[PATCH v1] lib: utils: Add LiteX UART support
Gabriel L. Somlo
gsomlo at gmail.com
Thu Nov 11 13:07:33 PST 2021
Hi Jess, thanks for the feedback. I'll work that into a v2 to be
tested and emailed out later this evening. I've realized there's
also a bit of additional cleanup I could do, see inline below.
Thanks,
--Gabriel
On Thu, Nov 11, 2021 at 03:31:11PM +0000, Jessica Clarke wrote:
> On 10 Nov 2021, at 23:04, Gabriel Somlo <gsomlo at gmail.com> wrote:
> >
> > The LiteX SoC framework (https://github.com/enjoy-digital/litex)
> > provides a wide range of building blocks that allow creation of
> > full FPGA based systems. CPU options supported by LiteX span
> > several RISC-V models, including Rocket (64-bit) and VexRiscv
> > (32-bit).
> >
> > This patch adds support for detecting and provisioning LiteX's
> > UART based on its FDT info (detailed in the Linux sources at
> > Documentation/devicetree/bindings/serial/litex,liteuart.yaml).
> >
> > Signed-off-by: Gabriel Somlo <gsomlo at gmail.com>
> > ---
> >
> > See https://github.com/litex-hub/linux-on-litex-rocket for instructions
> > on how to build a LiteX+Rocket bitstream for e.g. the nexys4ddr (Xilinx
> > Artix7 FPGA dev board), and https://pastebin.com/nu1dSE16 for a demo of
> > the board booting a linux payload via opensbi, using this patch.
> >
> > Thanks for your consideration,
> > --Gabriel
> >
> > include/sbi_utils/fdt/fdt_helper.h | 3 ++
> > include/sbi_utils/serial/litex-uart.h | 17 +++++++
> > lib/utils/fdt/fdt_helper.c | 28 ++++++++++++
> > lib/utils/serial/fdt_serial.c | 2 +
> > lib/utils/serial/fdt_serial_litex.c | 35 +++++++++++++++
> > lib/utils/serial/litex-uart.c | 64 +++++++++++++++++++++++++++
> > lib/utils/serial/objects.mk | 2 +
> > 7 files changed, 151 insertions(+)
> > create mode 100644 include/sbi_utils/serial/litex-uart.h
> > create mode 100644 lib/utils/serial/fdt_serial_litex.c
> > create mode 100644 lib/utils/serial/litex-uart.c
> >
> > diff --git a/include/sbi_utils/fdt/fdt_helper.h b/include/sbi_utils/fdt/fdt_helper.h
> > index 24fee7a..5f75f07 100644
> > --- a/include/sbi_utils/fdt/fdt_helper.h
> > +++ b/include/sbi_utils/fdt/fdt_helper.h
> > @@ -62,6 +62,9 @@ int fdt_parse_shakti_uart_node(void *fdt, int nodeoffset,
> > int fdt_parse_sifive_uart_node(void *fdt, int nodeoffset,
> > struct platform_uart_data *uart);
> >
> > +int fdt_parse_litex_uart_node(void *fdt, int nodeoffset,
> > + struct platform_uart_data *uart);
> > +
> > int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
> > struct platform_uart_data *uart);
> >
> > diff --git a/include/sbi_utils/serial/litex-uart.h b/include/sbi_utils/serial/litex-uart.h
> > new file mode 100644
> > index 0000000..002b525
> > --- /dev/null
> > +++ b/include/sbi_utils/serial/litex-uart.h
> > @@ -0,0 +1,17 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2021 Gabriel Somlo
> > + *
> > + * Authors:
> > + * Gabriel Somlo <gsomlo at gmail.com>
> > + */
> > +
> > +#ifndef __SERIAL_LITEX_UART_H__
> > +#define __SERIAL_LITEX_UART_H__
> > +
> > +#include <sbi/sbi_types.h>
> > +
> > +int litex_uart_init(unsigned long base, u32 in_freq, u32 baudrate);
LiteX UART doesn't need `in_freq` and `baudrate`, so I'll remove the
parameters.
> > +
> > +#endif
> > diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
> > index 5bf4021..3ba78e5 100644
> > --- a/lib/utils/fdt/fdt_helper.c
> > +++ b/lib/utils/fdt/fdt_helper.c
> > @@ -25,6 +25,11 @@
> > #define DEFAULT_SIFIVE_UART_REG_SHIFT 0
> > #define DEFAULT_SIFIVE_UART_REG_IO_WIDTH 4
> >
> > +#define DEFAULT_LITEX_UART_FREQ 0
> > +#define DEFAULT_LITEX_UART_BAUD 115200
> > +#define DEFAULT_LITEX_UART_REG_SHIFT 0
> > +#define DEFAULT_LITEX_UART_REG_IO_WIDTH 4
> > +
^^^ These aren't actually used by the LiteX UART ip block, so I'll get rid
of them.
> > #define DEFAULT_GAISLER_UART_REG_IO_WIDTH 4
> >
> > #define DEFAULT_SHAKTI_UART_FREQ 50000000
> > @@ -403,6 +408,29 @@ int fdt_parse_sifive_uart_node(void *fdt, int nodeoffset,
> > return 0;
> > }
> >
> > +int fdt_parse_litex_uart_node(void *fdt, int nodeoffset,
> > + struct platform_uart_data *uart)
> > +{
> > + int rc;
> > + uint64_t reg_addr, reg_size;
> > +
> > + if (nodeoffset < 0 || !uart || !fdt)
> > + return SBI_ENODEV;
> > +
> > + rc = fdt_get_node_addr_size(fdt, nodeoffset, 0, ®_addr, ®_size);
> > + if (rc < 0 || !reg_addr || !reg_size)
> > + return SBI_ENODEV;
> > + uart->addr = reg_addr;
> > +
> > + /* For LiteX UART, the following properties are ignored */
> > + uart->freq = DEFAULT_LITEX_UART_FREQ;
> > + uart->baud = DEFAULT_LITEX_UART_BAUD;
> > + uart->reg_shift = DEFAULT_LITEX_UART_REG_SHIFT;
> > + uart->reg_io_width = DEFAULT_LITEX_UART_REG_IO_WIDTH;
... ditto here ^^^^
> > +
> > + return 0;
> > +}
> > +
> > int fdt_parse_uart8250_node(void *fdt, int nodeoffset,
> > struct platform_uart_data *uart)
> > {
> > diff --git a/lib/utils/serial/fdt_serial.c b/lib/utils/serial/fdt_serial.c
> > index cedda04..f73d26a 100644
> > --- a/lib/utils/serial/fdt_serial.c
> > +++ b/lib/utils/serial/fdt_serial.c
> > @@ -15,6 +15,7 @@
> >
> > extern struct fdt_serial fdt_serial_uart8250;
> > extern struct fdt_serial fdt_serial_sifive;
> > +extern struct fdt_serial fdt_serial_litex;
> > extern struct fdt_serial fdt_serial_htif;
> > extern struct fdt_serial fdt_serial_shakti;
> > extern struct fdt_serial fdt_serial_gaisler;
> > @@ -22,6 +23,7 @@ extern struct fdt_serial fdt_serial_gaisler;
> > static struct fdt_serial *serial_drivers[] = {
> > &fdt_serial_uart8250,
> > &fdt_serial_sifive,
> > + &fdt_serial_litex,
> > &fdt_serial_htif,
> > &fdt_serial_shakti,
> > &fdt_serial_gaisler
> > diff --git a/lib/utils/serial/fdt_serial_litex.c b/lib/utils/serial/fdt_serial_litex.c
> > new file mode 100644
> > index 0000000..fda5746
> > --- /dev/null
> > +++ b/lib/utils/serial/fdt_serial_litex.c
> > @@ -0,0 +1,35 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2021 Gabriel Somlo
> > + *
> > + * Authors:
> > + * Gabriel Somlo <gsomlo at gmail.com>
> > + */
> > +
> > +#include <sbi_utils/fdt/fdt_helper.h>
> > +#include <sbi_utils/serial/fdt_serial.h>
> > +#include <sbi_utils/serial/litex-uart.h>
> > +
> > +static int serial_litex_init(void *fdt, int nodeoff,
> > + const struct fdt_match *match)
> > +{
> > + int rc;
> > + struct platform_uart_data uart;
> > +
> > + rc = fdt_parse_litex_uart_node(fdt, nodeoff, &uart);
> > + if (rc)
> > + return rc;
> > +
> > + return litex_uart_init(uart.addr, uart.freq, uart.baud);
... and here, lose `freq` and `baud`;
> > +}
> > +
> > +static const struct fdt_match serial_litex_match[] = {
> > + { .compatible = "litex,liteuart" },
> > + { },
> > +};
> > +
> > +struct fdt_serial fdt_serial_litex = {
> > + .match_table = serial_litex_match,
> > + .init = serial_litex_init
> > +};
> > diff --git a/lib/utils/serial/litex-uart.c b/lib/utils/serial/litex-uart.c
> > new file mode 100644
> > index 0000000..e6afa53
> > --- /dev/null
> > +++ b/lib/utils/serial/litex-uart.c
> > @@ -0,0 +1,64 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2021 Gabriel Somlo
> > + *
> > + * Authors:
> > + * Gabriel Somlo <gsomlo at gmail.com>
> > + */
> > +
> > +#include <sbi/riscv_io.h>
> > +#include <sbi/sbi_console.h>
> > +#include <sbi_utils/serial/litex-uart.h>
> > +
> > +/* clang-format off */
> > +
> > +#define UART_REG_RXTX 0
> > +#define UART_REG_TXFULL 1
> > +#define UART_REG_RXEMPTY 2
> > +#define UART_REG_EV_STATUS 3
> > +#define UART_REG_EV_PENDING 4
> > +#define UART_REG_EV_ENABLE 5
> > +
> > +/* clang-format on */
> > +
> > +static volatile void *uart_base;
> > +
> > +static u32 get_reg(u32 num)
> > +{
> > + return readl(uart_base + (num * 0x4));
>
> Arithmetic on void * is a GNU extension, and the parens aren’t needed.
Got it, thanks!
>
> > +}
> > +
> > +static void set_reg(u32 num, u32 val)
> > +{
> > + writel(val, uart_base + (num * 0x4));
> > +}
> > +
> > +static void litex_uart_putc(char ch)
> > +{
> > + while ((get_reg(UART_REG_TXFULL) & 0x01));
> > + set_reg(UART_REG_RXTX, ch);
> > +}
> > +
> > +static int litex_uart_getc(void)
> > +{
> > + int ret = -1;
> > + if (!(get_reg(UART_REG_RXEMPTY) & 0x01)) {
> > + ret = get_reg(UART_REG_RXTX);
> > + set_reg(UART_REG_EV_PENDING, 0x02); /* ack UART_EV_RX */
> > + }
> > + return ret;
> > +}
> > +
> > +static struct sbi_console_device litex_console = {
> > + .name = "litex_uart",
> > + .console_putc = litex_uart_putc,
> > + .console_getc = litex_uart_getc
> > +};
> > +
> > +int litex_uart_init(unsigned long base, u32 in_freq, u32 baudrate)
... again, get rid of `in_freq` and `baudrate`
> > +{
> > + uart_base = (volatile void *)base;
> > + sbi_console_set_device(&litex_console);
> > + return 0;
> > +}
> > diff --git a/lib/utils/serial/objects.mk b/lib/utils/serial/objects.mk
> > index 9fb0902..4f751ba 100644
> > --- a/lib/utils/serial/objects.mk
> > +++ b/lib/utils/serial/objects.mk
> > @@ -12,8 +12,10 @@ libsbiutils-objs-y += serial/fdt_serial_gaisler.o
> > libsbiutils-objs-y += serial/fdt_serial_htif.o
> > libsbiutils-objs-y += serial/fdt_serial_shakti.o
> > libsbiutils-objs-y += serial/fdt_serial_sifive.o
> > +libsbiutils-objs-y += serial/fdt_serial_litex.o
> > libsbiutils-objs-y += serial/fdt_serial_uart8250.o
> > libsbiutils-objs-y += serial/gaisler-uart.o
> > libsbiutils-objs-y += serial/shakti-uart.o
> > libsbiutils-objs-y += serial/sifive-uart.o
> > +libsbiutils-objs-y += serial/litex-uart.o
> > libsbiutils-objs-y += serial/uart8250.o
> > --
> > 2.31.1
> >
>
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