Re: [PATCH v5 2/2] serial:sunplus-uart:Add Sunplus SoC UART Driver

Jiri Slaby
2021-12-13T07:47:17Z

On 13. 12. 21, 8:10, Hammer Hsieh wrote:
> Add Sunplus SoC UART Driver
>
> Signed-off-by: Hammer Hsieh <hammer.hsieh@sunplus.com>

...

> --- /dev/null
> +++ b/drivers/tty/serial/sunplus-uart.c

...

> +static void receive_chars(struct uart_port *port)
> +{
> + unsigned int lsr = readl(port->membase + SUP_UART_LSR);
> + unsigned int ch, flag;
> +
> + do {
> + ch = readl(port->membase + SUP_UART_DATA);
> + flag = TTY_NORMAL;
> + port->icount.rx++;
> +
> + if (unlikely(lsr & SUP_UART_LSR_BRK_ERROR_BITS)) {
> + if (lsr & SUP_UART_LSR_BC) {
> + lsr &= ~(SUP_UART_LSR_FE | SUP_UART_LSR_PE);
> + port->icount.brk++;
> + if (uart_handle_break(port))
> + goto ignore_char;
> + } else if (lsr & SUP_UART_LSR_PE) {
> + port->icount.parity++;
> + } else if (lsr & SUP_UART_LSR_FE) {
> + port->icount.frame++;
> + }
> +
> + if (lsr & SUP_UART_LSR_OE)
> + port->icount.overrun++;
> +
> + if (lsr & SUP_UART_LSR_BC)
> + flag = TTY_BREAK;
> + else if (lsr & SUP_UART_LSR_PE)
> + flag = TTY_PARITY;
> + else if (lsr & SUP_UART_LSR_FE)
> + flag = TTY_FRAME;

Why do you handle these separately and not above?

> + }
> +
> + if (port->ignore_status_mask & SUP_DUMMY_READ)
> + goto ignore_char;
> +
> + if (uart_handle_sysrq_char(port, ch))
> + goto ignore_char;
> +
> + uart_insert_char(port, lsr, SUP_UART_LSR_OE, ch, flag);
> +
> +ignore_char:
> + lsr = readl(port->membase + SUP_UART_LSR);
> + } while (lsr & SUP_UART_LSR_RX);
> +
> + tty_flip_buffer_push(&port->state->port);
> +}
> +
> +static irqreturn_t sunplus_uart_irq(int irq, void *args)
> +{
> + struct uart_port *port = (struct uart_port *)args;

No need to cast here.

> + unsigned int isc = readl(port->membase + SUP_UART_ISC);

Shouldn't this be under the spinlock?

And "if (!isc) return IRQ_NONE"?

> + spin_lock(&port->lock);
> +
> + if (isc & SUP_UART_ISC_RX)
> + receive_chars(port);
> +
> + if (isc & SUP_UART_ISC_TX)
> + transmit_chars(port);
> +
> + spin_unlock(&port->lock);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int sunplus_startup(struct uart_port *port)
> +{
> + unsigned long flags;
> + unsigned int isc;
> + int ret;
> +
> + ret = request_irq(port->irq, sunplus_uart_irq, 0, "sunplus_uart", port);

Cannot the interrupt be shared?

> + if (ret)
> + return ret;
> +
> + spin_lock_irqsave(&port->lock, flags);
> +
> + isc |= SUP_UART_ISC_RXM;
> + writel(isc, port->membase + SUP_UART_ISC);
> +
> + spin_unlock_irqrestore(&port->lock, flags);
> +
> + return 0;
> +}
> +
> +static void sunplus_shutdown(struct uart_port *port)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&port->lock, flags);
> + writel(0, port->membase + SUP_UART_ISC);

What bus is this -- posting?

> + spin_unlock_irqrestore(&port->lock, flags);
> +
> + free_irq(port->irq, port);
> +}

...

> +static void sunplus_release_port(struct uart_port *port)
> +{
> +}
> +
> +static int sunplus_request_port(struct uart_port *port)
> +{
> + return 0;
> +}

These two are optional -- no need to provide them.

regards,
--
js
suse labs