linux-kernel - Re: [PATCH v3 3/6] drivers: of: implement reserved-memory handling for dma

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Date:	Tue, 18 Feb 2014 16:58:15 +0000
From:	Grant Likely <grant.likely@...aro.org>
To:	Marek Szyprowski <m.szyprowski@...sung.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-mm-sig@...ts.linaro.org, devicetree@...r.kernel.org,
	linux-doc@...r.kernel.org
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Arnd Bergmann <arnd@...db.de>,
	Michal Nazarewicz <mina86@...a86.com>,
	Tomasz Figa <t.figa@...sung.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Laura Abbott <lauraa@...eaurora.org>,
	Rob Herring <robh+dt@...nel.org>,
	Olof Johansson <olof@...om.net>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Ian Campbell <ian.campbell@...rix.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Kumar Gala <galak@...eaurora.org>,
	Nishanth Peethambaran <nishanth.p@...il.com>,
	Marc <marc.ceeeee@...il.com>,
	Josh Cartwright <joshc@...eaurora.org>
Subject: Re: [PATCH v3 3/6] drivers: of: implement reserved-memory handling for dma

On Tue, 18 Feb 2014 14:37:58 +0100, Marek Szyprowski <m.szyprowski@...sung.com> wrote:
> From: Josh Cartwright <joshc@...eaurora.org>
> 
> Add support for handling 'shared-dma-pool' reserved-memory nodes using
> dma exclusive driver (dma_alloc_coherent()).
> 
> Signed-off-by: Josh Cartwright <joshc@...eaurora.org>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>  drivers/of/Kconfig               |    7 ++++
>  drivers/of/Makefile              |    1 +
>  drivers/of/of_reserved_mem_dma.c |   65 ++++++++++++++++++++++++++++++++++++++

I don't see any reason to have this separate from of_reserved_mem.c

>  3 files changed, 73 insertions(+)
>  create mode 100644 drivers/of/of_reserved_mem_dma.c
> 
> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> index f25931dfc6db..7f00b801bcd2 100644
> --- a/drivers/of/Kconfig
> +++ b/drivers/of/Kconfig
> @@ -80,4 +80,11 @@ config OF_RESERVED_MEM
>  	help
>  	  Helpers to allow for reservation of memory regions
>  
> +config OF_RESERVED_MEM_DMA
> +	depends on OF_RESERVED_MEM
> +	depends on HAVE_GENERIC_DMA_COHERENT
> +	def_bool y
> +	help
> +	  Helpers for reserving memory regions for DMA use
> +
>  endmenu # OF
> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> index ed9660adad77..6142227ca854 100644
> --- a/drivers/of/Makefile
> +++ b/drivers/of/Makefile
> @@ -10,3 +10,4 @@ obj-$(CONFIG_OF_PCI)	+= of_pci.o
>  obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
>  obj-$(CONFIG_OF_MTD)	+= of_mtd.o
>  obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
> +obj-$(CONFIG_OF_RESERVED_MEM_DMA) += of_reserved_mem_dma.o
> diff --git a/drivers/of/of_reserved_mem_dma.c b/drivers/of/of_reserved_mem_dma.c
> new file mode 100644
> index 000000000000..a3e596d1091d
> --- /dev/null
> +++ b/drivers/of/of_reserved_mem_dma.c
> @@ -0,0 +1,65 @@
> +/*
> + * Device tree based initialization code for DMA reserved regions.
> + *
> + * Copyright (c) 2013, The Linux Foundation. All Rights Reserved.
> + * Copyright (c) 2013,2014 Samsung Electronics Co., Ltd.
> + *		http://www.samsung.com
> + * Author: Marek Szyprowski <m.szyprowski@...sung.com>
> + * Author: Josh Cartwright <joshc@...eaurora.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of the
> + * License or (at your optional) any later version of the license.
> + */
> +#include <linux/memblock.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_platform.h>
> +#include <linux/mm.h>
> +#include <linux/sizes.h>
> +#include <linux/mm_types.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/of_reserved_mem.h>
> +
> +static void rmem_dma_device_init(struct reserved_mem *rmem,
> +				 struct device *dev,
> +				 struct of_phandle_args *args)
> +{
> +	dma_declare_coherent_memory(dev, rmem->base, rmem->base,
> +		rmem->size, DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE);
> +}
> +
> +static void rmem_dma_device_release(struct reserved_mem *rmem,
> +				    struct device *dev)
> +{
> +	dma_release_declared_memory(dev);
> +}
> +
> +static const struct reserved_mem_ops rmem_dma_ops = {
> +	.device_init	= rmem_dma_device_init,
> +	.device_release	= rmem_dma_device_release,
> +};
> +
> +static int __init rmem_dma_setup(struct reserved_mem *rmem,
> +				 unsigned long node,
> +				 const char *uname)
> +{
> +	int err;
> +
> +	if (of_get_flat_dt_prop(node, "reusable", NULL))
> +		return -EINVAL;
> +
> +	err = memblock_remove(rmem->base, rmem->size);

Isn't the memblock_remove() now handled by the core code? Or am I
mis-reading it?

> +	if (err == 0) {
> +		rmem->ops = &rmem_dma_ops;
> +		pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
> +			&rmem->base, (unsigned long)rmem->size / SZ_1M);
> +	} else {
> +		pr_err("Reserved memory: unable to setup '%s' memory region for DMA.\n",
> +		       uname);
> +	}
> +	return err;
> +}
> +RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
> -- 
> 1.7.9.5
> 

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