machine: add flash start/end address that can be used for data

builder/builder_test.go

@@ -56,7 +56,6 @@ func TestClangAttributes(t *testing.T) {
 		{GOOS: "linux", GOARCH: "arm", GOARM: "6"},
 		{GOOS: "linux", GOARCH: "arm", GOARM: "7"},
 		{GOOS: "linux", GOARCH: "arm64"},
-		{GOOS: "linux", GOARCH: "mips"},
 		{GOOS: "darwin", GOARCH: "amd64"},
 		{GOOS: "darwin", GOARCH: "arm64"},
 		{GOOS: "windows", GOARCH: "amd64"},

compileopts/target.go

@@ -278,9 +278,6 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 	case "arm64":
 		spec.CPU = "generic"
 		spec.Features = "+neon"
-	case "mips":
-		spec.CPU = "mips32r2"
-		spec.Features = "+mips32r2,-noabicalls"
 	}
 	if goos == "darwin" {
 		spec.Linker = "ld.lld"
@@ -353,8 +350,6 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 				spec.Emulator = "qemu-arm {}"
 			case "arm64":
 				spec.Emulator = "qemu-aarch64 {}"
-			case "mips":
-				spec.Emulator = "qemu-mips {}"
 			}
 		}
 	}

compiler/defer.go

@@ -31,7 +31,7 @@ func (b *builder) supportsRecover() bool {
 		// proposal of WebAssembly:
 		// https://github.com/WebAssembly/exception-handling
 		return false
-	case "riscv64", "xtensa", "mips":
+	case "riscv64", "xtensa":
 		// TODO: add support for these architectures
 		return false
 	default:

main_test.go

@@ -34,7 +34,6 @@ var supportedLinuxArches = map[string]string{
 	"X86Linux":   "linux/386",
 	"ARMLinux":   "linux/arm/6",
 	"ARM64Linux": "linux/arm64",
-	"MIPSLinux":  "linux/mips",
 }
 
 var sema = make(chan struct{}, runtime.NumCPU())

src/examples/flash/main.go

@@ -0,0 +1,8 @@
+package main
+
+import "machine"
+
+func main() {
+	println("flash data start:", machine.FlashDataStart())
+	println("flash data end:  ", machine.FlashDataEnd())
+}

src/internal/task/task_stack_mips.S

@@ -1,69 +0,0 @@
-.section .text.tinygo_startTask
-.global  tinygo_startTask
-.type    tinygo_startTask, %function
-tinygo_startTask:
-    // Small assembly stub for starting a goroutine. This is already run on the
-    // new stack, with the callee-saved registers already loaded.
-    // Most importantly, s0 contains the pc of the to-be-started function and s1
-    // contains the only argument it is given. Multiple arguments are packed
-    // into one by storing them in a new allocation.
-
-    // Set the first argument of the goroutine start wrapper, which contains all
-    // the arguments.
-    move  $a0, $s1
-
-    // Branch to the "goroutine start" function. Use jalr to write the return
-    // address to ra so we'll return here after the goroutine exits.
-    jalr  $s0
-    nop
-    nop
-
-    // After return, exit this goroutine. This is a tail call.
-    j     tinygo_pause
-    nop
-    nop
-
-.section .text.tinygo_swapTask
-.global  tinygo_swapTask
-.type    tinygo_swapTask, %function
-tinygo_swapTask:
-    // This function gets the following parameters:
-    //   a0 = newStack uintptr
-    //   a1 = oldStack *uintptr
-
-    // Push all callee-saved registers.
-    addiu $sp, $sp, -40
-    sw $ra, 36($sp)
-    sw $s8, 32($sp)
-    sw $s7, 28($sp)
-    sw $s6, 24($sp)
-    sw $s5, 20($sp)
-    sw $s4, 16($sp)
-    sw $s3, 12($sp)
-    sw $s2,  8($sp)
-    sw $s1,  4($sp)
-    sw $s0,   ($sp)
-
-    // Save the current stack pointer in oldStack.
-    sw $sp, 0($a1)
-
-    // Switch to the new stack pointer.
-    move $sp, $a0
-
-    // Pop all saved registers from this new stack.
-    lw $ra,  36($sp)
-    lw $s8,  32($sp)
-    lw $s7,  28($sp)
-    lw $s6,  24($sp)
-    lw $s5,  20($sp)
-    lw $s4,  16($sp)
-    lw $s3,  12($sp)
-    lw $s2,   8($sp)
-    lw $s1,   4($sp)
-    lw $s0,    ($sp)
-    addiu $sp, $sp, 40
-
-    // Return into the task.
-    jalr $ra
-    nop
-    nop

src/internal/task/task_stack_mips.go

@@ -1,61 +0,0 @@
-//go:build scheduler.tasks && mips
-
-package task
-
-import "unsafe"
-
-var systemStack uintptr
-
-// calleeSavedRegs is the list of registers that must be saved and restored when
-// switching between tasks. Also see task_stack_mips.S that relies on the exact
-// layout of this struct.
-type calleeSavedRegs struct {
-	s0 uintptr
-	s1 uintptr
-	s2 uintptr
-	s3 uintptr
-	s4 uintptr
-	s5 uintptr
-	s6 uintptr
-	s7 uintptr
-	s8 uintptr
-	ra uintptr
-}
-
-// archInit runs architecture-specific setup for the goroutine startup.
-func (s *state) archInit(r *calleeSavedRegs, fn uintptr, args unsafe.Pointer) {
-	// Store the initial sp for the startTask function (implemented in assembly).
-	s.sp = uintptr(unsafe.Pointer(r))
-
-	// Initialize the registers.
-	// These will be popped off of the stack on the first resume of the goroutine.
-
-	// Start the function at tinygo_startTask (defined in src/internal/task/task_stack_mips.S).
-	// This assembly code calls a function (passed in s0) with a single argument
-	// (passed in s1). After the function returns, it calls Pause().
-	r.ra = uintptr(unsafe.Pointer(&startTask))
-
-	// Pass the function to call in s0.
-	// This function is a compiler-generated wrapper which loads arguments out of a struct pointer.
-	// See createGoroutineStartWrapper (defined in compiler/goroutine.go) for more information.
-	r.s0 = fn
-
-	// Pass the pointer to the arguments struct in s1.
-	r.s1 = uintptr(args)
-}
-
-func (s *state) resume() {
-	swapTask(s.sp, &systemStack)
-}
-
-func (s *state) pause() {
-	newStack := systemStack
-	systemStack = 0
-	swapTask(newStack, &s.sp)
-}
-
-// SystemStack returns the system stack pointer when called from a task stack.
-// When called from the system stack, it returns 0.
-func SystemStack() uintptr {
-	return systemStack
-}

src/machine/flash.go

@@ -0,0 +1,23 @@
+//go:build nrf
+
+package machine
+
+import "unsafe"
+
+//go:extern __flash_data_start
+var flashDataStart [0]byte
+
+//go:extern __flash_data_end
+var flashDataEnd [0]byte
+
+// Return the start of the writable flash area, aligned on a page boundary. This
+// is usually just after the program and static data.
+func FlashDataStart() uintptr {
+	return (uintptr(unsafe.Pointer(&flashDataStart)) + flashPageSize - 1) &^ (flashPageSize - 1)
+}
+
+// Return the end of the writable flash area. Usually this is the address one
+// past the end of the on-chip flash.
+func FlashDataEnd() uintptr {
+	return uintptr(unsafe.Pointer(&flashDataEnd))
+}

src/machine/machine_nrf51.go

@@ -6,6 +6,8 @@ import (
 	"device/nrf"
 )
 
+const flashPageSize = 1024
+
 // Get peripheral and pin number for this GPIO pin.
 func (p Pin) getPortPin() (*nrf.GPIO_Type, uint32) {
 	return nrf.GPIO, uint32(p)

src/machine/machine_nrf528xx.go

@@ -12,6 +12,8 @@ func CPUFrequency() uint32 {
 	return 64000000
 }
 
+const flashPageSize = 4096
+
 // InitADC initializes the registers needed for ADC.
 func InitADC() {
 	return // no specific setup on nrf52 machine.

src/runtime/arch_mips.go

@@ -1,19 +0,0 @@
-package runtime
-
-const GOARCH = "mips"
-
-// The bitness of the CPU (e.g. 8, 32, 64).
-const TargetBits = 32
-
-const deferExtraRegs = 0
-
-const flag_linux_MAP_ANONYMOUS = 0x800
-
-// Align on the maximum alignment for this platform (double).
-func align(ptr uintptr) uintptr {
-	return (ptr + 7) &^ 7
-}
-
-func getCurrentStackPointer() uintptr {
-	return uintptr(stacksave())
-}

src/runtime/os_linux.go

@@ -14,7 +14,7 @@ const (
 	flag_PROT_READ     = 0x1
 	flag_PROT_WRITE    = 0x2
 	flag_MAP_PRIVATE   = 0x2
-	flag_MAP_ANONYMOUS = flag_linux_MAP_ANONYMOUS
+	flag_MAP_ANONYMOUS = 0x20
 )
 
 // Source: https://github.com/torvalds/linux/blob/master/include/uapi/linux/time.h

targets/arm.ld

@@ -69,3 +69,7 @@ _heap_start = _ebss;
 _heap_end = ORIGIN(RAM) + LENGTH(RAM);
 _globals_start = _sdata;
 _globals_end = _ebss;
+
+/* For the flash API */
+__flash_data_start = LOADADDR(.data) + SIZEOF(.data);
+__flash_data_end = ORIGIN(FLASH_TEXT) + LENGTH(FLASH_TEXT);