linux-kernel - Re: [PATCH 1/4] serial: 8250_dw: Add support for big-endian MMIO accesses

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Message-ID: <55AF8A34.2060900@hurleysoftware.com>
Date:	Wed, 22 Jul 2015 08:19:00 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Noam Camus <noamc@...hip.com>
CC:	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org,
	Alexey.Brodkin@...opsys.com, vgupta@...opsys.com,
	gregkh@...uxfoundation.org, jslaby@...e.com
Subject: Re: [PATCH 1/4] serial: 8250_dw: Add support for big-endian MMIO
 accesses

Hi Noam,

On 07/22/2015 05:34 AM, Noam Camus wrote:
> From: Noam Camus <noamc@...hip.com>
> 
> Add support for UPIO_MEM32BE in addition to UPIO_MEM32.

This is not an adequate changelog.
Please describe the refactoring.

Regards,
Peter Hurley

> Signed-off-by: Noam Camus <noamc@...hip.com>
> ---
>  drivers/tty/serial/8250/8250_dw.c |   42 ++++++++++++++++++++++++++++++------
>  1 files changed, 35 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> index d48b506..fe0b487 100644
> --- a/drivers/tty/serial/8250/8250_dw.c
> +++ b/drivers/tty/serial/8250/8250_dw.c
> @@ -173,15 +173,13 @@ static void dw8250_serial_outq(struct uart_port *p, int offset, int value)
>  }
>  #endif /* CONFIG_64BIT */
>  
> -static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
> +static void dw8250_check_control(struct uart_port *p, int offset, int value)
>  {
>  	struct dw8250_data *d = p->private_data;
>  
>  	if (offset == UART_MCR)
>  		d->last_mcr = value;
>  
> -	writel(value, p->membase + (offset << p->regshift));
> -
>  	/* Make sure LCR write wasn't ignored */
>  	if (offset == UART_LCR) {
>  		int tries = 1000;
> @@ -190,7 +188,12 @@ static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
>  			if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
>  				return;
>  			dw8250_force_idle(p);
> -			writel(value, p->membase + (UART_LCR << p->regshift));
> +			if (p->iotype == UPIO_MEM32BE)
> +				iowrite32be(value,
> +					p->membase + (UART_LCR << p->regshift));
> +			else
> +				writel(value,
> +					p->membase + (UART_LCR << p->regshift));
>  		}
>  		/*
>  		 * FIXME: this deadlocks if port->lock is already held
> @@ -199,6 +202,12 @@ static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
>  	}
>  }
>  
> +static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
> +{
> +	writel(value, p->membase + (offset << p->regshift));
> +	dw8250_check_control(p, offset, value);
> +}
> +
>  static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
>  {
>  	unsigned int value = readl(p->membase + (offset << p->regshift));
> @@ -206,6 +215,19 @@ static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
>  	return dw8250_modify_msr(p, offset, value);
>  }
>  
> +static void dw8250_serial_out32be(struct uart_port *p, int offset, int value)
> +{
> +	iowrite32be(value, p->membase + (offset << p->regshift));
> +	dw8250_check_control(p, offset, value);
> +}
> +
> +static unsigned int dw8250_serial_in32be(struct uart_port *p, int offset)
> +{
> +	unsigned int value = ioread32be(p->membase + (offset << p->regshift));
> +
> +	return dw8250_modify_msr(p, offset, value);
> +}
> +
>  static int dw8250_handle_irq(struct uart_port *p)
>  {
>  	struct dw8250_data *d = p->private_data;
> @@ -322,9 +344,15 @@ static int dw8250_probe_of(struct uart_port *p,
>  		case 1:
>  			break;
>  		case 4:
> -			p->iotype = UPIO_MEM32;
> -			p->serial_in = dw8250_serial_in32;
> -			p->serial_out = dw8250_serial_out32;
> +			p->iotype = of_device_is_big_endian(np) ?
> +				    UPIO_MEM32BE : UPIO_MEM32;
> +			if (p->iotype == UPIO_MEM32) {
> +				p->serial_in = dw8250_serial_in32;
> +				p->serial_out = dw8250_serial_out32;
> +			} else {
> +				p->serial_in = dw8250_serial_in32be;
> +				p->serial_out = dw8250_serial_out32be;
> +			}
>  			break;
>  		default:
>  			dev_err(p->dev, "unsupported reg-io-width (%u)\n", val);
> 

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