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Diffstat (limited to '')
| -rw-r--r-- | drivers/tty/serial/earlycon-arm-semihost.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/drivers/tty/serial/earlycon-arm-semihost.c b/drivers/tty/serial/earlycon-arm-semihost.c new file mode 100644 index 000000000..fcdec5f42 --- /dev/null +++ b/drivers/tty/serial/earlycon-arm-semihost.c @@ -0,0 +1,51 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2012 ARM Ltd. + * Author: Marc Zyngier <marc.zyngier@arm.com> + * + * Adapted for ARM and earlycon: + * Copyright (C) 2014 Linaro Ltd. + * Author: Rob Herring <robh@kernel.org> + */ +#include <linux/kernel.h> +#include <linux/console.h> +#include <linux/init.h> +#include <linux/serial_core.h> + +#ifdef CONFIG_THUMB2_KERNEL +#define SEMIHOST_SWI "0xab" +#else +#define SEMIHOST_SWI "0x123456" +#endif + +/* + * Semihosting-based debug console + */ +static void smh_putc(struct uart_port *port, unsigned char c) +{ +#ifdef CONFIG_ARM64 + asm volatile("mov x1, %0\n" + "mov x0, #3\n" + "hlt 0xf000\n" + : : "r" (&c) : "x0", "x1", "memory"); +#else + asm volatile("mov r1, %0\n" + "mov r0, #3\n" + "svc " SEMIHOST_SWI "\n" + : : "r" (&c) : "r0", "r1", "memory"); +#endif +} + +static void smh_write(struct console *con, const char *s, unsigned n) +{ + struct earlycon_device *dev = con->data; + uart_console_write(&dev->port, s, n, smh_putc); +} + +static int +__init early_smh_setup(struct earlycon_device *device, const char *opt) +{ + device->con->write = smh_write; + return 0; +} +EARLYCON_DECLARE(smh, early_smh_setup); |