Diff: mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/spi_api.c

Revision:

18:6a4db94011d3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_Freescale/TARGET_K20XX/spi_api.c	Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,154 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2015 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "mbed_assert.h"
+#include "spi_api.h"
+
+#include <math.h>
+
+#include "cmsis.h"
+#include "pinmap.h"
+#include "clk_freqs.h"
+#include "PeripheralPins.h"
+
+void spi_init(spi_t *obj, PinName mosi, PinName miso, PinName sclk, PinName ssel) {
+    // determine the SPI to use
+    SPIName spi_mosi = (SPIName)pinmap_peripheral(mosi, PinMap_SPI_MOSI);
+    SPIName spi_miso = (SPIName)pinmap_peripheral(miso, PinMap_SPI_MISO);
+    SPIName spi_sclk = (SPIName)pinmap_peripheral(sclk, PinMap_SPI_SCLK);
+    SPIName spi_ssel = (SPIName)pinmap_peripheral(ssel, PinMap_SPI_SSEL);
+    SPIName spi_data = (SPIName)pinmap_merge(spi_mosi, spi_miso);
+    SPIName spi_cntl = (SPIName)pinmap_merge(spi_sclk, spi_ssel);
+    
+    obj->spi = (SPI_Type*)pinmap_merge(spi_data, spi_cntl);
+    MBED_ASSERT((int)obj->spi != NC);
+
+    SIM->SCGC5 |= SIM_SCGC5_PORTC_MASK | SIM_SCGC5_PORTD_MASK;
+    SIM->SCGC6 |= SIM_SCGC6_SPI0_MASK;
+
+    obj->spi->MCR &= ~(SPI_MCR_MDIS_MASK | SPI_MCR_HALT_MASK);
+    //obj->spi->MCR |= SPI_MCR_DIS_RXF_MASK | SPI_MCR_DIS_TXF_MASK;
+
+    // not halt in the debug mode
+    obj->spi->SR |= SPI_SR_EOQF_MASK;
+
+    // pin out the spi pins
+    pinmap_pinout(mosi, PinMap_SPI_MOSI);
+    pinmap_pinout(miso, PinMap_SPI_MISO);
+    pinmap_pinout(sclk, PinMap_SPI_SCLK);
+    if (ssel != NC) {
+        pinmap_pinout(ssel, PinMap_SPI_SSEL);
+    }
+}
+
+void spi_free(spi_t *obj) {
+    // [TODO]
+}
+void spi_format(spi_t *obj, int bits, int mode, int slave) {
+    MBED_ASSERT((bits > 4) || (bits < 16));
+    MBED_ASSERT((mode >= 0) && (mode <= 3));
+
+    uint8_t polarity = (mode & 0x2) ? 1 : 0;
+    uint8_t phase = (mode & 0x1) ? 1 : 0;
+    uint8_t old_polarity = (obj->spi->CTAR[0] & SPI_CTAR_CPOL_MASK) != 0;
+
+    // set master/slave
+    if (slave) {
+        obj->spi->MCR &= ~SPI_MCR_MSTR_MASK;
+    } else {
+        obj->spi->MCR |= (1UL << SPI_MCR_MSTR_SHIFT);
+    }
+
+    // CTAR0 is used
+    obj->spi->CTAR[0] &= ~(SPI_CTAR_CPHA_MASK | SPI_CTAR_CPOL_MASK | SPI_CTAR_FMSZ_MASK);
+    obj->spi->CTAR[0] |= (polarity << SPI_CTAR_CPOL_SHIFT) | (phase << SPI_CTAR_CPHA_SHIFT) | ((bits - 1) << SPI_CTAR_FMSZ_SHIFT);
+    
+    //If clk idle state was changed, start a dummy transmission
+    //This is a 'feature' in DSPI: https://community.freescale.com/thread/105526
+    if ((old_polarity != polarity) && (slave == 0)) {
+        //Start transfer (CS should be high, so shouldn't matter)
+        spi_master_write(obj, 0xFFFF);
+    }
+}
+
+static const uint8_t baudrate_prescaler[] = {2,3,5,7};
+static const uint16_t baudrate_scaler[] = {2,4,6,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768};
+
+void spi_frequency(spi_t *obj, int hz) {
+    uint32_t f_error = 0;
+    uint32_t p_error = 0xffffffff;
+    uint32_t ref = 0;
+    uint32_t br = 0;
+    uint32_t ref_spr = 0;
+    uint32_t ref_prescaler = 0;
+    uint32_t ref_dr = 0;
+
+    // bus clk
+    uint32_t PCLK = bus_frequency();
+
+    for (uint32_t i = 0; i < 4; i++) {
+        for (br = 0; br <= 15; br++) {
+            for (uint32_t dr = 0; dr < 2; dr++) {
+                ref = (PCLK * (1U + dr) / baudrate_prescaler[i]) / baudrate_scaler[br];
+                if (ref > (uint32_t)hz)
+                    continue;
+                f_error = hz - ref;
+                if (f_error < p_error) {
+                    ref_spr = br;
+                    ref_prescaler = i;
+                    ref_dr = dr;
+                    p_error = f_error;
+                }
+            }
+        }
+    }
+
+    // set PBR and BR
+    obj->spi->CTAR[0] &= ~(SPI_CTAR_PBR_MASK | SPI_CTAR_BR_MASK | SPI_CTAR_DBR_MASK);
+    obj->spi->CTAR[0] |= (ref_prescaler << SPI_CTAR_PBR_SHIFT) | (ref_spr << SPI_CTAR_BR_SHIFT) | (ref_dr << SPI_CTAR_DBR_SHIFT);
+}
+
+static inline int spi_writeable(spi_t *obj) {
+    return (obj->spi->SR & SPI_SR_TFFF_MASK) ? 1 : 0;
+}
+
+static inline int spi_readable(spi_t *obj) {
+    return (obj->spi->SR & SPI_SR_RFDF_MASK) ? 1 : 0;
+}
+
+int spi_master_write(spi_t *obj, int value) {
+    //clear RX buffer flag
+    obj->spi->SR |= SPI_SR_RFDF_MASK;
+    // wait tx buffer empty
+    while(!spi_writeable(obj));
+    obj->spi->PUSHR = SPI_PUSHR_TXDATA(value & 0xffff) /*| SPI_PUSHR_EOQ_MASK*/;
+
+    // wait rx buffer full
+    while (!spi_readable(obj));
+    return obj->spi->POPR;
+}
+
+int spi_slave_receive(spi_t *obj) {
+    return spi_readable(obj);
+}
+
+int spi_slave_read(spi_t *obj) {
+    obj->spi->SR |= SPI_SR_RFDF_MASK;
+    return obj->spi->POPR;
+}
+
+void spi_slave_write(spi_t *obj, int value) {
+    while (!spi_writeable(obj));
+}