[PATCH v2 6/8] tty/serial: Add RISC-V SBI debug console based earlycon
From: Anup Patel <hidden>
Date: 2023-10-12 05:16:45
Also in:
kvm, kvm-riscv, linux-riscv, linux-serial, lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
We extend the existing RISC-V SBI earlycon support to use the new RISC-V SBI debug console extension. Signed-off-by: Anup Patel <redacted> --- drivers/tty/serial/Kconfig | 2 +- drivers/tty/serial/earlycon-riscv-sbi.c | 32 +++++++++++++++++++++---- 2 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index bdc568a4ab66..cec46091a716 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig@@ -87,7 +87,7 @@ config SERIAL_EARLYCON_SEMIHOST config SERIAL_EARLYCON_RISCV_SBI bool "Early console using RISC-V SBI" - depends on RISCV_SBI_V01 + depends on RISCV_SBI select SERIAL_CORE select SERIAL_CORE_CONSOLE select SERIAL_EARLYCON
diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
index 27afb0b74ea7..c21cdef254e7 100644
--- a/drivers/tty/serial/earlycon-riscv-sbi.c
+++ b/drivers/tty/serial/earlycon-riscv-sbi.c@@ -15,17 +15,41 @@ static void sbi_putc(struct uart_port *port, unsigned char c) sbi_console_putchar(c); } -static void sbi_console_write(struct console *con, - const char *s, unsigned n) +static void sbi_0_1_console_write(struct console *con, + const char *s, unsigned int n) { struct earlycon_device *dev = con->data; uart_console_write(&dev->port, s, n, sbi_putc); } +static void sbi_dbcn_console_write(struct console *con, + const char *s, unsigned int n) +{ + phys_addr_t pa = __pa(s); + + if (IS_ENABLED(CONFIG_32BIT)) + sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE, + n, lower_32_bits(pa), upper_32_bits(pa), 0, 0, 0); + else + sbi_ecall(SBI_EXT_DBCN, SBI_EXT_DBCN_CONSOLE_WRITE, + n, pa, 0, 0, 0, 0); +} + static int __init early_sbi_setup(struct earlycon_device *device, const char *opt) { - device->con->write = sbi_console_write; - return 0; + int ret = 0; + + if ((sbi_spec_version >= sbi_mk_version(2, 0)) && + (sbi_probe_extension(SBI_EXT_DBCN) > 0)) { + device->con->write = sbi_dbcn_console_write; + } else { + if (IS_ENABLED(CONFIG_RISCV_SBI_V01)) + device->con->write = sbi_0_1_console_write; + else + ret = -ENODEV; + } + + return ret; } EARLYCON_DECLARE(sbi, early_sbi_setup);
--
2.34.1