From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shannon Zhao <zhaoshenglong@huawei.com>
Subject: Re: [PATCH v4 01/21] arm/acpi: Emulate io ports for arm
Date: Thu, 28 Jan 2016 20:13:48 +0800
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: ian.campbell@citrix.com, peter.huangpeng@huawei.com, xen-devel@lists.xen.org, julien.grall@citrix.com, stefano.stabellini@citrix.com, shannon.zhao@linaro.org
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On 2016/1/27 20:52, Stefano Stabellini wrote:
> On Sat, 23 Jan 2016, Shannon Zhao wrote:
>> From: Shannon Zhao <shannon.zhao@linaro.org>
>>
>> Add macros to emulate x86 style ports for arm. This avoids modification in
>> common code for acpi. Here just print a warning on ARM.
>>
>> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
>> ---
>> V4: print warning
>> ---
>>  xen/include/asm-arm/arm64/io.h | 18 ++++++++++++++++++
>>  1 file changed, 18 insertions(+)
>>
>> diff --git a/xen/include/asm-arm/arm64/io.h b/xen/include/asm-arm/arm64/io.h
>> index 37abc47..ec5815d 100644
>> --- a/xen/include/asm-arm/arm64/io.h
>> +++ b/xen/include/asm-arm/arm64/io.h
>> @@ -20,6 +20,7 @@
>>  #ifndef _ARM_ARM64_IO_H
>>  #define _ARM_ARM64_IO_H
>>  
>> +#include <asm/system.h>
>>  #include <asm/byteorder.h>
>>  
>>  /*
>> @@ -109,4 +110,21 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
>>  #define writel(v,c)             ({ __iowmb(); writel_relaxed((v),(c)); })
>>  #define writeq(v,c)             ({ __iowmb(); writeq_relaxed((v),(c)); })
>>  
>> +/*
>> + * Emulate x86 io ports for ARM.
>> + */
>> +static inline void __iomem * __armio(u64 addr)
>> +{
>> +    printk(XENLOG_G_WARNING "Can't access IO %lx\n", addr);
>> +    return (void __iomem *)addr;
>> +}
>> +
>> +#define inb(c) ( readb( __armio(c) ) )
>> +#define inw(c) ( readw( __armio(c) ) )
>> +#define inl(c) ( readl( __armio(c) ) )
>> +
>> +#define outb(v, c) ( writeb(v, __armio(c) ) )
>> +#define outw(v, c) ( writew(v, __armio(c) ) )
>> +#define outl(v, c) ( writel(v, __armio(c) ) )
> 
> This is better than before, but it would still end up causing a write to
> happen on outb, outw and outl. I would define them in a way so that
> only the warning gets printed when they are called and nothing else.
> 

How about this?

+/*
+ * Emulate x86 io ports for ARM.
+ */
+static inline int emulate_read(u64 addr)
+{
+    printk(XENLOG_G_WARNING "Can't access IO %lx\n", addr);
+    return 0;
+}
+
+static inline void emulate_write(u64 addr)
+{
+    printk(XENLOG_G_WARNING "Can't access IO %lx\n", addr);
+}
+
+#define inb(c) ( emulate_read(c) )
+#define inw(c) ( emulate_read(c) )
+#define inl(c) ( emulate_read(c) )
+
+#define outb(v, c) ( emulate_write(c) )
+#define outw(v, c) ( emulate_write(c) )
+#define outl(v, c) ( emulate_write(c) )

Thanks,
-- 
Shannon