From 2d2682512f0faf4d09a696184bf3c0bb6838baca Mon Sep 17 00:00:00 2001 From: Palmer Dabbelt Date: Tue, 14 Apr 2020 13:43:24 +0900 Subject: riscv: Allow device trees to be built into the kernel Some systems don't provide a useful device tree to the kernel on boot. Chasing around bootloaders for these systems is a headache, so instead le't's just keep a device tree table in the kernel, keyed by the SOC's unique identifier, that contains the relevant DTB. This is only implemented for M mode right now. While we could implement this via the SBI calls that allow access to these identifiers, we don't have any systems that need this right now. Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/soc.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'arch/riscv/kernel/soc.c') diff --git a/arch/riscv/kernel/soc.c b/arch/riscv/kernel/soc.c index 0b3b3dc9ad0f..1fc87621c728 100644 --- a/arch/riscv/kernel/soc.c +++ b/arch/riscv/kernel/soc.c @@ -26,3 +26,30 @@ void __init soc_early_init(void) } } } + +static bool soc_builtin_dtb_match(unsigned long vendor_id, + unsigned long arch_id, unsigned long imp_id, + const struct soc_builtin_dtb *entry) +{ + return entry->vendor_id == vendor_id && + entry->arch_id == arch_id && + entry->imp_id == imp_id; +} + +void * __init soc_lookup_builtin_dtb(void) +{ + unsigned long vendor_id, arch_id, imp_id; + const struct soc_builtin_dtb *s; + + __asm__ ("csrr %0, mvendorid" : "=r"(vendor_id)); + __asm__ ("csrr %0, marchid" : "=r"(arch_id)); + __asm__ ("csrr %0, mimpid" : "=r"(imp_id)); + + for (s = (void *)&__soc_builtin_dtb_table_start; + (void *)s < (void *)&__soc_builtin_dtb_table_end; s++) { + if (soc_builtin_dtb_match(vendor_id, arch_id, imp_id, s)) + return s->dtb_func(); + } + + return NULL; +} -- cgit v1.2.3