Merge pull request #158 from sifive/trace-encoder

Trace encoder putc() support

Makefile.am

@@ -75,6 +75,7 @@ nobase_include_HEADERS = \
 	metal/drivers/sifive_rtc0.h \
 	metal/drivers/sifive_spi0.h \
 	metal/drivers/sifive_test0.h \
+	metal/drivers/sifive_trace.h \
 	metal/drivers/sifive_uart0.h \
 	metal/drivers/sifive_wdog0.h \
 	metal/machine/inline.h \
@@ -179,6 +180,7 @@ libriscv__mmachine__@MACHINE_NAME@_a_SOURCES = \
 	src/drivers/sifive_rtc0.c \
 	src/drivers/sifive_spi0.c \
 	src/drivers/sifive_test0.c \
+	src/drivers/sifive_trace.c \
 	src/drivers/sifive_uart0.c \
 	src/drivers/sifive_wdog0.c \
 	src/button.c \

metal/drivers/sifive_trace.h

@@ -0,0 +1,23 @@
+/* Copyright 2019 SiFive, Inc */
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#ifndef METAL__DRIVERS__SIFIVE_TRACE_H
+#define METAL__DRIVERS__SIFIVE_TRACE_H
+
+#include <metal/compiler.h>
+#include <metal/io.h>
+#include <metal/uart.h>
+
+struct __metal_driver_vtable_sifive_trace {
+    const struct metal_uart_vtable uart;
+};
+
+struct __metal_driver_sifive_trace;
+
+__METAL_DECLARE_VTABLE(__metal_driver_vtable_sifive_trace)
+
+struct __metal_driver_sifive_trace {
+    struct metal_uart uart;
+};
+
+#endif /* METAL__DRIVERS__SIFIVE_TRACE_H */

src/drivers/sifive_trace.c

@@ -0,0 +1,95 @@
+/* Copyright 2019 SiFive, Inc */
+/* SPDX-License-Identifier: Apache-2.0 */
+
+#include <metal/machine/platform.h>
+
+#ifdef METAL_SIFIVE_TRACE
+
+#include <metal/drivers/sifive_trace.h>
+#include <metal/machine.h>
+
+#define TRACE_REG(offset) (((unsigned long)base + (offset)))
+#define TRACE_REG8(offset)                                                     \
+    (__METAL_ACCESS_ONCE((__metal_io_u8 *)TRACE_REG(offset)))
+#define TRACE_REG16(offset)                                                    \
+    (__METAL_ACCESS_ONCE((__metal_io_u16 *)TRACE_REG(offset)))
+#define TRACE_REG32(offset)                                                    \
+    (__METAL_ACCESS_ONCE((__metal_io_u32 *)TRACE_REG(offset)))
+
+static void write_itc_uint32(struct metal_uart *trace, uint32_t data) {
+    long base = __metal_driver_sifive_trace_base(trace);
+
+    TRACE_REG32(METAL_SIFIVE_TRACE_ITCSTIMULUS) = data;
+}
+
+static void write_itc_uint16(struct metal_uart *trace, uint16_t data) {
+    long base = __metal_driver_sifive_trace_base(trace);
+
+    TRACE_REG16(METAL_SIFIVE_TRACE_ITCSTIMULUS + 2) = data;
+}
+
+static void write_itc_uint8(struct metal_uart *trace, uint8_t data) {
+    long base = __metal_driver_sifive_trace_base(trace);
+
+    TRACE_REG8(METAL_SIFIVE_TRACE_ITCSTIMULUS + 3) = data;
+}
+
+int __metal_driver_sifive_trace_putc(struct metal_uart *trace,
+                                     unsigned char c) {
+    static uint32_t buffer = 0;
+    static int bytes_in_buffer = 0;
+
+    buffer |= (((uint32_t)c) << (bytes_in_buffer * 8));
+
+    bytes_in_buffer += 1;
+
+    if (bytes_in_buffer >= 4) {
+        write_itc_uint32(trace, buffer);
+
+        buffer = 0;
+        bytes_in_buffer = 0;
+    } else if ((c == '\n') || (c == '\r')) { // partial write
+        switch (bytes_in_buffer) {
+        case 3: // do a full word write
+            write_itc_uint16(trace, (uint16_t)(buffer));
+            write_itc_uint8(trace, (uint8_t)(buffer >> 16));
+            break;
+        case 2: // do a 16 bit write
+            write_itc_uint16(trace, (uint16_t)buffer);
+            break;
+        case 1: // do a 1 byte write
+            write_itc_uint8(trace, (uint8_t)buffer);
+            break;
+        }
+
+        buffer = 0;
+        bytes_in_buffer = 0;
+    }
+
+    return (int)c;
+}
+
+void __metal_driver_sifive_trace_init(struct metal_uart *trace, int baud_rate) {
+    // The only init we do here is to make sure ITC 0 is enabled. It is up to
+    // Freedom Studio or other mechanisms to make sure tracing is enabled. If we
+    // try to enable tracing here, it will likely conflict with Freedom Studio,
+    // and they will just fight with each other.
+
+    long base = __metal_driver_sifive_trace_base(trace);
+
+    TRACE_REG32(METAL_SIFIVE_TRACE_ITCTRACEENABLE) |= 0x00000001;
+}
+
+__METAL_DEFINE_VTABLE(__metal_driver_vtable_sifive_trace) = {
+    .uart.init = __metal_driver_sifive_trace_init,
+    .uart.putc = __metal_driver_sifive_trace_putc,
+    .uart.getc = NULL,
+
+    .uart.get_baud_rate = NULL,
+    .uart.set_baud_rate = NULL,
+
+    .uart.controller_interrupt = NULL,
+    .uart.get_interrupt_id = NULL,
+};
+
+#endif /* METAL_SIFIVE_TRACE */