ARM - Initial backlight support (#6487)

* Move AVR backlight to own file, add borrowed ARM implementation

* Tiny fix for backlight custom logic

* Remove duplicate board from rebase

* Fix f303 onekey example

* clang-format

* clang-format

* Remove backlight keymap debug

* Initial pass of ARM backlight docs

* Initial pass of ARM backlight docs - resolve todos

* fix rules validation logic

* Add f072 warning

* Add f072 warning

* tidy up breathing in backlight keymap

* tidy up breathing in backlight keymap

* add missing break to backlight keymap

1 files changed, 218 insertions, 0 deletions

diff --git a/quantum/backlight/backlight_arm.c b/quantum/backlight/backlight_arm.c
new file mode 100644
index 0000000000..3f94ccef8e
--- /dev/null
+++ b/quantum/backlight/backlight_arm.c
@@ -0,0 +1,218 @@
+#include "quantum.h"
+#include "backlight.h"
+#include <hal.h>
+#include "debug.h"
+
+// TODO: remove short term bodge when refactoring BACKLIGHT_CUSTOM_DRIVER out
+#ifdef BACKLIGHT_PIN
+
+#    if defined(STM32F0XX) || defined(STM32F0xx)
+#        error "Backlight support for STMF072 is not available. Please disable."
+#    endif
+
+#    if defined(STM32F1XX) || defined(STM32F1xx)
+#        define USE_GPIOV1
+#    endif
+
+// GPIOV2 && GPIOV3
+#    ifndef BACKLIGHT_PAL_MODE
+#        define BACKLIGHT_PAL_MODE 2
+#    endif
+
+// GENERIC
+#    ifndef BACKLIGHT_PWM_DRIVER
+#        define BACKLIGHT_PWM_DRIVER PWMD4
+#    endif
+#    ifndef BACKLIGHT_PWM_CHANNEL
+#        define BACKLIGHT_PWM_CHANNEL 3
+#    endif
+
+static void breathing_callback(PWMDriver *pwmp);
+
+static PWMConfig pwmCFG = {0xFFFF, /* PWM clock frequency  */
+                           256,    /* PWM period (in ticks) 1S (1/10kHz=0.1mS 0.1ms*10000 ticks=1S) */
+                           NULL,   /* No Callback */
+                           {       /* Default all channels to disabled - Channels will be configured durring init */
+                            {PWM_OUTPUT_DISABLED, NULL},
+                            {PWM_OUTPUT_DISABLED, NULL},
+                            {PWM_OUTPUT_DISABLED, NULL},
+                            {PWM_OUTPUT_DISABLED, NULL}},
+                           0, /* HW dependent part.*/
+                           0};
+
+static PWMConfig pwmCFG_breathing = {0xFFFF,             /** PWM clock frequency  */
+                                     256,                /* PWM period (in ticks) 1S (1/10kHz=0.1mS 0.1ms*10000 ticks=1S) */
+                                     breathing_callback, /* Breathing Callback */
+                                     {                   /* Default all channels to disabled - Channels will be configured durring init */
+                                      {PWM_OUTPUT_DISABLED, NULL},
+                                      {PWM_OUTPUT_DISABLED, NULL},
+                                      {PWM_OUTPUT_DISABLED, NULL},
+                                      {PWM_OUTPUT_DISABLED, NULL}},
+                                     0, /* HW dependent part.*/
+                                     0};
+
+// See http://jared.geek.nz/2013/feb/linear-led-pwm
+static uint16_t cie_lightness(uint16_t v) {
+    if (v <= 5243)     // if below 8% of max
+        return v / 9;  // same as dividing by 900%
+    else {
+        uint32_t y = (((uint32_t)v + 10486) << 8) / (10486 + 0xFFFFUL);  // add 16% of max and compare
+        // to get a useful result with integer division, we shift left in the expression above
+        // and revert what we've done again after squaring.
+        y = y * y * y >> 8;
+        if (y > 0xFFFFUL)  // prevent overflow
+            return 0xFFFFU;
+        else
+            return (uint16_t)y;
+    }
+}
+
+void backlight_init_ports(void) {
+    // printf("backlight_init_ports()\n");
+
+#    ifdef USE_GPIOV1
+    palSetPadMode(PAL_PORT(BACKLIGHT_PIN), PAL_PAD(BACKLIGHT_PIN), PAL_MODE_STM32_ALTERNATE_PUSHPULL);
+#    else
+    palSetPadMode(PAL_PORT(BACKLIGHT_PIN), PAL_PAD(BACKLIGHT_PIN), PAL_MODE_ALTERNATE(BACKLIGHT_PAL_MODE));
+#    endif
+
+    pwmCFG.channels[BACKLIGHT_PWM_CHANNEL - 1].mode           = PWM_OUTPUT_ACTIVE_HIGH;
+    pwmCFG_breathing.channels[BACKLIGHT_PWM_CHANNEL - 1].mode = PWM_OUTPUT_ACTIVE_HIGH;
+    pwmStart(&BACKLIGHT_PWM_DRIVER, &pwmCFG);
+
+    backlight_set(get_backlight_level());
+    if (is_backlight_breathing()) {
+        breathing_enable();
+    }
+}
+
+void backlight_set(uint8_t level) {
+    // printf("backlight_set(%d)\n", level);
+    if (level == 0) {
+        // Turn backlight off
+        pwmDisableChannel(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1);
+    } else {
+        // Turn backlight on
+        if (!is_breathing()) {
+            uint32_t duty = (uint32_t)(cie_lightness(0xFFFF * (uint32_t)level / BACKLIGHT_LEVELS));
+            // printf("duty: (%d)\n", duty);
+            pwmEnableChannel(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1, PWM_FRACTION_TO_WIDTH(&BACKLIGHT_PWM_DRIVER, 0xFFFF, duty));
+        }
+    }
+}
+
+uint8_t backlight_tick = 0;
+
+void backlight_task(void) {}
+
+#    define BREATHING_NO_HALT 0
+#    define BREATHING_HALT_OFF 1
+#    define BREATHING_HALT_ON 2
+#    define BREATHING_STEPS 128
+
+static uint8_t  breathing_period  = BREATHING_PERIOD;
+static uint8_t  breathing_halt    = BREATHING_NO_HALT;
+static uint16_t breathing_counter = 0;
+
+bool is_breathing(void) { return BACKLIGHT_PWM_DRIVER.config == &pwmCFG_breathing; }
+
+static inline void breathing_min(void) { breathing_counter = 0; }
+
+static inline void breathing_max(void) { breathing_counter = breathing_period * 256 / 2; }
+
+void breathing_interrupt_enable(void) {
+    pwmStop(&BACKLIGHT_PWM_DRIVER);
+    pwmStart(&BACKLIGHT_PWM_DRIVER, &pwmCFG_breathing);
+    chSysLockFromISR();
+    pwmEnablePeriodicNotification(&BACKLIGHT_PWM_DRIVER);
+    pwmEnableChannelI(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1, PWM_FRACTION_TO_WIDTH(&BACKLIGHT_PWM_DRIVER, 0xFFFF, 0xFFFF));
+    chSysUnlockFromISR();
+}
+
+void breathing_interrupt_disable(void) {
+    pwmStop(&BACKLIGHT_PWM_DRIVER);
+    pwmStart(&BACKLIGHT_PWM_DRIVER, &pwmCFG);
+}
+
+void breathing_enable(void) {
+    breathing_counter = 0;
+    breathing_halt    = BREATHING_NO_HALT;
+    breathing_interrupt_enable();
+}
+
+void breathing_pulse(void) {
+    if (get_backlight_level() == 0)
+        breathing_min();
+    else
+        breathing_max();
+    breathing_halt = BREATHING_HALT_ON;
+    breathing_interrupt_enable();
+}
+
+void breathing_disable(void) {
+    // printf("breathing_disable()\n");
+    breathing_interrupt_disable();
+    // Restore backlight level
+    backlight_set(get_backlight_level());
+}
+
+void breathing_self_disable(void) {
+    if (get_backlight_level() == 0)
+        breathing_halt = BREATHING_HALT_OFF;
+    else
+        breathing_halt = BREATHING_HALT_ON;
+}
+
+void breathing_toggle(void) {
+    if (is_breathing())
+        breathing_disable();
+    else
+        breathing_enable();
+}
+
+void breathing_period_set(uint8_t value) {
+    if (!value) value = 1;
+    breathing_period = value;
+}
+
+void breathing_period_default(void) { breathing_period_set(BREATHING_PERIOD); }
+
+void breathing_period_inc(void) { breathing_period_set(breathing_period + 1); }
+
+void breathing_period_dec(void) { breathing_period_set(breathing_period - 1); }
+
+/* To generate breathing curve in python:
+ * from math import sin, pi; [int(sin(x/128.0*pi)**4*255) for x in range(128)]
+ */
+static const uint8_t breathing_table[BREATHING_STEPS] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 24, 28, 32, 36, 41, 46, 51, 57, 63, 70, 76, 83, 91, 98, 106, 113, 121, 129, 138, 146, 154, 162, 170, 178, 185, 193, 200, 207, 213, 220, 225, 231, 235, 240, 244, 247, 250, 252, 253, 254, 255, 254, 253, 252, 250, 247, 244, 240, 235, 231, 225, 220, 213, 207, 200, 193, 185, 178, 170, 162, 154, 146, 138, 129, 121, 113, 106, 98, 91, 83, 76, 70, 63, 57, 51, 46, 41, 36, 32, 28, 24, 20, 17, 15, 12, 10, 8, 6, 5, 4, 3, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+
+// Use this before the cie_lightness function.
+static inline uint16_t scale_backlight(uint16_t v) { return v / BACKLIGHT_LEVELS * get_backlight_level(); }
+
+static void breathing_callback(PWMDriver *pwmp) {
+    (void)pwmp;
+    uint16_t interval = (uint16_t)breathing_period * 256 / BREATHING_STEPS;
+    // resetting after one period to prevent ugly reset at overflow.
+    breathing_counter = (breathing_counter + 1) % (breathing_period * 256);
+    uint8_t index     = breathing_counter / interval % BREATHING_STEPS;
+
+    if (((breathing_halt == BREATHING_HALT_ON) && (index == BREATHING_STEPS / 2)) || ((breathing_halt == BREATHING_HALT_OFF) && (index == BREATHING_STEPS - 1))) {
+        breathing_interrupt_disable();
+    }
+
+    uint32_t duty = cie_lightness(scale_backlight(breathing_table[index] * 256));
+
+    chSysLockFromISR();
+    pwmEnableChannelI(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1, PWM_FRACTION_TO_WIDTH(&BACKLIGHT_PWM_DRIVER, 0xFFFF, duty));
+    chSysUnlockFromISR();
+}
+
+#else
+
+__attribute__((weak)) void backlight_init_ports(void) {}
+
+__attribute__((weak)) void backlight_set(uint8_t level) {}
+
+__attribute__((weak)) void backlight_task(void) {}
+
+#endif