Le 19/08/2022 à 23:12, Pali Rohár a écrit : > Currently powerpc early debugging contains lot of platform specific > options, but does not support standard UART / serial 16550 console. > > Later legacy_serial.c code supports registering UART as early debug console > from device tree but it is not early during booting, but rather later after > machine description code finishes. > > So for real early debugging via UART is current code unsuitable. > > Add support for new early debugging option CONFIG_PPC_EARLY_DEBUG_16550 > which enable Serial 16550 console on address defined by new option > CONFIG_PPC_EARLY_DEBUG_16550_PHYSADDR and by stride by option > CONFIG_PPC_EARLY_DEBUG_16550_STRIDE. > > With this change it is possible to debug powerpc machine descriptor code. > For example this early debugging code can print on serial console also > "No suitable machine description found" error which is done before > legacy_serial.c code. > > Signed-off-by: Pali Rohár <p...@kernel.org> > --- > Tested on P2020 board. It allowed me do debug and implement this patch series: > https://lore.kernel.org/linuxppc-dev/20220819191557.28116-1-p...@kernel.org/
Build failure if I select it on mpc885_ads_defconfig : LD vmlinux.o MODPOST vmlinux.symvers MODINFO modules.builtin.modinfo GEN modules.builtin CC .vmlinux.export.o LD .tmp_vmlinux.kallsyms1 powerpc64-linux-ld: arch/powerpc/kernel/udbg.o: in function `udbg_early_init': /home/chleroy/linux-powerpc/arch/powerpc/kernel/udbg.c:71: undefined reference to `udbg_init_debug_16550' > --- > arch/powerpc/Kconfig.debug | 14 ++++++++++++++ > arch/powerpc/include/asm/udbg.h | 1 + > arch/powerpc/kernel/udbg.c | 2 ++ > arch/powerpc/kernel/udbg_16550.c | 33 ++++++++++++++++++++++++++++++++ > 4 files changed, 50 insertions(+) > > diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug > index 9f363c143d86..a4e7d90a45d2 100644 > --- a/arch/powerpc/Kconfig.debug > +++ b/arch/powerpc/Kconfig.debug > @@ -276,6 +276,11 @@ config PPC_EARLY_DEBUG_OPAL_HVSI > Select this to enable early debugging for the PowerNV platform > using an "hvsi" console > > +config PPC_EARLY_DEBUG_16550 > + bool "Serial 16550" > + help > + Select this to enable early debugging via Serial 16550 console > + Putting it before EARLY_DEBUG_MEMCONS means that configs that were previously selectiong EARLY_DEBUG_MEMCONS will now select EARLY_DEBUG_16550 instead. Add a dependency to PPC_UDBG_16550 to avoid the build failure I mentionned ? > config PPC_EARLY_DEBUG_MEMCONS > bool "In memory console" > help > @@ -355,6 +360,15 @@ config PPC_EARLY_DEBUG_CPM_ADDR > platform probing is done, all platforms selected must > share the same address. > > +config PPC_EARLY_DEBUG_16550_PHYSADDR > + hex "Early debug Serial 16550 physical address" > + depends on PPC_EARLY_DEBUG_16550 A default value is necessary here to avoid prompts during defconfig builds. > + > +config PPC_EARLY_DEBUG_16550_STRIDE > + int "Early debug Serial 16550 stride" > + depends on PPC_EARLY_DEBUG_16550 > + default 1 > + > config FAIL_IOMMU > bool "Fault-injection capability for IOMMU" > depends on FAULT_INJECTION > diff --git a/arch/powerpc/include/asm/udbg.h b/arch/powerpc/include/asm/udbg.h > index b4aa0d88ce2c..20b5a37ab772 100644 > --- a/arch/powerpc/include/asm/udbg.h > +++ b/arch/powerpc/include/asm/udbg.h > @@ -53,6 +53,7 @@ extern void __init udbg_init_ehv_bc(void); > extern void __init udbg_init_ps3gelic(void); > extern void __init udbg_init_debug_opal_raw(void); > extern void __init udbg_init_debug_opal_hvsi(void); > +extern void __init udbg_init_debug_16550(void); 'extern' keywork is pointless and deprecated for function prototypes, please don't add new ones. Checkpatch reports: CHECK: extern prototypes should be avoided in .h files #77: FILE: arch/powerpc/include/asm/udbg.h:56: +extern void __init udbg_init_debug_16550(void); > > #endif /* __KERNEL__ */ > #endif /* _ASM_POWERPC_UDBG_H */ > diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c > index b1544b2f6321..92b3fc258d11 100644 > --- a/arch/powerpc/kernel/udbg.c > +++ b/arch/powerpc/kernel/udbg.c > @@ -67,6 +67,8 @@ void __init udbg_early_init(void) > udbg_init_debug_opal_raw(); > #elif defined(CONFIG_PPC_EARLY_DEBUG_OPAL_HVSI) > udbg_init_debug_opal_hvsi(); > +#elif defined(CONFIG_PPC_EARLY_DEBUG_16550) > + udbg_init_debug_16550(); > #endif > > #ifdef CONFIG_PPC_EARLY_DEBUG > diff --git a/arch/powerpc/kernel/udbg_16550.c > b/arch/powerpc/kernel/udbg_16550.c > index d3942de254c6..46f2d831d7c9 100644 > --- a/arch/powerpc/kernel/udbg_16550.c > +++ b/arch/powerpc/kernel/udbg_16550.c > @@ -8,6 +8,7 @@ > #include <asm/udbg.h> > #include <asm/io.h> > #include <asm/reg_a2.h> > +#include <asm/early_ioremap.h> > > extern u8 real_readb(volatile u8 __iomem *addr); > extern void real_writeb(u8 data, volatile u8 __iomem *addr); > @@ -335,3 +336,35 @@ void __init udbg_init_debug_microwatt(void) > } > > #endif /* CONFIG_PPC_EARLY_DEBUG_MICROWATT */ > + > +#ifdef CONFIG_PPC_EARLY_DEBUG_16550 > + > +static void __iomem *udbg_uart_early_addr; > + > +void __init udbg_init_debug_16550(void) > +{ > + udbg_uart_early_addr = > early_ioremap(CONFIG_PPC_EARLY_DEBUG_16550_PHYSADDR, 0x1000); > + udbg_uart_init_mmio(udbg_uart_early_addr, > CONFIG_PPC_EARLY_DEBUG_16550_STRIDE); > +} > + > +static int __init udbg_init_debug_16550_ioremap(void) > +{ > + void __iomem *addr; > + > + if (!udbg_uart_early_addr) > + return 0; > + > + addr = ioremap(CONFIG_PPC_EARLY_DEBUG_16550_PHYSADDR, 0x1000); > + if (WARN_ON(!addr)) > + return -ENOMEM; > + > + udbg_uart_init_mmio(addr, CONFIG_PPC_EARLY_DEBUG_16550_STRIDE); > + early_iounmap(udbg_uart_early_addr, 0x1000); > + udbg_uart_early_addr = NULL; > + > + return 0; > +} > + > +early_initcall(udbg_init_debug_16550_ioremap); > + > +#endif /* CONFIG_PPC_EARLY_DEBUG_16550 */