On Mon, Aug 22, 2022 at 05:33:35PM +0200, Pali Rohár wrote: > On Monday 22 August 2022 14:25:57 Christophe Leroy wrote: > > 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 ? > > Yea, there is really missing dependency. I will fix it. > > > > 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. > > I used extern keyword to follow existing coding style.
In this case it's better to remove existing extern specifications in the surrounding lines. Increasing a bit the footprint of the patch is justified, and does not significantly increase the risk of conflicts with other patches, unlike the gratuitous churn we see sometimes. Gabriel > > > 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 */