[PATCH v3] lib: utils/serial: add semihosting support
Kautuk Consul
kconsul at ventanamicro.com
Tue Sep 13 21:35:32 PDT 2022
On Tue, Sep 13, 2022 at 9:12 PM Anup Patel <anup at brainfault.org> wrote:
>
> On Mon, Sep 12, 2022 at 4:28 PM Kautuk Consul <kconsul at ventanamicro.com> wrote:
> >
> > 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 at ventanamicro.com>
> > Signed-off-by: Kautuk Consul <kconsul at ventanamicro.com>
>
> Looks good to me.
>
> Reviewed-by: Anup Patel <anup at brainfault.org>
Thanks, Anup.
This is the first time I have submitted an opensbi patch so I deeply
appreciate it!
>
> Applied this patch to the riscv/opensbi repo.
>
> Thanks,
> Anup
>
> > ---
> > include/sbi_utils/serial/semihosting.h | 47 +++++++
> > lib/utils/serial/Kconfig | 4 +
> > lib/utils/serial/objects.mk | 1 +
> > lib/utils/serial/semihosting.c | 177 +++++++++++++++++++++++++
> > platform/generic/configs/defconfig | 1 +
> > platform/generic/platform.c | 11 +-
> > 6 files changed, 240 insertions(+), 1 deletion(-)
> > create mode 100644 include/sbi_utils/serial/semihosting.h
> > create mode 100644 lib/utils/serial/semihosting.c
> >
> > diff --git a/include/sbi_utils/serial/semihosting.h b/include/sbi_utils/serial/semihosting.h
> > new file mode 100644
> > index 0000000..8cc4a86
> > --- /dev/null
> > +++ b/include/sbi_utils/serial/semihosting.h
> > @@ -0,0 +1,47 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2022 Ventana Micro Systems Inc.
> > + *
> > + * Authors:
> > + * Anup Patel <apatel at ventanamicro.com>
> > + * Kautuk Consul <kconsul at ventanamicro.com>
> > + */
> > +
> > +#ifndef __SERIAL_SEMIHOSTING_H__
> > +#define __SERIAL_SEMIHOSTING_H__
> > +
> > +#include <sbi/sbi_types.h>
> > +
> > +/**
> > + * enum semihosting_open_mode - Numeric file modes for use with semihosting_open()
> > + * MODE_READ: 'r'
> > + * MODE_BINARY: 'b'
> > + * MODE_PLUS: '+'
> > + * MODE_WRITE: 'w'
> > + * MODE_APPEND: 'a'
> > + *
> > + * These modes represent the mode string used by fopen(3) in a form which can
> > + * be passed to semihosting_open(). These do NOT correspond directly to %O_RDONLY,
> > + * %O_CREAT, etc; see fopen(3) for details. In particular, @MODE_PLUS
> > + * effectively results in adding %O_RDWR, and @MODE_WRITE will add %O_TRUNC.
> > + * For compatibility, @MODE_BINARY should be added when opening non-text files
> > + * (such as images).
> > + */
> > +enum semihosting_open_mode {
> > + MODE_READ = 0x0,
> > + MODE_BINARY = 0x1,
> > + MODE_PLUS = 0x2,
> > + MODE_WRITE = 0x4,
> > + MODE_APPEND = 0x8,
> > +};
> > +
> > +#ifdef CONFIG_SERIAL_SEMIHOSTING
> > +int semihosting_init(void);
> > +int semihosting_enabled(void);
> > +#else
> > +static inline int semihosting_init(void) { return SBI_ENODEV; }
> > +static inline int semihosting_enabled(void) { return 0; }
> > +#endif
> > +
> > +#endif
> > diff --git a/lib/utils/serial/Kconfig b/lib/utils/serial/Kconfig
> > index 6e425f2..da549a7 100644
> > --- a/lib/utils/serial/Kconfig
> > +++ b/lib/utils/serial/Kconfig
> > @@ -79,4 +79,8 @@ config SERIAL_XILINX_UARTLITE
> > bool "Xilinx UART Lite support"
> > default n
> >
> > +config SERIAL_SEMIHOSTING
> > + bool "Semihosting support"
> > + default n
> > +
> > endmenu
> > diff --git a/lib/utils/serial/objects.mk b/lib/utils/serial/objects.mk
> > index efb1d9e..98f3f9a 100644
> > --- a/lib/utils/serial/objects.mk
> > +++ b/lib/utils/serial/objects.mk
> > @@ -41,3 +41,4 @@ libsbiutils-objs-$(CONFIG_SERIAL_SIFIVE) += serial/sifive-uart.o
> > libsbiutils-objs-$(CONFIG_SERIAL_LITEX) += serial/litex-uart.o
> > libsbiutils-objs-$(CONFIG_SERIAL_UART8250) += serial/uart8250.o
> > libsbiutils-objs-$(CONFIG_SERIAL_XILINX_UARTLITE) += serial/xlnx-uartlite.o
> > +libsbiutils-objs-$(CONFIG_SERIAL_SEMIHOSTING) += serial/semihosting.o
> > diff --git a/lib/utils/serial/semihosting.c b/lib/utils/serial/semihosting.c
> > new file mode 100644
> > index 0000000..7298049
> > --- /dev/null
> > +++ b/lib/utils/serial/semihosting.c
> > @@ -0,0 +1,177 @@
> > +/*
> > + * SPDX-License-Identifier: BSD-2-Clause
> > + *
> > + * Copyright (c) 2022 Ventana Micro Systems Inc.
> > + *
> > + * Authors:
> > + * Anup Patel <apatel at ventanamicro.com>
> > + * Kautuk Consul <kconsul at ventanamicro.com>
> > + */
> > +
> > +#include <sbi/sbi_console.h>
> > +#include <sbi/sbi_string.h>
> > +#include <sbi/sbi_error.h>
> > +#include <sbi_utils/serial/semihosting.h>
> > +
> > +#define SYSOPEN 0x01
> > +#define SYSWRITEC 0x03
> > +#define SYSREAD 0x06
> > +#define SYSREADC 0x07
> > +#define SYSERRNO 0x13
> > +
> > +static long semihosting_trap(int sysnum, void *addr)
> > +{
> > + register int ret asm ("a0") = sysnum;
> > + register void *param0 asm ("a1") = addr;
> > +
> > + asm volatile (
> > + "\t.option push\n"
> > + "\t.option norvc\n"
> > + "\tj 1f\n"
> > + "\t.align 4\n"
> > + "\t1: slli zero, zero, 0x1f\n"
> > + "\tebreak\n"
> > + "\tsrai zero, zero, 7\n"
> > + "\t.option pop\n"
> > + : "+r" (ret) : "r" (param0) : "memory");
> > +
> > + return ret;
> > +}
> > +
> > +static bool _semihosting_enabled = true;
> > +static bool try_semihosting = true;
> > +
> > +bool semihosting_enabled(void)
> > +{
> > + register int ret asm ("a0") = SYSERRNO;
> > + register void *param0 asm ("a1") = NULL;
> > + unsigned long tmp = 0;
> > +
> > + if (!try_semihosting)
> > + return _semihosting_enabled;
> > +
> > + asm volatile (
> > + "\t.option push\n"
> > + "\t.option norvc\n"
> > +
> > + "\tj _semihost_test_vector_next\n"
> > + "\t.align 4\n"
> > + "\t_semihost_test_vector:\n"
> > + "\t\tcsrr %[en], mepc\n"
> > + "\t\taddi %[en], %[en], 4\n"
> > + "\t\tcsrw mepc, %[en]\n"
> > + "\t\tadd %[en], zero, zero\n"
> > + "\t\tmret\n"
> > + "\t_semihost_test_vector_next:\n"
> > +
> > + "\tla %[tmp], _semihost_test_vector\n"
> > + "\tcsrrw %[tmp], mtvec, %[tmp]\n"
> > + "\tj 1f\n"
> > + "\t.align 4\n"
> > + "\t1: slli zero, zero, 0x1f\n"
> > + "\tebreak\n"
> > + "\tsrai zero, zero, 7\n"
> > + "\tcsrw mtvec, %[tmp]\n"
> > +
> > + "\t.option pop\n"
> > + : [tmp] "+r" (tmp), [en] "+r" (_semihosting_enabled),
> > + [ret] "+r" (ret)
> > + : "r" (param0) : "memory");
> > +
> > + try_semihosting = false;
> > + return _semihosting_enabled;
> > +}
> > +
> > +static int semihosting_errno(void)
> > +{
> > + long ret = semihosting_trap(SYSERRNO, NULL);
> > +
> > + if (ret > 0)
> > + return -ret;
> > + return SBI_EIO;
> > +}
> > +
> > +static int semihosting_infd = SBI_ENODEV;
> > +
> > +static long semihosting_open(const char *fname, enum semihosting_open_mode mode)
> > +{
> > + long fd;
> > + struct semihosting_open_s {
> > + const char *fname;
> > + unsigned long mode;
> > + size_t len;
> > + } open;
> > +
> > + open.fname = fname;
> > + open.len = sbi_strlen(fname);
> > + open.mode = mode;
> > +
> > + /* Open the file on the host */
> > + fd = semihosting_trap(SYSOPEN, &open);
> > + if (fd == -1)
> > + return semihosting_errno();
> > + return fd;
> > +}
> > +
> > +/**
> > + * struct semihosting_rdwr_s - Arguments for read and write
> > + * @fd: A file descriptor returned from semihosting_open()
> > + * @memp: Pointer to a buffer of memory of at least @len bytes
> > + * @len: The number of bytes to read or write
> > + */
> > +struct semihosting_rdwr_s {
> > + long fd;
> > + void *memp;
> > + size_t len;
> > +};
> > +
> > +static long semihosting_read(long fd, void *memp, size_t len)
> > +{
> > + long ret;
> > + struct semihosting_rdwr_s read;
> > +
> > + read.fd = fd;
> > + read.memp = memp;
> > + read.len = len;
> > +
> > + ret = semihosting_trap(SYSREAD, &read);
> > + if (ret < 0)
> > + return semihosting_errno();
> > + return len - ret;
> > +}
> > +
> > +/* clang-format on */
> > +
> > +static void semihosting_putc(char ch)
> > +{
> > + semihosting_trap(SYSWRITEC, &ch);
> > +}
> > +
> > +static int semihosting_getc(void)
> > +{
> > + char ch = 0;
> > + int ret;
> > +
> > + if (semihosting_infd < 0) {
> > + ch = semihosting_trap(SYSREADC, NULL);
> > + ret = ch > -1 ? ch : -1;
> > + } else
> > + ret = semihosting_read(semihosting_infd, &ch, 1) > 0 ? ch : -1;
> > +
> > + return ret;
> > +}
> > +
> > +static struct sbi_console_device semihosting_console = {
> > + .name = "semihosting",
> > + .console_putc = semihosting_putc,
> > + .console_getc = semihosting_getc
> > +};
> > +
> > +int semihosting_init(void)
> > +{
> > + semihosting_infd = semihosting_open(":tt", MODE_READ);
> > +
> > + sbi_console_set_device(&semihosting_console);
> > +
> > + return 0;
> > +}
> > diff --git a/platform/generic/configs/defconfig b/platform/generic/configs/defconfig
> > index e324173..c95b7fa 100644
> > --- a/platform/generic/configs/defconfig
> > +++ b/platform/generic/configs/defconfig
> > @@ -28,3 +28,4 @@ CONFIG_FDT_SERIAL_UART8250=y
> > CONFIG_FDT_SERIAL_XILINX_UARTLITE=y
> > CONFIG_FDT_TIMER=y
> > CONFIG_FDT_TIMER_MTIMER=y
> > +CONFIG_SERIAL_SEMIHOSTING=y
> > diff --git a/platform/generic/platform.c b/platform/generic/platform.c
> > index cc3620f..bf51aba 100644
> > --- a/platform/generic/platform.c
> > +++ b/platform/generic/platform.c
> > @@ -23,6 +23,7 @@
> > #include <sbi_utils/timer/fdt_timer.h>
> > #include <sbi_utils/ipi/fdt_ipi.h>
> > #include <sbi_utils/reset/fdt_reset.h>
> > +#include <sbi_utils/serial/semihosting.h>
> >
> > /* List of platform override modules generated at compile time */
> > extern const struct platform_override *platform_override_modules[];
> > @@ -242,6 +243,14 @@ static uint64_t generic_pmu_xlate_to_mhpmevent(uint32_t event_idx,
> > return evt_val;
> > }
> >
> > +static int generic_console_init(void)
> > +{
> > + if (semihosting_enabled())
> > + return semihosting_init();
> > + else
> > + return fdt_serial_init();
> > +}
> > +
> > const struct sbi_platform_operations platform_ops = {
> > .nascent_init = generic_nascent_init,
> > .early_init = generic_early_init,
> > @@ -249,7 +258,7 @@ const struct sbi_platform_operations platform_ops = {
> > .early_exit = generic_early_exit,
> > .final_exit = generic_final_exit,
> > .domains_init = generic_domains_init,
> > - .console_init = fdt_serial_init,
> > + .console_init = generic_console_init,
> > .irqchip_init = fdt_irqchip_init,
> > .irqchip_exit = fdt_irqchip_exit,
> > .ipi_init = fdt_ipi_init,
> > --
> > 2.34.1
> >
> >
> > --
> > opensbi mailing list
> > opensbi at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/opensbi
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