Messages in this thread | | | Subject | Re: [Nios2-dev] [PATCH 2/2] serial: Add driver for the Altera UART | From | Ian Abbott <> | Date | Thu, 6 May 2010 11:44:44 +0100 |
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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@mev.co.uk> )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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