Diff: targets/hal/TARGET_Atmel/TARGET_SAM21/drivers/sercom/sercom.c

Revision:

579:53297373a894

Child:

592:a274ee790e56

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/hal/TARGET_Atmel/TARGET_SAM21/drivers/sercom/sercom.c	Wed Jul 01 09:45:11 2015 +0100
@@ -0,0 +1,296 @@
+/**
+ * \file
+ *
+ * \brief SAM Serial Peripheral Interface Driver
+ *
+ * Copyright (C) 2012-2014 Atmel Corporation. All rights reserved.
+ *
+ * \asf_license_start
+ *
+ * \page License
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. The name of Atmel may not be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * 4. This software may only be redistributed and used in connection with an
+ *    Atmel microcontroller product.
+ *
+ * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
+ * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * \asf_license_stop
+ *
+ */
+/**
+* Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
+*/
+#include "sercom.h"
+
+#define SHIFT 32
+#define BAUD_INT_MAX   8192
+#define BAUD_FP_MAX     8
+
+#if !defined(__DOXYGEN__)
+/**
+ * \internal Configuration structure to save current gclk status.
+ */
+struct _sercom_conf {
+    /* Status of gclk generator initialization. */
+    bool generator_is_set;
+    /* Sercom gclk generator used. */
+    enum gclk_generator generator_source;
+};
+
+static struct _sercom_conf _sercom_config;
+
+
+/**
+ * \internal Calculate 64 bit division, ref can be found in
+ * http://en.wikipedia.org/wiki/Division_algorithm#Long_division
+ */
+static uint64_t long_division(uint64_t n, uint64_t d)
+{
+    int32_t i;
+    uint64_t q = 0, r = 0, bit_shift;
+    for (i = 63; i >= 0; i--) {
+        bit_shift = (uint64_t)1 << i;
+
+        r = r << 1;
+
+        if (n & bit_shift) {
+            r |= 0x01;
+        }
+
+        if (r >= d) {
+            r = r - d;
+            q |= bit_shift;
+        }
+    }
+
+    return q;
+}
+
+/**
+ * \internal Calculate synchronous baudrate value (SPI/UART)
+ */
+enum status_code _sercom_get_sync_baud_val(
+    const uint32_t baudrate,
+    const uint32_t external_clock,
+    uint16_t *const baudvalue)
+{
+    /* Baud value variable */
+    uint16_t baud_calculated = 0;
+    uint32_t clock_value = external_clock;
+
+
+    /* Check if baudrate is outside of valid range. */
+    if (baudrate > (external_clock / 2)) {
+        /* Return with error code */
+        return STATUS_ERR_BAUDRATE_UNAVAILABLE;
+    }
+
+    /* Calculate BAUD value from clock frequency and baudrate */
+    clock_value = external_clock / 2;
+    while (clock_value >= baudrate) {
+        clock_value = clock_value - baudrate;
+        baud_calculated++;
+    }
+    baud_calculated = baud_calculated - 1;
+
+    /* Check if BAUD value is more than 255, which is maximum
+     * for synchronous mode */
+    if (baud_calculated > 0xFF) {
+        /* Return with an error code */
+        return STATUS_ERR_BAUDRATE_UNAVAILABLE;
+    } else {
+        *baudvalue = baud_calculated;
+        return STATUS_OK;
+    }
+}
+
+/**
+ * \internal Calculate asynchronous baudrate value (UART)
+*/
+enum status_code _sercom_get_async_baud_val(
+    const uint32_t baudrate,
+    const uint32_t peripheral_clock,
+    uint16_t *const baudval,
+    enum sercom_asynchronous_operation_mode mode,
+    enum sercom_asynchronous_sample_num sample_num)
+{
+    /* Temporary variables  */
+    uint64_t ratio = 0;
+    uint64_t scale = 0;
+    uint64_t baud_calculated = 0;
+    uint8_t baud_fp;
+    uint32_t baud_int = 0;
+    uint64_t temp1, temp2;
+
+    /* Check if the baudrate is outside of valid range */
+    if ((baudrate * sample_num) > peripheral_clock) {
+        /* Return with error code */
+        return STATUS_ERR_BAUDRATE_UNAVAILABLE;
+    }
+
+    if(mode == SERCOM_ASYNC_OPERATION_MODE_ARITHMETIC) {
+        /* Calculate the BAUD value */
+        temp1 = ((sample_num * (uint64_t)baudrate) << SHIFT);
+        ratio = long_division(temp1, peripheral_clock);
+        scale = ((uint64_t)1 << SHIFT) - ratio;
+        baud_calculated = (65536 * scale) >> SHIFT;
+    } else if(mode == SERCOM_ASYNC_OPERATION_MODE_FRACTIONAL) {
+        for(baud_fp = 0; baud_fp < BAUD_FP_MAX; baud_fp++) {
+            temp1 = BAUD_FP_MAX * (uint64_t)peripheral_clock;
+            temp2 = ((uint64_t)baudrate * sample_num);
+            baud_int = long_division(temp1, temp2);
+            baud_int -= baud_fp;
+            baud_int = baud_int / BAUD_FP_MAX;
+            if(baud_int < BAUD_INT_MAX) {
+                break;
+            }
+        }
+        if(baud_fp == BAUD_FP_MAX) {
+            return STATUS_ERR_BAUDRATE_UNAVAILABLE;
+        }
+        baud_calculated = baud_int | (baud_fp << 13);
+    }
+
+    *baudval = baud_calculated;
+    return STATUS_OK;
+}
+#endif
+
+/**
+ * \brief Set GCLK channel to generator.
+ *
+ * This will set the appropriate GCLK channel to the requested GCLK generator.
+ * This will set the generator for all SERCOM instances, and the user will thus
+ * only be able to set the same generator that has previously been set, if any.
+ *
+ * After the generator has been set the first time, the generator can be changed
+ * using the \c force_change flag.
+ *
+ * \param[in]  generator_source The generator to use for SERCOM.
+ * \param[in]  force_change     Force change the generator.
+ *
+ * \return Status code indicating the GCLK generator change operation.
+ * \retval STATUS_OK                       If the generator update request was
+ *                                         successful.
+ * \retval STATUS_ERR_ALREADY_INITIALIZED  If a generator was already configured
+ *                                         and the new configuration was not
+ *                                         forced.
+ */
+enum status_code sercom_set_gclk_generator(
+    const enum gclk_generator generator_source,
+    const bool force_change)
+{
+    /* Check if valid option. */
+    if (!_sercom_config.generator_is_set || force_change) {
+        /* Create and fill a GCLK configuration structure for the new config. */
+        struct system_gclk_chan_config gclk_chan_conf;
+        system_gclk_chan_get_config_defaults(&gclk_chan_conf);
+        gclk_chan_conf.source_generator = generator_source;
+        system_gclk_chan_set_config(SERCOM_GCLK_ID, &gclk_chan_conf);
+        system_gclk_chan_enable(SERCOM_GCLK_ID);
+
+        /* Save config. */
+        _sercom_config.generator_source = generator_source;
+        _sercom_config.generator_is_set = true;
+
+        return STATUS_OK;
+    } else if (generator_source == _sercom_config.generator_source) {
+        /* Return status OK if same config. */
+        return STATUS_OK;
+    }
+
+    /* Return invalid config to already initialized GCLK. */
+    return STATUS_ERR_ALREADY_INITIALIZED;
+}
+
+/** \internal
+ * Creates a switch statement case entry to convert a SERCOM instance and pad
+ * index to the default SERCOM pad MUX setting.
+ */
+#define _SERCOM_PAD_DEFAULTS_CASE(n, pad) \
+		case (uintptr_t)SERCOM##n: \
+			switch (pad) { \
+				case 0: \
+					return SERCOM##n##_PAD0_DEFAULT; \
+				case 1: \
+					return SERCOM##n##_PAD1_DEFAULT; \
+				case 2: \
+					return SERCOM##n##_PAD2_DEFAULT; \
+				case 3: \
+					return SERCOM##n##_PAD3_DEFAULT; \
+			} \
+			break;
+
+/**
+ * \internal Gets the default PAD pinout for a given SERCOM.
+ *
+ * Returns the pinmux settings for the given SERCOM and pad. This is used
+ * for default configuration of pins.
+ *
+ * \param[in]  sercom_module   Pointer to the SERCOM module
+ * \param[in]  pad             PAD to get default pinout for
+ *
+ * \returns The default pinmux for the given SERCOM instance and PAD
+ *
+ */
+uint32_t _sercom_get_default_pad(
+    Sercom *const sercom_module,
+    const uint8_t pad)
+{
+    switch ((uintptr_t)sercom_module) {
+            /* Auto-generate a lookup table for the default SERCOM pad defaults */
+            MREPEAT(SERCOM_INST_NUM, _SERCOM_PAD_DEFAULTS_CASE, pad)
+    }
+
+    Assert(false);
+    return 0;
+}
+
+/**
+ * \internal
+ * Find index of given instance.
+ *
+ * \param[in] sercom_instance  Instance pointer.
+ *
+ * \return Index of given instance.
+ */
+uint8_t _sercom_get_sercom_inst_index(
+    Sercom *const sercom_instance)
+{
+    /* Save all available SERCOM instances for compare. */
+    Sercom *sercom_instances[SERCOM_INST_NUM] = SERCOM_INSTS;
+
+    /* Find index for sercom instance. */
+    for (uint32_t i = 0; i < SERCOM_INST_NUM; i++) {
+        if ((uintptr_t)sercom_instance == (uintptr_t)sercom_instances[i]) {
+            return i;
+        }
+    }
+
+    /* Invalid data given. */
+    Assert(false);
+    return 0;
+}