On Wed, 2010-05-05 at 09:35 +0100, Tobias Klauser wrote:
> Add an UART driver for the UART component available as a SOPC (System on
> Programmable Chip) component for Altera FPGAs.
[...]
> +static void altera_uart_start_tx(struct uart_port *port)
> +{
> + struct altera_uart *pp = container_of(port, struct altera_uart, port);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> + pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
> + writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +static void altera_uart_stop_tx(struct uart_port *port)
> +{
> + struct altera_uart *pp = container_of(port, struct altera_uart, port);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> + pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
> + writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
> +
> +static void altera_uart_stop_rx(struct uart_port *port)
> +{
> + struct altera_uart *pp = container_of(port, struct altera_uart, port);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> + pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
> + writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
> + spin_unlock_irqrestore(&port->lock, flags);
> +}
Those four functions shouldn't grab port->lock because the caller in
serial_core.c grabs it before calling them.
> +static irqreturn_t altera_uart_interrupt(int irq, void *data)
> +{
> + struct uart_port *port = data;
> + struct altera_uart *pp = container_of(port, struct altera_uart, port);
> + unsigned int isr;
> +
> + isr = readl(port->membase + ALTERA_UART_STATUS_REG) & pp->imr;
> + if (isr & ALTERA_UART_STATUS_RRDY_MSK)
> + altera_uart_rx_chars(pp);
> + if (isr & ALTERA_UART_STATUS_TRDY_MSK)
> + altera_uart_tx_chars(pp);
> + return IRQ_RETVAL(isr);
> +}
Either the interrupt routine should grab port->lock (see equivalent
function in altera_jtaguart.c for an example), or this could be done
lower down in altera_uart_rx_chars() and altera_uart_tx_chars(). (It's
less messing about to do it here in the interrupt routine though.)
> +static void altera_uart_console_putc(struct console *co, const char c)
> +{
> + struct uart_port *port = &(altera_uart_ports + co->index)->port;
> + int i;
> +
> + for (i = 0; i < 0x10000; i++) {
> + if (readl(port->membase + ALTERA_UART_STATUS_REG) &
> + ALTERA_UART_STATUS_TRDY_MSK)
> + break;
> + }
> + writel(c, port->membase + ALTERA_UART_TXDATA_REG);
> + for (i = 0; i < 0x10000; i++) {
> + if (readl(port->membase + ALTERA_UART_STATUS_REG) &
> + ALTERA_UART_STATUS_TRDY_MSK)
> + break;
> + }
> +}
I'd suggest calling udelay(1) in each iteration of the loop. Perhaps
the second loop is overkill.
I was also going to suggest using the port->lock spin lock, but I'm not
sure about the policy regarding that for console output (the 8250 driver
console output doesn't use the spin lock for example).
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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