Hi Daniel, On Tue, Aug 25, 2026 at 4:24 PM Daniel Henrique Barboza <[email protected]> wrote: > > Add a common uart FDT helper to be used by 'virt' and 'tt-atlantis'. > > To accomodate both boards the helper is doing the following: > - an 'additional_reg_props' flag is used to control whether we want > 'reg-shift' and 'reg-io-width' elements added. OpenSBI won't boot > with the tt-atlantis board without them, but 'virt' can't deal with > them being added unconditionally either. > - an 'is_serial0' flag is added to control whether we need to set > additional properties related to the first serial. This is required > because the 'virt' board adds two uarts in the FDT. > > No FDT changes intended. > > Signed-off-by: Daniel Henrique Barboza <[email protected]> > --- > hw/riscv/fdt-common.c | 39 +++++++++++++++++++++++++++++++ > hw/riscv/tt_atlantis.c | 21 +---------------- > hw/riscv/virt.c | 44 +++++++---------------------------- > include/hw/riscv/fdt-common.h | 4 ++++ > 4 files changed, 52 insertions(+), 56 deletions(-) > > diff --git a/hw/riscv/fdt-common.c b/hw/riscv/fdt-common.c > index f31cc9d3cc..b3f3af3762 100644 > --- a/hw/riscv/fdt-common.c > +++ b/hw/riscv/fdt-common.c > @@ -791,3 +791,42 @@ void create_fdt_socket_aclint(void *fdt, ACLINTFdtProps > *props, > g_free(name); > } > } > + > +void create_fdt_uart(void *fdt, const MemMapEntry *uart_mem, > + int uart_irq, int aia_type, > + bool additional_reg_props, bool is_serial0, > + uint32_t irq_mmio_phandle) > +{ > + g_autofree char *name = NULL; > + > + name = g_strdup_printf("/soc/serial@%"HWADDR_PRIx, uart_mem->base); > + qemu_fdt_add_subnode(fdt, name); > + qemu_fdt_setprop_string(fdt, name, "compatible", "ns16550a"); > + qemu_fdt_setprop_sized_cells(fdt, name, "reg", > + 2, uart_mem->base, > + 2, uart_mem->size); > + > + /* > + * The tt-atlantis board requires these extra props in the > + * DT, but adding them unconditionally will break OpenSBI > + * for 'virt'. > + */ > + if (additional_reg_props) { > + qemu_fdt_setprop_cell(fdt, name, "reg-shift", 2); > + qemu_fdt_setprop_cell(fdt, name, "reg-io-width", 4); > + }
I think the issue is that atlantis uses a uart that has 32 bit register spacing (0x0, 0x4, 0x8, 0xc....) rather than 8 bit spacing (0x0, 0x1, 0x2...). So rather than "additional_reg_props", would a name like "word_addressing" or "32_bit_spacing" make sense? Regards Anirudh Srinivasan
