From d96380e65496912e0f68e6531565f4b45efd1623 Mon Sep 17 00:00:00 2001
From: Joel Challis <git@zvecr.com>
Date: Sat, 21 Mar 2020 05:20:04 +0000
Subject: Initial arm->chibios pass - simplify some platform logic (#8450)

---
 drivers/chibios/ws2812.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 drivers/chibios/ws2812.c

(limited to 'drivers/chibios/ws2812.c')

diff --git a/drivers/chibios/ws2812.c b/drivers/chibios/ws2812.c
new file mode 100644
index 0000000000..bdca565d88
--- /dev/null
+++ b/drivers/chibios/ws2812.c
@@ -0,0 +1,95 @@
+#include "quantum.h"
+#include "ws2812.h"
+#include "ch.h"
+#include "hal.h"
+
+/* Adapted from https://github.com/bigjosh/SimpleNeoPixelDemo/ */
+
+#ifndef NOP_FUDGE
+#    if defined(STM32F0XX) || defined(STM32F1XX) || defined(STM32F3XX) || defined(STM32F4XX) || defined(STM32L0XX)
+#        define NOP_FUDGE 0.4
+#    else
+#        error("NOP_FUDGE configuration required")
+#        define NOP_FUDGE 1  // this just pleases the compile so the above error is easier to spot
+#    endif
+#endif
+
+#define NUMBER_NOPS 6
+#define CYCLES_PER_SEC (STM32_SYSCLK / NUMBER_NOPS * NOP_FUDGE)
+#define NS_PER_SEC (1000000000L)  // Note that this has to be SIGNED since we want to be able to check for negative values of derivatives
+#define NS_PER_CYCLE (NS_PER_SEC / CYCLES_PER_SEC)
+#define NS_TO_CYCLES(n) ((n) / NS_PER_CYCLE)
+
+#define wait_ns(x)                                  \
+    do {                                            \
+        for (int i = 0; i < NS_TO_CYCLES(x); i++) { \
+            __asm__ volatile("nop\n\t"              \
+                             "nop\n\t"              \
+                             "nop\n\t"              \
+                             "nop\n\t"              \
+                             "nop\n\t"              \
+                             "nop\n\t");            \
+        }                                           \
+    } while (0)
+
+// These are the timing constraints taken mostly from the WS2812 datasheets
+// These are chosen to be conservative and avoid problems rather than for maximum throughput
+
+#define T1H 900           // Width of a 1 bit in ns
+#define T1L (1250 - T1H)  // Width of a 1 bit in ns
+
+#define T0H 350           // Width of a 0 bit in ns
+#define T0L (1250 - T0H)  // Width of a 0 bit in ns
+
+// The reset gap can be 6000 ns, but depending on the LED strip it may have to be increased
+// to values like 600000 ns. If it is too small, the pixels will show nothing most of the time.
+#define RES 10000  // Width of the low gap between bits to cause a frame to latch
+
+void sendByte(uint8_t byte) {
+    // WS2812 protocol wants most significant bits first
+    for (unsigned char bit = 0; bit < 8; bit++) {
+        bool is_one = byte & (1 << (7 - bit));
+        // using something like wait_ns(is_one ? T1L : T0L) here throws off timings
+        if (is_one) {
+            // 1
+            writePinHigh(RGB_DI_PIN);
+            wait_ns(T1H);
+            writePinLow(RGB_DI_PIN);
+            wait_ns(T1L);
+        } else {
+            // 0
+            writePinHigh(RGB_DI_PIN);
+            wait_ns(T0H);
+            writePinLow(RGB_DI_PIN);
+            wait_ns(T0L);
+        }
+    }
+}
+
+void ws2812_init(void) { setPinOutput(RGB_DI_PIN); }
+
+// Setleds for standard RGB
+void ws2812_setleds(LED_TYPE *ledarray, uint16_t leds) {
+    static bool s_init = false;
+    if (!s_init) {
+        ws2812_init();
+        s_init = true;
+    }
+
+    // this code is very time dependent, so we need to disable interrupts
+    chSysLock();
+
+    for (uint8_t i = 0; i < leds; i++) {
+        // WS2812 protocol dictates grb order
+        sendByte(ledarray[i].g);
+        sendByte(ledarray[i].r);
+        sendByte(ledarray[i].b);
+#ifdef RGBW
+        sendByte(ledarray[i].w);
+#endif
+    }
+
+    wait_ns(RES);
+
+    chSysUnlock();
+}
-- 
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