 drivers. It would be good to convert those to regular platform drivers. Rob
On Saturday 20 April 2013, Rob Herring wrote: > The only remaining user of of_platform_driver is ibmebus and 2 drivers. > It would be good to convert those to regular platform drivers. > Right, I would not expect any trouble in converting ibmebus to use a regular platform_driver. It already uses platform_device anyway. We cannot remove ibmebus itself because it has special DMA requirements, but we could move it to drivers/bus if the powerpc maintainers like that. Arnd.
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 <linux/bootmem.h> #include <linux/seq_file.h> #include <linux/screen_info.h> +#include <linux/of_platform.h> #include <linux/init.h> #include <linux/kexec.h> #include <linux/of_fdt.h> @@ -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);