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Message-ID: <8adfe182-4939-479d-6013-25ec40021b20@huawei.com>
Date:   Tue, 8 Nov 2016 16:33:44 +0000
From:   John Garry <john.garry@...wei.com>
To:     Will Deacon <will.deacon@....com>,
        "zhichang.yuan" <yuanzhichang@...ilicon.com>
CC:     <catalin.marinas@....com>, <robh+dt@...nel.org>,
        <bhelgaas@...gle.com>, <mark.rutland@....com>, <olof@...om.net>,
        <arnd@...db.de>, <linux-arm-kernel@...ts.infradead.org>,
        <lorenzo.pieralisi@....com>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...wei.com>, <devicetree@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <linux-serial@...r.kernel.org>,
        <minyard@....org>, <benh@...nel.crashing.org>,
        <liviu.dudau@....com>, <zourongrong@...il.com>,
        <gabriele.paoloni@...wei.com>, <zhichang.yuan02@...il.com>,
        <kantyzc@....com>, <xuwei5@...ilicon.com>
Subject: Re: [PATCH V5 1/3] ARM64 LPC: Indirect ISA port IO introduced

On 08/11/2016 16:12, Will Deacon wrote:
> On Tue, Nov 08, 2016 at 11:47:07AM +0800, zhichang.yuan wrote:
>> For arm64, there is no I/O space as other architectural platforms, such as
>> X86. Most I/O accesses are achieved based on MMIO. But for some arm64 SoCs,
>> such as Hip06, when accessing some legacy ISA devices connected to LPC, those
>> known port addresses are used to control the corresponding target devices, for
>> example, 0x2f8 is for UART, 0xe4 is for ipmi-bt. It is different from the
>> normal MMIO mode in using.
>>
>> To drive these devices, this patch introduces a method named indirect-IO.
>> In this method the in/out pair in arch/arm64/include/asm/io.h will be
>> redefined. When upper layer drivers call in/out with those known legacy port
>> addresses to access the peripherals, the hooking functions corrresponding to
>> those target peripherals will be called. Through this way, those upper layer
>> drivers which depend on in/out can run on Hip06 without any changes.
>>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Will Deacon <will.deacon@....com>
>> Signed-off-by: zhichang.yuan <yuanzhichang@...ilicon.com>
>> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@...wei.com>
>> ---
>>  arch/arm64/Kconfig             |  6 +++
>>  arch/arm64/include/asm/extio.h | 94 ++++++++++++++++++++++++++++++++++++++++++
>>  arch/arm64/include/asm/io.h    | 29 +++++++++++++
>>  arch/arm64/kernel/Makefile     |  1 +
>>  arch/arm64/kernel/extio.c      | 27 ++++++++++++
>>  5 files changed, 157 insertions(+)
>>  create mode 100644 arch/arm64/include/asm/extio.h
>>  create mode 100644 arch/arm64/kernel/extio.c
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 969ef88..b44070b 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -163,6 +163,12 @@ config ARCH_MMAP_RND_COMPAT_BITS_MIN
>>  config ARCH_MMAP_RND_COMPAT_BITS_MAX
>>         default 16
>>
>> +config ARM64_INDIRECT_PIO
>> +	bool "access peripherals with legacy I/O port"
>> +	help
>> +	  Support special accessors for ISA I/O devices. This is needed for
>> +	  SoCs that do not support standard read/write for the ISA range.
>> +
>>  config NO_IOPORT_MAP
>>  	def_bool y if !PCI
>>
>> diff --git a/arch/arm64/include/asm/extio.h b/arch/arm64/include/asm/extio.h
>> new file mode 100644
>> index 0000000..6ae0787
>> --- /dev/null
>> +++ b/arch/arm64/include/asm/extio.h
>> @@ -0,0 +1,94 @@
>> +/*
>> + * Copyright (C) 2016 Hisilicon Limited, All Rights Reserved.
>> + * Author: Zhichang Yuan <yuanzhichang@...ilicon.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#ifndef __LINUX_EXTIO_H
>> +#define __LINUX_EXTIO_H
>> +
>> +struct extio_ops {
>> +	unsigned long start;/* inclusive, sys io addr */
>> +	unsigned long end;/* inclusive, sys io addr */
>> +
>> +	u64 (*pfin)(void *devobj, unsigned long ptaddr,	size_t dlen);
>> +	void (*pfout)(void *devobj, unsigned long ptaddr, u32 outval,
>> +					size_t dlen);
>> +	u64 (*pfins)(void *devobj, unsigned long ptaddr, void *inbuf,
>> +				size_t dlen, unsigned int count);
>> +	void (*pfouts)(void *devobj, unsigned long ptaddr,
>> +				const void *outbuf, size_t dlen,
>> +				unsigned int count);
>> +	void *devpara;
>> +};
>> +
>> +extern struct extio_ops *arm64_extio_ops;
>> +
>> +#define DECLARE_EXTIO(bw, type)						\
>> +extern type in##bw(unsigned long addr);					\
>> +extern void out##bw(type value, unsigned long addr);			\
>> +extern void ins##bw(unsigned long addr, void *buffer, unsigned int count);\
>> +extern void outs##bw(unsigned long addr, const void *buffer, unsigned int count);
>> +
>> +#define BUILD_EXTIO(bw, type)						\
>> +type in##bw(unsigned long addr)						\
>> +{									\
>> +	if (!arm64_extio_ops || arm64_extio_ops->start > addr ||	\
>> +			arm64_extio_ops->end < addr)			\
>> +		return read##bw(PCI_IOBASE + addr);			\
>> +	return arm64_extio_ops->pfin ?					\
>> +		arm64_extio_ops->pfin(arm64_extio_ops->devpara,		\
>> +			addr, sizeof(type)) : -1;			\
>> +}									\
>> +									\
>> +void out##bw(type value, unsigned long addr)				\
>> +{									\
>> +	if (!arm64_extio_ops || arm64_extio_ops->start > addr ||	\
>> +			arm64_extio_ops->end < addr)			\
>> +		write##bw(value, PCI_IOBASE + addr);			\
>> +	else								\
>> +		if (arm64_extio_ops->pfout)				\
>> +			arm64_extio_ops->pfout(arm64_extio_ops->devpara,\
>> +				addr, value, sizeof(type));		\
>> +}									\
>> +									\
>> +void ins##bw(unsigned long addr, void *buffer, unsigned int count)	\
>> +{									\
>> +	if (!arm64_extio_ops || arm64_extio_ops->start > addr ||	\
>> +			arm64_extio_ops->end < addr)			\
>> +		reads##bw(PCI_IOBASE + addr, buffer, count);		\
>> +	else								\
>> +		if (arm64_extio_ops->pfins)				\
>> +			arm64_extio_ops->pfins(arm64_extio_ops->devpara,\
>> +				addr, buffer, sizeof(type), count);	\
>> +}									\
>> +									\
>> +void outs##bw(unsigned long addr, const void *buffer, unsigned int count)	\
>> +{									\
>> +	if (!arm64_extio_ops || arm64_extio_ops->start > addr ||	\
>> +			arm64_extio_ops->end < addr)			\
>> +		writes##bw(PCI_IOBASE + addr, buffer, count);		\
>> +	else								\
>> +		if (arm64_extio_ops->pfouts)				\
>> +			arm64_extio_ops->pfouts(arm64_extio_ops->devpara,\
>> +				addr, buffer, sizeof(type), count);	\
>> +}
>> +
>> +static inline void arm64_set_extops(struct extio_ops *ops)
>> +{
>> +	if (ops)
>> +		WRITE_ONCE(arm64_extio_ops, ops);
>
> Why does this need to be WRITE_ONCE? You don't have READ_ONCE on the reader
> side. Also, what if multiple drivers want to set different ops for distinct
> address ranges?

I think that the idea here is that we only have possibly one master in 
the system which offers indirectIO backend, so another one could not 
possibly re-set this value.

>
>> +}
>> +
>> +#endif /* __LINUX_EXTIO_H*/
>> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
>> index 0bba427..136735d 100644
>> --- a/arch/arm64/include/asm/io.h
>> +++ b/arch/arm64/include/asm/io.h
>> @@ -31,6 +31,7 @@
>>  #include <asm/early_ioremap.h>
>>  #include <asm/alternative.h>
>>  #include <asm/cpufeature.h>
>> +#include <asm/extio.h>
>>
>>  #include <xen/xen.h>
>>
>> @@ -149,6 +150,34 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
>>  #define IO_SPACE_LIMIT		(PCI_IO_SIZE - 1)
>>  #define PCI_IOBASE		((void __iomem *)PCI_IO_START)
>>
>> +
>> +/*
>> + * redefine the in(s)b/out(s)b for indirect-IO.
>> + */
>> +#ifdef CONFIG_ARM64_INDIRECT_PIO
>> +#define inb inb
>> +#define outb outb
>> +#define insb insb
>> +#define outsb outsb
>> +/* external declaration */
>> +DECLARE_EXTIO(b, u8)
>> +
>> +#define inw inw
>> +#define outw outw
>> +#define insw insw
>> +#define outsw outsw
>> +
>> +DECLARE_EXTIO(w, u16)
>> +
>> +#define inl inl
>> +#define outl outl
>> +#define insl insl
>> +#define outsl outsl
>> +
>> +DECLARE_EXTIO(l, u32)
>> +#endif
>> +
>> +
>>  /*
>>   * String version of I/O memory access operations.
>>   */
>> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
>> index 7d66bba..60e0482 100644
>> --- a/arch/arm64/kernel/Makefile
>> +++ b/arch/arm64/kernel/Makefile
>> @@ -31,6 +31,7 @@ arm64-obj-$(CONFIG_COMPAT)		+= sys32.o kuser32.o signal32.o 	\
>>  					   sys_compat.o entry32.o
>>  arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
>>  arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
>> +arm64-obj-$(CONFIG_ARM64_INDIRECT_PIO)	+= extio.o
>>  arm64-obj-$(CONFIG_ARM64_MODULE_PLTS)	+= module-plts.o
>>  arm64-obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o perf_callchain.o
>>  arm64-obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o
>> diff --git a/arch/arm64/kernel/extio.c b/arch/arm64/kernel/extio.c
>> new file mode 100644
>> index 0000000..647b3fa
>> --- /dev/null
>> +++ b/arch/arm64/kernel/extio.c
>> @@ -0,0 +1,27 @@
>> +/*
>> + * Copyright (C) 2016 Hisilicon Limited, All Rights Reserved.
>> + * Author: Zhichang Yuan <yuanzhichang@...ilicon.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/io.h>
>> +
>> +struct extio_ops *arm64_extio_ops;
>> +
>> +
>> +BUILD_EXTIO(b, u8)
>> +
>> +BUILD_EXTIO(w, u16)
>> +
>> +BUILD_EXTIO(l, u32)
>
> Is there no way to make this slightly more generic, so that it can be
> re-used elsewhere? For example, if struct extio_ops was common, then
> you could have the singleton (which maybe should be an interval tree?),
> type definition, setter function and the BUILD_EXTIO invocations
> somewhere generic, rather than squirelled away in the arch backend.
>
> Will

The concern would be that some architecture which uses generic 
higher-level ISA accessor ops, but have IO space, could be affected.

John

>
> .
>


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