> Date: Thu, 18 Aug 2016 11:41:52 +0200
> From: Marcus Glocker <mar...@nazgul.ch>
>
> On Wed, Aug 17, 2016 at 04:05:05PM +0200, Mark Kettenis wrote:
>
> > > Date: Wed, 17 Aug 2016 15:36:21 +0200
> > > From: Marcus Glocker <mar...@nazgul.ch>
> > >
> > > Enables FIFO for Synopsis DesignWare APB UART.
> > >
> > > ok?
> >
> > Apparently the FIFO is optional. There is a register that tells you
> > whether it is enabled or not. Not sure we'll ever encounter an
> > implementation that has that option turned off. But we probably
> > should check to be sure.
>
> Ok. This updated diff tries to find out about FIFO support by reading
> the CPR registers FIFO_MODE field. If it contains zero, no FIFO
> support, otherwise it conains the supported FIFO depth.
>
> Unfortunately on my allwinner,sun5i-r8 it returns zero which suprises
> me a bit. Therefore it would be interessting if it could be tested on
> other sunxi boards as well to see whether it returns non-zero there and
> hence you should find a com-line showing the FIFO size.
Same on allwinner,sun8i-a20. The data sheet says there is a 64-byte
FIFO, but they have conveniently disabled the registers that tell you
that! Not sure to what extent we should trust the data sheet though.
This is cheap Chinese hardware in the end. Probably best to leave
things as they are right now. Unless you move large volumes of data,
the FIFO isn't terribly important I'd say.
> Index: com_fdt.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/armv7/dev/com_fdt.c,v
> retrieving revision 1.6
> diff -u -p -r1.6 com_fdt.c
> --- com_fdt.c 17 Aug 2016 13:44:48 -0000 1.6
> +++ com_fdt.c 18 Aug 2016 09:36:05 -0000
> @@ -38,6 +38,8 @@
> #include <dev/ofw/ofw_pinctrl.h>
>
> #define com_usr 31 /* Synopsys DesignWare UART */
> +#define com_cpr 61 /* Component Parameter Register */
> +#define CPR_MASK_FIFO(val) ((val >> 16) & 0x00ff) /* CPR FIFO_MODE */
>
> int com_fdt_match(struct device *, void *, void *);
> void com_fdt_attach(struct device *, struct device *, void *);
> @@ -98,6 +100,7 @@ com_fdt_attach(struct device *parent, st
> struct fdt_attach_args *faa = aux;
> int (*intr)(void *) = comintr;
> int node;
> + uint32_t reg;
>
> if (faa->fa_nreg < 1)
> return;
> @@ -115,11 +118,6 @@ com_fdt_attach(struct device *parent, st
> sc->sc.sc_frequency = 48000000;
> sc->sc.sc_uarttype = COM_UART_TI16750;
>
> - if (OF_is_compatible(faa->fa_node, "snps,dw-apb-uart")) {
> - sc->sc.sc_uarttype = COM_UART_16550;
> - intr = com_fdt_intr_designware;
> - }
> -
> if ((node = OF_finddevice("/")) != 0 &&
> (OF_is_compatible(node, "allwinner,sun4i-a10") ||
> OF_is_compatible(node, "allwinner,sun5i-a10s") ||
> @@ -136,6 +134,15 @@ com_fdt_attach(struct device *parent, st
> faa->fa_reg[0].size, 0, &sc->sc.sc_ioh)) {
> printf("%s: bus_space_map failed\n", __func__);
> return;
> + }
> +
> + if (OF_is_compatible(faa->fa_node, "snps,dw-apb-uart")) {
> + reg = bus_space_read_4(sc->sc.sc_iot, sc->sc.sc_ioh, com_cpr);
> + if (CPR_MASK_FIFO(reg) > 0)
> + sc->sc.sc_uarttype = COM_UART_16550A;
> + else
> + sc->sc.sc_uarttype = COM_UART_16550;
> + intr = com_fdt_intr_designware;
> }
>
> pinctrl_byname(faa->fa_node, "default");
>
