cc26x2_cc13x2: add function to change AUX opmode

This function is needed to setup the AUX operational mode at startup,
also used for managing low-power states.

Signed-off-by: Jean Pierre Dudey <jeandudey@hotmail.com>

cpu/cc26x2_cc13x2/aux.c

@@ -0,0 +1,91 @@
+
+/*
+ * Copyright (C) 2020 Locha Inc
+ *
+ * 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_cc26x2_cc13x2
+ * @{
+ *
+ * @file
+ * @brief           CC26x2, CC13x2 AUX functions
+ * @author          Jean Pierre Dudey <jeandudey@hotmail.com>
+ * @}
+ */
+
+#include <assert.h>
+#include "cpu.h"
+
+/**
+ * @brief   Order of operation modes
+ *
+ * This is to calculate which mode follows the other, to change step-by-step
+ * the mode.
+ *
+ * @{
+ */
+#define OPMODE_PDA_ORDER  (0)
+#define OPMODE_A_ORDER    (1)
+#define OPMODE_LP_ORDER   (2)
+#define OPMODE_PDLP_ORDER (3)
+/** @} */
+
+/** Array to map an operation mode to it's order when changing it */
+static const uint8_t _opmode_to_order[4] = {
+    OPMODE_A_ORDER,
+    OPMODE_LP_ORDER,
+    OPMODE_PDA_ORDER,
+    OPMODE_PDLP_ORDER
+};
+/** Array to map an order to an operation mode, used to get the next operation
+ * mode. This is because we need to change the operation in ordered steps */
+static const uint8_t _order_to_opmode[4] = {
+    AUX_SYSIF_OPMODEREQ_REQ_PDA,
+    AUX_SYSIF_OPMODEREQ_REQ_A,
+    AUX_SYSIF_OPMODEREQ_REQ_LP,
+    AUX_SYSIF_OPMODEREQ_REQ_PDLP
+};
+
+void aux_sysif_opmode_change(uint32_t target_opmode)
+{
+    assert((target_opmode == AUX_SYSIF_OPMODEREQ_REQ_PDLP) ||
+           (target_opmode == AUX_SYSIF_OPMODEREQ_REQ_PDA)  ||
+           (target_opmode == AUX_SYSIF_OPMODEREQ_REQ_LP)   ||
+           (target_opmode == AUX_SYSIF_OPMODEREQ_REQ_A));
+
+    uint32_t current_opmode;
+    uint32_t next_mode;
+
+    /* Change AUX operation mode following hardware rules, operation mode
+     * change needs to be done in order, and one step at a time:
+     *
+     * PDA -> A -> LP -> PDLP
+     */
+    do {
+        current_opmode = AUX_SYSIF->OPMODEREQ;
+
+        /* Wait for change ACK */
+        while (current_opmode != AUX_SYSIF->OPMODEACK) {}
+
+        if (current_opmode == target_opmode) {
+            break;
+        }
+
+        /* At this point we aren't in the mode we want, now we calculate which
+         * mode follows this and make the change to that mode, this is repeated
+         * in this loop until we get to the desired mode */
+        uint32_t current_order = _opmode_to_order[current_opmode];
+        if (current_order < _opmode_to_order[target_opmode]) {
+            next_mode = _order_to_opmode[current_order + 1];
+        }
+        else {
+            next_mode = _order_to_opmode[current_order - 1];
+        }
+
+        /* Request next mode */
+        AUX_SYSIF->OPMODEREQ = next_mode;
+    } while (current_opmode != target_opmode);
+}

cpu/cc26x2_cc13x2/include/cc26x2_cc13x2_aux.h

@@ -217,6 +217,17 @@ typedef struct {
     reg32_t SWPWRPROF; /**< Software Power Profiler */
 } aux_sysif_regs_t;
 
+
+/**
+ * @brief   AUX_SYSIF register values
+ * @{
+ */
+#define AUX_SYSIF_OPMODEREQ_REQ_PDLP 0x00000003
+#define AUX_SYSIF_OPMODEREQ_REQ_PDA  0x00000002
+#define AUX_SYSIF_OPMODEREQ_REQ_LP   0x00000001
+#define AUX_SYSIF_OPMODEREQ_REQ_A    0x00000000
+/** @} */
+
 /**
  * @ingroup cpu_specific_peripheral_memory_map
  * @{
@@ -232,6 +243,21 @@ typedef struct {
  */
 #define AUX_SYSIF            ((aux_sysif_regs_t *) (AUX_SYSIF_BASE))
 
+/**
+ * @brief   AUX_SYSIF functions
+ * @{
+ */
+/**
+ * @brief    Changes the AUX operational mode
+ *
+ * @note Only this function should be used to change the operational mode,
+ * because it needs to be done in order.
+ *
+ * @param[in] target_opmode The opmode we want to change to.
+ */
+void aux_sysif_opmode_change(uint32_t target_opmode);
+/** @} */
+
 /**
  * @brief   AUX_TIMER01 registers
  */