#define UARTBAUD_SBNS 0x00002000
#define UARTBAUD_SBR 0x00000000
#define UARTBAUD_SBR_MASK 0x1fff
+#define UARTBAUD_OSR_MASK 0x1f
+#define UARTBAUD_OSR_SHIFT 24
#define UARTSTAT_LBKDIF 0x80000000
#define UARTSTAT_RXEDGIF 0x40000000
}
static void
+lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate)
+{
+ u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp;
+ u32 clk = sport->port.uartclk;
+
+ /*
+ * The idea is to use the best OSR (over-sampling rate) possible.
+ * Note, OSR is typically hard-set to 16 in other LPUART instantiations.
+ * Loop to find the best OSR value possible, one that generates minimum
+ * baud_diff iterate through the rest of the supported values of OSR.
+ *
+ * Calculation Formula:
+ * Baud Rate = baud clock / ((OSR+1) × SBR)
+ */
+ baud_diff = baudrate;
+ osr = 0;
+ sbr = 0;
+
+ for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) {
+ /* calculate the temporary sbr value */
+ tmp_sbr = (clk / (baudrate * tmp_osr));
+ if (tmp_sbr == 0)
+ tmp_sbr = 1;
+
+ /*
+ * calculate the baud rate difference based on the temporary
+ * osr and sbr values
+ */
+ tmp_diff = clk / (tmp_osr * tmp_sbr) - baudrate;
+
+ /* select best values between sbr and sbr+1 */
+ tmp = clk / (tmp_osr * (tmp_sbr + 1));
+ if (tmp_diff > (baudrate - tmp)) {
+ tmp_diff = baudrate - tmp;
+ tmp_sbr++;
+ }
+
+ if (tmp_diff <= baud_diff) {
+ baud_diff = tmp_diff;
+ osr = tmp_osr;
+ sbr = tmp_sbr;
+
+ if (!baud_diff)
+ break;
+ }
+ }
+
+ /* handle buadrate outside acceptable rate */
+ if (baud_diff > ((baudrate / 100) * 3))
+ dev_warn(sport->port.dev,
+ "unacceptable baud rate difference of more than 3%%\n");
+
+ tmp = lpuart32_read(&sport->port, UARTBAUD);
+
+ if ((osr > 3) && (osr < 8))
+ tmp |= UARTBAUD_BOTHEDGE;
+
+ tmp &= ~(UARTBAUD_OSR_MASK << UARTBAUD_OSR_SHIFT);
+ tmp |= (((osr-1) & UARTBAUD_OSR_MASK) << UARTBAUD_OSR_SHIFT);
+
+ tmp &= ~UARTBAUD_SBR_MASK;
+ tmp |= sbr & UARTBAUD_SBR_MASK;
+
+ tmp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE);
+
+ lpuart32_write(&sport->port, tmp, UARTBAUD);
+}
+
+static void
lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
unsigned long ctrl, old_ctrl, bd, modem;
unsigned int baud;
unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
- unsigned int sbr;
ctrl = old_ctrl = lpuart32_read(&sport->port, UARTCTRL);
bd = lpuart32_read(&sport->port, UARTBAUD);
lpuart32_write(&sport->port, old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE),
UARTCTRL);
- sbr = sport->port.uartclk / (16 * baud);
- bd &= ~UARTBAUD_SBR_MASK;
- bd |= sbr & UARTBAUD_SBR_MASK;
- bd |= UARTBAUD_BOTHEDGE;
- bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE);
- lpuart32_write(&sport->port, bd, UARTBAUD);
+ lpuart32_serial_setbrg(sport, baud);
lpuart32_write(&sport->port, modem, UARTMODIR);
lpuart32_write(&sport->port, ctrl, UARTCTRL);
/* restore control register */