Several fixes and cleanups for RP2xxx (#630)

* Fixes default vector table not being aligned to 256 in RAM images.

* Fixes Pio.can_add_program_at_offset not finding a position for any program except the first.

* Fixes immutable slice bug in Pio.Assembler

* Makes I2C.apply unfailable

* Makes fn get_regs() for some peripherials public, optimizes codegen for GPIOs by making some functions inline

* Fixes build error in i2c_bus_scan.zig

* Fixes src/mlx90640.zig

* Fixes pcf8574.zig

* Fixes src/hd44780.zig

---------

Co-authored-by: Felix "xq" Queißner <[email protected]>

Author: ikskuh

core/src/cpus/cortex_m.zig

@@ -652,7 +652,9 @@ pub const startup_logic = struct {
 
                 @memcpy(ram_vectors[0..vector_count], flash_vector[0..vector_count]);
 
-                peripherals.scb.VTOR = @intFromPtr(&ram_vectors);
+                const vtor_addr: u32 = @intFromPtr(&ram_vectors);
+                std.debug.assert(std.mem.isAligned(vtor_addr, 256));
+                peripherals.scb.VTOR = vtor_addr;
             }
         }
 
@@ -662,7 +664,8 @@ pub const startup_logic = struct {
     const VectorTable = microzig.chip.VectorTable;
 
     // will be imported by microzig.zig to allow system startup.
-    pub const _vector_table: VectorTable = blk: {
+    // must be aligned to 256 as VTOR ignores the lower 8 bits of the address.
+    pub const _vector_table: VectorTable align(256) = blk: {
         var tmp: VectorTable = .{
             .initial_stack_pointer = microzig.config.end_of_stack,
             .Reset = .{ .c = microzig.cpu.startup_logic._start },

examples/raspberrypi/rp2xxx/src/i2c_bus_scan.zig

@@ -35,7 +35,7 @@ pub fn main() !void {
         pin.set_function(.i2c);
     }
 
-    try i2c0.apply(.{
+    i2c0.apply(.{
         .clock_config = rp2xxx.clock_config,
     });
 

examples/raspberrypi/rp2xxx/src/mlx90640.zig

@@ -76,7 +76,7 @@ fn init() !void {
         .clock_config = rpxxxx.clock_config,
     });
 
-    try i2c0.apply(i2c.Config{ .clock_config = rpxxxx.clock_config });
+    i2c0.apply(i2c.Config{ .clock_config = rpxxxx.clock_config });
 
     rpxxxx.uart.init_logger(uart);
     pin_config.apply();

examples/raspberrypi/rp2xxx/src/rp2040_only/hd44780.zig

@@ -31,7 +31,7 @@ pub fn main() !void {
         pin.set_function(.i2c);
     }
 
-    try i2c0.apply(.{
+    i2c0.apply(.{
         .clock_config = rp2040.clock_config,
     });
     var expander = PCF8574(.{ .Datagram_Device = I2C_Device }).init(i2c_device);

examples/raspberrypi/rp2xxx/src/rp2040_only/pcf8574.zig

@@ -23,7 +23,7 @@ pub fn main() !void {
         pin.set_function(.i2c);
     }
 
-    try i2c0.apply(.{
+    i2c0.apply(.{
         .clock_config = rp2040.clock_config,
     });
     var expander = PCF8574(.{ .Datagram_Device = I2C_Device }).init(i2c_device);

port/raspberrypi/rp2xxx/src/hal/dma.zig

@@ -100,7 +100,7 @@ pub const Channel = enum(u4) {
         al3_read_addr_trig: u32,
     };
 
-    fn get_regs(chan: Channel) *volatile Regs {
+    pub inline fn get_regs(chan: Channel) *volatile Regs {
         const regs = @as(*volatile [num_channels]Regs, @ptrCast(&DMA.CH0_READ_ADDR));
         return &regs[@intFromEnum(chan)];
     }

port/raspberrypi/rp2xxx/src/hal/gpio.zig

@@ -318,22 +318,22 @@ pub const Pin = enum(u6) {
         .RP2350 => *volatile [48]PadsReg,
     };
 
-    fn get_regs(gpio: Pin) *volatile Regs {
+    pub inline fn get_regs(gpio: Pin) *volatile Regs {
         const regs = @as(RegsArray, @ptrCast(&IO_BANK0.GPIO0_STATUS));
         return &regs[@intFromEnum(gpio)];
     }
 
-    fn get_pads_reg(gpio: Pin) *volatile PadsReg {
+    pub inline fn get_pads_reg(gpio: Pin) *volatile PadsReg {
         const regs = @as(PadsRegArray, @ptrCast(&PADS_BANK0.GPIO0));
         return &regs[@intFromEnum(gpio)];
     }
 
     /// Only relevant for RP2350 which has 48 GPIOs
-    fn is_upper(gpio: Pin) bool {
+    pub inline fn is_upper(gpio: Pin) bool {
         return @intFromEnum(gpio) > 31;
     }
 
-    pub fn mask(gpio: Pin) u32 {
+    pub inline fn mask(gpio: Pin) u32 {
         const bitshift_val: u5 = switch (chip) {
             .RP2040 => @intCast(@intFromEnum(gpio)),
             .RP2350 =>

port/raspberrypi/rp2xxx/src/hal/i2c.zig

@@ -216,7 +216,7 @@ pub const instance = struct {
 pub const I2C = enum(u1) {
     _,
 
-    fn get_regs(i2c: I2C) *volatile I2cRegs {
+    pub inline fn get_regs(i2c: I2C) *volatile I2cRegs {
         return switch (@intFromEnum(i2c)) {
             0 => I2C0,
             1 => I2C1,
@@ -246,7 +246,7 @@ pub const I2C = enum(u1) {
     /// - TX_EMPTY_CTRL is always enabled for easy detection of TX finished
     /// - TX and RX FIFO detection thresholds set to 1, this makes polling for TX finished/RX ready much simpler
     /// - DREQ signalling is always enabled, harmless if DMA isn't configured to listen for this
-    pub fn apply(i2c: I2C, comptime config: Config) ConfigError!void {
+    pub fn apply(i2c: I2C, comptime config: Config) void {
         i2c.disable();
         const regs = i2c.get_regs();
         regs.IC_CON.write(.{
@@ -273,8 +273,11 @@ pub const I2C = enum(u1) {
         });
 
         const peripheral_block_freq = (comptime config.clock_config.get_frequency(.clk_sys)) orelse @compileError("clk_sys must be set for I²C");
+
+        const timings = comptime translate_baudrate(config.baud_rate, peripheral_block_freq) catch @compileError("baud_rate is not possible with the provided clock_config");
+
         // set_baudrate() enables I2C block before returning
-        try i2c.set_baudrate(config.baud_rate, peripheral_block_freq);
+        i2c.set_computed_baudrate(timings);
     }
 
     /// Disables I2C, returns peripheral registers to reset state.
@@ -289,13 +292,23 @@ pub const I2C = enum(u1) {
     /// pin rise/fall time as that is board specific, so actual baud rates may be
     /// slightly lower than specified.
     pub fn set_baudrate(i2c: I2C, baud_rate: u32, freq_in: u32) ConfigError!void {
-        const reg_vals = try translate_baudrate(baud_rate, freq_in);
+        const timings = try translate_baudrate(baud_rate, freq_in);
+        i2c.set_computed_baudrate(timings);
+    }
+
+    /// Configures I2C to run at a specified baud rate given a peripheral clock frequency.
+    ///
+    /// Validates configuration to ensure it's both within I2C spec, and the peripheral
+    /// block's configuration capabilities. Note that this does NOT take into account
+    /// pin rise/fall time as that is board specific, so actual baud rates may be
+    /// slightly lower than specified.
+    pub fn set_computed_baudrate(i2c: I2C, timings: TimingRegisterValues) void {
         i2c.disable();
         const regs = i2c.get_regs();
-        regs.IC_FS_SCL_HCNT.write(.{ .IC_FS_SCL_HCNT = reg_vals.scl_hcnt });
-        regs.IC_FS_SCL_LCNT.write(.{ .IC_FS_SCL_LCNT = reg_vals.scl_lcnt });
-        regs.IC_FS_SPKLEN.write(.{ .IC_FS_SPKLEN = reg_vals.spklen });
-        regs.IC_SDA_HOLD.modify(.{ .IC_SDA_TX_HOLD = reg_vals.sda_tx_hold_count });
+        regs.IC_FS_SCL_HCNT.write(.{ .IC_FS_SCL_HCNT = timings.scl_hcnt });
+        regs.IC_FS_SCL_LCNT.write(.{ .IC_FS_SCL_LCNT = timings.scl_lcnt });
+        regs.IC_FS_SPKLEN.write(.{ .IC_FS_SPKLEN = timings.spklen });
+        regs.IC_SDA_HOLD.modify(.{ .IC_SDA_TX_HOLD = timings.sda_tx_hold_count });
         i2c.enable();
     }
 

port/raspberrypi/rp2xxx/src/hal/pio/assembler.zig

@@ -72,6 +72,12 @@ pub const Diagnostics = struct {
     }
 };
 
+/// Creates a copy of a slice at comptime that is guaranteed to be immutable.
+fn comptime_copy(comptime T: type, comptime slice: []const T) []const T {
+    const arr: [slice.len]T = slice[0..slice.len].*;
+    return &arr;
+}
+
 pub fn assemble_impl(comptime chip: Chip, comptime source: []const u8, diags: *?Diagnostics, options: AssembleOptions) !Output {
     const tokens = try tokenizer.tokenize(chip, source, diags, options.tokenize);
     const encoder_output = try encoder.encode(chip, tokens.slice(), diags, options.encode);
@@ -87,9 +93,9 @@ pub fn assemble_impl(comptime chip: Chip, comptime source: []const u8, diags: *?
                     .name = define.name,
                     .value = define.value,
                 }) catch unreachable;
-            break :blk tmp.constSlice();
+            break :blk comptime_copy(Define, tmp.slice());
         },
-        .programs = programs.constSlice(),
+        .programs = comptime_copy(Program, programs.slice()),
     };
 }
 

port/raspberrypi/rp2xxx/src/hal/pio/common.zig

@@ -133,8 +133,12 @@ pub fn PioImpl(EnumType: type, chip: Chip) type {
                 if (origin != offset)
                     return false;
 
+            // Will never fit in the first place:
+            if (offset + program.instructions.len > 32)
+                return false;
+
             const used_mask = UsedInstructionSpace(chip).val[@intFromEnum(self)];
-            const program_mask = program.get_mask();
+            const program_mask = (program.get_mask() << offset);
 
             // We can add the program if the masks don't overlap, if there is
             // overlap the result of a bitwise AND will have a non-zero result
@@ -537,6 +541,7 @@ pub fn PioImpl(EnumType: type, chip: Chip) type {
 
             // TODO: check program settings vs pin mapping
             const offset = try self.add_program(program);
+
             self.sm_init(sm, offset, .{
                 .clkdiv = options.clkdiv,
                 .shift = options.shift,