[mc1322x] problems with the UART

[Jon Smirl]

On Mon, Jan 4, 2010 at 11:39 PM, Jim Paris <jim at jtan.com> wrote:
> Your numbers "0" and "31" seem strange.  The MC1322xRM says that

That was just test code. This is my real put_char(). I'm now able to
run at 921,600 baud without dropping chars. The missing trick was
turning on hardware flow control so that I don't overrun the ft232.

I'm trying to fix up the serial_802154 code to work with linux-zigbee
and run at the full ~250Kb radio speed.

char tx_buf[1024];
int head, tail;

void uart1_isr(void) {
 	while( reg32(UT1CON) != 0 ) {
		if (head == tail) {
			disable_irq(UART1);
			return;
		}
		reg32(UART1_DATA) = tx_buf[tail];
		tail++;		
		if (tail >= sizeof(tx_buf))
			tail = 0;
	}
}

int uart1_putchar(int c) {
	int h;

	disable_irq(UART1);
	h = head + 1;
	if (h >= sizeof(tx_buf))
		h = 0;
	if (h == tail) /* drop chars when no room */
		return;
	tx_buf[head] = c;
	head = h;

	uart1_isr();
	enable_irq(UART1);
	return c;
}



-- 
Jon Smirl
jonsmirl at gmail.com