Backlight driver refactoring

core/embed/trezorhal/stm32f4/backlight_pwm.c

@@ -1,212 +1,279 @@
+/*
+ * This file is part of the Trezor project, https://trezor.io/
+ *
+ * Copyright (c) SatoshiLabs
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdbool.h>
+#include <string.h>
 
 #include "backlight_pwm.h"
+#include "common.h"
 
 #include STM32_HAL_H
 #include TREZOR_BOARD
 
+// Requested PWM Timer clock frequency [Hz]
 #define TIM_FREQ 10000000
-
+// Prescaler divider for the PWM Timer
 #define LED_PWM_PRESCALER (SystemCoreClock / TIM_FREQ - 1)
-
-#define LED_PWM_PRESCALER_SLOW (SystemCoreClock / 1000000 - 1)  // 1 MHz
-
+// Period of the PWM Timer
 #define LED_PWM_TIM_PERIOD (TIM_FREQ / BACKLIGHT_PWM_FREQ)
 
-static int BACKLIGHT = -1;
+// Backlight driver state
+typedef struct {
+  // Set if driver is initialized
+  bool initialized;
+  // Current backlight level in range 0-255
+  int current_level;
 
-static int pwm_period = 0;
+} backlight_driver_t;
 
-int backlight_pwm_set(int val) {
-  if (BACKLIGHT != val && val >= 0 && val <= 255) {
-    // TPS61043 goes to shutdown when duty cycle is 0 (after 32ms),
-    // so we need to set GPIO to high for at least 500us
-    // to wake it up.
-    if (BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR == 0) {
-      GPIO_InitTypeDef GPIO_InitStructure = {0};
-
-      HAL_GPIO_WritePin(BACKLIGHT_PWM_PORT, BACKLIGHT_PWM_PIN, GPIO_PIN_SET);
-      // LCD_PWM/PA7 (backlight control)
-      GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
-      GPIO_InitStructure.Pull = GPIO_NOPULL;
-      GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
-      GPIO_InitStructure.Pin = BACKLIGHT_PWM_PIN;
-      HAL_GPIO_Init(BACKLIGHT_PWM_PORT, &GPIO_InitStructure);
-
-      hal_delay_us(500);
-
-      GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
-      GPIO_InitStructure.Pull = GPIO_NOPULL;
-      GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
-      GPIO_InitStructure.Alternate = BACKLIGHT_PWM_TIM_AF;
-      GPIO_InitStructure.Pin = BACKLIGHT_PWM_PIN;
-      HAL_GPIO_Init(BACKLIGHT_PWM_PORT, &GPIO_InitStructure);
-    }
+// Backlight driver instance
+static backlight_driver_t g_backlight_driver = {
+    .initialized = false,
+};
+
+void backlight_pwm_init(backlight_action_t action) {
+  backlight_driver_t *drv = &g_backlight_driver;
 
-    BACKLIGHT = val;
-    BACKLIGHT_PWM_TIM->CCR1 = (pwm_period * val) / 255;
+  if (drv->initialized) {
+    return;
   }
-  return BACKLIGHT;
-}
 
-int backlight_pwm_get(void) { return BACKLIGHT; }
+  memset(drv, 0, sizeof(backlight_driver_t));
+
+  int initial_level = 0;
+
+  if (action == BACKLIGHT_RETAIN) {
+    // We expect the BACKLIGHT_PWM_TIM to be already initialized
+    // (e.g. by the bootloader or boardloader)
+    uint32_t prev_arr = BACKLIGHT_PWM_TIM->ARR;
+    uint32_t prev_ccr1 = BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR;
+
+    initial_level = (prev_ccr1 * 255) / (prev_arr + 1);
+    if (initial_level > 255) {
+      initial_level = 255;
+    }
+  }
 
-void backlight_pwm_init(void) {
-  // init peripherals
+  // Enable peripheral clocks
   BACKLIGHT_PWM_PORT_CLK_EN();
   BACKLIGHT_PWM_TIM_CLK_EN();
 
+  // Initialize PWM GPIO
   GPIO_InitTypeDef GPIO_InitStructure = {0};
-
-  // LCD_PWM (backlight control)
   GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
   GPIO_InitStructure.Pull = GPIO_NOPULL;
   GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
   GPIO_InitStructure.Alternate = BACKLIGHT_PWM_TIM_AF;
   GPIO_InitStructure.Pin = BACKLIGHT_PWM_PIN;
   HAL_GPIO_Init(BACKLIGHT_PWM_PORT, &GPIO_InitStructure);
 
+  // Initialize PWM timer
+
   uint32_t tmpcr1 = 0;
 
-  /* Select the Counter Mode */
+  // Select the Counter Mode
   tmpcr1 |= TIM_COUNTERMODE_UP;
 
-  /* Set the clock division */
+  // Set the clock division
   tmpcr1 |= (uint32_t)TIM_CLOCKDIVISION_DIV1;
 
-  /* Set the auto-reload preload */
+  // Set the auto-reload preload
 #ifdef STM32U5
   tmpcr1 |= TIM_AUTORELOAD_PRELOAD_DISABLE;
 #endif
 
   BACKLIGHT_PWM_TIM->CR1 = tmpcr1;
 
-  /* Set the Autoreload value */
+  // Set the Autoreload value
   BACKLIGHT_PWM_TIM->ARR = (uint32_t)LED_PWM_TIM_PERIOD - 1;
 
-  /* Set the Prescaler value */
+  // Set the Prescaler value
   BACKLIGHT_PWM_TIM->PSC = LED_PWM_PRESCALER;
 
-  /* Set the Repetition Counter value */
+  // Set the Repetition Counter value
   BACKLIGHT_PWM_TIM->RCR = 0;
 
-  /* Generate an update event to reload the Prescaler
-     and the repetition counter (only for advanced timer) value immediately */
+  // Generate an update event to reload the Prescaler
+  // and the repetition counter (only for advanced timer) value immediately
   BACKLIGHT_PWM_TIM->EGR = TIM_EGR_UG;
 
-  pwm_period = LED_PWM_TIM_PERIOD;
-
-  /* Set the Preload enable bit for channel1 */
+  // Set the Preload enable bit for channel1
   BACKLIGHT_PWM_TIM->CCMR1 |= TIM_CCMR1_OC1PE;
 
-  /* Configure the Output Fast mode */
+  // Configure the Output Fast mode
   BACKLIGHT_PWM_TIM->CCMR1 &= ~TIM_CCMR1_OC1FE;
   BACKLIGHT_PWM_TIM->CCMR1 |= TIM_OCFAST_DISABLE;
 
   uint32_t tmpccmrx;
   uint32_t tmpccer;
   uint32_t tmpcr2;
 
-  /* Get the TIMx CCER register value */
+  // Get the TIMx CCER register value
   tmpccer = BACKLIGHT_PWM_TIM->CCER;
 
-  /* Disable the Channel 1: Reset the CC1E Bit */
+  // Disable the Channel 1: Reset the CC1E Bit
   BACKLIGHT_PWM_TIM->CCER &= ~TIM_CCER_CC1E;
   tmpccer |= TIM_CCER_CC1E;
 
-  /* Get the TIMx CR2 register value */
+  // Get the TIMx CR2 register value
   tmpcr2 = BACKLIGHT_PWM_TIM->CR2;
 
-  /* Get the TIMx CCMR1 register value */
+  // Get the TIMx CCMR1 register value
   tmpccmrx = BACKLIGHT_PWM_TIM->CCMR1;
 
-  /* Reset the Output Compare Mode Bits */
+  // Reset the Output Compare Mode Bits
   tmpccmrx &= ~TIM_CCMR1_OC1M;
   tmpccmrx &= ~TIM_CCMR1_CC1S;
-  /* Select the Output Compare Mode */
+  // Select the Output Compare Mode
   tmpccmrx |= BACKLIGHT_PWM_TIM_OCMODE;
 
-  /* Reset the Output Polarity level */
+  // Reset the Output Polarity level
   tmpccer &= ~TIM_CCER_CC1P;
-  /* Set the Output Compare Polarity */
+  // Set the Output Compare Polarity
   tmpccer |= TIM_OCPOLARITY_HIGH;
 
   if (IS_TIM_CCXN_INSTANCE(BACKLIGHT_PWM_TIM, TIM_CHANNEL_1)) {
-    /* Check parameters */
+    // Check parameters
     assert_param(IS_TIM_OCN_POLARITY(OC_Config->OCNPolarity));
 
-    /* Reset the Output N Polarity level */
+    // Reset the Output N Polarity level
     tmpccer &= ~TIM_CCER_CC1NP;
-    /* Set the Output N Polarity */
+    // Set the Output N Polarity
     tmpccer |= TIM_OCNPOLARITY_HIGH;
-    /* Set the Output N State */
+    // Set the Output N State
     tmpccer |= TIM_CCER_CC1NE;
   }
 
   if (IS_TIM_BREAK_INSTANCE(BACKLIGHT_PWM_TIM)) {
-    /* Check parameters */
+    // Check parameters
     assert_param(IS_TIM_OCNIDLE_STATE(OC_Config->OCNIdleState));
     assert_param(IS_TIM_OCIDLE_STATE(OC_Config->OCIdleState));
 
-    /* Reset the Output Compare and Output Compare N IDLE State */
+    // Reset the Output Compare and Output Compare N IDLE State
     tmpcr2 &= ~TIM_CR2_OIS1;
     tmpcr2 &= ~TIM_CR2_OIS1N;
-    /* Set the Output Idle state */
+    // Set the Output Idle state
     tmpcr2 |= TIM_OCIDLESTATE_SET;
-    /* Set the Output N Idle state */
+    // Set the Output N Idle state
     tmpcr2 |= TIM_OCNIDLESTATE_SET;
   }
 
-  /* Write to TIMx CR2 */
+  // Write to TIMx CR2
   BACKLIGHT_PWM_TIM->CR2 = tmpcr2;
-
-  /* Write to TIMx CCMR1 */
+  // Write to TIMx CCMR1
   BACKLIGHT_PWM_TIM->CCMR1 = tmpccmrx;
-
-  /* Set the Capture Compare Register value */
+  // Set the Capture Compare Register value
   BACKLIGHT_PWM_TIM->CCR1 = 0;
-
-  /* Write to TIMx CCER */
+  // Write to TIMx CCER
   BACKLIGHT_PWM_TIM->CCER = tmpccer;
 
-  backlight_pwm_set(0);
-
   BACKLIGHT_PWM_TIM->BDTR |= TIM_BDTR_MOE;
   BACKLIGHT_PWM_TIM->CR1 |= TIM_CR1_CEN;
+
+  drv->initialized = true;
+
+  backlight_pwm_set(initial_level);
 }
 
-void backlight_pwm_reinit(void) {
-  uint32_t prev_arr = BACKLIGHT_PWM_TIM->ARR;
-  uint32_t prev_ccr1 = BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR;
+void backlight_pwm_deinit(backlight_action_t action) {
+  backlight_driver_t *drv = &g_backlight_driver;
 
-  uint32_t prev_val = (prev_ccr1 * 255) / (prev_arr + 1);
-  prev_val = prev_val > 255 ? 255 : prev_val;
-  BACKLIGHT = prev_val;
+  if (!drv->initialized) {
+    return;
+  }
 
-  pwm_period = LED_PWM_TIM_PERIOD;
-  BACKLIGHT_PWM_TIM->PSC = LED_PWM_PRESCALER;
-  BACKLIGHT_PWM_TIM->CR1 |= TIM_CR1_ARPE;
-  BACKLIGHT_PWM_TIM->CR2 |= TIM_CR2_CCPC;
-  BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR = (pwm_period * prev_val) / 255;
-  BACKLIGHT_PWM_TIM->ARR = LED_PWM_TIM_PERIOD - 1;
-}
+  if (action == BACKLIGHT_RETAIN) {
+    // We keep both the GPIO and the timer running
 
 #ifdef TREZOR_MODEL_T
+    // This code here is for backward compatibility with the old
+    // bootloader that used a different PWM settings.
+
+// about 10Hz (with PSC = (SystemCoreClock / 1000000) - 1)
+#define LED_PWM_SLOW_TIM_PERIOD (10000)
+#define LED_PWM_PRESCALER_SLOW (SystemCoreClock / 1000000 - 1)  // 1 MHz
 
-#define LED_PWM_SLOW_TIM_PERIOD \
-  (10000)  // about 10Hz (with PSC = (SystemCoreClock / 1000000) - 1)
+    BACKLIGHT_PWM_TIM->PSC = LED_PWM_PRESCALER_SLOW;
+    BACKLIGHT_PWM_TIM->CR1 |= TIM_CR1_ARPE;
+    BACKLIGHT_PWM_TIM->CR2 |= TIM_CR2_CCPC;
+    BACKLIGHT_PWM_TIM->ARR = LED_PWM_SLOW_TIM_PERIOD - 1;
+    BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR =
+        (LED_PWM_SLOW_TIM_PERIOD * drv->current_level) / 255;
+#endif
+  } else {
+    // TODO: deinitialize GPIOs and the TIMER
+  }
 
-void backlight_pwm_set_slow(void) {
-  uint32_t prev_arr = BACKLIGHT_PWM_TIM->ARR;
-  uint32_t prev_ccr1 = BACKLIGHT_PWM_TIM->CCR1;
+  drv->initialized = false;
+}
 
-  uint32_t prev_val = (prev_ccr1 * 255) / (prev_arr + 1);
-  prev_val = prev_val > 255 ? 255 : prev_val;
+// Generate a pulse on the backlight control pin to wake up the TPS61043
+static void backlight_pwm_wakeup_pulse(void) {
+  GPIO_InitTypeDef GPIO_InitStructure = {0};
 
-  pwm_period = LED_PWM_SLOW_TIM_PERIOD;
-  BACKLIGHT_PWM_TIM->PSC = LED_PWM_PRESCALER_SLOW;
-  BACKLIGHT_PWM_TIM->CR1 |= TIM_CR1_ARPE;
-  BACKLIGHT_PWM_TIM->CR2 |= TIM_CR2_CCPC;
-  BACKLIGHT_PWM_TIM->ARR = LED_PWM_SLOW_TIM_PERIOD - 1;
-  BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR = pwm_period * prev_val / 255;
+  HAL_GPIO_WritePin(BACKLIGHT_PWM_PORT, BACKLIGHT_PWM_PIN, GPIO_PIN_SET);
+
+  GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
+  GPIO_InitStructure.Pull = GPIO_NOPULL;
+  GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
+  GPIO_InitStructure.Pin = BACKLIGHT_PWM_PIN;
+  HAL_GPIO_Init(BACKLIGHT_PWM_PORT, &GPIO_InitStructure);
+
+  hal_delay_us(500);
+
+  GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
+  GPIO_InitStructure.Pull = GPIO_NOPULL;
+  GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
+  GPIO_InitStructure.Alternate = BACKLIGHT_PWM_TIM_AF;
+  GPIO_InitStructure.Pin = BACKLIGHT_PWM_PIN;
+  HAL_GPIO_Init(BACKLIGHT_PWM_PORT, &GPIO_InitStructure);
+}
+
+int backlight_pwm_set(int level) {
+  backlight_driver_t *drv = &g_backlight_driver;
+
+  if (!drv->initialized) {
+    return 0;
+  }
+
+  if (level >= 0 && level <= 255) {
+    // TPS61043 goes to shutdown when duty cycle is 0 (after 32ms),
+    // so we need to set GPIO to high for at least 500us
+    // to wake it up.
+    if (BACKLIGHT_PWM_TIM->BACKLIGHT_PWM_TIM_CCR == 0 && level != 0) {
+      backlight_pwm_wakeup_pulse();
+    }
+
+    BACKLIGHT_PWM_TIM->CCR1 = (LED_PWM_TIM_PERIOD * level) / 255;
+
+    drv->current_level = level;
+  }
+
+  return drv->current_level;
+}
+
+int backlight_pwm_get(void) {
+  backlight_driver_t *drv = &g_backlight_driver;
+
+  if (!drv->initialized) {
+    return 0;
+  }
+
+  return drv->current_level;
 }
-#endif