From: Thierry Reding treding@nvidia.com
This function can be used to add subnodes in the /reserved-memory node.
Reviewed-by: Simon Glass sjg@chromium.org Signed-off-by: Thierry Reding treding@nvidia.com --- Changes in v3: - use fdt_generate_phandle() instead of fdtdec_generate_phandle() - add device tree bindings for /reserved-memory - add examples to code comments
Changes in v2: - split fdt_{addr,size}_unpack() helpers into separate patch - use name@x,y notation only if the upper cell is > 0 - use debug() instead of printf() to save code size - properly compute number of cells in reg property - fix carveout size computations, was off by one - use #size-cells where appropriate
.../reserved-memory/reserved-memory.txt | 136 ++++++++++++++++++ include/fdtdec.h | 48 +++++++ lib/fdtdec.c | 131 +++++++++++++++++ 3 files changed, 315 insertions(+) create mode 100644 Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt new file mode 100644 index 000000000000..bac4afa3b197 --- /dev/null +++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt @@ -0,0 +1,136 @@ +*** Reserved memory regions *** + +Reserved memory is specified as a node under the /reserved-memory node. +The operating system shall exclude reserved memory from normal usage +one can create child nodes describing particular reserved (excluded from +normal use) memory regions. Such memory regions are usually designed for +the special usage by various device drivers. + +Parameters for each memory region can be encoded into the device tree +with the following nodes: + +/reserved-memory node +--------------------- +#address-cells, #size-cells (required) - standard definition + - Should use the same values as the root node +ranges (required) - standard definition + - Should be empty + +/reserved-memory/ child nodes +----------------------------- +Each child of the reserved-memory node specifies one or more regions of +reserved memory. Each child node may either use a 'reg' property to +specify a specific range of reserved memory, or a 'size' property with +optional constraints to request a dynamically allocated block of memory. + +Following the generic-names recommended practice, node names should +reflect the purpose of the node (ie. "framebuffer" or "dma-pool"). Unit +address (@<address>) should be appended to the name if the node is a +static allocation. + +Properties: +Requires either a) or b) below. +a) static allocation + reg (required) - standard definition +b) dynamic allocation + size (required) - length based on parent's #size-cells + - Size in bytes of memory to reserve. + alignment (optional) - length based on parent's #size-cells + - Address boundary for alignment of allocation. + alloc-ranges (optional) - prop-encoded-array (address, length pairs). + - Specifies regions of memory that are + acceptable to allocate from. + +If both reg and size are present, then the reg property takes precedence +and size is ignored. + +Additional properties: +compatible (optional) - standard definition + - may contain the following strings: + - shared-dma-pool: This indicates a region of memory meant to be + used as a shared pool of DMA buffers for a set of devices. It can + be used by an operating system to instantiate the necessary pool + management subsystem if necessary. + - vendor specific string in the form <vendor>,[<device>-]<usage> +no-map (optional) - empty property + - Indicates the operating system must not create a virtual mapping + of the region as part of its standard mapping of system memory, + nor permit speculative access to it under any circumstances other + than under the control of the device driver using the region. +reusable (optional) - empty property + - The operating system can use the memory in this region with the + limitation that the device driver(s) owning the region need to be + able to reclaim it back. Typically that means that the operating + system can use that region to store volatile or cached data that + can be otherwise regenerated or migrated elsewhere. + +Linux implementation note: +- If a "linux,cma-default" property is present, then Linux will use the + region for the default pool of the contiguous memory allocator. + +- If a "linux,dma-default" property is present, then Linux will use the + region for the default pool of the consistent DMA allocator. + +Device node references to reserved memory +----------------------------------------- +Regions in the /reserved-memory node may be referenced by other device +nodes by adding a memory-region property to the device node. + +memory-region (optional) - phandle, specifier pairs to children of /reserved-memory + +Example +------- +This example defines 3 contiguous regions are defined for Linux kernel: +one default of all device drivers (named linux,cma@72000000 and 64MiB in size), +one dedicated to the framebuffer device (named framebuffer@78000000, 8MiB), and +one for multimedia processing (named multimedia-memory@77000000, 64MiB). + +/ { + #address-cells = <1>; + #size-cells = <1>; + + memory { + reg = <0x40000000 0x40000000>; + }; + + reserved-memory { + #address-cells = <1>; + #size-cells = <1>; + ranges; + + /* global autoconfigured region for contiguous allocations */ + linux,cma { + compatible = "shared-dma-pool"; + reusable; + size = <0x4000000>; + alignment = <0x2000>; + linux,cma-default; + }; + + display_reserved: framebuffer@78000000 { + reg = <0x78000000 0x800000>; + }; + + multimedia_reserved: multimedia@77000000 { + compatible = "acme,multimedia-memory"; + reg = <0x77000000 0x4000000>; + }; + }; + + /* ... */ + + fb0: video@12300000 { + memory-region = <&display_reserved>; + /* ... */ + }; + + scaler: scaler@12500000 { + memory-region = <&multimedia_reserved>; + /* ... */ + }; + + codec: codec@12600000 { + memory-region = <&multimedia_reserved>; + /* ... */ + }; +}; diff --git a/include/fdtdec.h b/include/fdtdec.h index 55600026c488..b54ed38fb362 100644 --- a/include/fdtdec.h +++ b/include/fdtdec.h @@ -992,6 +992,54 @@ int fdtdec_setup_memory_banksize(void); */ int fdtdec_set_phandle(void *blob, int node, uint32_t phandle);
+/** + * fdtdec_add_reserved_memory() - add or find a reserved-memory node + * + * If a reserved-memory node already exists for the given carveout, a phandle + * for that node will be returned. Otherwise a new node will be created and a + * phandle corresponding to it will be returned. + * + * See Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt + * for details on how to use reserved memory regions. + * + * As an example, consider the following code snippet: + * + * struct fdt_memory fb = { + * .start = 0x92cb3000, + * .end = 0x934b2fff, + * }; + * uint32_t phandle; + * + * fdtdec_add_reserved_memory(fdt, "framebuffer", &fb, &phandle); + * + * This results in the following subnode being added to the top-level + * /reserved-memory node: + * + * reserved-memory { + * #address-cells = <0x00000002>; + * #size-cells = <0x00000002>; + * ranges; + * + * framebuffer@92cb3000 { + * reg = <0x00000000 0x92cb3000 0x00000000 0x00800000>; + * phandle = <0x0000004d>; + * }; + * }; + * + * If the top-level /reserved-memory node does not exist, it will be created. + * The phandle returned from the function call can be used to reference this + * reserved memory region from other nodes. + * + * @param blob FDT blob + * @param basename base name of the node to create + * @param carveout information about the carveout region + * @param phandlep return location for the phandle of the carveout region + * @return 0 on success or a negative error code on failure + */ +int fdtdec_add_reserved_memory(void *blob, const char *basename, + const struct fdt_memory *carveout, + uint32_t *phandlep); + /** * Set up the device tree ready for use */ diff --git a/lib/fdtdec.c b/lib/fdtdec.c index 00db90e3cdfd..be54ad5bd092 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -1250,6 +1250,137 @@ int fdtdec_set_phandle(void *blob, int node, uint32_t phandle) return fdt_setprop(blob, node, "phandle", &value, sizeof(value)); }
+static int fdtdec_init_reserved_memory(void *blob) +{ + int na, ns, node, err; + fdt32_t value; + + /* inherit #address-cells and #size-cells from the root node */ + na = fdt_address_cells(blob, 0); + ns = fdt_size_cells(blob, 0); + + node = fdt_add_subnode(blob, 0, "reserved-memory"); + if (node < 0) + return node; + + err = fdt_setprop(blob, node, "ranges", NULL, 0); + if (err < 0) + return err; + + value = cpu_to_fdt32(ns); + + err = fdt_setprop(blob, node, "#size-cells", &value, sizeof(value)); + if (err < 0) + return err; + + value = cpu_to_fdt32(na); + + err = fdt_setprop(blob, node, "#address-cells", &value, sizeof(value)); + if (err < 0) + return err; + + return node; +} + +int fdtdec_add_reserved_memory(void *blob, const char *basename, + const struct fdt_memory *carveout, + uint32_t *phandlep) +{ + fdt32_t cells[4] = {}, *ptr = cells; + uint32_t upper, lower, phandle; + int parent, node, na, ns, err; + char name[64]; + + /* create an empty /reserved-memory node if one doesn't exist */ + parent = fdt_path_offset(blob, "/reserved-memory"); + if (parent < 0) { + parent = fdtdec_init_reserved_memory(blob); + if (parent < 0) + return parent; + } + + /* only 1 or 2 #address-cells and #size-cells are supported */ + na = fdt_address_cells(blob, parent); + if (na < 1 || na > 2) + return -FDT_ERR_BADNCELLS; + + ns = fdt_size_cells(blob, parent); + if (ns < 1 || ns > 2) + return -FDT_ERR_BADNCELLS; + + /* find a matching node and return the phandle to that */ + fdt_for_each_subnode(node, blob, parent) { + const char *name = fdt_get_name(blob, node, NULL); + phys_addr_t addr, size; + + addr = fdtdec_get_addr_size(blob, node, "reg", &size); + if (addr == FDT_ADDR_T_NONE) { + debug("failed to read address/size for %s\n", name); + continue; + } + + if (addr == carveout->start && (addr + size) == carveout->end) { + *phandlep = fdt_get_phandle(blob, node); + return 0; + } + } + + /* + * Unpack the start address and generate the name of the new node + * base on the basename and the unit-address. + */ + lower = fdt_addr_unpack(carveout->start, &upper); + + if (na > 1 && upper > 0) + snprintf(name, sizeof(name), "%s@%x,%x", basename, upper, + lower); + else { + if (upper > 0) { + debug("address %08x:%08x exceeds addressable space\n", + upper, lower); + return -FDT_ERR_BADVALUE; + } + + snprintf(name, sizeof(name), "%s@%x", basename, lower); + } + + node = fdt_add_subnode(blob, parent, name); + if (node < 0) + return node; + + err = fdt_generate_phandle(blob, &phandle); + if (err < 0) + return err; + + err = fdtdec_set_phandle(blob, node, phandle); + if (err < 0) + return err; + + /* store one or two address cells */ + if (na > 1) + *ptr++ = cpu_to_fdt32(upper); + + *ptr++ = cpu_to_fdt32(lower); + + /* store one or two size cells */ + lower = fdt_size_unpack(carveout->end - carveout->start + 1, &upper); + + if (ns > 1) + *ptr++ = cpu_to_fdt32(upper); + + *ptr++ = cpu_to_fdt32(lower); + + err = fdt_setprop(blob, node, "reg", cells, (na + ns) * sizeof(*cells)); + if (err < 0) + return err; + + /* return the phandle for the new node for the caller to use */ + if (phandlep) + *phandlep = phandle; + + return 0; +} + int fdtdec_setup(void) { #if CONFIG_IS_ENABLED(OF_CONTROL)