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@ -4,7 +4,7 @@
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Now that we enabled safe globals in the previous tutorial, the infrastructure is
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laid for adding the first real device drivers. We throw out the magic QEMU
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console and use a real UART now. Like real tough embedded people do!
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console and use a real UART now. Like serious embedded hackers do!
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- A `DeviceDriver` trait is added for abstracting `BSP` driver implementations
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from kernel code.
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@ -55,11 +55,18 @@ diff -uNr 05_safe_globals/Cargo.toml 06_drivers_gpio_uart/Cargo.toml
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diff -uNr 05_safe_globals/src/arch/aarch64.rs 06_drivers_gpio_uart/src/arch/aarch64.rs
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--- 05_safe_globals/src/arch/aarch64.rs
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+++ 06_drivers_gpio_uart/src/arch/aarch64.rs
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@@ -33,6 +33,8 @@
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@@ -33,6 +33,15 @@
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// Implementation of the kernel's architecture abstraction code
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//--------------------------------------------------------------------------------------------------
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+pub use asm::nop;
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+
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+/// Spin for `n` cycles.
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+pub fn spin_for_cycles(n: usize) {
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+ for _ in 0..n {
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+ asm::nop();
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+ }
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+}
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+
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/// Pause execution on the calling CPU core.
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#[inline(always)]
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@ -68,7 +75,7 @@ diff -uNr 05_safe_globals/src/arch/aarch64.rs 06_drivers_gpio_uart/src/arch/aarc
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diff -uNr 05_safe_globals/src/bsp/driver/bcm/bcm2837_gpio.rs 06_drivers_gpio_uart/src/bsp/driver/bcm/bcm2837_gpio.rs
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--- 05_safe_globals/src/bsp/driver/bcm/bcm2837_gpio.rs
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+++ 06_drivers_gpio_uart/src/bsp/driver/bcm/bcm2837_gpio.rs
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@@ -0,0 +1,162 @@
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@@ -0,0 +1,158 @@
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+// SPDX-License-Identifier: MIT
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+//
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+// Copyright (c) 2018-2019 Andre Richter <andre.o.richter@gmail.com>
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@ -184,15 +191,11 @@ diff -uNr 05_safe_globals/src/bsp/driver/bcm/bcm2837_gpio.rs 06_drivers_gpio_uar
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+
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+ // Enable pins 14 and 15.
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+ self.GPPUD.set(0);
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+ for _ in 0..150 {
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+ arch::nop();
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+ }
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+ arch::spin_for_cycles(150);
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+
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+ self.GPPUDCLK0
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+ .write(GPPUDCLK0::PUDCLK14::AssertClock + GPPUDCLK0::PUDCLK15::AssertClock);
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+ for _ in 0..150 {
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+ arch::nop();
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+ }
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+ arch::spin_for_cycles(150);
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+
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+ self.GPPUDCLK0.set(0);
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+ }
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@ -575,7 +578,7 @@ diff -uNr 05_safe_globals/src/bsp/rpi3/memory_map.rs 06_drivers_gpio_uart/src/bs
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diff -uNr 05_safe_globals/src/bsp/rpi3.rs 06_drivers_gpio_uart/src/bsp/rpi3.rs
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--- 05_safe_globals/src/bsp/rpi3.rs
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+++ 06_drivers_gpio_uart/src/bsp/rpi3.rs
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@@ -4,114 +4,58 @@
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@@ -4,114 +4,47 @@
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//! Board Support Package for the Raspberry Pi 3.
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@ -697,8 +700,11 @@ diff -uNr 05_safe_globals/src/bsp/rpi3.rs 06_drivers_gpio_uart/src/bsp/rpi3.rs
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-//--------------------------------------------------------------------------------------------------
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-
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-static QEMU_OUTPUT: QEMUOutput = QEMUOutput::new();
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+/// Return an array of references to all `DeviceDriver` compatible `BSP`
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+/// drivers.
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-
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-//--------------------------------------------------------------------------------------------------
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-// Implementation of the kernel's BSP calls
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-//--------------------------------------------------------------------------------------------------
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+/// Return an array of references to all `DeviceDriver` compatible `BSP` drivers.
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+///
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+/// # Safety
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+///
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@ -707,24 +713,11 @@ diff -uNr 05_safe_globals/src/bsp/rpi3.rs 06_drivers_gpio_uart/src/bsp/rpi3.rs
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+ [&GPIO, &MINI_UART]
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+}
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-//--------------------------------------------------------------------------------------------------
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-// Implementation of the kernel's BSP calls
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-//--------------------------------------------------------------------------------------------------
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+/// The BSP's main initialization function.
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+///
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+/// Called early on kernel start.
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+pub fn init() {
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+ for i in device_drivers().iter() {
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+ if let Err(()) = i.init() {
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+ // This message will only be readable if, at the time of failure, the return value of
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+ // `bsp::console()` is already in functioning state.
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+ panic!("Error loading driver: {}", i.compatible())
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+ }
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+ }
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-/// Return a reference to a `console::All` implementation.
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-pub fn console() -> &'static impl interface::console::All {
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- &QEMU_OUTPUT
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+/// BSP initialization code that runs after driver init.
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+pub fn post_driver_init() {
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+ // Configure MiniUart's output pins.
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+ GPIO.map_mini_uart();
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}
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@ -763,7 +756,7 @@ diff -uNr 05_safe_globals/src/interface.rs 06_drivers_gpio_uart/src/interface.rs
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+ /// Driver result type, e.g. for indicating successful driver init.
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+ pub type Result = core::result::Result<(), ()>;
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+
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+ /// Device Driver operations.
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+ /// Device Driver functions.
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+ pub trait DeviceDriver {
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+ /// Return a compatibility string for identifying the driver.
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+ fn compatible(&self) -> &str;
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@ -778,30 +771,58 @@ diff -uNr 05_safe_globals/src/interface.rs 06_drivers_gpio_uart/src/interface.rs
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diff -uNr 05_safe_globals/src/main.rs 06_drivers_gpio_uart/src/main.rs
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--- 05_safe_globals/src/main.rs
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+++ 06_drivers_gpio_uart/src/main.rs
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@@ -41,12 +41,23 @@
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@@ -41,16 +41,50 @@
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/// Entrypoint of the `kernel`.
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fn kernel_entry() -> ! {
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/// Early init code.
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///
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+/// Concerned with with initializing `BSP` and `arch` parts.
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+///
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/// # Safety
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///
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/// - Only a single core must be active and running this function.
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+/// - The init calls in this function must appear in the correct order.
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unsafe fn kernel_init() -> ! {
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- use interface::console::Statistics;
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+ for i in bsp::device_drivers().iter() {
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+ if let Err(()) = i.init() {
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+ // This message will only be readable if, at the time of failure, the return value of
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+ // `bsp::console()` is already in functioning state.
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+ panic!("Error loading driver: {}", i.compatible())
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+ }
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+ }
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+
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+ bsp::post_driver_init();
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+
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+ // Transition from unsafe to safe.
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+ kernel_main()
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+}
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+
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+/// The main function running after the early init.
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+fn kernel_main() -> ! {
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+ use interface::console::All;
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- println!("[0] Hello from pure Rust!");
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+ // Run the BSP's initialization code.
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+ bsp::init();
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- println!("[1] Chars written: {}", bsp::console().chars_written());
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+
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+ // UART should be functional now. Wait for user to hit Enter.
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+ loop {
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+ if bsp::console().read_char() == '
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' {
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+ break;
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+ }
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+ }
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+
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+ println!("[0] Booting on: {}", bsp::board_name());
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- println!("[2] Stopping here.");
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- arch::wait_forever()
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- println!("[0] Hello from pure Rust!");
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+ println!("[1] Drivers loaded:");
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+ for (i, driver) in bsp::device_drivers().iter().enumerate() {
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+ println!(" {}. {}", i + 1, driver.compatible());
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+ }
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+
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- println!("[1] Chars written: {}", bsp::console().chars_written());
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+ println!("[2] Chars written: {}", bsp::console().chars_written());
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+ println!("[3] Echoing input now");
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+
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- println!("[2] Stopping here.");
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- arch::wait_forever()
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+ loop {
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+ let c = bsp::console().read_char();
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+ bsp::console().write_char(c);
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Andre Richter
5 years ago