diff options
Diffstat (limited to 'drivers/tty/serial/mvebu-uart.c')
| -rw-r--r-- | drivers/tty/serial/mvebu-uart.c | 80 |
1 files changed, 54 insertions, 26 deletions
diff --git a/drivers/tty/serial/mvebu-uart.c b/drivers/tty/serial/mvebu-uart.c index fb9d369e0f50..70f74ebc25dc 100644 --- a/drivers/tty/serial/mvebu-uart.c +++ b/drivers/tty/serial/mvebu-uart.c @@ -72,6 +72,7 @@ #define BRDV_BAUD_MASK 0x3FF #define UART_OSAMP 0x14 +#define OSAMP_DEFAULT_DIVISOR 16 #define MVEBU_NR_UARTS 2 @@ -162,7 +163,7 @@ static unsigned int mvebu_uart_tx_empty(struct uart_port *port) st = readl(port->membase + UART_STAT); spin_unlock_irqrestore(&port->lock, flags); - return (st & STAT_TX_FIFO_EMP) ? TIOCSER_TEMT : 0; + return (st & STAT_TX_EMP) ? TIOCSER_TEMT : 0; } static unsigned int mvebu_uart_get_mctrl(struct uart_port *port) @@ -236,6 +237,7 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status) struct tty_port *tport = &port->state->port; unsigned char ch = 0; char flag = 0; + int ret; do { if (status & STAT_RX_RDY(port)) { @@ -248,6 +250,16 @@ static void mvebu_uart_rx_chars(struct uart_port *port, unsigned int status) port->icount.parity++; } + /* + * For UART2, error bits are not cleared on buffer read. + * This causes interrupt loop and system hang. + */ + if (IS_EXTENDED(port) && (status & STAT_BRK_ERR)) { + ret = readl(port->membase + UART_STAT); + ret |= STAT_BRK_ERR; + writel(ret, port->membase + UART_STAT); + } + if (status & STAT_BRK_DET) { port->icount.brk++; status &= ~(STAT_FRM_ERR | STAT_PAR_ERR); @@ -441,29 +453,34 @@ static void mvebu_uart_shutdown(struct uart_port *port) } } -static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud) +static unsigned int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud) { struct mvebu_uart *mvuart = to_mvuart(port); - unsigned int baud_rate_div; + unsigned int d_divisor, m_divisor; u32 brdv; if (IS_ERR(mvuart->clk)) - return -PTR_ERR(mvuart->clk); + return 0; /* - * The UART clock is divided by the value of the divisor to generate - * UCLK_OUT clock, which is 16 times faster than the baudrate. - * This prescaler can achieve all standard baudrates until 230400. - * Higher baudrates could be achieved for the extended UART by using the - * programmable oversampling stack (also called fractional divisor). + * The baudrate is derived from the UART clock thanks to two divisors: + * > D ("baud generator"): can divide the clock from 2 to 2^10 - 1. + * > M ("fractional divisor"): allows a better accuracy for + * baudrates higher than 230400. + * + * As the derivation of M is rather complicated, the code sticks to its + * default value (x16) when all the prescalers are zeroed, and only + * makes use of D to configure the desired baudrate. */ - baud_rate_div = DIV_ROUND_UP(port->uartclk, baud * 16); + m_divisor = OSAMP_DEFAULT_DIVISOR; + d_divisor = DIV_ROUND_CLOSEST(port->uartclk, baud * m_divisor); + brdv = readl(port->membase + UART_BRDV); brdv &= ~BRDV_BAUD_MASK; - brdv |= baud_rate_div; + brdv |= d_divisor; writel(brdv, port->membase + UART_BRDV); - return 0; + return DIV_ROUND_CLOSEST(port->uartclk, d_divisor * m_divisor); } static void mvebu_uart_set_termios(struct uart_port *port, @@ -471,7 +488,7 @@ static void mvebu_uart_set_termios(struct uart_port *port, struct ktermios *old) { unsigned long flags; - unsigned int baud; + unsigned int baud, min_baud, max_baud; spin_lock_irqsave(&port->lock, flags); @@ -490,20 +507,21 @@ static void mvebu_uart_set_termios(struct uart_port *port, port->ignore_status_mask |= STAT_RX_RDY(port) | STAT_BRK_ERR; /* + * Maximal divisor is 1023 * 16 when using default (x16) scheme. * Maximum achievable frequency with simple baudrate divisor is 230400. * Since the error per bit frame would be of more than 15%, achieving * higher frequencies would require to implement the fractional divisor * feature. */ - baud = uart_get_baud_rate(port, termios, old, 0, 230400); - if (mvebu_uart_baud_rate_set(port, baud)) { - /* No clock available, baudrate cannot be changed */ - if (old) - baud = uart_get_baud_rate(port, old, NULL, 0, 230400); - } else { - tty_termios_encode_baud_rate(termios, baud, baud); - uart_update_timeout(port, termios->c_cflag, baud); - } + min_baud = DIV_ROUND_UP(port->uartclk, 1023 * 16); + max_baud = 230400; + + baud = uart_get_baud_rate(port, termios, old, min_baud, max_baud); + baud = mvebu_uart_baud_rate_set(port, baud); + + /* In case baudrate cannot be changed, report previous old value */ + if (baud == 0 && old) + baud = tty_termios_baud_rate(old); /* Only the following flag changes are supported */ if (old) { @@ -514,6 +532,11 @@ static void mvebu_uart_set_termios(struct uart_port *port, termios->c_cflag |= CS8; } + if (baud != 0) { + tty_termios_encode_baud_rate(termios, baud, baud); + uart_update_timeout(port, termios->c_cflag, baud); + } + spin_unlock_irqrestore(&port->lock, flags); } @@ -637,6 +660,14 @@ static void wait_for_xmitr(struct uart_port *port) (val & STAT_TX_RDY(port)), 1, 10000); } +static void wait_for_xmite(struct uart_port *port) +{ + u32 val; + + readl_poll_timeout_atomic(port->membase + UART_STAT, val, + (val & STAT_TX_EMP), 1, 10000); +} + static void mvebu_uart_console_putchar(struct uart_port *port, int ch) { wait_for_xmitr(port); @@ -664,7 +695,7 @@ static void mvebu_uart_console_write(struct console *co, const char *s, uart_console_write(port, s, count, mvebu_uart_console_putchar); - wait_for_xmitr(port); + wait_for_xmite(port); if (ier) writel(ier, port->membase + UART_CTRL(port)); @@ -799,9 +830,6 @@ static int mvebu_uart_probe(struct platform_device *pdev) return -EINVAL; } - if (!match) - return -ENODEV; - /* Assume that all UART ports have a DT alias or none has */ id = of_alias_get_id(pdev->dev.of_node, "serial"); if (!pdev->dev.of_node || id < 0) |