Messages in this thread Patch in this message | | | From | "Andrew F. Davis" <> | Subject | [RFC][PATCH] misc: sram: Add dma-heap-export reserved SRAM area type | Date | Thu, 21 Mar 2019 11:02:57 -0500 |
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This new export type exposes to userspace the SRAM area as a DMA-Heap, this allows for allocations as DMA-BUFs that can be consumed by various DMA-BUF supporting devices.
Signed-off-by: Andrew F. Davis <afd@ti.com> ---
Hello all,
This is an example user of the currently RFC DMA-HEAP framework. It exports a defined SRAM area showing how various memory presenting devices can use the DMA-HEAP framework to provide DMA-BUF allocations to userspace and other devices.
It has a couple problems still, one being that the SRAM subsystem probes before the DMA-BUF subsystem, can the SRAM driver be changed from postcore_initcall to subsys_initcall or even device_initcall?
Thanks, Andrew
.../devicetree/bindings/sram/sram.txt | 7 +- drivers/misc/Kconfig | 7 + drivers/misc/Makefile | 1 + drivers/misc/sram-dma-heap.c | 235 ++++++++++++++++++ drivers/misc/sram.c | 20 +- drivers/misc/sram.h | 17 ++ 6 files changed, 282 insertions(+), 5 deletions(-) create mode 100644 drivers/misc/sram-dma-heap.c
diff --git a/Documentation/devicetree/bindings/sram/sram.txt b/Documentation/devicetree/bindings/sram/sram.txt index e98908bd4227..c5584f1f6ae8 100644 --- a/Documentation/devicetree/bindings/sram/sram.txt +++ b/Documentation/devicetree/bindings/sram/sram.txt @@ -43,11 +43,16 @@ Optional properties in the area nodes: - export : indicates that the reserved SRAM area may be accessed outside of the kernel, e.g. by bootloader or userspace - protect-exec : Same as 'pool' above but with the additional - constraint that code wil be run from the region and + constraint that code will be run from the region and that the memory is maintained as read-only, executable during code execution. NOTE: This region must be page aligned on start and end in order to properly allow manipulation of the page attributes. +- dma-heap-export : Similar to 'pool' and 'export' this region will be + exported for use by drivers, devices, and userspace + using the DMA-Heaps framework. NOTE: This region must + be page aligned on start and end in order to properly + allow manipulation of the page attributes. - label : the name for the reserved partition, if omitted, the label is taken from the node name excluding the unit address. - clocks : a list of phandle and clock specifier pair that controls the diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 42ab8ec92a04..5e655890458d 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -487,6 +487,13 @@ config SRAM config SRAM_EXEC bool +config SRAM_DMA_HEAP + bool "Export on-chip SRAM pools using DMA-Heaps" + depends on SRAM + help + This driver allows the export of on-chip SRAM marked as exportable + to userspace using the DMA-Heaps interface. + config VEXPRESS_SYSCFG bool "Versatile Express System Configuration driver" depends on VEXPRESS_CONFIG diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index d5b7d3404dc7..f9db5326e0f7 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -49,6 +49,7 @@ obj-$(CONFIG_VMWARE_VMCI) += vmw_vmci/ obj-$(CONFIG_LATTICE_ECP3_CONFIG) += lattice-ecp3-config.o obj-$(CONFIG_SRAM) += sram.o obj-$(CONFIG_SRAM_EXEC) += sram-exec.o +obj-$(CONFIG_SRAM_DMA_HEAP) += sram-dma-heap.o obj-y += mic/ obj-$(CONFIG_GENWQE) += genwqe/ obj-$(CONFIG_ECHO) += echo/ diff --git a/drivers/misc/sram-dma-heap.c b/drivers/misc/sram-dma-heap.c new file mode 100644 index 000000000000..bc930fced648 --- /dev/null +++ b/drivers/misc/sram-dma-heap.c @@ -0,0 +1,235 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * SRAM DMA-Heaps userspace exporter + * + * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis <afd@ti.com> + */ + +#include <linux/dma-mapping.h> +#include <linux/err.h> +#include <linux/genalloc.h> +#include <linux/io.h> +#include <linux/mm.h> +#include <linux/scatterlist.h> +#include <linux/slab.h> +#include <linux/dma-buf.h> +#include <linux/dma-heap.h> + +#include "sram.h" + +struct sram_dma_heap { + struct dma_heap heap; + struct gen_pool *pool; +}; + +struct sram_dma_heap_buffer { + struct gen_pool *pool; + struct list_head attachments; + struct mutex attachments_lock; + unsigned long len; + unsigned long vaddr; + phys_addr_t paddr; +}; + +struct dma_heaps_attachment { + struct device *dev; + struct sg_table *table; + struct list_head list; +}; + +static int dma_heap_attach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct sram_dma_heap_buffer *buffer = dmabuf->priv; + struct dma_heaps_attachment *a; + struct sg_table *table; + + a = kzalloc(sizeof(*a), GFP_KERNEL); + if (!a) + return -ENOMEM; + + table = kmalloc(sizeof(*table), GFP_KERNEL); + if (!table) { + kfree(a); + return -ENOMEM; + } + if (sg_alloc_table(table, 1, GFP_KERNEL)) { + kfree(a); + return -ENOMEM; + } + sg_set_page(table->sgl, pfn_to_page(PFN_DOWN(buffer->paddr)), buffer->len, 0); + + a->table = table; + a->dev = attachment->dev; + INIT_LIST_HEAD(&a->list); + + attachment->priv = a; + + mutex_lock(&buffer->attachments_lock); + list_add(&a->list, &buffer->attachments); + mutex_unlock(&buffer->attachments_lock); + + return 0; +} + +static void dma_heap_detatch(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct sram_dma_heap_buffer *buffer = dmabuf->priv; + struct dma_heaps_attachment *a = attachment->priv; + + mutex_lock(&buffer->attachments_lock); + list_del(&a->list); + mutex_unlock(&buffer->attachments_lock); + + sg_free_table(a->table); + kfree(a->table); + kfree(a); +} + +static struct sg_table *dma_heap_map_dma_buf(struct dma_buf_attachment *attachment, + enum dma_data_direction direction) +{ + struct dma_heaps_attachment *a = attachment->priv; + struct sg_table *table = a->table; + + if (!dma_map_sg_attrs(attachment->dev, table->sgl, table->nents, + direction, DMA_ATTR_SKIP_CPU_SYNC)) + return ERR_PTR(-ENOMEM); + + return table; +} + +static void dma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment, + struct sg_table *table, + enum dma_data_direction direction) +{ + dma_unmap_sg_attrs(attachment->dev, table->sgl, table->nents, + direction, DMA_ATTR_SKIP_CPU_SYNC); +} + +static void dma_heap_dma_buf_release(struct dma_buf *dmabuf) +{ + struct sram_dma_heap_buffer *buffer = dmabuf->priv; + + gen_pool_free(buffer->pool, buffer->vaddr, buffer->len); + kfree(buffer); +} + +static void *dma_heap_kmap(struct dma_buf *dmabuf, unsigned long page_num) +{ + struct sram_dma_heap_buffer *buffer = dmabuf->priv; + + return (void *)buffer->vaddr + (page_num * PAGE_SIZE); +} + +static int dma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) +{ + struct sram_dma_heap_buffer *buffer = dmabuf->priv; + int ret; + + /* SRAM mappings are not cached */ + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); + + ret = vm_iomap_memory(vma, buffer->paddr, buffer->len); + if (ret) + pr_err("Could not map buffer to userspace\n"); + + return ret; +} + +const struct dma_buf_ops sram_dma_heap_buf_ops = { + .attach = dma_heap_attach, + .detach = dma_heap_detatch, + .map_dma_buf = dma_heap_map_dma_buf, + .unmap_dma_buf = dma_heap_unmap_dma_buf, + .release = dma_heap_dma_buf_release, + .map = dma_heap_kmap, + .mmap = dma_heap_mmap, +}; + +static int sram_dma_heap_allocate(struct dma_heap *heap, + unsigned long len, + unsigned long flags) +{ + struct sram_dma_heap *sram_dma_heap = container_of(heap, struct sram_dma_heap, heap); + struct sram_dma_heap_buffer *buffer; + + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + struct dma_buf *dmabuf; + int ret; + + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); + if (!buffer) + return -ENOMEM; + buffer->pool = sram_dma_heap->pool; + INIT_LIST_HEAD(&buffer->attachments); + mutex_init(&buffer->attachments_lock); + buffer->len = len; + + buffer->vaddr = gen_pool_alloc(buffer->pool, buffer->len); + if (!buffer->vaddr) { + ret = -ENOMEM; + goto free_buffer; + } + + buffer->paddr = gen_pool_virt_to_phys(buffer->pool, buffer->vaddr); + if (buffer->paddr == -1) { + ret = -ENOMEM; + goto free_pool; + } + + /* create the dmabuf */ + exp_info.ops = &sram_dma_heap_buf_ops; + exp_info.size = buffer->len; + exp_info.flags = O_RDWR; + exp_info.priv = buffer; + dmabuf = dma_buf_export(&exp_info); + if (IS_ERR(dmabuf)) { + ret = PTR_ERR(dmabuf); + goto free_pool; + } + + ret = dma_buf_fd(dmabuf, O_CLOEXEC); + if (ret < 0) { + dma_buf_put(dmabuf); + /* just return, as put will call release and that will free */ + return ret; + } + + return ret; + +free_pool: + gen_pool_free(buffer->pool, buffer->vaddr, buffer->len); +free_buffer: + kfree(buffer); + + return ret; +} + +static struct dma_heap_ops sram_dma_heap_ops = { + .allocate = sram_dma_heap_allocate, +}; + +int sram_dma_heap_export(struct sram_dev *sram, + struct sram_reserve *block, + phys_addr_t start, + struct sram_partition *part) +{ + struct sram_dma_heap *sram_dma_heap; + + dev_info(sram->dev, "Exporting SRAM pool '%s'\n", block->label); + + sram_dma_heap = kzalloc(sizeof(*sram_dma_heap), GFP_KERNEL); + if (!sram_dma_heap) + return -ENOMEM; + + sram_dma_heap->heap.name = block->label; + sram_dma_heap->heap.ops = &sram_dma_heap_ops; + sram_dma_heap->pool = part->pool; + + dma_heap_add(&sram_dma_heap->heap); + + return 0; +} diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c index 80d8cbe8c01a..d11a3ab7b9b2 100644 --- a/drivers/misc/sram.c +++ b/drivers/misc/sram.c @@ -122,6 +122,15 @@ static int sram_add_partition(struct sram_dev *sram, struct sram_reserve *block, if (ret) return ret; } + if (block->dma_heap_export) { + ret = sram_add_pool(sram, block, start, part); + if (ret) + return ret; + + ret = sram_dma_heap_export(sram, block, start, part); + if (ret) + return ret; + } if (block->protect_exec) { ret = sram_check_protect_exec(sram, block, part); if (ret) @@ -222,8 +231,11 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res) if (of_find_property(child, "protect-exec", NULL)) block->protect_exec = true; - if ((block->export || block->pool || block->protect_exec) && - block->size) { + if (of_find_property(child, "dma-heap-export", NULL)) + block->dma_heap_export = true; + + if ((block->export || block->pool || block->protect_exec || + block->dma_heap_export) && block->size) { exports++; label = NULL; @@ -285,8 +297,8 @@ static int sram_reserve_regions(struct sram_dev *sram, struct resource *res) goto err_chunks; } - if ((block->export || block->pool || block->protect_exec) && - block->size) { + if ((block->export || block->pool || block->protect_exec || + block->dma_heap_export) && block->size) { ret = sram_add_partition(sram, block, res->start + block->start); if (ret) { diff --git a/drivers/misc/sram.h b/drivers/misc/sram.h index c181ce4c8fca..c1eef4c32152 100644 --- a/drivers/misc/sram.h +++ b/drivers/misc/sram.h @@ -35,6 +35,7 @@ struct sram_reserve { bool export; bool pool; bool protect_exec; + bool dma_heap_export; const char *label; }; @@ -55,4 +56,20 @@ static inline int sram_add_protect_exec(struct sram_partition *part) return -ENODEV; } #endif /* CONFIG_SRAM_EXEC */ + +#ifdef CONFIG_SRAM_DMA_HEAP +int sram_dma_heap_export(struct sram_dev *sram, + struct sram_reserve *block, + phys_addr_t start, + struct sram_partition *part); +#else +static inline int sram_dma_heap_export(struct sram_dev *sram, + struct sram_reserve *block, + phys_addr_t start, + struct sram_partition *part) +{ + return 0; +} +#endif /* CONFIG_SRAM_DMA_HEAP */ + #endif /* __SRAM_H */ -- 2.21.0
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