fdtdec: Implement fdtdec_add_reserved_memory()

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>
This commit is contained in:
Thierry Reding 2019-03-21 19:10:02 +01:00 committed by Simon Glass
parent 8153d53b93
commit c9222a08b3
3 changed files with 315 additions and 0 deletions

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@ -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>;
/* ... */
};
};

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@ -1031,6 +1031,54 @@ 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
*/

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@ -1268,6 +1268,137 @@ 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)