riscv: Add kconfig option to run U-Boot in S-mode
This patch adds kconfig option RISCV_SMODE to run U-Boot in
S-mode. When this opition is enabled we use s<xyz> CSRs instead
of m<xyz> CSRs.
It is important to note that there is no equivalent S-mode CSR
for misa and mhartid CSRs so we expect M-mode runtime firmware
(BBL or equivalent) to emulate misa and mhartid CSR read.
In-future, we will have more patches to avoid accessing misa and
mhartid CSRs from S-mode.
Signed-off-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
diff --git a/arch/riscv/lib/interrupts.c b/arch/riscv/lib/interrupts.c
index 903a1c4..3aff006 100644
--- a/arch/riscv/lib/interrupts.c
+++ b/arch/riscv/lib/interrupts.c
@@ -34,17 +34,30 @@
return 0;
}
-ulong handle_trap(ulong mcause, ulong epc, struct pt_regs *regs)
+ulong handle_trap(ulong cause, ulong epc, struct pt_regs *regs)
{
- ulong is_int;
+ ulong is_irq, irq;
- is_int = (mcause & MCAUSE_INT);
- if ((is_int) && ((mcause & MCAUSE_CAUSE) == IRQ_M_EXT))
- external_interrupt(0); /* handle_m_ext_interrupt */
- else if ((is_int) && ((mcause & MCAUSE_CAUSE) == IRQ_M_TIMER))
- timer_interrupt(0); /* handle_m_timer_interrupt */
- else
- _exit_trap(mcause, epc, regs);
+ is_irq = (cause & MCAUSE_INT);
+ irq = (cause & ~MCAUSE_INT);
+
+ if (is_irq) {
+ switch (irq) {
+ case IRQ_M_EXT:
+ case IRQ_S_EXT:
+ external_interrupt(0); /* handle external interrupt */
+ break;
+ case IRQ_M_TIMER:
+ case IRQ_S_TIMER:
+ timer_interrupt(0); /* handle timer interrupt */
+ break;
+ default:
+ _exit_trap(cause, epc, regs);
+ break;
+ };
+ } else {
+ _exit_trap(cause, epc, regs);
+ }
return epc;
}