cpu/atxmega: Add periph power management

boards/atxmega-a1u-xpro/include/periph_conf.h

@@ -36,6 +36,7 @@ extern "C" {
 static const timer_conf_t timer_config[] = {
     {
         .dev            = (void *)&TCC1,
+        .pwr            = PWR_RED_REG(PWR_PORT_C, PR_TC1_bm),
         .type           = TC_TYPE_1,
         .int_lvl        = { CPU_INT_LVL_LOW,
                             CPU_INT_LVL_OFF,
@@ -44,6 +45,7 @@ static const timer_conf_t timer_config[] = {
     },
     {
         .dev            = (void *)&TCC0,
+        .pwr            = PWR_RED_REG(PWR_PORT_C, PR_TC0_bm),
         .type           = TC_TYPE_0,
         .int_lvl        = { CPU_INT_LVL_LOW,
                             CPU_INT_LVL_LOW,
@@ -69,6 +71,7 @@ static const timer_conf_t timer_config[] = {
 static const uart_conf_t uart_config[] = {
     {   /* CDC-ACM */
         .dev            = &USARTE0,
+        .pwr            = PWR_RED_REG(PWR_PORT_E, PR_USART0_bm),
         .rx_pin         = GPIO_PIN(PORT_E, 2),
         .tx_pin         = GPIO_PIN(PORT_E, 3),
 #ifdef MODULE_PERIPH_UART_HW_FC

cpu/atxmega/atxmega_cpu.c

@@ -22,6 +22,7 @@
 
 #include "cpu.h"
 #include "cpu_clock.h"
+#include "cpu_pm.h"
 #include "panic.h"
 
 #define ENABLE_DEBUG 0
@@ -63,18 +64,7 @@ void avr8_reset_cause(void)
 
 void __attribute__((weak)) avr8_clk_init(void)
 {
-    volatile uint8_t *reg = (uint8_t *)&PR.PRGEN;
-    uint8_t i;
-
-    /* Turn off all peripheral clocks that can be turned off. */
-    for (i = 0; i <= 7; i++) {
-        reg[i] = 0xff;
-    }
-
-    /* Turn on all peripheral clocks that can be turned on. */
-    for (i = 0; i <= 7; i++) {
-        reg[i] = 0x00;
-    }
+    pm_periph_power_off();
 
     /* XMEGA A3U [DATASHEET] p.23 After reset, the device starts up running
      * from the 2MHz internal oscillator. The other clock sources, DFLLs

cpu/atxmega/include/cpu_pm.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 Gerson Fernando Budke
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup         cpu_atxmega
+ * @{
+ *
+ * @file
+ * @brief           Power Management and Power Reduction API
+ *
+ * This help to save power disabling all non used peripherals.  It can help to
+ * save power when in active or sleep modes.  For any other low power modes
+ * xmega will freeze all peripherals clock.
+ *
+ * @author          Gerson Fernando Budke <nandojve@gmail.com>
+ */
+
+#include "periph_cpu.h"
+
+#ifndef CPU_PM_H
+#define CPU_PM_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void pm_periph_enable(pwr_reduction_t pwr);
+void pm_periph_disable(pwr_reduction_t pwr);
+void pm_periph_power_off(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CPU_PM_H */
+/** @} */

cpu/atxmega/include/periph_cpu.h

@@ -68,6 +68,29 @@ enum {
     PORT_MAX,
 };
 
+/**
+ * @brief   Power Reduction Peripheral Mask
+ */
+typedef uint16_t pwr_reduction_t;
+
+/**
+ * @brief   Define a CPU specific Power Reduction index macro
+ */
+#define PWR_RED_REG(reg, dev) ((reg << 8) | dev)
+
+/**
+ * @brief   Define a CPU specific Power Reduction index macro
+ */
+enum {
+    PWR_GENERAL_POWER,
+    PWR_PORT_A,
+    PWR_PORT_B,
+    PWR_PORT_C,
+    PWR_PORT_D,
+    PWR_PORT_E,
+    PWR_PORT_F,
+};
+
 /**
  * @name    Power management configuration
  * @{
@@ -190,6 +213,7 @@ typedef enum {
  */
 typedef struct {
     USART_t *dev;                   /**< pointer to the used UART device */
+    pwr_reduction_t pwr;            /**< Power Management */
     gpio_t rx_pin;                  /**< pin used for RX */
     gpio_t tx_pin;                  /**< pin used for TX */
 #ifdef MODULE_PERIPH_UART_HW_FC
@@ -235,6 +259,7 @@ typedef enum {
  */
 typedef struct {
     TC0_t *dev;                                 /**< Pointer to the used as Timer device */
+    pwr_reduction_t pwr;                        /**< Power Management */
     timer_type_t type;                          /**< Timer Type */
     cpu_int_lvl_t int_lvl[TIMER_CH_MAX_NUMOF];  /**< Interrupt channels level */
 } timer_conf_t;

cpu/atxmega/periph/pm.c

@@ -23,10 +23,41 @@
 
 #include "periph_conf.h"
 #include "periph/pm.h"
+#include "cpu_pm.h"
 
 #define ENABLE_DEBUG 0
 #include "debug.h"
 
+#define PWR_REG_BASE        ((uint16_t)&PR)
+#define PWR_REG_OFFSET      (0x01)
+
+/**
+ * @brief     Extract the device id of the given power reduction mask
+ */
+static inline uint8_t _device_mask(pwr_reduction_t pwr)
+{
+    return (pwr & 0xff);
+}
+
+/**
+ * @brief     Extract the register id of the given power reduction mask
+ */
+static inline uint8_t _register_id(pwr_reduction_t pwr)
+{
+    return (pwr >> 8) & 0xff;
+}
+
+/**
+ * @brief     Generate the register index of the given power reduction mask
+ */
+static inline uint8_t *_register_addr(pwr_reduction_t pwr)
+{
+    uint8_t id = _register_id(pwr);
+    uint16_t addr = PWR_REG_BASE + (id * PWR_REG_OFFSET);
+
+    return (uint8_t *)addr;
+}
+
 void pm_reboot(void)
 {
     DEBUG("Reboot Software Reset\n" );
@@ -78,3 +109,30 @@ void pm_set(unsigned mode)
     sleep_disable();
     irq_restore(irq_state);
 }
+
+void pm_periph_enable(pwr_reduction_t pwr)
+{
+    uint8_t mask = _device_mask(pwr);
+    uint8_t *reg = _register_addr(pwr);
+
+    *reg &= ~mask;
+}
+
+void pm_periph_disable(pwr_reduction_t pwr)
+{
+    uint8_t mask = _device_mask(pwr);
+    uint8_t *reg = _register_addr(pwr);
+
+    *reg |= mask;
+}
+
+void pm_periph_power_off(void)
+{
+    uint8_t *reg = _register_addr(PWR_GENERAL_POWER);
+    uint8_t i;
+
+    /* Freeze all peripheral clocks */
+    for (i = 0; i <= 7; i++) {
+        reg[i] = 0xff;
+    }
+}

cpu/atxmega/periph/timer.c

@@ -24,6 +24,7 @@
 #include <assert.h>
 
 #include "cpu.h"
+#include "cpu_pm.h"
 #include "thread.h"
 
 #include "periph/timer.h"
@@ -112,6 +113,8 @@ int timer_init(tim_t tim, unsigned long freq, timer_cb_t cb, void *arg)
         return -1;
     }
 
+    pm_periph_enable(timer_config[tim].pwr);
+
     dev = timer_config[tim].dev;
 
     /* stop and reset timer */
@@ -301,6 +304,7 @@ void timer_stop(tim_t tim)
     DEBUG("timer_stop\n");
     timer_config[tim].dev->CTRLA = 0;
     timer_config[tim].dev->CTRLFSET = TC_CMD_RESTART_gc;
+    pm_periph_disable(timer_config[tim].pwr);
 }
 
 void timer_start(tim_t tim)
@@ -310,6 +314,7 @@ void timer_start(tim_t tim)
     }
 
     DEBUG("timer_start\n");
+    pm_periph_enable(timer_config[tim].pwr);
     timer_config[tim].dev->CTRLA = ctx[tim].prescaler;
 }
 

cpu/atxmega/periph/uart.c

@@ -29,6 +29,7 @@
 
 #include "board.h"
 #include "cpu.h"
+#include "cpu_pm.h"
 #include "sched.h"
 #include "thread.h"
 #include "periph/uart.h"
@@ -257,6 +258,8 @@ int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
     isr_ctx[uart].rx_cb = rx_cb;
     isr_ctx[uart].arg = arg;
 
+    pm_periph_enable(uart_config[uart].pwr);
+
     /* disable and reset UART */
     dev(uart)->CTRLA = 0;
     dev(uart)->CTRLB = 0;
@@ -315,14 +318,12 @@ void uart_write(uart_t uart, const uint8_t *data, size_t len)
 
 void uart_poweron(uart_t uart)
 {
-    (void)uart;
-    /* not implemented (yet) */
+    pm_periph_enable(uart_config[uart].pwr);
 }
 
 void uart_poweroff(uart_t uart)
 {
-    (void)uart;
-    /* not implemented (yet) */
+    pm_periph_disable(uart_config[uart].pwr);
 }
 
 static inline void _rx_isr_handler(int num)