[PATCH v3] lib: utils: Add LiteX UART support
Xiang W
wxjstz at 126.com
Sat Nov 13 17:32:22 PST 2021
在 2021-11-13星期六的 17:07 -0500，Gabriel L. Somlo写道：
> Hi Xiang,
>
> On Sat, 13 Nov 2021 13:57:03 +0800, wxjstz at 126.com wrote:
> > 在 2021-11-12星期五的 10:03 -0500，Gabriel Somlo写道：
> > > This patch adds support for the UART provided by the LiteX
> > > SoC framework (https://github.com/enjoy-digital/litex),
> > > based its FDT info described in the Linux sources at
> > > Documentation/devicetree/bindings/serial/litex,liteuart.yaml).
> > >
> > > Signed-off-by: Gabriel Somlo <gsomlo at gmail.com>
> > > ---
> > >
> > > New in v3:
> > > - less verbose / more concise commit blurb :)
> > > - fixed serial_litex_init() alignment
> > > - fixed `uart_base` pointer arithmetic
> > > - treat single-bit registers as Boolean
> > > - removed access to `event` (irq-related) register
> > > (not needed since UART is operated in polling mode)
> > >
> > > > New in v2:
> > > > - remove properties (and parameters) not actually used
> > > > by the
> > > > LiteX UART
> > > > - remove redundant parentheses from pointer arithmetic
> > > > (thanks jrtc27!)
> > > >
> > > > > 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.
> > >
> > > include/sbi_utils/fdt/fdt_helper.h | 3 ++
> > > include/sbi_utils/serial/litex-uart.h | 17 ++++++++
> > > lib/utils/fdt/fdt_helper.c | 19 ++++++++
> > > lib/utils/serial/fdt_serial.c | 2 +
> > > lib/utils/serial/fdt_serial_litex.c | 35 +++++++++++++++
> > > lib/utils/serial/litex-uart.c | 62
> > > +++++++++++++++++++++++++++
> > > lib/utils/serial/objects.mk | 2 +
> > > 7 files changed, 140 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..91ab644
> > > --- /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);
> > > +
> > > +#endif
> > > diff --git a/lib/utils/fdt/fdt_helper.c
> > > b/lib/utils/fdt/fdt_helper.c
> > > index 5bf4021..a42f53b 100644
> > > --- a/lib/utils/fdt/fdt_helper.c
> > > +++ b/lib/utils/fdt/fdt_helper.c
> > > @@ -403,6 +403,25 @@ 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;
> > > +
> > > + /* LiteX UART has no further configurable properties */
> > > +
> > > + 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..0fa5777
> > > --- /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);
> > > +}
> > > +
> > > +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..e35fbe8
> > > --- /dev/null
> > > +++ b/lib/utils/serial/litex-uart.c
> > > @@ -0,0 +1,62 @@
> > > +/*
> > > + * 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 u32 *uart_base;
> > > +
> > > +static u8 get_reg(u8 reg)
> > > +{
> > > + return readb(uart_base + reg);
> > > +}
> > > +
> > > +static void set_reg(u8 reg, u8 val)
> > > +{
> > > + writeb(val, uart_base + reg);
> > > +}
> > > +
> > > +static void litex_uart_putc(char ch)
> > > +{
> > > + while (get_reg(UART_REG_TXFULL));
> > > + set_reg(UART_REG_RXTX, ch);
> > > +}
> > > +
> > > +static int litex_uart_getc(void)
> > > +{
> > We should wait here before reading
>
> Wait for what condition, and/or for how long?
>
> Are you perhaps referring to your recently submitted patch at
> https://lists.infradead.org/pipermail/opensbi/2021-November/002174.html
> ?
> (where you suggest we should loop or block until a character becomes
> available, instead of returning -1)?
I am sorry for the wrong advice I provided.
Regards,
Xiang W
>
> If that's the case, I should probably wait until your patch is
> applied
> upstream (hopefully soon :) ), before re-submitting a v4 of LiteX
> UART
> with similar modifications.
>
> Otherwise, please clarify.
>
> Thanks much,
> --Gabriel
>
> > Regards,
> > Xiang W
> > > + if (get_reg(UART_REG_RXEMPTY))
> > > + return -1;
> > > + else
> > > + return get_reg(UART_REG_RXTX);
> > > +}
> > > +
> > > +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)
> > > +{
> > > + uart_base = (volatile u32 *)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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