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.

4 files changed, 253 insertions, 0 deletions

diff --git a/libmaple/libmaple_types.h b/libmaple/libmaple_types.h
index ca98f6f..d49f95a 100644
--- a/libmaple/libmaple_types.h
+++ b/libmaple/libmaple_types.h
@@ -43,5 +43,7 @@ typedef long long int64;
 
 typedef void (*voidFuncPtr)(void);
 
+#define __io volatile
+
 #endif
 
diff --git a/libmaple/rcc.h b/libmaple/rcc.h
index 8f786ee..9973bca 100644
--- a/libmaple/rcc.h
+++ b/libmaple/rcc.h
@@ -100,6 +100,10 @@
 #define RCC_APB1ENR_TIM4EN     BIT(2)
 #define RCC_APB1ENR_USART2EN   BIT(17)
 #define RCC_APB1ENR_USART3EN   BIT(18)
+#define RCC_APB1ENR_SPI2EN     BIT(14)
+
+#define rcc_enable_clk_spi1()     __set_bits(RCC_APB2ENR, RCC_APB2ENR_SPI1EN)
+#define rcc_enable_clk_spi2()     __set_bits(RCC_APB1ENR, RCC_APB1ENR_SPI2EN)
 
 #define rcc_enable_clk_timer1()   __set_bits(RCC_APB2ENR, RCC_APB2ENR_TIM1EN)
 #define rcc_enable_clk_timer2()   __set_bits(RCC_APB1ENR, RCC_APB1ENR_TIM2EN)
diff --git a/libmaple/spi.c b/libmaple/spi.c
new file mode 100644
index 0000000..5a77b03
--- /dev/null
+++ b/libmaple/spi.c
@@ -0,0 +1,132 @@
+/* *****************************************************************************
+ * 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 libmaple serial peripheral interface (SPI) definitions
+ *
+ * Initial implementation for the SPI interface.
+ *
+ * This driver implements only the bare essentials of a polling driver at the
+ * moment. Master mode only, 8-bit data frames, and polling.
+ *
+ * The caller is responsible for controlling the chip select line.
+ *
+ * TODO: interrupt based driver, DMA.
+ *
+ */
+
+#include "libmaple.h"
+#include "gpio.h"
+#include "rcc.h"
+#include "spi.h"
+
+typedef struct spi_dev {
+   SPI *base;
+   GPIO_Port *port;
+   uint8 sck_pin;
+   uint8 miso_pin;
+   uint8 mosi_pin;
+} spi_dev;
+
+static const spi_dev spi_dev1 = {
+   .base     = (SPI*)SPI1_BASE,
+   .port     = GPIOA_BASE,
+   .sck_pin  = 5,
+   .miso_pin = 6,
+   .mosi_pin = 7
+};
+
+static const spi_dev spi_dev2 = {
+   .base     = (SPI*)SPI2_BASE,
+   .port     = GPIOB_BASE,
+   .sck_pin  = 13,
+   .miso_pin = 14,
+   .mosi_pin = 15
+};
+
+static void spi_gpio_cfg(spi_dev *dev);
+
+/**
+ * @brief Initialize a spi peripheral
+ * @param spi_num which spi to turn on, SPI1 or SPI2?
+ * @param prescale prescale factor on the input clock.
+ * @param endian data frame format (LSBFIRST?)
+ * @param mode SPI mode number
+ */
+void spi_init(uint32 spi_num,
+              uint32 prescale,
+              uint32 endian,
+              uint32 mode) {
+   ASSERT(spi_num == 1 || spi_num == 2);
+   ASSERT(mode < 4);
+
+   SPI *spi;
+   uint32 cr1 = 0;
+
+   switch (spi_num) {
+   case 1:
+      /* limit to 18 mhz max speed  */
+      ASSERT(prescale != CR1_BR_PRESCALE_2);
+      spi = (SPI*)SPI1_BASE;
+      rcc_enable_clk_spi1();
+      spi_gpio_cfg(&spi_dev1);
+      break;
+   case 2:
+      spi = (SPI*)SPI2_BASE;
+      rcc_enable_clk_spi2();
+      spi_gpio_cfg(&spi_dev2);
+      break;
+   }
+
+   cr1 = prescale | endian | mode | CR1_MSTR | CR1_SSI | CR1_SSM;
+   spi->CR1 = cr1;
+
+   /* Peripheral enable */
+   spi->CR1 |= CR1_SPE;
+}
+
+
+/**
+ * @brief SPI synchronous 8-bit write, blocking.
+ * @param spi_num which spi to send on
+ * @return data shifted back from the slave
+ */
+void spi_tx(uint32 spi_num, uint8 data) {
+   SPI *spi;
+
+   ASSERT(spi_num == 1 || spi_num == 2);
+
+   spi = (spi_num == 1) ? (SPI*)SPI1_BASE : (SPI*)SPI2_BASE;
+
+   spi->DR = data;
+
+   while (!(spi->SR & SR_TXE) || (spi->SR & SR_BSY))
+      ;
+}
+
+static void spi_gpio_cfg(spi_dev *dev) {
+   gpio_set_mode(dev->port, dev->sck_pin, GPIO_MODE_AF_OUTPUT_PP);
+   gpio_set_mode(dev->port, dev->miso_pin, GPIO_MODE_AF_OUTPUT_PP);
+   gpio_set_mode(dev->port, dev->mosi_pin, GPIO_MODE_AF_OUTPUT_PP);
+}
diff --git a/libmaple/spi.h b/libmaple/spi.h
new file mode 100644
index 0000000..cde3b42
--- /dev/null
+++ b/libmaple/spi.h
@@ -0,0 +1,115 @@
+/* *****************************************************************************
+ * 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 libmaple serial peripheral interface (SPI) prototypes and declarations
+ */
+
+#ifndef _SPI_H_
+#define _SPI_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* peripheral addresses */
+#define SPI1_BASE                   0x40013000
+#define SPI2_BASE                   0x40003800
+
+/* baud rate prescaler bits */
+#define CR1_BR                      0x00000038
+#define CR1_BR_PRESCALE_2           0x00000000
+#define CR1_BR_PRESCALE_4           0x00000008
+#define CR1_BR_PRESCALE_8           0x00000010
+#define CR1_BR_PRESCALE_16          0x00000018
+#define CR1_BR_PRESCALE_32          0x00000020
+#define CR1_BR_PRESCALE_64          0x00000028
+#define CR1_BR_PRESCALE_128         0x00000030
+#define CR1_BR_PRESCALE_256         0x00000038
+
+#define CR1_LSBFIRST                    BIT(7)     // data frame format
+#define CR1_MSTR                        BIT(2)     // master selection
+#define CR1_SSM                         BIT(9)     // software slave management
+#define CR1_SSI                         BIT(8)     // internal slave select
+#define CR1_SPE                         BIT(6)     // peripheral enable
+
+/* Status register bits  */
+#define SR_RXNE                         BIT(0)     // rx buffer not empty
+#define SR_TXE                          BIT(1)     // transmit buffer empty
+#define SR_BSY                          BIT(7)     // busy flag
+
+typedef struct SPI {
+   __io uint16 CR1;
+   uint16 pad0;
+   __io uint8 CR2;
+   uint8 pad1[3];
+   __io uint8 SR;
+   uint8 pad2[3];
+   __io uint16 DR;
+   uint16 pad3;
+   __io uint16 CRCPR;
+   uint16 pad4;
+   __io uint16 RXCRCR;
+   uint16 pad5;
+   __io uint16 TXCRCR;
+   uint16 pad6;
+} SPI;
+
+enum {
+   SPI_MSBFIRST         = 0,
+   SPI_LSBFIRST         = BIT(7),
+};
+
+enum {
+   SPI_PRESCALE_2       = (0x0 << 3),
+   SPI_PRESCALE_4       = (0x1 << 3),
+   SPI_PRESCALE_8       = (0x2 << 3),
+   SPI_PRESCALE_16      = (0x3 << 3),
+   SPI_PRESCALE_32      = (0x4 << 3),
+   SPI_PRESCALE_64      = (0x5 << 3),
+   SPI_PRESCALE_128     = (0x6 << 3),
+   SPI_PRESCALE_256     = (0x7 << 3)
+};
+
+void spi_init(uint32 spi_num,
+              uint32 prescale,
+              uint32 endian,
+              uint32 mode);
+void spi_tx(uint32 spi_num, uint8 data);
+
+static inline uint8 spi_rx(uint32 spi_num) {
+   SPI *spi;
+
+   ASSERT(spi_num == 1 || spi_num == 2);
+   spi = (spi_num == 1) ? (SPI*)SPI1_BASE : (SPI*)SPI2_BASE;
+
+   return spi->DR;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+