[PATCH v3] lib: utils: Add LiteX UART support
Gabriel L. Somlo
gsomlo at gmail.com
Sat Nov 13 14:07:21 PST 2021
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)?
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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