From 036bb15ec94216e28cb1550af0fdcdfb90c549df Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Sat, 5 Jul 2008 10:02:44 +0200 Subject: [PATCH] IMX UART: do not assume 16MHz reference frequency We assumed a 16MHz reference frequency for the UART. While this is true for i.MX1 most of the time it is not true for MX27/MX31. Also, add handling for the ONEMS register which is present on newer versions of the chip and pass a sane minimum baudrate to uart_get_baud_rate(). Signed-off-by: Sascha Hauer --- drivers/serial/imx.c | 50 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 39 insertions(+), 11 deletions(-) diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c index 5a375bf0eb..6226e66c79 100644 --- a/drivers/serial/imx.c +++ b/drivers/serial/imx.c @@ -589,6 +589,7 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, unsigned long flags; unsigned int ucr2, old_ucr1, old_txrxen, baud, quot; unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8; + unsigned int div, num, denom, ufcr; /* * If we don't support modem control lines, don't allow @@ -634,7 +635,7 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, /* * Ask the core to calculate the divisor for us. */ - baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); + baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16); quot = uart_get_divisor(port, baud); spin_lock_irqsave(&sport->port.lock, flags); @@ -684,14 +685,41 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios, sport->port.membase + UCR2); old_txrxen &= (UCR2_TXEN | UCR2_RXEN); - /* set the baud rate. We assume uartclk = 16 MHz - * - * baud * 16 UBIR - 1 - * --------- = -------- - * uartclk UBMR - 1 - */ - writel((baud / 100) - 1, sport->port.membase + UBIR); - writel(10000 - 1, sport->port.membase + UBMR); + div = sport->port.uartclk / (baud * 16); + if (div > 7) + div = 7; + if (!div) + div = 1; + + num = baud; + denom = port->uartclk / div / 16; + + /* shift num and denom right until they fit into 16 bits */ + while (num > 0x10000 || denom > 0x10000) { + num >>= 1; + denom >>= 1; + } + if (num > 0) + num -= 1; + if (denom > 0) + denom -= 1; + + writel(num, sport->port.membase + UBIR); + writel(denom, sport->port.membase + UBMR); + + if (div == 7) + div = 6; /* 6 in RFDIV means divide by 7 */ + else + div = 6 - div; + + ufcr = readl(sport->port.membase + UFCR); + ufcr = (ufcr & (~UFCR_RFDIV)) | + (div << 7); + writel(ufcr, sport->port.membase + UFCR); + +#ifdef ONEMS + writel(sport->port.uartclk / div / 1000, sport->port.membase + ONEMS); +#endif writel(old_ucr1, sport->port.membase + UCR1); @@ -812,7 +840,6 @@ static struct imx_port imx_ports[] = { .membase = (void *)IMX_UART1_BASE, .mapbase = 0x00206000, .irq = UART1_MINT_RX, - .uartclk = 16000000, .fifosize = 32, .flags = UPF_BOOT_AUTOCONF, .ops = &imx_pops, @@ -828,7 +855,6 @@ static struct imx_port imx_ports[] = { .membase = (void *)IMX_UART2_BASE, .mapbase = 0x00207000, .irq = UART2_MINT_RX, - .uartclk = 16000000, .fifosize = 32, .flags = UPF_BOOT_AUTOCONF, .ops = &imx_pops, @@ -858,6 +884,8 @@ static void __init imx_init_ports(void) init_timer(&imx_ports[i].timer); imx_ports[i].timer.function = imx_timeout; imx_ports[i].timer.data = (unsigned long)&imx_ports[i]; + + imx_ports[i].port.uartclk = imx_get_perclk1(); } } -- 2.39.5