minor

13 files changed, 381 insertions, 4 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7fbd128
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.*.sw*
+build
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..64f908d
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,5 @@
+.PHONY: flash-blink
+
+flash-blink:
+	make -B -C blink
+	./ox-flash/ox-flash -payload blink/build/blink.bin
diff --git a/blink/Makefile b/blink/Makefile
new file mode 100644
index 0000000..87d82d3
--- /dev/null
+++ b/blink/Makefile
@@ -0,0 +1,41 @@
+# adapted from
+# https://github.com/Akshay-Srivatsan/ox64-baremetal-setup/blob/main/examples/Makefile
+
+MEMMAP=memmap.ld
+
+RV=riscv64-unknown-elf
+CC=$(RV)-gcc
+AS=$(RV)-as
+LD=$(RV)-ld
+OBJCOPY=$(RV)-objcopy
+OBJDUMP=$(RV)-objdump
+
+CFLAGS += -ffreestanding -nostdlib -nostartfiles -Wall -Werror \
+	  -Wno-unused-function -march=rv64imac -mabi=lp64 -Iinc -mcmodel=medany
+ASFLAGS += -ffreestanding -nostdlib -nostartfiles -Wall -Werror \
+	   -Wno-unused-function -march=rv64imac -mabi=lp64 -Iinc -mcmodel=medany
+LDFLAGS += -march=rv64imac -mabi=lp64 -nostdlib -nostartfiles -mcmodel=medany
+
+OBJECTS = build/blink.o \
+	  build/start.o \
+	  build/gpio.o \
+	  build/uart.o
+
+all: build/blink.bin
+
+build/%.o: %.c
+	@mkdir -p $(dir $@)
+	$(CC) $< $(CFLAGS) -c -o $@
+
+build/%.o: %.S
+	@mkdir -p $(dir $@)
+	$(CC) $< $(ASFLAGS) -c -o $@
+
+build/%.elf: $(OBJECTS) $(MEMMAP)
+	@mkdir -p $(dir $@)
+	$(CC) $(LDFLAGS) -T$(MEMMAP) $(SHARED) $(OBJECTS) -o $@
+
+build/%.bin build/%.list: build/%.elf
+	@mkdir -p $(dir $@)
+	$(OBJCOPY) $< -Obinary $@
+	$(OBJDUMP) $< -D > $(@:.bin=.list)
diff --git a/blink/blink.c b/blink/blink.c
new file mode 100644
index 0000000..b59c950
--- /dev/null
+++ b/blink/blink.c
@@ -0,0 +1,20 @@
+#include "gpio.h"
+#include "uart.h"
+
+extern unsigned __bss_start__;
+extern unsigned __bss_end__;
+
+int notmain() {
+    unsigned *bss = &__bss_start__;
+    unsigned *bss_end = &__bss_end__;
+    while (bss < bss_end) {
+        *bss++ = 0;
+    }
+
+    size_t pin = 29;
+    gpio_set_function(pin, GPIO_GPIO);
+    gpio_set_input(pin, 0);
+    gpio_set_output(pin, 1);
+
+    return 0;
+}
diff --git a/blink/gpio.c b/blink/gpio.c
new file mode 100644
index 0000000..39c5d51
--- /dev/null
+++ b/blink/gpio.c
@@ -0,0 +1,55 @@
+#include "gpio.h"
+#include "memory.h"
+
+struct PACKED gpio_config {
+    bool input_enable: 1;
+    bool schmitt_trigger_enable: 1;
+    unsigned drive_strength: 2;
+    bool pullup_enable: 1;
+    bool pulldown_enable: 1;
+    bool output_enable: 1;
+    unsigned : 1;
+    unsigned alternate_function: 5;
+    unsigned : 3;
+    unsigned interrupt_mode: 4;
+    bool interrupt_clear: 1;
+    bool interrupt_state: 1;
+    bool interrupt_mask: 1;
+    unsigned: 1;
+    bool output_value: 1;
+    bool output_set: 1;
+    bool output_clear: 1;
+    unsigned: 1;
+    bool input_value: 1;
+    unsigned: 1;
+    unsigned io_mode: 2;
+};
+
+static volatile struct gpio_config *const GPIO_CONFIG = (volatile struct gpio_config *)0x200008c4;
+
+enum gpio_io_mode {
+  IO_MODE_NORMAL,
+  IO_MODE_SET_CLEAR,
+  IO_MODE_BUFFER,
+  IO_MODE_CACHE,
+};
+
+void gpio_set_input(gpio_t pin, bool enable) {
+  struct gpio_config x = get32_type(struct gpio_config, GPIO_CONFIG + pin);
+  x.io_mode = IO_MODE_SET_CLEAR;
+  x.input_enable = enable;
+  put32_type(struct gpio_config, GPIO_CONFIG + pin, x);
+}
+
+void gpio_set_output(gpio_t pin, bool enable) {
+  struct gpio_config x = get32_type(struct gpio_config, GPIO_CONFIG + pin);
+  x.io_mode = IO_MODE_SET_CLEAR;
+  x.output_enable = enable;
+  put32_type(struct gpio_config, GPIO_CONFIG + pin, x);
+}
+
+void gpio_set_function(gpio_t pin, enum gpio_alternate_function function) {
+  struct gpio_config x = get32_type(struct gpio_config, GPIO_CONFIG + pin);
+  x.alternate_function = function;
+  put32_type(struct gpio_config, GPIO_CONFIG + pin, x);
+}
diff --git a/blink/gpio.h b/blink/gpio.h
new file mode 100644
index 0000000..1f0d651
--- /dev/null
+++ b/blink/gpio.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include "types.h"
+
+enum gpio_alternate_function {
+    GPIO_SDH,
+    GPIO_SPI0,
+    GPIO_FLASH,
+    GPIO_I2S,
+    GPIO_PDM,
+    GPIO_I2C0,
+    GPIO_I2C1,
+    GPIO_UART,
+    GPIO_EMAC,
+    GPIO_CAM,
+    GPIO_ANALOG,
+    GPIO_GPIO,
+    GPIO_PWM0,
+    GPIO_PWM1,
+    GPIO_SPI1,
+    GPIO_I2C2,
+    GPIO_I2C3,
+    GPIO_MM_UART,
+    GPIO_DBI_B,
+    GPIO_DBI_C,
+    GPIO_DPI,
+    GPIO_JTAG_LP,
+    GPIO_JTAG_M0,
+    GPIO_JTAG_D0,
+    GPIO_CLOCK_OUT,
+};
+
+typedef size_t gpio_t;
+
+void gpio_set_input(gpio_t pin, bool enable);
+void gpio_set_output(gpio_t pin, bool enable);
+void gpio_set_function(gpio_t pin, enum gpio_alternate_function function);
diff --git a/blink/memmap.ld b/blink/memmap.ld
new file mode 100644
index 0000000..1aacaf3
--- /dev/null
+++ b/blink/memmap.ld
@@ -0,0 +1,72 @@
+OUTPUT_ARCH(riscv)
+OUTPUT_FORMAT(elf64-littleriscv)
+
+ENTRY (_start)
+
+MEMORY
+{
+  OCRAM (rwx) : ORIGIN = 0x22020000, LENGTH = 64K
+  WRAM (rwx) : ORIGIN = 0x22030000, LENGTH = 160K
+  DRAM (rwx) : ORIGIN = 0x3ef80000, LENGTH = 16K
+  VRAM (rwx) : ORIGIN = 0x3f000000, LENGTH = 16K
+  XRAM (rwx) : ORIGIN = 0x40000000, LENGTH = 16K
+
+  PSRAM (rwx) : ORIGIN = 0x50000000, LENGTH = 64M
+  FLASH (rx) : ORIGIN = 0x58000000, LENGTH = 64M
+
+  ROM (rx) : ORIGIN = 0x90000000, LENGTH = 128K
+}
+
+SECTIONS {
+  . = ORIGIN(PSRAM);
+  __stack_size = 2K;
+
+  .text : {
+    __code_start__ = .;
+    KEEP(*(.text.boot))
+    *(.text*)
+    . = ALIGN(4);
+    __code_end__ = .;
+  }
+
+  .rodata . : {
+    . = ALIGN(4);
+    __global_pointer$ = . + 0x800;
+    *(.rodata*)
+    *(.srodata*)
+    . = ALIGN(8);
+  }
+
+  .sdata : {
+    . = ALIGN(4);
+    __global_pointer$ = . + 0x800;
+    *(.sdata*)
+    *(.srodata*)
+  }
+
+  .data : {
+    __data_start__ = .;
+    *(.data*)
+    __data_end__ = .;
+  }
+
+  .bss : {
+    __bss_start__ = .;
+    *(.bss*)
+    *(.sbss*)
+    *(COMMON)
+    __bss_end__ = .;
+    . = ALIGN(8);
+  }
+
+  .kstack (NOLOAD) : {
+    . = ALIGN(16),
+    . += 4K,
+    __stack_start = .;
+  }
+
+  /DISCARD/ : {
+    *(.comment)
+    *(.riscv.attributes)
+  }
+}
diff --git a/blink/memory.h b/blink/memory.h
new file mode 100644
index 0000000..a4f204c
--- /dev/null
+++ b/blink/memory.h
@@ -0,0 +1,18 @@
+#pragma once
+#include <stdint.h>
+
+extern void put32(volatile uint32_t *addr, uint32_t value);
+extern uint32_t get32(volatile uint32_t *addr);
+
+#define get32_type(T, addr) \
+  ({ \
+    _Static_assert(sizeof(T) == 4); \
+    uint32_t raw = get32((volatile uint32_t *)addr); \
+    *(T *)&raw; \
+  })
+#define put32_type(T, addr, val) \
+  ({ \
+    _Static_assert(sizeof(T) == 4); \
+    uint32_t raw = *(uint32_t *)&val; \
+    put32((volatile uint32_t *)addr, raw); \
+  })
diff --git a/blink/start.S b/blink/start.S
new file mode 100644
index 0000000..1d3eb47
--- /dev/null
+++ b/blink/start.S
@@ -0,0 +1,30 @@
+// based on dddrrree's fork based on dwelch's start for bootloader.
+
+// To keep this in the first portion of the binary.
+.section ".text.boot"
+
+// give ourselves a stack
+.globl _start
+_start:
+    .option push
+    .option norelax
+    la gp, __global_pointer$
+    .option pop
+    la sp, __stack_start
+    call notmain
+halt:
+    nop
+    j halt
+
+.globl put32
+put32:
+    fence rw,rw
+    sw a1, 0(a0)
+    fence rw,rw
+    ret
+
+.globl get32
+get32:
+    fence rw,rw
+    lw a0, 0(a0)
+    ret
diff --git a/blink/types.h b/blink/types.h
new file mode 100644
index 0000000..a043494
--- /dev/null
+++ b/blink/types.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#define PACKED __attribute__((packed))
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stddef.h>
+
+#define i8 int8_t
+#define i16 int16_t
+#define i32 int32_t
+#define i64 int64_t
+#define isize ssize_t
+
+#define u8 uint8_t
+#define u16 uint16_t
+#define u32 uint32_t
+#define u64 uint64_t
+#define usize size_t
+#define uint unsigned
diff --git a/blink/uart.c b/blink/uart.c
new file mode 100644
index 0000000..f4f6732
--- /dev/null
+++ b/blink/uart.c
@@ -0,0 +1,72 @@
+#include <stdbool.h>
+
+#include "types.h"
+#include "uart.h"
+#include "memory.h"
+
+// from the bl808 reference manual
+struct uart {
+    u32 tx_config;
+    u32 rx_config;
+    u32 bit_prd;
+    u32 data_config;
+    u32 tx_ir_position;
+    u32 rx_ir_position;
+    u32 rx_rto_timer;
+    u32 sw_mode;
+    u32 int_sts;
+    u32 int_mask;
+    u32 int_clear;
+    u32 int_en;
+    u32 status;
+    u32 sts_urx_abr_prd;
+    u32 rx_abr_prd_b01;
+    u32 rx_abr_prd_b23;
+    u32 rx_abr_prd_b45;
+    u32 rx_abr_prd_b67;
+    u32 rx_abr_pw_tol;
+    u32 rx_bcr_int_cfg;
+    u32 unknown;
+    u32 tx_rs485_cfg;
+    u32 reserved[10];
+    u32 fifo_config_0;
+    u32 fifo_config_1;
+    u32 fifo_wdata;
+    u32 fifo_rdata;
+};
+
+static volatile struct uart *const UART0 = (volatile struct uart *)0x2000A000;
+#define UART_CLOCK 40000000UL
+
+bool uart_can_putc(void) {
+  return true;
+  return (get32(&UART0->fifo_config_1) & 0x3f) != 0;
+}
+
+void uart_putc(char c) {
+  while (!uart_can_putc())
+    ;
+  put32(&UART0->fifo_wdata, c);
+}
+
+void uart_puts(const char *c) {
+  while (*c) {
+    uart_putc(*c++);
+  }
+}
+
+void uart_init(unsigned baud) {
+  // p302
+  uint32_t val = 0;
+  val |= 1 << 0;  // enable
+  val |= 1 << 2;  // freerun mode
+  val |= 7 << 8;  // 8 data bits
+  val |= 2 << 11; // 1 stop bit
+  put32(&UART0->tx_config, val);
+
+  uint32_t bit_period_value =
+      (2 * UART_CLOCK / baud) - 1; // for some reason the uart clock seems to be
+                                   // off by a factor of 2 from what we expect
+  val = bit_period_value << 16 | bit_period_value;
+  put32(&UART0->bit_prd, val);
+}
diff --git a/blink/uart.h b/blink/uart.h
new file mode 100644
index 0000000..dd9721a
--- /dev/null
+++ b/blink/uart.h
@@ -0,0 +1,8 @@
+#pragma once
+#include <stdbool.h>
+#include <stdint.h>
+
+bool uart_can_putc(void);
+void uart_putc(char c);
+void uart_puts(const char *c);
+void uart_init(unsigned baud);
diff --git a/bootloader/Makefile b/bootloader/Makefile
index c2ef1f4..3576608 100644
--- a/bootloader/Makefile
+++ b/bootloader/Makefile
@@ -19,14 +19,11 @@ CFLAGS=$(COMMON_FLAGS) -O$(OPT)
 ASFLAGS=$(COMMON_FLAGS)
 LDFLAGS=-nostdlib -flto
 
-all: tags $(TARGET)
+all: $(TARGET)
 
 clean:
 	rm -f *.o *.elf *.bin *.d tags
 
-tags: $(wildcard *.[chS])
-	ctags *.[chS]
-
 ifneq ($(MAKECMDGOALS),clean)
 -include $(wildcard *.d)
 endif