Hello all,
So I've got a new IP on our new SoC I'm looking to make use of and would like some help figuring out what framework best matches its function. The IP is called a "Page-based Address Translator" or PAT. A PAT instance (there are 5 of these things on our J721e device[0]) is basically a really simple IOMMU sitting on the interconnect between the device bus and what is effectively our northbridge called MSMC (DRAM/SRAM/L3-Cache/Coherency controller).
Simplified it looks about like this:
CPUs | DRAM --- MSMC --- SRAM/L3 | NAVSS - (PATs) | --- Device Bus --------- | | | | Device Device Device etc..
Each PAT has a set a window in high memory (about 0x48_0000_0000 area) for which any transaction with an address targeting its window will be routed into that PAT. The PAT then does a simple calculation based on the how far into the window the address is and the current page size, does a lookup to an internally held table of translations, then sends the transaction back out on the interconnect with a new address. Usually this address should be towards somewhere in DRAM, but can be some other device or even back into PAT (I'm not sure there is a valid use-case for this but just a point of interest).
My gut reaction is that this is an IOMMU which belongs in the IOMMU subsystem. But there are a couple oddities that make me less sure it is really suitable for the IOMMU framework. First it doesn't sit in front of any devices, it sits in front of *all* devices, this means we would have every device claim it as an IOMMU parent, even though many devices also have a traditional IOMMU connected. Second, there is only a limited window of address space per PAT, this means we will get fragmentation and allocation failures on occasion, in this way it looks to me more like AGP GART. Third, the window is in high-memory, so unlike some IOMMU devices which can be used to allow DMA to high-mem from low-mem only devices, PAT can't be used for that. Lastly it doesn't provide any isolation, if the access does not target the PAT window it is not used (that is not to say we don't have isolation, just that it is taken care of by other parts of the interconnect).
This means, to me, that PAT has one main purpose: making physically-contiguous views of scattered pages in system memory for DMA. But it does that really well, the whole translation table is held in a PAT-internal SRAM giving 1 bus cycle latency and at full bus bandwidth.
So what are my options here, is IOMMU the right way to go or not?
Looking around the kernel I also see the char dev ARP/GART interface which looks like a good fit, but also looks quite dated and my guess deprecated at this point. Moving right along..
Another thing I saw is we have the support upstream of the DMM device[1] available in some OMAPx/AM57x SoCs. I'm a little more familiar with this device. The DMM is a bundle of IPs and in fact one of them is called "PAT" and it even does basically the same thing this incarnation of "PAT" does. It's upstream integration design is a bit questionable unfortunately, the DMM support was integrated into the OMAPDRM display driver, which does make some sense then given its support for rotation (using TILER IP contained in DMM). The issue with this was that the DMM/TILER/PAT IP was not part of the our display IP, but instead out at the end of the shared device bus, inside the external memory controller. Like this new PAT this meant that any IP that could make use of it, but only the display framework could actually provide buffers backed by it. This meant, for instance, if we wanted to decode some video buffer using our video decoder we would have to allocate from DRM framework then pass that over to the V4L2 system. This doesn't make much sense and required the user-space to know about this odd situation and allocate from the right spot or else have to use up valuable CMA space or waste memory with dedicated carveouts.
Another idea would be to have this as a special central allocator (exposed through DMA-BUF heaps[2] or ION) that would give out normal system memory as a DMA-BUF but remap it with PAT if a device that only supports contiguous memory tries to attach/map that DMA-BUF.
One last option would be to allow user-space to choose to make the buffer contiguous when it needs. That's what the driver in this series allows. We expose a remapping device, user-space passes it a non-contiguous DMA-BUF handle and it passes a contiguous one back. Simple as that.
So how do we use this, lets take Android for example, we don't know at allocation time if a rendering buffer will end up going back into the GPU for further processing, or if it will be consumed directly by the display. This is a problem for us as our GPU can work with non-contiguous buffers but our display cannot, so any buffers that could possibly go to the display at some point currently needs to be allocated as contiguous from the start, this leads to a lot of unneeded use of carveout/CMA memory. With this driver on the other hand, we allocate regular non-contiguous system memory (again using DMA-BUF heaps, but ION could work here too), then only when a buffer is about to be sent to the display we pass the handle to this DMA-BUF to our driver here and take the handle it gives back and pass that to the display instead.
As said, it is probably not the ideal solution but it does work and was used for some early testing of the IP.
Well, sorry for the wall of text. Any and all suggestions very welcome and appreciated.
Thanks, Andrew
[0] http://www.ti.com/lit/pdf/spruil1 [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv... [2] https://lkml.org/lkml/2019/6/6/1211
Andrew F. Davis (2): dt-bindings: soc: ti: Add TI PAT bindings soc: ti: Add Support for the TI Page-based Address Translator (PAT)
.../devicetree/bindings/misc/ti,pat.txt | 34 ++ drivers/soc/ti/Kconfig | 9 + drivers/soc/ti/Makefile | 1 + drivers/soc/ti/ti-pat.c | 569 ++++++++++++++++++ include/uapi/linux/ti-pat.h | 44 ++ 5 files changed, 657 insertions(+) create mode 100644 Documentation/devicetree/bindings/misc/ti,pat.txt create mode 100644 drivers/soc/ti/ti-pat.c create mode 100644 include/uapi/linux/ti-pat.h
This patch adds the bindings for the Page-based Address Translator (PAT) present on various TI SoCs. A Page-based Address Translator (PAT) device performs address translation using tables stored in an internal SRAM. Each PAT supports a set number of pages, each occupying a programmable 4KB, 16KB, 64KB, or 1MB of addresses in a window for which an incoming transaction will be translated.
Signed-off-by: Andrew F. Davis afd@ti.com --- .../devicetree/bindings/misc/ti,pat.txt | 34 +++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 Documentation/devicetree/bindings/misc/ti,pat.txt
diff --git a/Documentation/devicetree/bindings/misc/ti,pat.txt b/Documentation/devicetree/bindings/misc/ti,pat.txt new file mode 100644 index 000000000000..fac20d45ad4c --- /dev/null +++ b/Documentation/devicetree/bindings/misc/ti,pat.txt @@ -0,0 +1,34 @@ +Texas Instruments Page-based Address Translator (PAT) driver binding +-------------------------------------------------------------------- + +A Page-based Address Translator (PAT) device performs address translation +using tables stored in an internal SRAM. Each PAT supports a set number of +pages, each occupying a programmable 4KB, 16KB, 64KB, or 1MB of addresses +in a window for which an incoming transaction will be translated. + +TI-PAT controller Device Node +============================= + +The TI-PAT node describes the Texas Instrument's Page-based Address +Translator (PAT). + +Required properties: +------------------- +- compatible: should be "ti,j721e-pat" +- reg-names: + mmrs - Memory mapped registers region + table - Location of the table of translation pages + window - Window of memory addresses translated by this PAT +- reg: register addresses corresponding to the above + +Example: + +navss_pat0: pat@31010000 { + compatible = "ti,j721e-pat"; + reg = <0x00 0x31010000 0x00 0x00000100>, + <0x00 0x36400000 0x00 0x00040000>, + <0x48 0x00000000 0x00 0x40000000>; + reg-names = "mmrs", + "table", + "window"; +};
This patch adds a driver for the Page-based Address Translator (PAT) present on various TI SoCs. A PAT device performs address translation using tables stored in an internal SRAM. Each PAT supports a set number of pages, each occupying a programmable 4KB, 16KB, 64KB, or 1MB of addresses in a window for which an incoming transaction will be translated.
Signed-off-by: Andrew F. Davis afd@ti.com --- drivers/soc/ti/Kconfig | 9 + drivers/soc/ti/Makefile | 1 + drivers/soc/ti/ti-pat.c | 569 ++++++++++++++++++++++++++++++++++++ include/uapi/linux/ti-pat.h | 44 +++ 4 files changed, 623 insertions(+) create mode 100644 drivers/soc/ti/ti-pat.c create mode 100644 include/uapi/linux/ti-pat.h
diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig index f0be35d3dcba..b838ae74d01f 100644 --- a/drivers/soc/ti/Kconfig +++ b/drivers/soc/ti/Kconfig @@ -86,4 +86,13 @@ config TI_SCI_INTA_MSI_DOMAIN help Driver to enable Interrupt Aggregator specific MSI Domain.
+config TI_PAT + tristate "TI PAT DMA-BUF exporter" + select REGMAP + help + Driver for TI Page-based Address Translator (PAT). This driver + provides the an API allowing the remapping of a non-contiguous + DMA-BUF into a contiguous one that is sutable for devices needing + coniguous memory. + endif # SOC_TI diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile index b3868d392d4f..1369642b40c3 100644 --- a/drivers/soc/ti/Makefile +++ b/drivers/soc/ti/Makefile @@ -9,3 +9,4 @@ obj-$(CONFIG_AMX3_PM) += pm33xx.o obj-$(CONFIG_WKUP_M3_IPC) += wkup_m3_ipc.o obj-$(CONFIG_TI_SCI_PM_DOMAINS) += ti_sci_pm_domains.o obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN) += ti_sci_inta_msi.o +obj-$(CONFIG_TI_PAT) += ti-pat.o diff --git a/drivers/soc/ti/ti-pat.c b/drivers/soc/ti/ti-pat.c new file mode 100644 index 000000000000..7359ea0f7ccf --- /dev/null +++ b/drivers/soc/ti/ti-pat.c @@ -0,0 +1,569 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TI PAT mapped DMA-BUF memory re-exporter + * + * Copyright (C) 2018-2019 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis afd@ti.com + */ + +#include <linux/fs.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/mod_devicetable.h> +#include <linux/uaccess.h> +#include <linux/miscdevice.h> +#include <linux/regmap.h> +#include <linux/dma-buf.h> +#include <linux/genalloc.h> +#include <linux/vmalloc.h> +#include <linux/slab.h> + +#include <linux/ti-pat.h> + +#define TI_PAT_DRIVER_NAME "ti-pat" + +/* TI PAT MMRS registers */ +#define TI_PAT_MMRS_PID 0x0 /* Revision Register */ +#define TI_PAT_MMRS_CONFIG 0x4 /* Config Register */ +#define TI_PAT_MMRS_CONTROL 0x10 /* Control Register */ + +/* TI PAT CONTROL register field values */ +#define TI_PAT_CONTROL_ARB_MODE_UF 0x0 /* Updates first */ +#define TI_PAT_CONTROL_ARB_MODE_RR 0x2 /* Round-robin */ + +#define TI_PAT_CONTROL_PAGE_SIZE_4KB 0x0 +#define TI_PAT_CONTROL_PAGE_SIZE_16KB 0x1 +#define TI_PAT_CONTROL_PAGE_SIZE_64KB 0x2 +#define TI_PAT_CONTROL_PAGE_SIZE_1MB 0x3 + +static unsigned int ti_pat_page_sizes[] = { + [TI_PAT_CONTROL_PAGE_SIZE_4KB] = 4 * 1024, + [TI_PAT_CONTROL_PAGE_SIZE_16KB] = 16 * 1024, + [TI_PAT_CONTROL_PAGE_SIZE_64KB] = 64 * 1024, + [TI_PAT_CONTROL_PAGE_SIZE_1MB] = 1024 * 1024, +}; + +enum ti_pat_mmrs_fields { + /* Revision */ + F_PID_MAJOR, + F_PID_MINOR, + + /* Controls */ + F_CONTROL_ARB_MODE, + F_CONTROL_PAGE_SIZE, + F_CONTROL_REPLACE_OID_EN, + F_CONTROL_EN, + + /* sentinel */ + F_MAX_FIELDS +}; + +static const struct reg_field ti_pat_mmrs_reg_fields[] = { + /* Revision */ + [F_PID_MAJOR] = REG_FIELD(TI_PAT_MMRS_PID, 8, 10), + [F_PID_MINOR] = REG_FIELD(TI_PAT_MMRS_PID, 0, 5), + /* Controls */ + [F_CONTROL_ARB_MODE] = REG_FIELD(TI_PAT_MMRS_CONTROL, 6, 7), + [F_CONTROL_PAGE_SIZE] = REG_FIELD(TI_PAT_MMRS_CONTROL, 4, 5), + [F_CONTROL_REPLACE_OID_EN] = REG_FIELD(TI_PAT_MMRS_CONTROL, 1, 1), + [F_CONTROL_EN] = REG_FIELD(TI_PAT_MMRS_CONTROL, 0, 0), +}; + +/** + * struct ti_pat_data - PAT device instance data + * @dev: PAT device structure + * @mdev: misc device + * @mmrs_map: Register map of MMRS region + * @table_base: Base address of TABLE region + */ +struct ti_pat_data { + struct device *dev; + struct miscdevice mdev; + struct regmap *mmrs_map; + struct regmap_field *mmrs_fields[F_MAX_FIELDS]; + void __iomem *table_base; + unsigned int page_count; + unsigned int page_size; + phys_addr_t window_base; + struct gen_pool *pool; +}; + +struct ti_pat_dma_buf_attachment { + struct device *dev; + struct sg_table *table; + struct ti_pat_buffer *buffer; + struct list_head list; +}; + +struct ti_pat_buffer { + struct ti_pat_data *pat; + struct dma_buf *i_dma_buf; + size_t size; + unsigned long offset; + struct dma_buf *e_dma_buf; + + struct dma_buf_attachment *attachment; + struct sg_table *sgt; + + struct list_head attachments; + int map_count; + + struct mutex lock; +}; + +static const struct regmap_config ti_pat_regmap_config = { + .reg_bits = 32, + .val_bits = 32, + .reg_stride = 4, +}; + +static int ti_pat_dma_buf_attach(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct ti_pat_dma_buf_attachment *a; + struct ti_pat_buffer *buffer = dmabuf->priv; + + a = kzalloc(sizeof(*a), GFP_KERNEL); + if (!a) + return -ENOMEM; + + a->dev = attachment->dev; + a->buffer = buffer; + INIT_LIST_HEAD(&a->list); + + a->table = kzalloc(sizeof(*a->table), GFP_KERNEL); + if (!a->table) { + kfree(a); + return -ENOMEM; + } + + if (sg_alloc_table(a->table, 1, GFP_KERNEL)) { + kfree(a->table); + kfree(a); + return -ENOMEM; + } + + sg_set_page(a->table->sgl, pfn_to_page(PFN_DOWN(buffer->offset)), buffer->size, 0); + + attachment->priv = a; + + mutex_lock(&buffer->lock); + /* First time attachment we attach to parent */ + if (list_empty(&buffer->attachments)) { + buffer->attachment = dma_buf_attach(buffer->i_dma_buf, buffer->pat->dev); + if (IS_ERR(buffer->attachment)) { + dev_err(buffer->pat->dev, "Unable to attach to parent DMA-BUF\n"); + mutex_unlock(&buffer->lock); + kfree(a->table); + kfree(a); + return PTR_ERR(buffer->attachment); + } + } + list_add(&a->list, &buffer->attachments); + mutex_unlock(&buffer->lock); + + return 0; +} + +static void ti_pat_dma_buf_detatch(struct dma_buf *dmabuf, + struct dma_buf_attachment *attachment) +{ + struct ti_pat_dma_buf_attachment *a = attachment->priv; + struct ti_pat_buffer *buffer = dmabuf->priv; + + mutex_lock(&buffer->lock); + list_del(&a->list); + /* Last attachment we detach from parent */ + if (list_empty(&buffer->attachments)) { + dma_buf_detach(buffer->i_dma_buf, buffer->attachment); + buffer->attachment = NULL; + } + mutex_unlock(&buffer->lock); + + kfree(a); +} + +static void ti_pat_set_page(struct ti_pat_data *pat, size_t page_id, dma_addr_t dma_address) +{ + unsigned int j = page_id >> 8; + unsigned int k = page_id & 0xff; + dma_addr_t offset = (j * 0x1000) + (k * 0x8); + void __iomem *table_base_l = pat->table_base + offset; + void __iomem *table_base_h = table_base_l + 0x4; + + u32 base_l = dma_address >> 12; + u32 base_h = (dma_address >> 44) & GENMASK(3, 0); + + dev_dbg(pat->dev, "Enabling PAT index: %zu pointing to %pad\n", page_id, &dma_address); + + writel(base_l, table_base_l); + writel(BIT(31) | base_h, table_base_h); +} + +static void ti_pat_unset_page(struct ti_pat_data *pat, size_t page_id) +{ + unsigned int j = page_id >> 8; + unsigned int k = page_id & 0xff; + dma_addr_t offset = (j * 0x1000) + (k * 0x8); + void __iomem *table_base_l = pat->table_base + offset; + void __iomem *table_base_h = table_base_l + 0x4; + + dev_dbg(pat->dev, "Disabling PAT index: %zu\n", page_id); + + writel(0, table_base_h); +} + +static struct sg_table *ti_pat_map_dma_buf(struct dma_buf_attachment *attachment, + enum dma_data_direction direction) +{ + struct ti_pat_dma_buf_attachment *a = attachment->priv; + struct ti_pat_buffer *buffer = a->buffer; + struct ti_pat_data *pat = buffer->pat; + struct sg_table *table = a->table; + struct scatterlist *s; + unsigned int i, s_len; + size_t page_id; + int ret; + + mutex_lock(&buffer->lock); + /* First time mapping we map to parent */ + if (!buffer->map_count) { + buffer->sgt = dma_buf_map_attachment(buffer->attachment, DMA_BIDIRECTIONAL); + if (IS_ERR(buffer->sgt)) { + dev_err(pat->dev, "Unable to map parent DMA-BUF\n"); + return buffer->sgt; + } + + /* And program PAT area for this set of pages */ + page_id = (buffer->offset - pat->window_base) / pat->page_size; + for_each_sg(buffer->sgt->sgl, s, buffer->sgt->nents, i) { + if (s->offset) { + dev_err(pat->dev, "Cannot use offset buffers\n"); + ret = -EINVAL; + goto unmap; + } + + if (s->length % pat->page_size) { + dev_err(pat->dev, "Cannot use buffers not a multiple of page size\n"); + ret = -EINVAL; + goto unmap; + } + + for (s_len = 0; s_len < s->length; s_len += pat->page_size) + ti_pat_set_page(pat, page_id++, s->dma_address + s_len); + } + } + buffer->map_count++; + mutex_unlock(&buffer->lock); + + /* Map the attached device's table to get DMA addresses */ + if (!dma_map_sg_attrs(attachment->dev, table->sgl, table->nents, direction, DMA_ATTR_SKIP_CPU_SYNC)) + return ERR_PTR(-ENOMEM); + + return table; + +unmap: + dma_buf_unmap_attachment(buffer->attachment, buffer->sgt, DMA_BIDIRECTIONAL); + return ERR_PTR(ret); +} + +static void ti_pat_unmap_dma_buf(struct dma_buf_attachment *attachment, + struct sg_table *table, + enum dma_data_direction direction) +{ + struct ti_pat_dma_buf_attachment *a = attachment->priv; + struct ti_pat_buffer *buffer = a->buffer; + struct ti_pat_data *pat = buffer->pat; + + /* Unmap the attached device's table */ + dma_unmap_sg_attrs(attachment->dev, table->sgl, table->nents, direction, DMA_ATTR_SKIP_CPU_SYNC); + + mutex_lock(&buffer->lock); + buffer->map_count--; + /* Last mapping we unmap from parent */ + if (!buffer->map_count) { + /* Disable PAT pages for this area */ + size_t page_start = (buffer->offset - pat->window_base) / pat->page_size; + size_t page_end = page_start + (buffer->size / pat->page_size); + for (; page_start < page_end; page_start++) + ti_pat_unset_page(pat, page_start); + + dma_buf_unmap_attachment(buffer->attachment, buffer->sgt, DMA_BIDIRECTIONAL); + buffer->sgt = NULL; + } + mutex_unlock(&buffer->lock); +} + +static void ti_pat_dma_buf_release(struct dma_buf *dmabuf) +{ + struct ti_pat_buffer *buffer = dmabuf->priv; + + if (buffer->attachment && buffer->sgt) + dma_buf_unmap_attachment(buffer->attachment, buffer->sgt, DMA_BIDIRECTIONAL); + if (buffer->i_dma_buf && !IS_ERR_OR_NULL(buffer->attachment)) + dma_buf_detach(buffer->i_dma_buf, buffer->attachment); + if (buffer->i_dma_buf) + dma_buf_put(buffer->i_dma_buf); + + if (buffer->offset) + gen_pool_free(buffer->pat->pool, buffer->offset, buffer->size); + + kfree(buffer); +} + +void *ti_pat_dma_buf_map(struct dma_buf *dma_buf, unsigned long page_num) +{ + return NULL; +} + +int ti_pat_dma_buf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma) +{ + return -EINVAL; +} + +static const struct dma_buf_ops dma_buf_ops = { + .attach = ti_pat_dma_buf_attach, + .detach = ti_pat_dma_buf_detatch, + + .map_dma_buf = ti_pat_map_dma_buf, + .unmap_dma_buf = ti_pat_unmap_dma_buf, + + .release = ti_pat_dma_buf_release, + + .map = ti_pat_dma_buf_map, + .mmap = ti_pat_dma_buf_mmap, +}; + +int ti_pat_export(struct ti_pat_data *pat, + struct dma_buf *i_dma_buf, + struct dma_buf **e_dma_buf) +{ + struct ti_pat_buffer *buffer; + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + int ret; + + buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); + if (!buffer) + return -ENOMEM; + + buffer->pat = pat; + buffer->i_dma_buf = i_dma_buf; + buffer->size = buffer->i_dma_buf->size; + mutex_init(&buffer->lock); + INIT_LIST_HEAD(&buffer->attachments); + buffer->map_count = 0; + + /* Reserve PAT space */ + buffer->offset = gen_pool_alloc(buffer->pat->pool, buffer->size); + if (!buffer->offset) { + ret = -ENOMEM; + goto free_buffer; + } + + exp_info.ops = &dma_buf_ops; + exp_info.size = buffer->size; + exp_info.flags = O_RDWR; + exp_info.priv = buffer; + + *e_dma_buf = dma_buf_export(&exp_info); + if (IS_ERR(*e_dma_buf)) { + ret = PTR_ERR(*e_dma_buf); + goto free_pool; + } + + return 0; + +free_pool: + gen_pool_free(buffer->pat->pool, buffer->offset, buffer->size); +free_buffer: + kfree(buffer); + return ret; +} +EXPORT_SYMBOL_GPL(ti_pat_export); + +static long ti_pat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct ti_pat_data *pat = container_of(file->private_data, struct ti_pat_data, mdev); + + switch (cmd) { + case TI_PAT_IOC_EXPORT: + { + struct ti_pat_export_data export; + struct dma_buf *i_dma_buf; + struct dma_buf *e_dma_buf; + int ret; + + if (_IOC_SIZE(cmd) > sizeof(export)) + return -EINVAL; + + if (copy_from_user(&export, (void __user *)arg, _IOC_SIZE(cmd))) + return -EFAULT; + + i_dma_buf = dma_buf_get(export.fd); + if (IS_ERR(i_dma_buf)) + return PTR_ERR(i_dma_buf); + + ret = ti_pat_export(pat, i_dma_buf, &e_dma_buf); + if (ret) { + dma_buf_put(i_dma_buf); + return ret; + } + + export.fd = dma_buf_fd(e_dma_buf, O_CLOEXEC); + if (export.fd < 0) { + dma_buf_put(e_dma_buf); + dma_buf_put(i_dma_buf); + return export.fd; + } + + if (copy_to_user((void __user *)arg, &export, _IOC_SIZE(cmd))) + return -EFAULT; + + break; + } + default: + return -ENOTTY; + } + + return 0; +} + +static const struct file_operations ti_pat_fops = { + .owner = THIS_MODULE, + .unlocked_ioctl = ti_pat_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = ti_pat_ioctl, +#endif +}; + +static const struct of_device_id ti_pat_of_match[] = { + { .compatible = "ti,j721e-pat", }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, ti_pat_of_match); + +static int ti_pat_probe(struct platform_device *pdev) +{ + struct ti_pat_data *pat; + struct resource *res; + void __iomem *base; + unsigned int revision_major; + unsigned int revision_minor; + resource_size_t size; + size_t page_size; + int i, ret; + + pat = devm_kzalloc(&pdev->dev, sizeof(*pat), GFP_KERNEL); + if (!pat) + return -ENOMEM; + platform_set_drvdata(pdev, pat); + pat->dev = &pdev->dev; + + /* MMRS */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + base = devm_ioremap_resource(pat->dev, res); + if (IS_ERR(base)) + return PTR_ERR(base); + + pat->mmrs_map = devm_regmap_init_mmio(pat->dev, base, &ti_pat_regmap_config); + if (IS_ERR(pat->mmrs_map)) { + dev_err(pat->dev, "Unable to allocate MMRS register map\n"); + return PTR_ERR(pat->mmrs_map); + } + + for (i = 0; i < F_MAX_FIELDS; i++) { + pat->mmrs_fields[i] = devm_regmap_field_alloc(pat->dev, pat->mmrs_map, ti_pat_mmrs_reg_fields[i]); + if (IS_ERR(pat->mmrs_fields[i])) { + dev_err(pat->dev, "Unable to allocate Regmap fields\n"); + return PTR_ERR(pat->mmrs_fields[i]); + } + } + + ret = regmap_read(pat->mmrs_map, TI_PAT_MMRS_CONFIG, &pat->page_count); + if (ret) { + dev_err(pat->dev, "Unable to read device page count\n"); + return ret; + } + + ret = regmap_field_read(pat->mmrs_fields[F_PID_MAJOR], &revision_major); + if (ret) { + dev_err(pat->dev, "Unable to read device major revision\n"); + return ret; + } + + ret = regmap_field_read(pat->mmrs_fields[F_PID_MINOR], &revision_minor); + if (ret) { + dev_err(pat->dev, "Unable to read device minor revision\n"); + return ret; + } + + dev_info(pat->dev, "Found PAT Rev %d.%d with %d pages\n", revision_major, revision_minor, pat->page_count); + + /* TABLE */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 1); + if (!res) { + dev_err(pat->dev, "Unable to find TABLE IO resource\n"); + return -ENOENT; + } + size = resource_size(res); + + /* 256 pages per 4KB of table space */ + if (size != (pat->page_count << 4)) + dev_warn(pat->dev, "TABLE region size (%llu) does not match reported page count\n", size); + + pat->table_base = devm_ioremap_resource(pat->dev, res); + if (IS_ERR(base)) + return PTR_ERR(base); + + /* WINDOW */ + res = platform_get_resource(pdev, IORESOURCE_MEM, 2); + if (!res) { + dev_err(pat->dev, "Unable to find WINDOW IO resource\n"); + return -ENOENT; + } + pat->window_base = res->start; + size = resource_size(res); + + pat->page_size = PAGE_SIZE; + for (page_size = 0; page_size < ARRAY_SIZE(ti_pat_page_sizes); page_size++) + if (ti_pat_page_sizes[page_size] == pat->page_size) + break; + if (page_size == ARRAY_SIZE(ti_pat_page_sizes)) { + dev_err(pat->dev, "Unsupported PAGE_SIZE (%d)\n", pat->page_size); + return -EINVAL; + } + regmap_field_write(pat->mmrs_fields[F_CONTROL_PAGE_SIZE], page_size); + + /* Enable this PAT module */ + regmap_field_write(pat->mmrs_fields[F_CONTROL_EN], 1); + + pat->pool = gen_pool_create(PAGE_SHIFT, -1); + if (!pat->pool) + return -ENOMEM; + gen_pool_add(pat->pool, pat->window_base, size, -1); + + pat->mdev.minor = MISC_DYNAMIC_MINOR; + pat->mdev.name = pdev->name; + pat->mdev.fops = &ti_pat_fops; + pat->mdev.parent = NULL; + ret = misc_register(&pat->mdev); + if (ret) { + dev_err(pat->dev, "Unable to register misc device\n"); + return ret; + } + + return 0; +} + +static struct platform_driver ti_pat_driver = { + .probe = ti_pat_probe, + .driver = { + .name = TI_PAT_DRIVER_NAME, + .of_match_table = ti_pat_of_match, + }, +}; +module_platform_driver(ti_pat_driver); + +MODULE_AUTHOR("Andrew F. Davis afd@ti.com"); +MODULE_DESCRIPTION("TI PAT mapped DMA-BUF memory exporter"); +MODULE_LICENSE("GPL v2"); diff --git a/include/uapi/linux/ti-pat.h b/include/uapi/linux/ti-pat.h new file mode 100644 index 000000000000..b06d79454815 --- /dev/null +++ b/include/uapi/linux/ti-pat.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * TI PAT mapped DMA-BUF memory exporter UAPI + * + * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis afd@ti.com + */ + +#ifndef _UAPI_LINUX_TI_PAT_H +#define _UAPI_LINUX_TI_PAT_H + +#include <linux/ioctl.h> +#include <linux/types.h> + +/** + * DOC: TI PAT Userspace API + * + * create a client by opening /dev/ti-pat + * most operations handled via following ioctls + */ + +/** + * struct ti_pat_allocation_data - metadata passed from userspace for allocations + * @fd: populated with DMA-BUF FD for this allocation + * @flags: flags for the allocation + * + * Provided by userspace as an argument to the ioctl + */ +struct ti_pat_export_data { + __u32 fd; + __u32 flags; +}; + +#define TI_PAT_IOC_MAGIC 'P' + +/** + * DOC: TI_PAT_IOC_EXPORT - Re-export DMA-BUF through TI PAT + * + * Takes an ti_pat_export_data struct and returns it with the fd field + * populated with the DMA-BUF handle for the new export. + */ +#define TI_PAT_IOC_EXPORT _IOWR(TI_PAT_IOC_MAGIC, 0, struct ti_pat_export_data) + +#endif /* _UAPI_LINUX_TI_PAT_H */
On 07/06/2019 22:35, Andrew F. Davis wrote:
What is the reasoning for using regmap for internal register access? Why not just use direct readl/writel for everything? To me it seems this is only used during probe time also...
Minor typo: contiguous.
Why do you have a define for this seeing it is only used in single location?
Please add kerneldoc comments for all fields.
Kerneldoc comments for below structs would be also useful, especially for ti_pat_buffer.
Func name should be ti_pat_dma_buf_detach instead?
Other than that, I can't see anything obvious with my limited experience with dma_buf. Is there a simple way to test this driver btw?
-Tero
-- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
On 6/18/19 5:07 AM, Tero Kristo wrote:
There are two register spaces, the configuration space, and the actual translation table data. I use regmap for all the configuration space. Direct readl/writel would also work, but I prefer regmap as it lets me work with field names vs using masks and shifts, even if it adds a little extra code in tables at the top.
ACK
Just habit when starting a driver, but you are right it is not needed here.
Will add.
Will add.
Good catch, will fix.
Other than that, I can't see anything obvious with my limited experience with dma_buf. Is there a simple way to test this driver btw?
Simple way? No not really.. What I've been doing is allocating a non-contiguous buffer (from system DMA-BUF heaps), writing some test pattern to it, using this driver to convert the buffer, then sending the new handle to our DSS (display subsystem which cannot handle non-contiguous buffers). If all is working the test pattern is displayed correctly.
Thanks, Andrew
On 07/06/2019 20:35, Andrew F. Davis wrote:
FWIW, that sounds almost exactly like my (vague) understanding of other GARTs, and as such should be pretty well manageable via the IOMMU API - we already have tegra-gart, for example. The aperture contention issue could certainly be mitigated by letting the firmware claim it's only associated with the display and any other devices which really need it.
A further interesting avenue of investigation - now that Christoph's recent work has made it much more possible - would be a second set of IOMMU DMA ops tailored for "GART-like" domains where force_aperture=0, which could behave as dma-direct wherever possible and only use IOMMU remaps when absolutely necessary.
Robin.
dri-devel@lists.freedesktop.org
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Andrew F. Davis -
Robin Murphy -
Tero Kristo