kernel: allow multiple LEDs for panic blinks

boards/ek-tm4c1294xl/src/io.rs

@@ -44,5 +44,5 @@ impl Write for Writer {
 pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
     let led = &mut led::LedLow::new(&mut tm4c129x::gpio::PF[0]);
     let writer = &mut WRITER;
-    debug::panic(led, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led], writer, pi, &cortexm4::support::nop)
 }

boards/hail/src/io.rs

@@ -51,5 +51,5 @@ pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
 
     let led_red = &mut led::LedLow::new(&mut sam4l::gpio::PA[13]);
     let writer = &mut WRITER;
-    debug::panic(led_red, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led_red], writer, pi, &cortexm4::support::nop)
 }

boards/imix/src/io.rs

@@ -42,5 +42,5 @@ impl Write for Writer {
 pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
     let led = &mut led::LedLow::new(&mut sam4l::gpio::PC[10]);
     let writer = &mut WRITER;
-    debug::panic(led, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led], writer, pi, &cortexm4::support::nop)
 }

boards/launchxl/src/io.rs

@@ -41,5 +41,5 @@ pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
 
     let led = &mut led::LedLow::new(&mut cc26xx::gpio::PORT[LED_PIN]);
     let writer = &mut WRITER;
-    debug::panic(led, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led], writer, pi, &cortexm4::support::nop)
 }

boards/nordic/nrf51dk/src/io.rs

@@ -44,5 +44,5 @@ pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
     const LED1_PIN: usize = 21;
     let led = &mut led::LedLow::new(&mut nrf5x::gpio::PORT[LED1_PIN]);
     let writer = &mut WRITER;
-    debug::panic(led, writer, pi, &cortexm0::support::nop)
+    debug::panic(&mut [led], writer, pi, &cortexm0::support::nop)
 }

boards/nordic/nrf52840dk/src/io.rs

@@ -44,5 +44,5 @@ pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
     const LED1_PIN: usize = 13;
     let led = &mut led::LedLow::new(&mut nrf5x::gpio::PORT[LED1_PIN]);
     let writer = &mut WRITER;
-    debug::panic(led, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led], writer, pi, &cortexm4::support::nop)
 }

boards/nordic/nrf52dk/src/io.rs

@@ -44,5 +44,5 @@ pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
     const LED1_PIN: usize = 17;
     let led = &mut led::LedLow::new(&mut nrf5x::gpio::PORT[LED1_PIN]);
     let writer = &mut WRITER;
-    debug::panic(led, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led], writer, pi, &cortexm4::support::nop)
 }

doc/courses/sensys/exercises/board/src/io.rs

@@ -51,5 +51,5 @@ pub unsafe extern "C" fn panic_fmt(pi: &PanicInfo) -> ! {
 
     let led_red = &mut led::LedLow::new(&mut sam4l::gpio::PA[13]);
     let writer = &mut WRITER;
-    debug::panic(led_red, writer, pi, &cortexm4::support::nop)
+    debug::panic(&mut [led_red], writer, pi, &cortexm4::support::nop)
 }

kernel/src/debug.rs

@@ -52,7 +52,7 @@ use returncode::ReturnCode;
 ///
 /// **NOTE:** The supplied `writer` must be synchronous.
 pub unsafe fn panic<L: hil::led::Led, W: Write>(
-    led: &mut L,
+    leds: &mut [&mut L],
     writer: &mut W,
     panic_info: &PanicInfo,
     nop: &Fn(),
@@ -62,7 +62,7 @@ pub unsafe fn panic<L: hil::led::Led, W: Write>(
     // Flush debug buffer if needed
     flush(writer);
     panic_process_info(writer);
-    panic_blink_forever(led)
+    panic_blink_forever(leds)
 }
 
 /// Generic panic entry.
@@ -124,20 +124,26 @@ pub unsafe fn panic_process_info<W: Write>(writer: &mut W) {
 ///
 /// If a multi-color LED is used for the panic pattern, it is
 /// advised to turn off other LEDs before calling this method.
-pub fn panic_blink_forever<L: hil::led::Led>(led: &mut L) -> ! {
-    led.init();
+///
+/// Generally, boards should blink red during panic if possible,
+/// otherwise choose the 'first' or most prominent LED. Some
+/// boards may find it appropriate to blink multiple LEDs (e.g.
+/// one on the top and one on the bottom), thus this method
+/// accepts an array, however most will only need one.
+pub fn panic_blink_forever<L: hil::led::Led>(leds: &mut [&mut L]) -> ! {
+    leds.iter_mut().for_each(|led| led.init());
     loop {
         for _ in 0..1000000 {
-            led.on();
+            leds.iter_mut().for_each(|led| led.on());
         }
         for _ in 0..100000 {
-            led.off();
+            leds.iter_mut().for_each(|led| led.off());
         }
         for _ in 0..1000000 {
-            led.on();
+            leds.iter_mut().for_each(|led| led.on());
         }
         for _ in 0..500000 {
-            led.off();
+            leds.iter_mut().for_each(|led| led.off());
         }
     }
 }