Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <435e1283-9ff6-f089-6436-3c31a178fd60@arm.com>
Date:   Mon, 5 Sep 2022 13:20:01 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:102.0) Gecko/20100101
 Thunderbird/102.2.1
Subject: Re: [PATCH V3 1/2] ACPI / scan: Support multiple dma windows with
 different offsets
Content-Language: en-GB
To:     Jianmin Lv <lvjianmin@loongson.cn>, lpieralisi@kernel.org,
        chenhuacai@loongson.cn
Cc:     guohanjun@huawei.com, sudeep.holla@arm.com, rafael@kernel.org,
        lenb@kernel.org, robert.moore@intel.com,
        linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
        loongarch@lists.linux.dev
References: <20220830030139.29899-1-lvjianmin@loongson.cn>
 <20220830030139.29899-2-lvjianmin@loongson.cn>
From:   Robin Murphy <robin.murphy@arm.com>
In-Reply-To: <20220830030139.29899-2-lvjianmin@loongson.cn>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 2022-08-30 04:01, Jianmin Lv wrote:
> For DT, of_dma_get_range returns bus_dma_region typed dma regions,
> which makes multiple dma windows with different offset available
> for translation between dma address and cpu address.
> 
> But for ACPI, acpi_dma_get_range doesn't return similar dma regions,
> causing no path for setting dev->dma_range_map conveniently. So the
> patch changes acpi_dma_get_range and returns bus_dma_region typed
> dma regions according to of_dma_get_range.
> 
> After changing acpi_dma_get_range, acpi_arch_dma_setup is changed for
> ARM64, where original dma_addr and size are removed as these
> arguments are now redundant, and pass 0 and U64_MAX for dma_base
> and size of arch_setup_dma_ops, so this is a simplification consistent
> with what other ACPI architectures also pass to iommu_setup_dma_ops().

Other than a micro-nit that acpi_dma_get_range() could probably use 
resource_size(),

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

It took me longer than I care to admit to figure out where the implicit 
declaration of struct bus_dma_region in the scope of acpi.h and 
acpi_bus.h comes from, but in the end I guess it's sufficiently 
well-defined by the C spec to be reliable.

Thanks for getting this done!

Robin.

> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
> ---
>   drivers/acpi/arm64/dma.c | 29 ++++++++++++++++----------
>   drivers/acpi/scan.c      | 53 +++++++++++++++++++++---------------------------
>   include/acpi/acpi_bus.h  |  3 +--
>   include/linux/acpi.h     |  7 +++----
>   4 files changed, 45 insertions(+), 47 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
> index f16739a..1ef8e7d 100644
> --- a/drivers/acpi/arm64/dma.c
> +++ b/drivers/acpi/arm64/dma.c
> @@ -4,11 +4,12 @@
>   #include <linux/device.h>
>   #include <linux/dma-direct.h>
>   
> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
> +void acpi_arch_dma_setup(struct device *dev)
>   {
>   	int ret;
>   	u64 end, mask;
> -	u64 dmaaddr = 0, size = 0, offset = 0;
> +	u64 size = 0;
> +	const struct bus_dma_region *map = NULL;
>   
>   	/*
>   	 * If @dev is expected to be DMA-capable then the bus code that created
> @@ -26,25 +27,31 @@ void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>   	else
>   		size = 1ULL << 32;
>   
> -	ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> +	ret = acpi_dma_get_range(dev, &map);
> +	if (!ret && map) {
> +		const struct bus_dma_region *r = map;
> +
> +		for (end = 0; r->size; r++) {
> +			if (r->dma_start + r->size - 1 > end)
> +				end = r->dma_start + r->size - 1;
> +		}
> +
> +		size = end + 1;
> +		dev->dma_range_map = map;
> +	}
> +
>   	if (ret == -ENODEV)
>   		ret = iort_dma_get_ranges(dev, &size);
> +
>   	if (!ret) {
>   		/*
>   		 * Limit coherent and dma mask based on size retrieved from
>   		 * firmware.
>   		 */
> -		end = dmaaddr + size - 1;
> +		end = size - 1;
>   		mask = DMA_BIT_MASK(ilog2(end) + 1);
>   		dev->bus_dma_limit = end;
>   		dev->coherent_dma_mask = min(dev->coherent_dma_mask, mask);
>   		*dev->dma_mask = min(*dev->dma_mask, mask);
>   	}
> -
> -	*dma_addr = dmaaddr;
> -	*dma_size = size;
> -
> -	ret = dma_direct_set_offset(dev, dmaaddr + offset, dmaaddr, size);
> -
> -	dev_dbg(dev, "dma_offset(%#08llx)%s\n", offset, ret ? " failed!" : "");
>   }
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 762b61f..8c0c2ca 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -20,6 +20,7 @@
>   #include <linux/platform_data/x86/apple.h>
>   #include <linux/pgtable.h>
>   #include <linux/crc32.h>
> +#include <linux/dma-direct.h>
>   
>   #include "internal.h"
>   
> @@ -1482,25 +1483,21 @@ enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
>    * acpi_dma_get_range() - Get device DMA parameters.
>    *
>    * @dev: device to configure
> - * @dma_addr: pointer device DMA address result
> - * @offset: pointer to the DMA offset result
> - * @size: pointer to DMA range size result
> + * @map: pointer to DMA ranges result
>    *
> - * Evaluate DMA regions and return respectively DMA region start, offset
> - * and size in dma_addr, offset and size on parsing success; it does not
> - * update the passed in values on failure.
> + * Evaluate DMA regions and return pointer to DMA regions on
> + * parsing success; it does not update the passed in values on failure.
>    *
>    * Return 0 on success, < 0 on failure.
>    */
> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
> -		       u64 *size)
> +int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
>   {
>   	struct acpi_device *adev;
>   	LIST_HEAD(list);
>   	struct resource_entry *rentry;
>   	int ret;
>   	struct device *dma_dev = dev;
> -	u64 len, dma_start = U64_MAX, dma_end = 0, dma_offset = 0;
> +	struct bus_dma_region *r;
>   
>   	/*
>   	 * Walk the device tree chasing an ACPI companion with a _DMA
> @@ -1525,31 +1522,28 @@ int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
>   
>   	ret = acpi_dev_get_dma_resources(adev, &list);
>   	if (ret > 0) {
> +		r = kcalloc(ret + 1, sizeof(*r), GFP_KERNEL);
> +		if (!r) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
> +
> +		*map = r;
> +
>   		list_for_each_entry(rentry, &list, node) {
> -			if (dma_offset && rentry->offset != dma_offset) {
> +			if (rentry->res->start >= rentry->res->end) {
>   				ret = -EINVAL;
> -				dev_warn(dma_dev, "Can't handle multiple windows with different offsets\n");
> +				dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
>   				goto out;
>   			}
> -			dma_offset = rentry->offset;
>   
> -			/* Take lower and upper limits */
> -			if (rentry->res->start < dma_start)
> -				dma_start = rentry->res->start;
> -			if (rentry->res->end > dma_end)
> -				dma_end = rentry->res->end;
> -		}
> -
> -		if (dma_start >= dma_end) {
> -			ret = -EINVAL;
> -			dev_dbg(dma_dev, "Invalid DMA regions configuration\n");
> -			goto out;
> +			r->cpu_start = rentry->res->start;
> +			r->dma_start = rentry->res->start - rentry->offset;
> +			r->size = rentry->res->end - rentry->res->start + 1;
> +			r->offset = rentry->offset;
> +			r++;
>   		}
>   
> -		*dma_addr = dma_start - dma_offset;
> -		len = dma_end - dma_start;
> -		*size = max(len, len + 1);
> -		*offset = dma_offset;
>   	}
>    out:
>   	acpi_dev_free_resource_list(&list);
> @@ -1639,20 +1633,19 @@ int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
>   			  const u32 *input_id)
>   {
>   	const struct iommu_ops *iommu;
> -	u64 dma_addr = 0, size = 0;
>   
>   	if (attr == DEV_DMA_NOT_SUPPORTED) {
>   		set_dma_ops(dev, &dma_dummy_ops);
>   		return 0;
>   	}
>   
> -	acpi_arch_dma_setup(dev, &dma_addr, &size);
> +	acpi_arch_dma_setup(dev);
>   
>   	iommu = acpi_iommu_configure_id(dev, input_id);
>   	if (PTR_ERR(iommu) == -EPROBE_DEFER)
>   		return -EPROBE_DEFER;
>   
> -	arch_setup_dma_ops(dev, dma_addr, size,
> +	arch_setup_dma_ops(dev, 0, U64_MAX,
>   				iommu, attr == DEV_DMA_COHERENT);
>   
>   	return 0;
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 0dc1ea0b..e106073 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -611,8 +611,7 @@ struct acpi_pci_root {
>   int acpi_iommu_fwspec_init(struct device *dev, u32 id,
>   			   struct fwnode_handle *fwnode,
>   			   const struct iommu_ops *ops);
> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset,
> -		       u64 *size);
> +int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map);
>   int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
>   			   const u32 *input_id);
>   static inline int acpi_dma_configure(struct device *dev,
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 44975c1..34e0545 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -280,12 +280,12 @@ int acpi_table_parse_madt(enum acpi_madt_type id,
>   
>   #ifdef CONFIG_ARM64
>   void acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa);
> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size);
> +void acpi_arch_dma_setup(struct device *dev);
>   #else
>   static inline void
>   acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa) { }
>   static inline void
> -acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) { }
> +acpi_arch_dma_setup(struct device *dev) { }
>   #endif
>   
>   int acpi_numa_memory_affinity_init (struct acpi_srat_mem_affinity *ma);
> @@ -974,8 +974,7 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev)
>   	return DEV_DMA_NOT_SUPPORTED;
>   }
>   
> -static inline int acpi_dma_get_range(struct device *dev, u64 *dma_addr,
> -				     u64 *offset, u64 *size)
> +static inline int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map)
>   {
>   	return -ENODEV;
>   }