esp: add support for the Espressif ESP32 chip

This is only very minimal support. More support (such as tinygo flash,
or peripheral access) should be added in later commits, to keep this one
focused.

Importantly, this commit changes the LLVM repo from llvm/llvm-project to
espressif/llvm-project. This should be fine, if we want to upgrade to
LLVM 11 it's easy to switch back to llvm/llvm-project until Espressif
has updated their fork.

Author: aykevl

.circleci/config.yml

@@ -44,16 +44,28 @@ commands:
           command: |
             wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
             sudo apt install ./google-chrome-stable_current_amd64.deb
+  install-xtensa-toolchain:
+    parameters:
+      variant:
+        type: string
+    steps:
+      - run:
+          name: "Install Xtensa toolchain"
+          command: |
+            curl -L https://github.com/espressif/crosstool-NG/releases/download/esp-2020r2/xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz -o xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz
+            sudo tar -C /usr/local -xf xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz
+            sudo ln -s /usr/local/xtensa-esp32-elf/bin/xtensa-esp32-elf-ld /usr/local/bin/xtensa-esp32-elf-ld
+            rm xtensa-esp32-elf-gcc8_2_0-esp-2020r2-<<parameters.variant>>.tar.gz
   llvm-source-linux:
     steps:
       - restore_cache:
           keys:
-            - llvm-source-10-v0
+            - llvm-source-10-v1
       - run:
           name: "Fetch LLVM source"
           command: make llvm-source
       - save_cache:
-          key: llvm-source-10-v0
+          key: llvm-source-10-v1
           paths:
             - llvm-project
   build-wasi-libc:
@@ -95,7 +107,7 @@ commands:
             - lib/wasi-libc/sysroot
       - run: go test -v -tags=llvm<<parameters.llvm>> ./cgo ./compileopts ./interp ./transform .
       - run: make gen-device -j4
-      - run: make smoketest
+      - run: make smoketest XTENSA=0
       - run: make wasmtest
       - save_cache:
           key: go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_BUILD_NUM }}
@@ -121,14 +133,16 @@ commands:
                 gcc-avr \
                 avr-libc
       - install-node
+      - install-xtensa-toolchain:
+          variant: "linux-amd64"
       - restore_cache:
           keys:
             - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
             - go-cache-v2-{{ checksum "go.mod" }}
       - llvm-source-linux
       - restore_cache:
           keys:
-            - llvm-build-10-linux-v0-assert
+            - llvm-build-10-linux-v1-assert
       - run:
           name: "Build LLVM"
           command: |
@@ -146,7 +160,7 @@ commands:
               make ASSERT=1 llvm-build
             fi
       - save_cache:
-          key: llvm-build-10-linux-v0-assert
+          key: llvm-build-10-linux-v1-assert
           paths:
             llvm-build
       - run: make ASSERT=1
@@ -179,14 +193,16 @@ commands:
                 gcc-avr \
                 avr-libc
       - install-node
+      - install-xtensa-toolchain:
+          variant: "linux-amd64"
       - restore_cache:
           keys:
             - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
             - go-cache-v2-{{ checksum "go.mod" }}
       - llvm-source-linux
       - restore_cache:
           keys:
-            - llvm-build-10-linux-v0
+            - llvm-build-10-linux-v1
       - run:
           name: "Build LLVM"
           command: |
@@ -204,7 +220,7 @@ commands:
               make llvm-build
             fi
       - save_cache:
-          key: llvm-build-10-linux-v0
+          key: llvm-build-10-linux-v1
           paths:
             llvm-build
       - build-wasi-libc
@@ -250,23 +266,25 @@ commands:
             sudo tar -C /usr/local -xzf go1.14.darwin-amd64.tar.gz
             ln -s /usr/local/go/bin/go /usr/local/bin/go
             HOMEBREW_NO_AUTO_UPDATE=1 brew install qemu
+      - install-xtensa-toolchain:
+          variant: "macos"
       - restore_cache:
           keys:
             - go-cache-macos-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
             - go-cache-macos-v2-{{ checksum "go.mod" }}
       - restore_cache:
           keys:
-            - llvm-source-10-macos-v0
+            - llvm-source-10-macos-v1
       - run:
           name: "Fetch LLVM source"
           command: make llvm-source
       - save_cache:
-          key: llvm-source-10-macos-v0
+          key: llvm-source-10-macos-v1
           paths:
             - llvm-project
       - restore_cache:
           keys:
-            - llvm-build-10-macos-v0
+            - llvm-build-10-macos-v1
       - run:
           name: "Build LLVM"
           command: |
@@ -278,7 +296,7 @@ commands:
               make llvm-build
             fi
       - save_cache:
-          key: llvm-build-10-macos-v0
+          key: llvm-build-10-macos-v1
           paths:
             llvm-build
       - restore_cache:

.gitignore

@@ -3,6 +3,7 @@ docs/_build
 src/device/avr/*.go
 src/device/avr/*.ld
 src/device/avr/*.s
+src/device/esp/*.go
 src/device/nrf/*.go
 src/device/nrf/*.s
 src/device/nxp/*.go

Makefile

@@ -118,7 +118,7 @@ fmt-check:
 	@unformatted=$$(gofmt -l $(FMT_PATHS)); [ -z "$$unformatted" ] && exit 0; echo "Unformatted:"; for fn in $$unformatted; do echo "  $$fn"; done; exit 1
 
 
-gen-device: gen-device-avr gen-device-nrf gen-device-sam gen-device-sifive gen-device-stm32 gen-device-kendryte gen-device-nxp
+gen-device: gen-device-avr gen-device-esp gen-device-nrf gen-device-sam gen-device-sifive gen-device-stm32 gen-device-kendryte gen-device-nxp
 
 gen-device-avr:
 	$(GO) build -o ./build/gen-device-avr ./tools/gen-device-avr/
@@ -129,6 +129,10 @@ gen-device-avr:
 build/gen-device-svd: ./tools/gen-device-svd/*.go
 	$(GO) build -o $@ ./tools/gen-device-svd/
 
+gen-device-esp: build/gen-device-svd
+	./build/gen-device-svd -source=https://github.com/posborne/cmsis-svd/tree/master/data/Espressif-Community -interrupts=software lib/cmsis-svd/data/Espressif-Community/ src/device/esp/
+	GO111MODULE=off $(GO) fmt ./src/device/esp
+
 gen-device-nrf: build/gen-device-svd
 	./build/gen-device-svd -source=https://github.com/NordicSemiconductor/nrfx/tree/master/mdk lib/nrfx/mdk/ src/device/nrf/
 	GO111MODULE=off $(GO) fmt ./src/device/nrf
@@ -156,13 +160,13 @@ gen-device-stm32: build/gen-device-svd
 
 # Get LLVM sources.
 $(LLVM_PROJECTDIR)/README.md:
-	git clone -b release/10.x --depth=1 https://github.com/llvm/llvm-project $(LLVM_PROJECTDIR)
+	git clone -b xtensa_release_10.0.1 --depth=1 https://github.com/espressif/llvm-project $(LLVM_PROJECTDIR)
 llvm-source: $(LLVM_PROJECTDIR)/README.md
 
 # Configure LLVM.
 TINYGO_SOURCE_DIR=$(shell pwd)
 $(LLVM_BUILDDIR)/build.ninja: llvm-source
-	mkdir -p $(LLVM_BUILDDIR); cd $(LLVM_BUILDDIR); cmake -G Ninja $(TINYGO_SOURCE_DIR)/$(LLVM_PROJECTDIR)/llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;RISCV;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR" -DCMAKE_BUILD_TYPE=Release -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_LIBEDIT=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF $(LLVM_OPTION)
+	mkdir -p $(LLVM_BUILDDIR); cd $(LLVM_BUILDDIR); cmake -G Ninja $(TINYGO_SOURCE_DIR)/$(LLVM_PROJECTDIR)/llvm "-DLLVM_TARGETS_TO_BUILD=X86;ARM;AArch64;RISCV;WebAssembly" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR;Xtensa" -DCMAKE_BUILD_TYPE=Release -DLIBCLANG_BUILD_STATIC=ON -DLLVM_ENABLE_TERMINFO=OFF -DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_LIBEDIT=OFF -DLLVM_ENABLE_Z3_SOLVER=OFF -DLLVM_ENABLE_OCAMLDOC=OFF -DLLVM_ENABLE_PROJECTS="clang;lld" -DLLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD=OFF $(LLVM_OPTION)
 
 # Build LLVM.
 $(LLVM_BUILDDIR): $(LLVM_BUILDDIR)/build.ninja
@@ -330,6 +334,9 @@ ifneq ($(AVR), 0)
 	@$(MD5SUM) test.hex
 	$(TINYGO) build -size short -o test.hex -target=digispark -gc=leaking examples/blinky1
 	@$(MD5SUM) test.hex
+endif
+ifneq ($(XTENSA), 0)
+	$(TINYGO) build -size short -o test.elf -target=esp32               examples/serial
 endif
 	$(TINYGO) build -size short -o test.hex -target=hifive1b            examples/blinky1
 	@$(MD5SUM) test.hex

azure-pipelines.yml

@@ -14,20 +14,24 @@ jobs:
       inputs:
         version: '1.15'
     - checkout: self
-    - task: CacheBeta@0
+    - task: Cache@2
       displayName: Cache LLVM source
       inputs:
-        key: llvm-source-10-windows-v0
+        key: llvm-source-10-windows-v1
         path: llvm-project
     - task: Bash@3
       displayName: Download LLVM source
       inputs:
         targetType: inline
-        script: make llvm-source
+        script: |
+          make llvm-source
+          # Workaround for bad symlinks:
+          # https://github.com/microsoft/azure-pipelines-tasks/issues/13418
+          rm -f llvm-project/libcxx/test/std/input.output/filesystems/Inputs/static_test_env/bad_symlink
     - task: CacheBeta@0
       displayName: Cache LLVM build
       inputs:
-        key: llvm-build-10-windows-v0
+        key: llvm-build-10-windows-v1
         path: llvm-build
     - task: Bash@3
       displayName: Build LLVM
@@ -80,4 +84,4 @@ jobs:
         script: |
           export PATH="$PATH:./llvm-build/bin:/c/Program Files/qemu"
           unset GOROOT
-          make smoketest TINYGO=build/tinygo AVR=0
+          make smoketest TINYGO=build/tinygo AVR=0 XTENSA=0

lib/cmsis-svd

@@ -0,0 +1,52 @@
+
+// The following definitions were copied from:
+// esp-idf/components/xtensa/include/xtensa/corebits.h
+#define PS_WOE_MASK                0x00040000
+#define PS_OWB_MASK                0x00000F00
+#define PS_CALLINC_MASK            0x00030000
+#define PS_WOE                     PS_WOE_MASK
+
+// Only calling it call_start_cpu0 for consistency with ESP-IDF.
+.section .text.call_start_cpu0
+1:
+    .long _stack_top
+.global call_start_cpu0
+call_start_cpu0:
+    // We need to set the stack pointer to a different value. This is somewhat
+    // complicated in the Xtensa architecture. The code below is a modified
+    // version of the following code:
+    // https://github.com/espressif/esp-idf/blob/c77c4ccf/components/xtensa/include/xt_instr_macros.h#L47
+
+    // Disable WOE.
+    rsr.ps a2
+    movi a3, ~(PS_WOE_MASK)
+    and a2, a2, a3
+    wsr.ps a2
+    rsync
+
+    // Set WINDOWBASE to 1 << WINDOWSTART.
+    rsr.windowbase  a2
+    ssl  a2
+    movi a2, 1
+    sll  a2, a2
+    wsr.windowstart a2
+    rsync
+
+    // Load new stack pointer.
+    l32r sp, 1b
+
+    // Re-enable WOE.
+    rsr.ps a2
+    movi a3, PS_WOE
+    or a2, a2, a3
+    wsr.ps a2
+    rsync
+
+    // Jump to the runtime start function written in Go.
+    j main
+
+.section .text.tinygo_scanCurrentStack
+.global tinygo_scanCurrentStack
+tinygo_scanCurrentStack:
+    // TODO: save callee saved registers on the stack
+    j tinygo_scanstack

src/device/esp/esp32.S

@@ -0,0 +1,44 @@
+// +build esp32
+
+package machine
+
+import "device/esp"
+
+const peripheralClock = 80000000 // 80MHz
+
+type PinMode uint8
+
+const (
+	PinOutput PinMode = iota
+	PinInput
+)
+
+func (p Pin) Set(value bool)
+
+var (
+	UART0 = UART{Bus: esp.UART0, Buffer: NewRingBuffer()}
+	UART1 = UART{Bus: esp.UART1, Buffer: NewRingBuffer()}
+	UART2 = UART{Bus: esp.UART2, Buffer: NewRingBuffer()}
+)
+
+type UART struct {
+	Bus    *esp.UART_Type
+	Buffer *RingBuffer
+}
+
+func (uart UART) Configure(config UARTConfig) {
+	if config.BaudRate == 0 {
+		config.BaudRate = 115200
+	}
+	uart.Bus.CLKDIV.Set(peripheralClock / config.BaudRate)
+}
+
+func (uart UART) WriteByte(b byte) error {
+	for (uart.Bus.STATUS.Get()>>16)&0xff >= 128 {
+		// Read UART_TXFIFO_CNT from the status register, which indicates how
+		// many bytes there are in the transmit buffer. Wait until there are
+		// less than 128 bytes in this buffer (the default buffer size).
+	}
+	uart.Bus.TX_FIFO.Set(b)
+	return nil
+}

src/machine/machine_esp32.go

@@ -1,4 +1,4 @@
-// +build avr nrf sam sifive stm32 k210 nxp
+// +build avr esp nrf sam sifive stm32 k210 nxp
 
 package machine
 

src/machine/uart.go

@@ -0,0 +1,15 @@
+// +build xtensa
+
+package runtime
+
+const GOARCH = "arm" // xtensa pretends to be arm
+
+// The bitness of the CPU (e.g. 8, 32, 64).
+const TargetBits = 32
+
+// Align on a word boundary.
+func align(ptr uintptr) uintptr {
+	return (ptr + 3) &^ 3
+}
+
+func getCurrentStackPointer() uintptr

src/runtime/arch_xtensa.go

@@ -0,0 +1,31 @@
+// +build xtensa
+
+package interrupt
+
+import "device"
+
+// State represents the previous global interrupt state.
+type State uintptr
+
+// Disable disables all interrupts and returns the previous interrupt state. It
+// can be used in a critical section like this:
+//
+//     state := interrupt.Disable()
+//     // critical section
+//     interrupt.Restore(state)
+//
+// Critical sections can be nested. Make sure to call Restore in the same order
+// as you called Disable (this happens naturally with the pattern above).
+func Disable() (state State) {
+	return State(device.AsmFull("rsil {}, 15", nil))
+}
+
+// Restore restores interrupts to what they were before. Give the previous state
+// returned by Disable as a parameter. If interrupts were disabled before
+// calling Disable, this will not re-enable interrupts, allowing for nested
+// cricital sections.
+func Restore(state State) {
+	device.AsmFull("wsr {state}, PS", map[string]interface{}{
+		"state": state,
+	})
+}