From a8450f2952f451ca11d1bc67385f92c43bcf6913 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Joakim=20Nohlg=C3=A5rd?= Date: Thu, 27 Apr 2017 15:37:40 +0200 Subject: [PATCH] kinetis: Simplify MCG state traversal algorithm The new implementation uses a precalculated map of which mode to switch to next if going from mode A to mode B. This simplifies the implementation for moving between modes which are not direct neighbors. See mcg.h documentation for a diagram of the state machine for the clocking modes. Also found in the CPU reference manual of all Kinetis CPUs, MCG chapter, MCG mode state diagram. --- cpu/kinetis_common/periph/mcg.c | 151 +++++++++----------------------- 1 file changed, 39 insertions(+), 112 deletions(-) diff --git a/cpu/kinetis_common/periph/mcg.c b/cpu/kinetis_common/periph/mcg.c index b567b348e4..6b5db9f9db 100644 --- a/cpu/kinetis_common/periph/mcg.c +++ b/cpu/kinetis_common/periph/mcg.c @@ -1,5 +1,6 @@ /* * Copyright (C) 2015 PHYTEC Messtechnik GmbH + * Copyright (C) 2017 Eistec AB * * 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 @@ -14,7 +15,8 @@ * @brief Implementation of the Kinetis Multipurpose Clock Generator * * @author Johann Fischer - * @} + * @author Joakim Nohlgård + * */ #include @@ -23,8 +25,18 @@ #if KINETIS_CPU_USE_MCG -/* MCG neighbor modes matrix */ -static uint8_t mcg_pm[8] = {0x02, 0x15, 0x12, 0x20, 0xe6, 0xd8, 0xb0, 0xf0}; +/* Pathfinding for the clocking modes, this table lists the next mode in the + * chain when moving from mode to mode */ +static const uint8_t mcg_mode_routing[8][8] = { + {0, 1, 1, 1, 1, 1, 1, 1}, /* from PEE */ + {0, 1, 2, 4, 4, 4, 4, 4}, /* from PBE */ + {1, 1, 2, 4, 4, 4, 4, 4}, /* from BLPE */ + {5, 5, 5, 3, 5, 5, 5, 5}, /* from BLPI */ + {1, 1, 2, 5, 4, 5, 6, 7}, /* from FBE */ + {4, 4, 4, 3, 4, 5, 6, 7}, /* from FBI */ + {4, 4, 4, 5, 4, 5, 6, 7}, /* from FEE */ + {4, 4, 4, 5, 4, 5, 6, 7}, /* from FEI */ +}; static uint8_t current_mode = KINETIS_MCG_FEI; @@ -361,124 +373,39 @@ int kinetis_mcg_set_mode(kinetis_mcg_mode_t mode) if (mode > KINETIS_MCG_FEI) { return -1; } - - if (mcg_pm[current_mode] & (1 << mode)) { - if (mode == KINETIS_MCG_FEI) { - kinetis_mcg_set_fei(); - } - - if (mode == KINETIS_MCG_FBI) { - kinetis_mcg_set_fbi(); - } - - if (mode == KINETIS_MCG_FEE) { - kinetis_mcg_set_fee(); - } - - if (mode == KINETIS_MCG_FBE) { - kinetis_mcg_set_fbe(); - } - - if (mode == KINETIS_MCG_BLPI) { - kinetis_mcg_set_blpi(); - } - - if (mode == KINETIS_MCG_BLPE) { - kinetis_mcg_set_blpe(); - } - - if (mode == KINETIS_MCG_PBE) { - kinetis_mcg_set_pbe(); - } - - if (mode == KINETIS_MCG_PEE) { - kinetis_mcg_set_pee(); - } - - return 0; - } - - switch (mode) { - case KINETIS_MCG_PEE: - /* cppcheck-suppress duplicateExpression */ - if (!(KINETIS_MCG_USE_ERC || KINETIS_MCG_USE_PLL)) { - return -1; - } - - if (current_mode == KINETIS_MCG_FEI) { - /* set FBE -> PBE -> PEE */ - kinetis_mcg_set_fbe(); - kinetis_mcg_set_pbe(); + while (current_mode != mode) { + switch(mcg_mode_routing[current_mode][mode]) { + case KINETIS_MCG_PEE: kinetis_mcg_set_pee(); - return 0; - } - - if (current_mode == KINETIS_MCG_BLPE) { - /* set PBE -> PEE */ - kinetis_mcg_set_pbe(); - kinetis_mcg_set_pee(); - return 0; - } - - break; - - case KINETIS_MCG_BLPE: - if (!KINETIS_MCG_USE_ERC) { - return -1; - } - - if (current_mode == KINETIS_MCG_PEE) { - /* set PBE -> BLPE */ + break; + case KINETIS_MCG_PBE: kinetis_mcg_set_pbe(); + break; + case KINETIS_MCG_BLPE: kinetis_mcg_set_blpe(); - return 0; - } - - if (current_mode == KINETIS_MCG_FEE) { - /* set FBE -> BLPE */ - kinetis_mcg_set_fbe(); - kinetis_mcg_set_blpe(); - return 0; - } - - break; - - case KINETIS_MCG_BLPI: - if (current_mode == KINETIS_MCG_FEE) { - /* set FBI -> BLPI */ - kinetis_mcg_set_fbi(); + break; + case KINETIS_MCG_BLPI: kinetis_mcg_set_blpi(); - return 0; - } - - break; - - case KINETIS_MCG_FEE: - if (!KINETIS_MCG_USE_ERC) { - return -1; - } - - if (current_mode == KINETIS_MCG_BLPE) { - /* set FBE -> FEE */ + break; + case KINETIS_MCG_FBE: kinetis_mcg_set_fbe(); - kinetis_mcg_set_fee(); - return 0; - } - - if (current_mode == KINETIS_MCG_BLPI) { - /* set FBI -> FEE */ + break; + case KINETIS_MCG_FBI: kinetis_mcg_set_fbi(); + break; + case KINETIS_MCG_FEE: kinetis_mcg_set_fee(); - return 0; - } - - break; - - default: - break; + break; + case KINETIS_MCG_FEI: + kinetis_mcg_set_fei(); + break; + default: + return -1; + } } - return -1; + return 0; } #endif /* KINETIS_CPU_USE_MCG */ +/** @} */