Re: [PATCH V5 1/3] ARM64 LPC: Indirect ISA port IO introduced

[Will Deacon]

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@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: zhichang.yuan <yuanzhichang@xxxxxxxxxxxxx>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@xxxxxxxxxx>
> ---
>  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@xxxxxxxxxxxxx>
> + *
> + * 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?

> +}
> +
> +#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@xxxxxxxxxxxxx>
> + *
> + * 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