[PATCH] serial: Add riscv_sbi console support

[光]

From: Kongou Hikari <hikari at nucleisys.com>

  - This patch supports debug serial and console from SBI syscall.

Signed-off-by: Kongou Hikari <hikari at nucleisys.com>
---
 drivers/serial/Kconfig            |  17 +++++
 drivers/serial/Makefile           |   1 +
 drivers/serial/serial_riscv_sbi.c | 104 ++++++++++++++++++++++++++++++
 3 files changed, 122 insertions(+)
 create mode 100644 drivers/serial/serial_riscv_sbi.c

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 90e3983170..60dcf9bc9a 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -388,12 +388,20 @@ config DEBUG_UART_MTK
    driver will be available until the real driver model serial is
    running.

+
+config DEBUG_UART_RISCV_SBI
+    bool "RISC-V SBI CONSOLE"
+    depends on RISCV_SBI_CONSOLE
+    help
+      Select this to enable a debug UART using RISC-V SBI console driver.
+
 endchoice

 config DEBUG_UART_BASE
  hex "Base address of UART"
  depends on DEBUG_UART
  default 0 if DEBUG_UART_SANDBOX
+ default 0 if DEBUG_UART_RISCV_SBI
  help
    This is the base address of your UART for memory-mapped UARTs.

@@ -404,6 +412,7 @@ config DEBUG_UART_CLOCK
  int "UART input clock"
  depends on DEBUG_UART
  default 0 if DEBUG_UART_SANDBOX
+ default 0 if DEBUG_UART_RISCV_SBI
  help
    The UART input clock determines the speed of the internal UART
    circuitry. The baud rate is derived from this by dividing the input
@@ -481,6 +490,14 @@ config ALTERA_JTAG_UART_BYPASS
    output will wait forever until a JTAG terminal is connected. If you
    not are sure, say Y.

+config RISCV_SBI_CONSOLE
+ bool "RISC-V SBI console support"
+ depends on RISCV
+ help
+   This enables support for console via RISC-V SBI calls.
+
+   If you don't know what do to here, say Y.
+
 config ALTERA_UART
  bool "Altera UART support"
  depends on DM_SERIAL
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index e4a92bbbb7..15b2a3ea6f 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_MXC_UART) += serial_mxc.o
 obj-$(CONFIG_PXA_SERIAL) += serial_pxa.o
 obj-$(CONFIG_MESON_SERIAL) += serial_meson.o
 obj-$(CONFIG_INTEL_MID_SERIAL) += serial_intel_mid.o
+obj-$(CONFIG_RISCV_SBI_CONSOLE) += serial_riscv_sbi.o
 ifdef CONFIG_SPL_BUILD
 obj-$(CONFIG_ROCKCHIP_SERIAL) += serial_rockchip.o
 endif
diff --git a/drivers/serial/serial_riscv_sbi.c b/drivers/serial/serial_riscv_sbi.c
new file mode 100644
index 0000000000..add11be04e
--- /dev/null
+++ b/drivers/serial/serial_riscv_sbi.c
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2008 David Gibson, IBM Corporation
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2020 Nuclei System Technologies
+ * Copyright (C) 2020 Ruigang Wan <rgwan at nucleisys.com>
+ */
+
+#include <common.h>
+#include <serial.h>
+#include <errno.h>
+#include <dm.h>
+#include <fdtdec.h>
+
+#include <asm/sbi.h>
+
+
+#ifdef CONFIG_DEBUG_UART_RISCV_SBI
+
+#include <debug_uart.h>
+
+
+static inline void _debug_uart_init(void)
+{
+ //Nothing
+}
+
+static inline void _debug_uart_putc(int ch)
+{
+ sbi_console_putchar(ch);
+}
+
+DEBUG_UART_FUNCS
+
+#endif
+
+static int sbi_tty_pending_char = -1;
+
+static int sbi_tty_put(struct udevice *dev, const char ch)
+{
+
+ sbi_console_putchar(ch);
+
+ return 0;
+}
+
+static int sbi_tty_get(struct udevice *dev)
+{
+ int c;
+ if (sbi_tty_pending_char != -1)
+ {
+  c = sbi_tty_pending_char;
+  sbi_tty_pending_char = -1;
+ }
+ else
+ {
+  c = sbi_console_getchar();
+  if (c < 0)
+   return -EAGAIN;
+ }
+
+ return c;
+}
+
+static int sbi_tty_setbrg(struct udevice *dev, int baudrate)
+{
+ return 0;
+}
+
+static int sbi_tty_pending(struct udevice *dev, bool input)
+{
+ int c;
+ if (input)
+ {
+  if (sbi_tty_pending_char != -1)
+   return 1;
+
+  c = sbi_console_getchar();
+  if(c < 0)
+   return 0;
+  sbi_tty_pending_char = c;
+  return 1;
+ }
+ return 0;
+}
+
+static const struct udevice_id serial_riscv_sbi_ids[] = {
+ { .compatible = "sbi,console" },
+ { }
+};
+
+const struct dm_serial_ops serial_riscv_sbi_ops = {
+ .putc = sbi_tty_put,
+ .pending = sbi_tty_pending,
+ .getc = sbi_tty_get,
+ .setbrg = sbi_tty_setbrg,
+};
+
+U_BOOT_DRIVER(serial_riscv_sbi) = {
+ .name = "serial_riscv_sbi",
+ .id = UCLASS_SERIAL,
+ .of_match = serial_riscv_sbi_ids,
+ .ops = &serial_riscv_sbi_ops,
+};
-- 
2.17.1