lib: utils/serial: add semihosting support
We add RISC-V semihosting based serial console for JTAG based early debugging. The RISC-V semihosting specification is available at: https://github.com/riscv/riscv-semihosting-spec/blob/main/riscv-semihosting-spec.adoc Signed-off-by: Anup Patel <apatel@ventanamicro.com> Signed-off-by: Kautuk Consul <kconsul@ventanamicro.com> Reviewed-by: Anup Patel <anup@brainfault.org>
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/*
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2022 Ventana Micro Systems Inc.
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*
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* Authors:
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* Anup Patel <apatel@ventanamicro.com>
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* Kautuk Consul <kconsul@ventanamicro.com>
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*/
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#ifndef __SERIAL_SEMIHOSTING_H__
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#define __SERIAL_SEMIHOSTING_H__
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#include <sbi/sbi_types.h>
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/**
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* enum semihosting_open_mode - Numeric file modes for use with semihosting_open()
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* MODE_READ: 'r'
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* MODE_BINARY: 'b'
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* MODE_PLUS: '+'
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* MODE_WRITE: 'w'
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* MODE_APPEND: 'a'
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*
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* These modes represent the mode string used by fopen(3) in a form which can
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* be passed to semihosting_open(). These do NOT correspond directly to %O_RDONLY,
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* %O_CREAT, etc; see fopen(3) for details. In particular, @MODE_PLUS
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* effectively results in adding %O_RDWR, and @MODE_WRITE will add %O_TRUNC.
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* For compatibility, @MODE_BINARY should be added when opening non-text files
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* (such as images).
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*/
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enum semihosting_open_mode {
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MODE_READ = 0x0,
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MODE_BINARY = 0x1,
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MODE_PLUS = 0x2,
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MODE_WRITE = 0x4,
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MODE_APPEND = 0x8,
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};
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#ifdef CONFIG_SERIAL_SEMIHOSTING
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int semihosting_init(void);
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int semihosting_enabled(void);
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#else
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static inline int semihosting_init(void) { return SBI_ENODEV; }
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static inline int semihosting_enabled(void) { return 0; }
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#endif
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#endif
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@ -79,4 +79,8 @@ config SERIAL_XILINX_UARTLITE
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bool "Xilinx UART Lite support"
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bool "Xilinx UART Lite support"
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default n
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default n
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config SERIAL_SEMIHOSTING
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bool "Semihosting support"
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default n
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endmenu
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endmenu
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@ -41,3 +41,4 @@ libsbiutils-objs-$(CONFIG_SERIAL_SIFIVE) += serial/sifive-uart.o
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libsbiutils-objs-$(CONFIG_SERIAL_LITEX) += serial/litex-uart.o
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libsbiutils-objs-$(CONFIG_SERIAL_LITEX) += serial/litex-uart.o
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libsbiutils-objs-$(CONFIG_SERIAL_UART8250) += serial/uart8250.o
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libsbiutils-objs-$(CONFIG_SERIAL_UART8250) += serial/uart8250.o
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libsbiutils-objs-$(CONFIG_SERIAL_XILINX_UARTLITE) += serial/xlnx-uartlite.o
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libsbiutils-objs-$(CONFIG_SERIAL_XILINX_UARTLITE) += serial/xlnx-uartlite.o
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libsbiutils-objs-$(CONFIG_SERIAL_SEMIHOSTING) += serial/semihosting.o
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/*
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2022 Ventana Micro Systems Inc.
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*
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* Authors:
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* Anup Patel <apatel@ventanamicro.com>
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* Kautuk Consul <kconsul@ventanamicro.com>
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*/
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#include <sbi/sbi_console.h>
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#include <sbi/sbi_string.h>
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#include <sbi/sbi_error.h>
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#include <sbi_utils/serial/semihosting.h>
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#define SYSOPEN 0x01
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#define SYSWRITEC 0x03
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#define SYSREAD 0x06
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#define SYSREADC 0x07
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#define SYSERRNO 0x13
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static long semihosting_trap(int sysnum, void *addr)
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{
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register int ret asm ("a0") = sysnum;
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register void *param0 asm ("a1") = addr;
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asm volatile (
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" .align 4\n"
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" .option push\n"
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" .option norvc\n"
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" slli zero, zero, 0x1f\n"
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" ebreak\n"
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" srai zero, zero, 7\n"
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" .option pop\n"
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: "+r" (ret) : "r" (param0) : "memory");
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return ret;
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}
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static bool _semihosting_enabled = true;
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static bool try_semihosting = true;
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bool semihosting_enabled(void)
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{
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register int ret asm ("a0") = SYSERRNO;
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register void *param0 asm ("a1") = NULL;
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unsigned long tmp = 0;
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if (!try_semihosting)
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return _semihosting_enabled;
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asm volatile (
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" .align 4\n"
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" .option push\n"
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" .option norvc\n"
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" j _semihost_test_vector_next\n"
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" .align 4\n"
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"_semihost_test_vector:\n"
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" csrr %[en], mepc\n"
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" addi %[en], %[en], 4\n"
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" csrw mepc, %[en]\n"
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" add %[en], zero, zero\n"
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" mret\n"
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"_semihost_test_vector_next:\n"
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" la %[tmp], _semihost_test_vector\n"
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" csrrw %[tmp], mtvec, %[tmp]\n"
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" .align 4\n"
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" slli zero, zero, 0x1f\n"
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" ebreak\n"
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" srai zero, zero, 7\n"
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" csrw mtvec, %[tmp]\n"
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" .option pop\n"
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: [tmp] "+r" (tmp), [en] "+r" (_semihosting_enabled),
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[ret] "+r" (ret)
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: "r" (param0) : "memory");
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try_semihosting = false;
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return _semihosting_enabled;
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}
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static int semihosting_errno(void)
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{
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long ret = semihosting_trap(SYSERRNO, NULL);
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if (ret > 0)
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return -ret;
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return SBI_EIO;
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}
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static int semihosting_infd = SBI_ENODEV;
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static long semihosting_open(const char *fname, enum semihosting_open_mode mode)
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{
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long fd;
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struct semihosting_open_s {
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const char *fname;
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unsigned long mode;
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size_t len;
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} open;
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open.fname = fname;
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open.len = sbi_strlen(fname);
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open.mode = mode;
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/* Open the file on the host */
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fd = semihosting_trap(SYSOPEN, &open);
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if (fd == -1)
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return semihosting_errno();
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return fd;
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}
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/**
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* struct semihosting_rdwr_s - Arguments for read and write
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* @fd: A file descriptor returned from semihosting_open()
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* @memp: Pointer to a buffer of memory of at least @len bytes
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* @len: The number of bytes to read or write
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*/
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struct semihosting_rdwr_s {
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long fd;
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void *memp;
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size_t len;
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};
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static long semihosting_read(long fd, void *memp, size_t len)
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{
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long ret;
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struct semihosting_rdwr_s read;
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read.fd = fd;
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read.memp = memp;
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read.len = len;
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ret = semihosting_trap(SYSREAD, &read);
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if (ret < 0)
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return semihosting_errno();
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return len - ret;
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}
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/* clang-format on */
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static void semihosting_putc(char ch)
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{
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semihosting_trap(SYSWRITEC, &ch);
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}
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static int semihosting_getc(void)
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{
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char ch = 0;
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int ret;
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if (semihosting_infd < 0) {
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ch = semihosting_trap(SYSREADC, NULL);
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ret = ch > -1 ? ch : -1;
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} else
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ret = semihosting_read(semihosting_infd, &ch, 1) > 0 ? ch : -1;
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return ret;
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}
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static struct sbi_console_device semihosting_console = {
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.name = "semihosting",
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.console_putc = semihosting_putc,
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.console_getc = semihosting_getc
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};
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int semihosting_init(void)
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{
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semihosting_infd = semihosting_open(":tt", MODE_READ);
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sbi_console_set_device(&semihosting_console);
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return 0;
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}
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@ -28,3 +28,4 @@ CONFIG_FDT_SERIAL_UART8250=y
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CONFIG_FDT_SERIAL_XILINX_UARTLITE=y
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CONFIG_FDT_SERIAL_XILINX_UARTLITE=y
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CONFIG_FDT_TIMER=y
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CONFIG_FDT_TIMER=y
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CONFIG_FDT_TIMER_MTIMER=y
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CONFIG_FDT_TIMER_MTIMER=y
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CONFIG_SERIAL_SEMIHOSTING=y
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@ -23,6 +23,7 @@
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#include <sbi_utils/timer/fdt_timer.h>
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#include <sbi_utils/timer/fdt_timer.h>
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#include <sbi_utils/ipi/fdt_ipi.h>
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#include <sbi_utils/ipi/fdt_ipi.h>
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#include <sbi_utils/reset/fdt_reset.h>
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#include <sbi_utils/reset/fdt_reset.h>
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#include <sbi_utils/serial/semihosting.h>
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/* List of platform override modules generated at compile time */
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/* List of platform override modules generated at compile time */
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extern const struct platform_override *platform_override_modules[];
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extern const struct platform_override *platform_override_modules[];
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@ -242,6 +243,14 @@ static uint64_t generic_pmu_xlate_to_mhpmevent(uint32_t event_idx,
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return evt_val;
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return evt_val;
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}
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}
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static int generic_console_init(void)
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{
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if (semihosting_enabled())
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return semihosting_init();
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else
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return fdt_serial_init();
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}
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const struct sbi_platform_operations platform_ops = {
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const struct sbi_platform_operations platform_ops = {
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.nascent_init = generic_nascent_init,
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.nascent_init = generic_nascent_init,
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.early_init = generic_early_init,
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.early_init = generic_early_init,
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@ -249,7 +258,7 @@ const struct sbi_platform_operations platform_ops = {
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.early_exit = generic_early_exit,
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.early_exit = generic_early_exit,
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.final_exit = generic_final_exit,
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.final_exit = generic_final_exit,
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.domains_init = generic_domains_init,
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.domains_init = generic_domains_init,
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.console_init = fdt_serial_init,
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.console_init = generic_console_init,
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.irqchip_init = fdt_irqchip_init,
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.irqchip_init = fdt_irqchip_init,
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.irqchip_exit = fdt_irqchip_exit,
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.irqchip_exit = fdt_irqchip_exit,
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.ipi_init = fdt_ipi_init,
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.ipi_init = fdt_ipi_init,
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