marcus chiou / mbed-src

mbed library sources

Fork of mbed-src by mbed official

targets/hal/TARGET_Atmel/TARGET_SAM21/drivers/sercom/sercom.c@592:a274ee790e56, 2015-07-17 (annotated)

Committer:
mbed_official
Date:
Fri Jul 17 09:15:10 2015 +0100
Revision:
592:a274ee790e56
Parent:
579:53297373a894 
Synchronized with git revision e7144f83a8d75df80c4877936b6ffe552b0be9e6



Full URL: https://github.com/mbedmicro/mbed/commit/e7144f83a8d75df80c4877936b6ffe552b0be9e6/



More API implementation for SAMR21

Who changed what in which revision?

UserRevisionLine numberNew contents of line
mbed_official 579:53297373a894 1 #include "sercom.h"
mbed_official 579:53297373a894 2
mbed_official 579:53297373a894 3 #define SHIFT 32
mbed_official 579:53297373a894 4 #define BAUD_INT_MAX 8192
mbed_official 579:53297373a894 5 #define BAUD_FP_MAX 8
mbed_official 579:53297373a894 6
mbed_official 579:53297373a894 7 #if !defined(__DOXYGEN__)
mbed_official 579:53297373a894 8 /**
mbed_official 579:53297373a894 9 * \internal Configuration structure to save current gclk status.
mbed_official 579:53297373a894 10 */
mbed_official 579:53297373a894 11 struct _sercom_conf {
mbed_official 579:53297373a894 12 /* Status of gclk generator initialization. */
mbed_official 579:53297373a894 13 bool generator_is_set;
mbed_official 579:53297373a894 14 /* Sercom gclk generator used. */
mbed_official 579:53297373a894 15 enum gclk_generator generator_source;
mbed_official 579:53297373a894 16 };
mbed_official 579:53297373a894 17
mbed_official 579:53297373a894 18 static struct _sercom_conf _sercom_config;
mbed_official 579:53297373a894 19
mbed_official 579:53297373a894 20
mbed_official 579:53297373a894 21 /**
mbed_official 579:53297373a894 22 * \internal Calculate 64 bit division, ref can be found in
mbed_official 579:53297373a894 23 * http://en.wikipedia.org/wiki/Division_algorithm#Long_division
mbed_official 579:53297373a894 24 */
mbed_official 579:53297373a894 25 static uint64_t long_division(uint64_t n, uint64_t d)
mbed_official 579:53297373a894 26 {
mbed_official 579:53297373a894 27 int32_t i;
mbed_official 579:53297373a894 28 uint64_t q = 0, r = 0, bit_shift;
mbed_official 579:53297373a894 29 for (i = 63; i >= 0; i--) {
mbed_official 579:53297373a894 30 bit_shift = (uint64_t)1 << i;
mbed_official 579:53297373a894 31
mbed_official 579:53297373a894 32 r = r << 1;
mbed_official 579:53297373a894 33
mbed_official 579:53297373a894 34 if (n & bit_shift) {
mbed_official 579:53297373a894 35 r |= 0x01;
mbed_official 579:53297373a894 36 }
mbed_official 579:53297373a894 37
mbed_official 579:53297373a894 38 if (r >= d) {
mbed_official 579:53297373a894 39 r = r - d;
mbed_official 579:53297373a894 40 q |= bit_shift;
mbed_official 579:53297373a894 41 }
mbed_official 579:53297373a894 42 }
mbed_official 579:53297373a894 43
mbed_official 579:53297373a894 44 return q;
mbed_official 579:53297373a894 45 }
mbed_official 579:53297373a894 46
mbed_official 579:53297373a894 47 /**
mbed_official 579:53297373a894 48 * \internal Calculate synchronous baudrate value (SPI/UART)
mbed_official 579:53297373a894 49 */
mbed_official 579:53297373a894 50 enum status_code _sercom_get_sync_baud_val(
mbed_official 579:53297373a894 51 const uint32_t baudrate,
mbed_official 579:53297373a894 52 const uint32_t external_clock,
mbed_official 579:53297373a894 53 uint16_t *const baudvalue)
mbed_official 579:53297373a894 54 {
mbed_official 579:53297373a894 55 /* Baud value variable */
mbed_official 579:53297373a894 56 uint16_t baud_calculated = 0;
mbed_official 579:53297373a894 57 uint32_t clock_value = external_clock;
mbed_official 579:53297373a894 58
mbed_official 579:53297373a894 59
mbed_official 579:53297373a894 60 /* Check if baudrate is outside of valid range. */
mbed_official 579:53297373a894 61 if (baudrate > (external_clock / 2)) {
mbed_official 579:53297373a894 62 /* Return with error code */
mbed_official 579:53297373a894 63 return STATUS_ERR_BAUDRATE_UNAVAILABLE;
mbed_official 579:53297373a894 64 }
mbed_official 579:53297373a894 65
mbed_official 579:53297373a894 66 /* Calculate BAUD value from clock frequency and baudrate */
mbed_official 579:53297373a894 67 clock_value = external_clock / 2;
mbed_official 579:53297373a894 68 while (clock_value >= baudrate) {
mbed_official 579:53297373a894 69 clock_value = clock_value - baudrate;
mbed_official 579:53297373a894 70 baud_calculated++;
mbed_official 579:53297373a894 71 }
mbed_official 579:53297373a894 72 baud_calculated = baud_calculated - 1;
mbed_official 579:53297373a894 73
mbed_official 579:53297373a894 74 /* Check if BAUD value is more than 255, which is maximum
mbed_official 579:53297373a894 75 * for synchronous mode */
mbed_official 579:53297373a894 76 if (baud_calculated > 0xFF) {
mbed_official 579:53297373a894 77 /* Return with an error code */
mbed_official 579:53297373a894 78 return STATUS_ERR_BAUDRATE_UNAVAILABLE;
mbed_official 579:53297373a894 79 } else {
mbed_official 579:53297373a894 80 *baudvalue = baud_calculated;
mbed_official 579:53297373a894 81 return STATUS_OK;
mbed_official 579:53297373a894 82 }
mbed_official 579:53297373a894 83 }
mbed_official 579:53297373a894 84
mbed_official 579:53297373a894 85 /**
mbed_official 579:53297373a894 86 * \internal Calculate asynchronous baudrate value (UART)
mbed_official 579:53297373a894 87 */
mbed_official 579:53297373a894 88 enum status_code _sercom_get_async_baud_val(
mbed_official 579:53297373a894 89 const uint32_t baudrate,
mbed_official 579:53297373a894 90 const uint32_t peripheral_clock,
mbed_official 579:53297373a894 91 uint16_t *const baudval,
mbed_official 579:53297373a894 92 enum sercom_asynchronous_operation_mode mode,
mbed_official 579:53297373a894 93 enum sercom_asynchronous_sample_num sample_num)
mbed_official 579:53297373a894 94 {
mbed_official 579:53297373a894 95 /* Temporary variables */
mbed_official 579:53297373a894 96 uint64_t ratio = 0;
mbed_official 579:53297373a894 97 uint64_t scale = 0;
mbed_official 579:53297373a894 98 uint64_t baud_calculated = 0;
mbed_official 579:53297373a894 99 uint8_t baud_fp;
mbed_official 579:53297373a894 100 uint32_t baud_int = 0;
mbed_official 579:53297373a894 101 uint64_t temp1, temp2;
mbed_official 579:53297373a894 102
mbed_official 579:53297373a894 103 /* Check if the baudrate is outside of valid range */
mbed_official 579:53297373a894 104 if ((baudrate * sample_num) > peripheral_clock) {
mbed_official 579:53297373a894 105 /* Return with error code */
mbed_official 579:53297373a894 106 return STATUS_ERR_BAUDRATE_UNAVAILABLE;
mbed_official 579:53297373a894 107 }
mbed_official 579:53297373a894 108
mbed_official 579:53297373a894 109 if(mode == SERCOM_ASYNC_OPERATION_MODE_ARITHMETIC) {
mbed_official 579:53297373a894 110 /* Calculate the BAUD value */
mbed_official 579:53297373a894 111 temp1 = ((sample_num * (uint64_t)baudrate) << SHIFT);
mbed_official 579:53297373a894 112 ratio = long_division(temp1, peripheral_clock);
mbed_official 579:53297373a894 113 scale = ((uint64_t)1 << SHIFT) - ratio;
mbed_official 579:53297373a894 114 baud_calculated = (65536 * scale) >> SHIFT;
mbed_official 579:53297373a894 115 } else if(mode == SERCOM_ASYNC_OPERATION_MODE_FRACTIONAL) {
mbed_official 579:53297373a894 116 for(baud_fp = 0; baud_fp < BAUD_FP_MAX; baud_fp++) {
mbed_official 579:53297373a894 117 temp1 = BAUD_FP_MAX * (uint64_t)peripheral_clock;
mbed_official 579:53297373a894 118 temp2 = ((uint64_t)baudrate * sample_num);
mbed_official 579:53297373a894 119 baud_int = long_division(temp1, temp2);
mbed_official 579:53297373a894 120 baud_int -= baud_fp;
mbed_official 579:53297373a894 121 baud_int = baud_int / BAUD_FP_MAX;
mbed_official 579:53297373a894 122 if(baud_int < BAUD_INT_MAX) {
mbed_official 579:53297373a894 123 break;
mbed_official 579:53297373a894 124 }
mbed_official 579:53297373a894 125 }
mbed_official 579:53297373a894 126 if(baud_fp == BAUD_FP_MAX) {
mbed_official 579:53297373a894 127 return STATUS_ERR_BAUDRATE_UNAVAILABLE;
mbed_official 579:53297373a894 128 }
mbed_official 579:53297373a894 129 baud_calculated = baud_int | (baud_fp << 13);
mbed_official 579:53297373a894 130 }
mbed_official 579:53297373a894 131
mbed_official 579:53297373a894 132 *baudval = baud_calculated;
mbed_official 579:53297373a894 133 return STATUS_OK;
mbed_official 579:53297373a894 134 }
mbed_official 579:53297373a894 135 #endif
mbed_official 579:53297373a894 136
mbed_official 579:53297373a894 137 /**
mbed_official 579:53297373a894 138 * \brief Set GCLK channel to generator.
mbed_official 579:53297373a894 139 *
mbed_official 579:53297373a894 140 * This will set the appropriate GCLK channel to the requested GCLK generator.
mbed_official 579:53297373a894 141 * This will set the generator for all SERCOM instances, and the user will thus
mbed_official 579:53297373a894 142 * only be able to set the same generator that has previously been set, if any.
mbed_official 579:53297373a894 143 *
mbed_official 579:53297373a894 144 * After the generator has been set the first time, the generator can be changed
mbed_official 579:53297373a894 145 * using the \c force_change flag.
mbed_official 579:53297373a894 146 *
mbed_official 579:53297373a894 147 * \param[in] generator_source The generator to use for SERCOM.
mbed_official 579:53297373a894 148 * \param[in] force_change Force change the generator.
mbed_official 579:53297373a894 149 *
mbed_official 579:53297373a894 150 * \return Status code indicating the GCLK generator change operation.
mbed_official 579:53297373a894 151 * \retval STATUS_OK If the generator update request was
mbed_official 579:53297373a894 152 * successful.
mbed_official 579:53297373a894 153 * \retval STATUS_ERR_ALREADY_INITIALIZED If a generator was already configured
mbed_official 579:53297373a894 154 * and the new configuration was not
mbed_official 579:53297373a894 155 * forced.
mbed_official 579:53297373a894 156 */
mbed_official 579:53297373a894 157 enum status_code sercom_set_gclk_generator(
mbed_official 579:53297373a894 158 const enum gclk_generator generator_source,
mbed_official 579:53297373a894 159 const bool force_change)
mbed_official 579:53297373a894 160 {
mbed_official 579:53297373a894 161 /* Check if valid option. */
mbed_official 579:53297373a894 162 if (!_sercom_config.generator_is_set || force_change) {
mbed_official 579:53297373a894 163 /* Create and fill a GCLK configuration structure for the new config. */
mbed_official 579:53297373a894 164 struct system_gclk_chan_config gclk_chan_conf;
mbed_official 579:53297373a894 165 system_gclk_chan_get_config_defaults(&gclk_chan_conf);
mbed_official 579:53297373a894 166 gclk_chan_conf.source_generator = generator_source;
mbed_official 579:53297373a894 167 system_gclk_chan_set_config(SERCOM_GCLK_ID, &gclk_chan_conf);
mbed_official 579:53297373a894 168 system_gclk_chan_enable(SERCOM_GCLK_ID);
mbed_official 579:53297373a894 169
mbed_official 579:53297373a894 170 /* Save config. */
mbed_official 579:53297373a894 171 _sercom_config.generator_source = generator_source;
mbed_official 579:53297373a894 172 _sercom_config.generator_is_set = true;
mbed_official 579:53297373a894 173
mbed_official 579:53297373a894 174 return STATUS_OK;
mbed_official 579:53297373a894 175 } else if (generator_source == _sercom_config.generator_source) {
mbed_official 579:53297373a894 176 /* Return status OK if same config. */
mbed_official 579:53297373a894 177 return STATUS_OK;
mbed_official 579:53297373a894 178 }
mbed_official 579:53297373a894 179
mbed_official 579:53297373a894 180 /* Return invalid config to already initialized GCLK. */
mbed_official 579:53297373a894 181 return STATUS_ERR_ALREADY_INITIALIZED;
mbed_official 579:53297373a894 182 }
mbed_official 579:53297373a894 183
mbed_official 579:53297373a894 184 /** \internal
mbed_official 579:53297373a894 185 * Creates a switch statement case entry to convert a SERCOM instance and pad
mbed_official 579:53297373a894 186 * index to the default SERCOM pad MUX setting.
mbed_official 579:53297373a894 187 */
mbed_official 579:53297373a894 188 #define _SERCOM_PAD_DEFAULTS_CASE(n, pad) \
mbed_official 579:53297373a894 189 case (uintptr_t)SERCOM##n: \
mbed_official 579:53297373a894 190 switch (pad) { \
mbed_official 579:53297373a894 191 case 0: \
mbed_official 579:53297373a894 192 return SERCOM##n##_PAD0_DEFAULT; \
mbed_official 579:53297373a894 193 case 1: \
mbed_official 579:53297373a894 194 return SERCOM##n##_PAD1_DEFAULT; \
mbed_official 579:53297373a894 195 case 2: \
mbed_official 579:53297373a894 196 return SERCOM##n##_PAD2_DEFAULT; \
mbed_official 579:53297373a894 197 case 3: \
mbed_official 579:53297373a894 198 return SERCOM##n##_PAD3_DEFAULT; \
mbed_official 579:53297373a894 199 } \
mbed_official 579:53297373a894 200 break;
mbed_official 579:53297373a894 201
mbed_official 579:53297373a894 202 /**
mbed_official 579:53297373a894 203 * \internal Gets the default PAD pinout for a given SERCOM.
mbed_official 579:53297373a894 204 *
mbed_official 579:53297373a894 205 * Returns the pinmux settings for the given SERCOM and pad. This is used
mbed_official 579:53297373a894 206 * for default configuration of pins.
mbed_official 579:53297373a894 207 *
mbed_official 579:53297373a894 208 * \param[in] sercom_module Pointer to the SERCOM module
mbed_official 579:53297373a894 209 * \param[in] pad PAD to get default pinout for
mbed_official 579:53297373a894 210 *
mbed_official 579:53297373a894 211 * \returns The default pinmux for the given SERCOM instance and PAD
mbed_official 579:53297373a894 212 *
mbed_official 579:53297373a894 213 */
mbed_official 579:53297373a894 214 uint32_t _sercom_get_default_pad(
mbed_official 579:53297373a894 215 Sercom *const sercom_module,
mbed_official 579:53297373a894 216 const uint8_t pad)
mbed_official 579:53297373a894 217 {
mbed_official 579:53297373a894 218 switch ((uintptr_t)sercom_module) {
mbed_official 579:53297373a894 219 /* Auto-generate a lookup table for the default SERCOM pad defaults */
mbed_official 579:53297373a894 220 MREPEAT(SERCOM_INST_NUM, _SERCOM_PAD_DEFAULTS_CASE, pad)
mbed_official 579:53297373a894 221 }
mbed_official 579:53297373a894 222
mbed_official 579:53297373a894 223 Assert(false);
mbed_official 579:53297373a894 224 return 0;
mbed_official 579:53297373a894 225 }
mbed_official 579:53297373a894 226
mbed_official 579:53297373a894 227 /**
mbed_official 579:53297373a894 228 * \internal
mbed_official 579:53297373a894 229 * Find index of given instance.
mbed_official 579:53297373a894 230 *
mbed_official 579:53297373a894 231 * \param[in] sercom_instance Instance pointer.
mbed_official 579:53297373a894 232 *
mbed_official 579:53297373a894 233 * \return Index of given instance.
mbed_official 579:53297373a894 234 */
mbed_official 579:53297373a894 235 uint8_t _sercom_get_sercom_inst_index(
mbed_official 579:53297373a894 236 Sercom *const sercom_instance)
mbed_official 579:53297373a894 237 {
mbed_official 579:53297373a894 238 /* Save all available SERCOM instances for compare. */
mbed_official 579:53297373a894 239 Sercom *sercom_instances[SERCOM_INST_NUM] = SERCOM_INSTS;
mbed_official 579:53297373a894 240
mbed_official 579:53297373a894 241 /* Find index for sercom instance. */
mbed_official 579:53297373a894 242 for (uint32_t i = 0; i < SERCOM_INST_NUM; i++) {
mbed_official 579:53297373a894 243 if ((uintptr_t)sercom_instance == (uintptr_t)sercom_instances[i]) {
mbed_official 579:53297373a894 244 return i;
mbed_official 579:53297373a894 245 }
mbed_official 579:53297373a894 246 }
mbed_official 579:53297373a894 247
mbed_official 579:53297373a894 248 /* Invalid data given. */
mbed_official 579:53297373a894 249 Assert(false);
mbed_official 579:53297373a894 250 return 0;
mbed_official 579:53297373a894 251 }