linux-kernel - Re: [PATCH v5 2/4] drivers/tty/serial/8250: refactor sirq and lpc address setting code

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Message-Id: <db7271d8-8d13-4a8c-a7ba-564e4e769ea5@www.fastmail.com>
Date:   Fri, 09 Apr 2021 14:36:16 +0930
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Zev Weiss" <zev@...ilderbeest.net>,
        "Joel Stanley" <joel@....id.au>
Cc:     openbmc@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Jiri Slaby" <jirislaby@...nel.org>, linux-serial@...r.kernel.org
Subject: Re: [PATCH v5 2/4] drivers/tty/serial/8250: refactor sirq and lpc address setting code

On Thu, 8 Apr 2021, at 10:46, Zev Weiss wrote:
> This splits dedicated aspeed_vuart_set_{sirq,lpc_address}() functions
> out of the sysfs store functions in preparation for adding DT
> properties that will be poking the same registers.  While we're at it,
> these functions now provide some basic bounds-checking on their
> arguments.
> 
> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
> ---
>  drivers/tty/serial/8250/8250_aspeed_vuart.c | 51 ++++++++++++++-------
>  1 file changed, 35 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_aspeed_vuart.c 
> b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> index c33e02cbde93..8433f8dbb186 100644
> --- a/drivers/tty/serial/8250/8250_aspeed_vuart.c
> +++ b/drivers/tty/serial/8250/8250_aspeed_vuart.c
> @@ -72,22 +72,31 @@ static ssize_t lpc_address_show(struct device *dev,
>  	return snprintf(buf, PAGE_SIZE - 1, "0x%x\n", addr);
>  }
>  
> +static int aspeed_vuart_set_lpc_address(struct aspeed_vuart *vuart, u32 addr)
> +{
> +	if (addr > U16_MAX)
> +		return -EINVAL;
> +
> +	writeb(addr >> 8, vuart->regs + ASPEED_VUART_ADDRH);
> +	writeb(addr >> 0, vuart->regs + ASPEED_VUART_ADDRL);
> +
> +	return 0;
> +}
> +
>  static ssize_t lpc_address_store(struct device *dev,
>  				 struct device_attribute *attr,
>  				 const char *buf, size_t count)
>  {
>  	struct aspeed_vuart *vuart = dev_get_drvdata(dev);
> -	unsigned long val;
> +	u32 val;
>  	int err;
>  
> -	err = kstrtoul(buf, 0, &val);
> +	err = kstrtou32(buf, 0, &val);
>  	if (err)
>  		return err;
>  
> -	writeb(val >> 8, vuart->regs + ASPEED_VUART_ADDRH);
> -	writeb(val >> 0, vuart->regs + ASPEED_VUART_ADDRL);
> -
> -	return count;
> +	err = aspeed_vuart_set_lpc_address(vuart, val);
> +	return err ? : count;
>  }
>  
>  static DEVICE_ATTR_RW(lpc_address);
> @@ -105,27 +114,37 @@ static ssize_t sirq_show(struct device *dev,
>  	return snprintf(buf, PAGE_SIZE - 1, "%u\n", reg);
>  }
>  
> +static int aspeed_vuart_set_sirq(struct aspeed_vuart *vuart, u32 sirq)
> +{
> +	u8 reg;
> +
> +	if (sirq > (ASPEED_VUART_GCRB_HOST_SIRQ_MASK >> ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT))
> +		return -EINVAL;
> +
> +	sirq <<= ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT;
> +	sirq &= ASPEED_VUART_GCRB_HOST_SIRQ_MASK;

This might be less verbose if we reordered things a little:

```
sirq <<= ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT;
if (sirq & ASPEED_VUART_GCRB_HOST_SIRQ_MASK)
	return -EINVAL;
sirq &= ASPEED_VUART_GCRB_HOST_SIRQ_MASK;
```

But otherwise it looks okay, so

Reviewed-by: Andrew Jeffery <andrew@...id.au>

> +
> +	reg = readb(vuart->regs + ASPEED_VUART_GCRB);
> +	reg &= ~ASPEED_VUART_GCRB_HOST_SIRQ_MASK;
> +	reg |= sirq;
> +	writeb(reg, vuart->regs + ASPEED_VUART_GCRB);
> +
> +	return 0;
> +}
> +
>  static ssize_t sirq_store(struct device *dev, struct device_attribute 
> *attr,
>  			  const char *buf, size_t count)
>  {
>  	struct aspeed_vuart *vuart = dev_get_drvdata(dev);
>  	unsigned long val;
>  	int err;
> -	u8 reg;
>  
>  	err = kstrtoul(buf, 0, &val);
>  	if (err)
>  		return err;
>  
> -	val <<= ASPEED_VUART_GCRB_HOST_SIRQ_SHIFT;
> -	val &= ASPEED_VUART_GCRB_HOST_SIRQ_MASK;
> -
> -	reg = readb(vuart->regs + ASPEED_VUART_GCRB);
> -	reg &= ~ASPEED_VUART_GCRB_HOST_SIRQ_MASK;
> -	reg |= val;
> -	writeb(reg, vuart->regs + ASPEED_VUART_GCRB);
> -
> -	return count;
> +	err = aspeed_vuart_set_sirq(vuart, val);
> +	return err ? : count;
>  }
>  
>  static DEVICE_ATTR_RW(sirq);
> -- 
> 2.31.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>

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