From e2f82f93f885dd3dd3ad74e98182add8ccd863e7 Mon Sep 17 00:00:00 2001 From: Stephan Gerhold Date: Wed, 7 Jul 2021 12:58:55 +0200 Subject: [PATCH] board: stemmy: Copy atags for booting downstream/vendor kernel The U-Boot "stemmy" board is mainly intended to simplify booting mainline Linux on various smartphones from Samsung based on ST-Ericsson Ux500. While the mainline kernel is working great, there are still some features missing there. In particular, it is currently not possible to charge the battery when using the mainline kernel. This means that it is still necessary to boot the downstream/vendor kernel from Samsung sometimes to charge the device. That kernel is ancient, still uses board files + ATAGS instead of device trees and relies on a strange very long kernel command line hardcoded in the Samsung bootloader. Actually, since mainline is booted with device trees there is a very simple way to make the old downstream kernel work as well: We can simply take most of the ATAGS passed to U-Boot from the Samsung bootloader and copy them as-is when booting a kernel without device tree. That way the long command line and other needed ATAGS are copied as-is without having to bother with them. The only exception is the ATAG_INITRD - since the initrd is loaded by U-Boot, the atag for that should be generated in U-Boot so it points to the correct address. All other ATAGS are copied as-is and not generated in U-Boot. Also use the chance and provide a serial# for U-Boot by parsing the ATAG_SERIAL that is also passed by the Samsung bootloader. Signed-off-by: Stephan Gerhold Reviewed-by: Linus Walleij --- arch/arm/mach-u8500/Kconfig | 1 + board/ste/stemmy/stemmy.c | 87 +++++++++++++++++++++++++++++++++++++ include/configs/stemmy.h | 3 ++ 3 files changed, 91 insertions(+) diff --git a/arch/arm/mach-u8500/Kconfig b/arch/arm/mach-u8500/Kconfig index 372fbeb80f..db7a29a54c 100644 --- a/arch/arm/mach-u8500/Kconfig +++ b/arch/arm/mach-u8500/Kconfig @@ -8,6 +8,7 @@ choice config TARGET_STEMMY bool "Samsung (stemmy) board" + select MISC_INIT_R help The Samsung "stemmy" board supports Samsung smartphones released with the ST-Ericsson NovaThor U8500 SoC, e.g. diff --git a/board/ste/stemmy/stemmy.c b/board/ste/stemmy/stemmy.c index 9e6c8e208e..5f1150c0c7 100644 --- a/board/ste/stemmy/stemmy.c +++ b/board/ste/stemmy/stemmy.c @@ -3,8 +3,10 @@ * Copyright (C) 2019 Stephan Gerhold */ #include +#include #include #include +#include #include #include #include @@ -15,6 +17,9 @@ DECLARE_GLOBAL_DATA_PTR; static ulong fw_mach __section(".data"); static ulong fw_atags __section(".data"); +static const struct tag *fw_atags_copy; +static uint fw_atags_size; + void save_boot_params(ulong r0, ulong r1, ulong r2, ulong r3) { fw_mach = r1; @@ -78,3 +83,85 @@ int board_init(void) gd->bd->bi_boot_params = fw_atags; return 0; } + +static void parse_serial(const struct tag_serialnr *serialnr) +{ + char serial[17]; + + if (env_get("serial#")) + return; + + sprintf(serial, "%08x%08x", serialnr->high, serialnr->low); + env_set("serial#", serial); +} + +/* + * The downstream/vendor kernel (provided by Samsung) uses ATAGS for booting. + * It also requires an extremely long cmdline provided by the primary bootloader + * that is not suitable for booting mainline. + * + * Since downstream is the only user of ATAGS, we emulate the behavior of the + * Samsung bootloader by generating only the initrd atag in U-Boot, and copying + * all other ATAGS as-is from the primary bootloader. + */ +static inline bool skip_atag(u32 tag) +{ + return (tag == ATAG_NONE || tag == ATAG_CORE || + tag == ATAG_INITRD || tag == ATAG_INITRD2); +} + +static void copy_atags(const struct tag *tags) +{ + const struct tag *t; + struct tag *copy; + + if (!tags) + return; + + /* Calculate necessary size for tags we want to copy */ + for_each_tag(t, tags) { + if (skip_atag(t->hdr.tag)) + continue; + + if (t->hdr.tag == ATAG_SERIAL) + parse_serial(&t->u.serialnr); + + fw_atags_size += t->hdr.size * sizeof(u32); + } + + if (!fw_atags_size) + return; /* No tags to copy */ + + copy = malloc(fw_atags_size); + if (!copy) + return; + fw_atags_copy = copy; + + /* Copy tags */ + for_each_tag(t, tags) { + if (skip_atag(t->hdr.tag)) + continue; + + memcpy(copy, t, t->hdr.size * sizeof(u32)); + copy = tag_next(copy); + } +} + +int misc_init_r(void) +{ + copy_atags(fw_atags_get()); + return 0; +} + +void setup_board_tags(struct tag **in_params) +{ + if (!fw_atags_copy) + return; + + /* + * fw_atags_copy contains only full "struct tag" (plus data) + * so copying it bytewise here should be fine. + */ + memcpy(*in_params, fw_atags_copy, fw_atags_size); + *(u8 **)in_params += fw_atags_size; +} diff --git a/include/configs/stemmy.h b/include/configs/stemmy.h index c446b09270..b94ef91c2b 100644 --- a/include/configs/stemmy.h +++ b/include/configs/stemmy.h @@ -23,4 +23,7 @@ #define CONFIG_SYS_L2_PL310 #define CONFIG_SYS_PL310_BASE 0xa0412000 +/* Generate initrd atag for downstream kernel (others are copied in stemmy.c) */ +#define CONFIG_INITRD_TAG + #endif -- 2.39.5