serial: sh-sci: Add calculation recive margin for HSCIF (730c4e78) · Commits · 戴 / test

drivers/tty/serial/sh-sci.c

+59 −18

Original line number	Diff line number	Diff line
		@@ -1776,13 +1776,30 @@ static unsigned int sci_scbrr_calc(struct sci_port *s, unsigned int bps,
		return ((freq + 16 * bps) / (32 * bps) - 1);
		}

		/* calculate frame length from SMR */
		static int sci_baud_calc_frame_len(unsigned int smr_val)
		{
		int len = 10;

		if (smr_val & SCSMR_CHR)
		len--;
		if (smr_val & SCSMR_PE)
		len++;
		if (smr_val & SCSMR_STOP)
		len++;

		return len;
		}


		/* calculate sample rate, BRR, and clock select for HSCIF */
		static void sci_baud_calc_hscif(unsigned int bps, unsigned long freq,
		int brr, unsigned int srr,
		unsigned int *cks)
		unsigned int *cks, int frame_len)
		{
		int sr, c, br, err;
		int sr, c, br, err, recv_margin;
		int min_err = 1000; /* 100% */
		int recv_max_margin = 0;

		/* Find the combination of sample rate and clock select with the
		smallest deviation from the desired baud rate. */
		@@ -1795,14 +1812,37 @@ static void sci_baud_calc_hscif(unsigned int bps, unsigned long freq,
		err = DIV_ROUND_CLOSEST(freq, ((br + 1) * bps * sr *
		(1 << (2 * c + 1)) / 1000)) -
		1000;
		if (err < 0)
		continue;

		/* Calc recv margin
		* M: Receive margin (%)
		* N: Ratio of bit rate to clock (N = sampling rate)
		* D: Clock duty (D = 0 to 1.0)
		* L: Frame length (L = 9 to 12)
		* F: Absolute value of clock frequency deviation
		*
		* M = \|(0.5 - 1 / 2 * N) - ((L - 0.5) * F) -
		* (\|D - 0.5\| / N * (1 + F))\|
		* NOTE: Usually, treat D for 0.5, F is 0 by this
		* calculation.
		*/
		recv_margin = abs((500 -
		DIV_ROUND_CLOSEST(1000, sr << 1)) / 10);
		if (min_err > err) {
		min_err = err;
		recv_max_margin = recv_margin;
		} else if ((min_err == err) &&
		(recv_margin > recv_max_margin))
		recv_max_margin = recv_margin;
		else
		continue;

		*brr = br;
		*srr = sr - 1;
		*cks = c;
		}
		}
		}

		if (min_err == 1000) {
		WARN_ON(1);
		@@ -1834,10 +1874,19 @@ static void sci_set_termios(struct uart_port port, struct ktermios termios,
		{
		struct sci_port *s = to_sci_port(port);
		struct plat_sci_reg *reg;
		unsigned int baud, smr_val, max_baud, cks = 0;
		unsigned int baud, smr_val = 0, max_baud, cks = 0;
		int t = -1;
		unsigned int srr = 15;

		if ((termios->c_cflag & CSIZE) == CS7)
		smr_val \|= SCSMR_CHR;
		if (termios->c_cflag & PARENB)
		smr_val \|= SCSMR_PE;
		if (termios->c_cflag & PARODD)
		smr_val \|= SCSMR_PE \| SCSMR_ODD;
		if (termios->c_cflag & CSTOPB)
		smr_val \|= SCSMR_STOP;

		/*
		* earlyprintk comes here early on with port->uartclk set to zero.
		* the clock framework is not up and running at this point so here
		@@ -1851,8 +1900,9 @@ static void sci_set_termios(struct uart_port port, struct ktermios termios,
		baud = uart_get_baud_rate(port, termios, old, 0, max_baud);
		if (likely(baud && port->uartclk)) {
		if (s->cfg->type == PORT_HSCIF) {
		int frame_len = sci_baud_calc_frame_len(smr_val);
		sci_baud_calc_hscif(baud, port->uartclk, &t, &srr,
		&cks);
		&cks, frame_len);
		} else {
		t = sci_scbrr_calc(s, baud, port->uartclk);
		for (cks = 0; t >= 256 && cks <= 3; cks++)
		@@ -1864,16 +1914,7 @@ static void sci_set_termios(struct uart_port port, struct ktermios termios,

		sci_reset(port);

		smr_val = serial_port_in(port, SCSMR) & 3;

		if ((termios->c_cflag & CSIZE) == CS7)
		smr_val \|= SCSMR_CHR;
		if (termios->c_cflag & PARENB)
		smr_val \|= SCSMR_PE;
		if (termios->c_cflag & PARODD)
		smr_val \|= SCSMR_PE \| SCSMR_ODD;
		if (termios->c_cflag & CSTOPB)
		smr_val \|= SCSMR_STOP;
		smr_val \|= serial_port_in(port, SCSMR) & 3;

		uart_update_timeout(port, termios->c_cflag, baud);

Admin message