[FIXME] Resurrected, shinier USART support.

FIXME:
- Test F1 support
- Solve problem of duplicated bytes being TXed unless delay is
  inserted after configuration but before first bytes are TXed.

Rip out nonportable bits from top-level interfaces. The USART register
maps are basically the same between F1 and F2, so leave these, but add
register bit definitions which had name changes to the libmaple header
to avoid needless repetition. There are also a few new bits in the F2
USART registers; add definitions for these in the F2 USART header. Add
Doxygen comments for all USART bit definitions.

Deprecate struct usart_dev's max_baud field. This is just bloat that
doesn't bring us much real benefit.

Add new series-specific USART files for F1 and F2:

- libmaple/stm32f[1,2]/usart.c
- libmaple/stm32f[1,2]/include/series/usart.h

These are standard series-specific files, providing register map base
pointers, defining devices, implementing nonportable routines, etc.

We need a portable way to configure the USART GPIOs. To this end, add
usart_async_gpio_cfg() to the top-level USART interface. This function
is implemented in new F1 and F2 USART backends to take the appropriate
action to configure the RX and TX pins for asynchronous full duplex
mode.

USART baud rate calculation is done differently on the different
series. Keep the usart_set_baud_rate() declaration in the top-level
USART header, but move the implementations into the series-specific
usart.c files.

In usart_set_baud_rate(), allow for deriving clock_speed automatically
by letting user tell us to figure out the peripheral clock speed by
mapping the device's rcc_clk_id onto an STM32_PCLK[1,2] value. This
preserves flexibility for users with non-default clock configurations,
but makes things easier on everyone else.

Add private USART files for portable private USART routines:

- libmaple/usart_private.h
- libmaple/usart_private.c

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

1 files changed, 3 insertions, 135 deletions

diff --git a/libmaple/usart.c b/libmaple/usart.c
index ba63b79..1070aa2 100644
--- a/libmaple/usart.c
+++ b/libmaple/usart.c
@@ -33,67 +33,6 @@
 
 #include <libmaple/usart.h>
 
-/*
- * Devices
- */
-
-static ring_buffer usart1_rb;
-static usart_dev usart1 = {
-    .regs     = USART1_BASE,
-    .rb       = &usart1_rb,
-    .max_baud = 4500000UL,
-    .clk_id   = RCC_USART1,
-    .irq_num  = NVIC_USART1
-};
-/** USART1 device */
-usart_dev *USART1 = &usart1;
-
-static ring_buffer usart2_rb;
-static usart_dev usart2 = {
-    .regs     = USART2_BASE,
-    .rb       = &usart2_rb,
-    .max_baud = 2250000UL,
-    .clk_id   = RCC_USART2,
-    .irq_num  = NVIC_USART2
-};
-/** USART2 device */
-usart_dev *USART2 = &usart2;
-
-static ring_buffer usart3_rb;
-static usart_dev usart3 = {
-    .regs     = USART3_BASE,
-    .rb       = &usart3_rb,
-    .max_baud = 2250000UL,
-    .clk_id   = RCC_USART3,
-    .irq_num  = NVIC_USART3
-};
-/** USART3 device */
-usart_dev *USART3 = &usart3;
-
-#ifdef STM32_HIGH_DENSITY
-static ring_buffer uart4_rb;
-static usart_dev uart4 = {
-    .regs     = UART4_BASE,
-    .rb       = &uart4_rb,
-    .max_baud = 2250000UL,
-    .clk_id   = RCC_UART4,
-    .irq_num  = NVIC_UART4
-};
-/** UART4 device */
-usart_dev *UART4 = &uart4;
-
-static ring_buffer uart5_rb;
-static usart_dev uart5 = {
-    .regs     = UART5_BASE,
-    .rb       = &uart5_rb,
-    .max_baud = 2250000UL,
-    .clk_id   = RCC_UART5,
-    .irq_num  = NVIC_UART5
-};
-/** UART5 device */
-usart_dev *UART5 = &uart5;
-#endif
-
 /**
  * @brief Initialize a serial port.
  * @param dev         Serial port to be initialized
@@ -105,27 +44,6 @@ void usart_init(usart_dev *dev) {
 }
 
 /**
- * @brief Configure a serial port's baud rate.
- *
- * @param dev         Serial port to be configured
- * @param clock_speed Clock speed, in megahertz.
- * @param baud        Baud rate for transmit/receive.
- */
-void usart_set_baud_rate(usart_dev *dev, uint32 clock_speed, uint32 baud) {
-    uint32 integer_part;
-    uint32 fractional_part;
-    uint32 tmp;
-
-    /* See ST RM0008 for the details on configuring the baud rate register */
-    integer_part = (25 * clock_speed) / (4 * baud);
-    tmp = (integer_part / 100) << 4;
-    fractional_part = integer_part - (100 * (tmp >> 4));
-    tmp |= (((fractional_part * 16) + 50) / 100) & ((uint8)0x0F);
-
-    dev->regs->BRR = (uint16)tmp;
-}
-
-/**
  * @brief Enable a serial port.
  *
  * USART is enabled in single buffer transmission mode, multibuffer
@@ -138,7 +56,8 @@ void usart_set_baud_rate(usart_dev *dev, uint32 clock_speed, uint32 baud) {
  */
 void usart_enable(usart_dev *dev) {
     usart_reg_map *regs = dev->regs;
-    regs->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE;
+    regs->CR1 = (USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE |
+                 USART_CR1_M_8N1);
     regs->CR1 |= USART_CR1_UE;
 }
 
@@ -147,7 +66,7 @@ void usart_enable(usart_dev *dev) {
  * @param dev Serial port to be disabled
  */
 void usart_disable(usart_dev *dev) {
-    /* FIXME this misbehaves if you try to use PWM on TX afterwards */
+    /* FIXME this misbehaves (on F1) if you try to use PWM on TX afterwards */
     usart_reg_map *regs = dev->regs;
 
     /* TC bit must be high before disabling the USART */
@@ -162,20 +81,6 @@ void usart_disable(usart_dev *dev) {
 }
 
 /**
- *  @brief Call a function on each USART.
- *  @param fn Function to call.
- */
-void usart_foreach(void (*fn)(usart_dev*)) {
-    fn(USART1);
-    fn(USART2);
-    fn(USART3);
-#ifdef STM32_HIGH_DENSITY
-    fn(UART4);
-    fn(UART5);
-#endif
-}
-
-/**
  * @brief Nonblocking USART transmit
  * @param dev Serial port to transmit over
  * @param buf Buffer to transmit
@@ -230,40 +135,3 @@ void usart_putudec(usart_dev *dev, uint32 val) {
         usart_putc(dev, digits[i]);
     }
 }
-
-/*
- * Interrupt handlers.
- */
-
-static inline void usart_irq(usart_dev *dev) {
-#ifdef USART_SAFE_INSERT
-    /* If the buffer is full and the user defines USART_SAFE_INSERT,
-     * ignore new bytes. */
-    rb_safe_insert(dev->rb, (uint8)dev->regs->DR);
-#else
-    /* By default, push bytes around in the ring buffer. */
-    rb_push_insert(dev->rb, (uint8)dev->regs->DR);
-#endif
-}
-
-void __irq_usart1(void) {
-    usart_irq(USART1);
-}
-
-void __irq_usart2(void) {
-    usart_irq(USART2);
-}
-
-void __irq_usart3(void) {
-    usart_irq(USART3);
-}
-
-#ifdef STM32_HIGH_DENSITY
-void __irq_uart4(void) {
-    usart_irq(UART4);
-}
-
-void __irq_uart5(void) {
-    usart_irq(UART5);
-}
-#endif