The variation in access size requirements and spacing of registers of

NS16550 clones is a bit of a mess.  There are FDT properties that describe
these but these proprties are optional for some variants and the default
values depend on the compatible string being used.  Most variants that have
shown up in the ARM world use 32-bit access and spacing.  But true NS16550A
implementations of course use 8-bit access and spacing.  So look at the
compatible strings to set up the appropriate defaults.  Makes the "true"
NS16550A implemented by QEMU work for RISCV targets.

ok jsg@, drahn@

diff --git a/sys/dev/fdt/com_fdt.c b/sys/dev/fdt/com_fdt.c
index 29a6528..c8192b2 100644 (file)
--- a/sys/dev/fdt/com_fdt.c
+++ b/sys/dev/fdt/com_fdt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: com_fdt.c,v 1.4 2020/03/23 21:40:01 uaa Exp $ */
+/* $OpenBSD: com_fdt.c,v 1.5 2021/04/24 10:33:09 kettenis Exp $ */
 /*
  * Copyright (c) 2016 Patrick Wildt <patrick@blueri.se>
  *
@@ -52,11 +52,13 @@ void
 com_fdt_init_cons(void)
 {
        struct fdt_reg reg;
+       uint32_t width, shift;
        void *node;
 
        if ((node = fdt_find_cons("brcm,bcm2835-aux-uart")) == NULL &&
-           (node = fdt_find_cons("snps,dw-apb-uart")) == NULL &&
            (node = fdt_find_cons("marvell,armada-38x-uart")) == NULL &&
+           (node = fdt_find_cons("ns16550a")) == NULL &&
+           (node = fdt_find_cons("snps,dw-apb-uart")) == NULL &&
            (node = fdt_find_cons("ti,omap3-uart")) == NULL &&
            (node = fdt_find_cons("ti,omap4-uart")) == NULL)
                        return;
@@ -71,8 +73,16 @@ com_fdt_init_cons(void)
         * comcnattach() does by doing the minimal setup here.
         */
 
-       comcons_reg_width = OF_getpropint(stdout_node, "reg-io-width", 4);
-       comcons_reg_shift = OF_getpropint(stdout_node, "reg-shift", 2);
+       if (OF_is_compatible(stdout_node, "ns16550a")) {
+               width = 1;
+               shift = 0;
+       } else {
+               width = 4;
+               shift = 2;
+       }
+
+       comcons_reg_width = OF_getpropint(stdout_node, "reg-io-width", width);
+       comcons_reg_shift = OF_getpropint(stdout_node, "reg-shift", shift);
 
        comconsiot = fdt_cons_bs_tag;
        if (bus_space_map(comconsiot, reg.addr, reg.size, 0, &comconsioh))
@@ -87,8 +97,9 @@ com_fdt_match(struct device *parent, void *match, void *aux)
        struct fdt_attach_args *faa = aux;
 
        return (OF_is_compatible(faa->fa_node, "brcm,bcm2835-aux-uart") ||
-           OF_is_compatible(faa->fa_node, "snps,dw-apb-uart") ||
            OF_is_compatible(faa->fa_node, "marvell,armada-38x-uart") ||
+           OF_is_compatible(faa->fa_node, "ns16550a") ||
+           OF_is_compatible(faa->fa_node, "snps,dw-apb-uart") ||
            OF_is_compatible(faa->fa_node, "ti,omap3-uart") ||
            OF_is_compatible(faa->fa_node, "ti,omap4-uart"));
 }
@@ -99,7 +110,7 @@ com_fdt_attach(struct device *parent, struct device *self, void *aux)
        struct com_softc *sc = (struct com_softc *)self;
        struct fdt_attach_args *faa = aux;
        int (*intr)(void *) = comintr;
-       uint32_t freq;
+       uint32_t freq, width, shift;
 
        if (faa->fa_nreg < 1)
                return;
@@ -121,8 +132,16 @@ com_fdt_attach(struct device *parent, struct device *self, void *aux)
        sc->sc_uarttype = COM_UART_16550;
        sc->sc_frequency = freq ? freq : COM_FREQ;
 
-       sc->sc_reg_width = OF_getpropint(faa->fa_node, "reg-io-width", 4);
-       sc->sc_reg_shift = OF_getpropint(faa->fa_node, "reg-shift", 2);
+       if (OF_is_compatible(stdout_node, "ns16550a")) {
+               width = 1;
+               shift = 0;
+       } else {
+               width = 4;
+               shift = 2;
+       }
+
+       sc->sc_reg_width = OF_getpropint(faa->fa_node, "reg-io-width", width);
+       sc->sc_reg_shift = OF_getpropint(faa->fa_node, "reg-shift", shift);
 
        if (OF_is_compatible(faa->fa_node, "snps,dw-apb-uart") ||
            OF_is_compatible(faa->fa_node, "marvell,armada-38x-uart"))