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SubjectRe: [PATCH v5 2/4] drivers/tty/serial/8250: refactor sirq and lpc address setting code
On Fri, Apr 09, 2021 at 12:06:16AM CDT, Andrew Jeffery wrote:
>
>
>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@bewilderbeest.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;
>```

Hmm, that (or something similar, perhaps with a '~' on the mask in the
if condition?) does seem like it'd be a nice improvement, though I
suppose it'd also mean we'd fail to reject some way-out-of-range sirq
values (e.g. if it had its MSB set) -- so I think I'll leave it as is,
just in the name of thoroughness/paranoia?

>
>But otherwise it looks okay, so
>
>Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
>

Thanks.

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