On Fri, Apr 24, 2020 at 3:27 PM Andrew F. Davis <afd@xxxxxx> wrote: > 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@xxxxxx> Nice! Very excited to have the first new heap (that didn't come with the initial patchset)! Overall looks good! I don't have any comment on the SRAM side of things, but a few minor questions/nits below. > diff --git a/drivers/misc/sram-dma-heap.c b/drivers/misc/sram-dma-heap.c > new file mode 100644 > index 000000000000..38df0397f294 > --- /dev/null > +++ b/drivers/misc/sram-dma-heap.c > @@ -0,0 +1,243 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * SRAM DMA-Heap userspace exporter > + * > + * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/ > + * Andrew F. Davis <afd@xxxxxx> > + */ > + > +#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; > + void *vaddr; > + phys_addr_t paddr; > +}; > + > +struct dma_heap_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_heap_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(table); > + 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_heap_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_heap_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)) Might be nice to have a comment as to why you're using SKIP_CPU_SYNC and why it's safe. > + 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, (unsigned long)buffer->vaddr, buffer->len); > + kfree(buffer); > +} > + > +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; > +} > + > +static void *dma_heap_vmap(struct dma_buf *dmabuf) > +{ > + struct sram_dma_heap_buffer *buffer = dmabuf->priv; > + > + return buffer->vaddr; > +} > + > +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, > + .mmap = dma_heap_mmap, > + .vmap = dma_heap_vmap, > +}; No begin/end_cpu_access functions here? I'm guessing it's because you're always using SKIP_CPU_SYNC so it wouldn't do anything? A small comment in the code might help. > + > +static int sram_dma_heap_allocate(struct dma_heap *heap, > + unsigned long len, > + unsigned long fd_flags, > + unsigned long heap_flags) > +{ > + struct sram_dma_heap *sram_dma_heap = dma_heap_get_drvdata(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 = (void *)gen_pool_alloc(buffer->pool, buffer->len); > + if (!buffer->vaddr) { > + ret = -ENOMEM; > + goto free_buffer; > + } > + > + buffer->paddr = gen_pool_virt_to_phys(buffer->pool, (unsigned long)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 = fd_flags; > + 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, fd_flags); > + 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, (unsigned long)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, This is totally a bikeshed thing (feel free to ignore), but maybe sram_dma_heap_create() or _add() would be a better name to avoid folks mixing it up with the dmabuf exporter? > + struct sram_reserve *block, > + phys_addr_t start, > + struct sram_partition *part) > +{ > + struct sram_dma_heap *sram_dma_heap; > + struct dma_heap_export_info exp_info; > + > + dev_info(sram->dev, "Exporting SRAM pool '%s'\n", block->label); Again, shed issue: but for terminology consistency (at least in the dmabuf heaps space), maybe heap instead of pool? Thanks so much again for submitting this! -john _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
