Initial SPI implementation.

Squashed commit of the following:

commit b41eb846ca60559cff242d0c550699eb8f309909
Author: Perry Hung <iperry@alum.mit.edu>
Date:   Sat Apr 24 04:09:16 2010 -0400

    Turn the other peripherals back on. Not extensively tested for
    interactions between peripherals.

commit bf4fc3bf6bc02342ae508b52fb4515d361d626f6
Author: Perry Hung <iperry@alum.mit.edu>
Date:   Sat Apr 24 03:16:35 2010 -0400

    Upper level libmaple interface

    Added a C++ HardwareSPI class to access the SPI interface. See
    HardwareSPI.cpp and HardwareSPI.h for documentation.

commit 17e0e5edde60e9bf2aa4d52173ad7d47d6d6da75
Author: Perry Hung <iperry@alum.mit.edu>
Date:   Thu Apr 22 02:36:01 2010 -0400

    Initial SPI Polling implementation.

    Initial commit of a polling-based SPI driver. The driver is limited to
    synchronous, blocking sends and a 8-bit data frame format. Tested on
    SPI1 and SPI2.

    Other peripherals are temporarily disabled, and the rx function
    is untested until I find a good peripheral to test everything on.

2 files changed, 195 insertions, 0 deletions

diff --git a/core/comm/HardwareSPI.cpp b/core/comm/HardwareSPI.cpp
new file mode 100644
index 0000000..51093cb
--- /dev/null
+++ b/core/comm/HardwareSPI.cpp
@@ -0,0 +1,138 @@
+/* *****************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ * ****************************************************************************/
+
+/**
+ * @brief HardwareSPI "wiring-like" api for SPI
+ */
+
+/* NOTES:
+ *
+ * Speeds:
+ * -----------------------------------
+ * Interface num:     SPI1        SPI2
+ * Bus                APB2        APB1
+ * -----------------------------------
+ * Prescaler         Frequencies
+ * -----------------------------------
+ * 2:                  N/A  18 000 000
+ * 4:           18 000 000   9 000 000
+ * 8:            9 000 000   4 500 000
+ * 16:           4 500 000   2 250 000
+ * 32:           2 250 000   1 125 000
+ * 64:           1 125 000     562 500
+ * 128:            562 500     281 250
+ * 256:            281 250     140 625
+ *
+ * TODO: Do the complementary PWM outputs mess up SPI2?
+ * */
+
+#include "wiring.h"
+#include "spi.h"
+#include "HardwareSPI.h"
+
+static const uint32 prescaleFactors[MAX_SPI_FREQS] = {
+   SPI_PRESCALE_2,               // SPI_18MHZ
+   SPI_PRESCALE_4,               // SPI_9MHZ
+   SPI_PRESCALE_8,               // SPI_4_5MHZ
+   SPI_PRESCALE_16,              // SPI_2_25MHZ
+   SPI_PRESCALE_32,              // SPI_1_125MHZ
+   SPI_PRESCALE_64,              // SPI_562_500KHZ
+   SPI_PRESCALE_128,             // SPI_281_250KHZ
+   SPI_PRESCALE_256,             // SPI_140_625KHZ
+};
+
+/**
+ * @brief Initialize a SPI peripheral
+ * @param freq frequency to run at, must one of the following values:
+ *           - SPI_18MHZ
+ *           - SPI_9MHZ
+ *           - SPI_4_5MHZ
+ *           - SPI_2_25MHZ
+ *           - SPI_1_125MHZ
+ *           - SPI_562_500KHZ
+ *           - SPI_281_250KHZ
+ *           - SPI_140_625KHZ
+ * @param endianness endianness of the data frame, must be either LSBFIRST
+ *           or MSBFIRST
+ * @param mode SPI standard CPOL and CPHA levels
+ */
+void HardwareSPI::begin(SPIFrequency freq, uint32 endianness, uint32 mode) {
+   uint32 spi_num    = this->spi_num;
+   uint32 high_speed = 0;
+   uint32 index;
+   uint32 prescale;
+
+   if ((freq >= MAX_SPI_FREQS)     ||
+       !((endianness == LSBFIRST)  ||
+         (endianness == MSBFIRST)) ||
+       (mode >= 4)) {
+      return;
+   }
+
+   if (spi_num == 1) {
+      /* SPI1 is too fast for 140625  */
+      if (freq == SPI_140_625KHZ) {
+         return;
+      }
+
+      /* Turn off PWM on shared pins */
+      timers_disable_channel(3, 2);
+      timers_disable_channel(3, 1);
+   }
+
+   endianness = (endianness == LSBFIRST) ? SPI_LSBFIRST : SPI_MSBFIRST;
+   prescale = (spi_num == 1) ? prescaleFactors[freq + 1] : prescaleFactors[freq];
+
+   spi_init(spi_num, prescale, endianness, 0);
+}
+
+/**
+ * @brief Initialize a SPI peripheral with a default speed of 1.125 MHZ, MSBFIRST,
+ *      mode 0
+ * @param mode SPI standard CPOL and CPHA levels
+ */
+void HardwareSPI::begin(void) {
+   begin(SPI_1_125MHZ, MSBFIRST, 0);
+}
+
+/**
+ * @brief send a byte out the spi peripheral
+ * @param data byte to send
+ */
+void HardwareSPI::send(uint8 data) {
+   spi_tx(this->spi_num, data);
+}
+
+
+/**
+ * @brief read a byte from the spi peripheral
+ * @return byte in the buffer
+ */
+uint8 HardwareSPI::recv(void) {
+   return spi_rx(this->spi_num);
+}
+
+HardwareSPI::HardwareSPI(uint32 spi_num) {
+   this->spi_num = spi_num;
+}
diff --git a/core/comm/HardwareSPI.h b/core/comm/HardwareSPI.h
new file mode 100644
index 0000000..b974334
--- /dev/null
+++ b/core/comm/HardwareSPI.h
@@ -0,0 +1,57 @@
+/* *****************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ * ****************************************************************************/
+
+/**
+ * @brief HardwareSPI definitions
+ */
+
+#ifndef _HARDWARESPI_H_
+#define _HARDWARESPI_H_
+
+typedef enum SPIFrequency {
+   SPI_18MHZ       = 0,
+   SPI_9MHZ        = 1,
+   SPI_4_5MHZ      = 2,
+   SPI_2_25MHZ     = 3,
+   SPI_1_125MHZ    = 4,
+   SPI_562_500KHZ  = 5,
+   SPI_281_250KHZ  = 6,
+   SPI_140_625KHZ  = 7,
+   MAX_SPI_FREQS   = 8,
+} SPIFrequency;
+
+class HardwareSPI {
+   private:
+      uint32 spi_num;
+
+   public:
+      HardwareSPI(uint32 spi_num);
+      void begin(void);
+      void begin(SPIFrequency freq, uint32 endianness, uint32 mode);
+      void send(uint8 data);
+      uint8 recv(void);
+};
+
+#endif
+