Additional cleanup on lcd-serial

Remove the ISR function and remains of the hack in lcd-spi.c and
convert console.c to use the LOC3 system reset code rather than
the hack which only works on the F4 as it turns out.

Author: ChuckM

examples/stm32/f4/stm32f429i-discovery/lcd-serial/console.c

@@ -68,23 +68,9 @@ void usart1_isr(void) {
 #ifdef RESET_ON_CTRLC
 			/* Check for "reset" */
 			if (recv_buf[recv_ndx_nxt] == '\003') {
-				/* reset the system
-				 * volatile definition of return address on the stack
-				 * to insure it gets stored, changed to point to
-				 * the trampoline function (do_the_nasty) which is
-				 * required because we need to return of an interrupt
-				 * to get the internal value of the LR register reset
-				 * and put the processor back into "Thread" mode from
-				 * "Handler" mode.
-				 *
-				 * See the PM0214 Programming Manual for Cortex M,
-				 * pg 42, to see the format of the Cortex M4 stack after
-				 * an interrupt or exception has occurred.
-				 */
-				volatile uint32_t *ret = (&reg) + 7;
-				
-				*ret = (uint32_t) &reset_handler;
-				return;
+				/* reset the system */
+				scb_reset_system();
+				return; /* not reached */
 			}
 #endif
 			/* Check for "overrun" */

examples/stm32/f4/stm32f429i-discovery/lcd-serial/lcd-spi.c

@@ -35,30 +35,6 @@
 static int print_decimal(int v);
 static int print_hex(int v);
 
-/*
- * This is an ungainly workaround (aka hack) basically I want to know
- * when the SPI port is 'done' sending all of the bits out, and it is
- * done when it has clocked enough bits that it would have received a
- * byte. Since we're using the SPI port in write_only mode I am not
- * collecting the "received" bytes into a buffer, but one could of
- * course. I keep track of how many bytes should have been returned
- * by decrementing the 'rx_pend' volatile. When it reaches 0 we know
- * we are done.
- */
-
-volatile int rx_pend;
-volatile uint16_t spi_rx_buf;
-
-/*
- * This is the ISR we use. Note that the name is based on the name
- * in the irq.json file of libopencm3 plus the "_isr" extension.
- */
-void
-spi5_isr(void) {
-    spi_rx_buf = SPI_DR(SPI5);
-    --rx_pend;
-}
-
 /* Simple double buffering, one frame is displayed, the
  * other being built.
  */
@@ -343,10 +319,6 @@ lcd_spi_init(void) {
 	cur_frame = (uint16_t *)(SDRAM_BASE_ADDRESS);
 	display_frame = cur_frame + (LCD_WIDTH * LCD_HEIGHT);
 
-	rx_pend = 0;
-	/* Implement state management hack */
-	// nvic_enable_irq(NVIC_SPI5_IRQ);
-
 	rcc_periph_clock_enable(RCC_SPI5);
 	spi_init_master(LCD_SPI, SPI_CR1_BAUDRATE_FPCLK_DIV_4,
 					SPI_CR1_CPOL_CLK_TO_0_WHEN_IDLE,