Implement a console over legacy SBI (version 0.1.0). There is a tiny ringbuffer to simplify checking for presence and reading characters as separate steps. Signed-off-by: Marcelo Politzer <marcelo.politzer@xxxxxxxxxx> --- arch/riscv/cpu/core.c | 13 ++++++++ arch/riscv/lib/sbi.c | 11 +++++++ drivers/serial/Kconfig | 8 +++++ drivers/serial/Makefile | 1 + drivers/serial/serial_sbi.c | 60 +++++++++++++++++++++++++++++++++++++ 5 files changed, 93 insertions(+) create mode 100644 drivers/serial/serial_sbi.c diff --git a/arch/riscv/cpu/core.c b/arch/riscv/cpu/core.c index 80730c05b..9226037f3 100644 --- a/arch/riscv/cpu/core.c +++ b/arch/riscv/cpu/core.c @@ -24,6 +24,7 @@ #include <magicvar.h> #include <asm/system.h> #include <io.h> +#include <asm/sbi.h> static int riscv_request_stack(void) { @@ -33,6 +34,7 @@ static int riscv_request_stack(void) coredevice_initcall(riscv_request_stack); static struct device_d timer_dev; +static struct device_d serial_sbi_dev; static s64 hartid; @@ -75,6 +77,17 @@ static int riscv_probe(struct device_d *parent) return ret; } + if (IS_ENABLED(CONFIG_SERIAL_SBI) && !serial_sbi_dev.parent) { + serial_sbi_dev.id = DEVICE_ID_SINGLE; + serial_sbi_dev.device_node = 0; + serial_sbi_dev.parent = parent; + dev_set_name(&serial_sbi_dev, "riscv-serial-sbi"); + + ret = platform_device_register(&serial_sbi_dev); + if (ret) + return ret; + } + hartid = riscv_hartid(); if (hartid >= 0) globalvar_add_simple_uint64("hartid", &hartid, "%llu"); diff --git a/arch/riscv/lib/sbi.c b/arch/riscv/lib/sbi.c index 45a04fb82..209069c98 100644 --- a/arch/riscv/lib/sbi.c +++ b/arch/riscv/lib/sbi.c @@ -64,3 +64,14 @@ static int sbi_init(void) } core_initcall(sbi_init); + + +void sbi_console_putchar(int ch) +{ + sbi_ecall(SBI_EXT_0_1_CONSOLE_PUTCHAR, 0, ch, 0, 0, 0, 0, 0); +} + +int sbi_console_getchar(void) +{ + return sbi_ecall(SBI_EXT_0_1_CONSOLE_GETCHAR, 0, 0, 0, 0, 0, 0, 0).error; +} diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index b9750d177..5e30ea388 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -173,4 +173,12 @@ config SERIAL_SIFIVE contains a SiFive UART IP block. This type of UART is present on SiFive FU540 SoCs, among others. +config SERIAL_SBI + tristate "RISCV Serial support over SBI's HTIF" + depends on OFDEVICE + depends on RISCV_SBI + help + Select this option if you are building barebox for a RISCV platform + that implements a serial over SBI. + endmenu diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile index 5120b1737..b1de436ed 100644 --- a/drivers/serial/Makefile +++ b/drivers/serial/Makefile @@ -24,3 +24,4 @@ obj-$(CONFIG_DRIVER_SERIAL_DIGIC) += serial_digic.o obj-$(CONFIG_DRIVER_SERIAL_LPUART) += serial_lpuart.o obj-$(CONFIG_VIRTIO_CONSOLE) += virtio_console.o obj-$(CONFIG_SERIAL_SIFIVE) += serial_sifive.o +obj-$(CONFIG_SERIAL_SBI) += serial_sbi.o diff --git a/drivers/serial/serial_sbi.c b/drivers/serial/serial_sbi.c new file mode 100644 index 000000000..7217ce9cc --- /dev/null +++ b/drivers/serial/serial_sbi.c @@ -0,0 +1,60 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2021 Marcelo Politzer <marcelo.politzer@xxxxxxxxxx> + */ + +#include <common.h> +#include <driver.h> +#include <malloc.h> +#include <io.h> +#include <of.h> +#include <asm/sbi.h> + +struct sbi_serial_priv { + struct console_device cdev; + uint8_t b[2], head, tail; +}; + +static int sbi_serial_getc(struct console_device *cdev) +{ + struct sbi_serial_priv *priv = cdev->dev->priv; + if (priv->head == priv->tail) + return -1; + return priv->b[priv->head++ & 0x1]; +} + +static void sbi_serial_putc(struct console_device *cdev, const char ch) +{ + sbi_console_putchar(ch); +} + +static int sbi_serial_tstc(struct console_device *cdev) +{ + struct sbi_serial_priv *priv = cdev->dev->priv; + int c = sbi_console_getchar(); + + if (c != -1) + priv->b[priv->tail++ & 0x1] = c; + return priv->head != priv->tail; +} + +static int sbi_serial_probe(struct device_d *dev) +{ + struct sbi_serial_priv *priv; + + priv = dev->priv = xzalloc(sizeof(*priv)); + priv->cdev.dev = dev; + priv->cdev.putc = sbi_serial_putc; + priv->cdev.getc = sbi_serial_getc; + priv->cdev.tstc = sbi_serial_tstc; + priv->cdev.flush = 0; + priv->cdev.setbrg = 0; + + return console_register(&priv->cdev); +} + +static struct driver_d serial_sbi_driver = { + .name = "riscv-serial-sbi", + .probe = sbi_serial_probe, +}; +postcore_platform_driver(serial_sbi_driver); -- 2.32.0 _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox