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of: Respect #{iommu,msi}-cells in maps

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So far our parsing of {iommu,msi}-map properties has always blindly
assumed that the output specifiers will always have exactly 1 cell.
This typically does happen to be the case, but is not actually enforced
(and the PCI msi-map binding even explicitly states support for 0 or 1
cells) - as a result we've now ended up with dodgy DTs out in the field
which depend on this behaviour to map a 1-cell specifier for a 2-cell
provider, despite that being bogus per the bindings themselves.

Since there is some potential use in being able to map at least single
input IDs to multi-cell output specifiers (and properly support 0-cell
outputs as well), add support for properly parsing and using the target
nodes' #cells values, albeit with the unfortunate complication of still
having to work around expectations of the old behaviour too.

Since there are multi-cell output specifiers, the callers of of_map_id()
may need to get the exact cell output value for further processing.
Update of_map_id() to set args_count in the output to reflect the actual
number of output specifier cells.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
Link: https://patch.msgid.link/20260603-parse_iommu_cells-v16-3-dc509dacb19a@oss.qualcomm.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
This commit is contained in:
Robin Murphy
2026-06-03 12:43:14 +05:30
committed by Rob Herring (Arm)
parent f71f07bee9
commit ccb2fd725d
2 changed files with 135 additions and 39 deletions
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168
drivers/of/base.c
View File

@@ -2125,19 +2125,49 @@ int of_find_last_cache_level(unsigned int cpu)
return cache_level;
}
/*
* Some DTs have an iommu-map targeting a 2-cell IOMMU node while
* specifying only 1 cell. Fortunately they all consist of value '1'
* as the 2nd cell entry with the same target, so check for that pattern.
*
* Example:
* IOMMU node:
* #iommu-cells = <2>;
*
* Device node:
* iommu-map = <0x0000 &smmu 0x0000 0x1>,
* <0x0100 &smmu 0x0100 0x1>;
*/
static bool of_check_bad_map(const __be32 *map, int len)
{
__be32 phandle = map[1];
if (len % 4)
return false;
for (int i = 0; i < len; i += 4) {
if (map[i + 1] != phandle || map[i + 3] != cpu_to_be32(1))
return false;
}
return true;
}
/**
* of_map_id - Translate an ID through a downstream mapping.
* @np: root complex device node.
* @id: device ID to map.
* @map_name: property name of the map to use.
* @cells_name: property name of target specifier cells.
* @map_mask_name: optional property name of the mask to use.
* @filter_np: pointer to an optional filter node, or NULL to allow bypass.
* If non-NULL, the map property must exist (-ENODEV if absent). If
* *filter_np is also non-NULL, only entries targeting that node match.
* @arg: pointer to a &struct of_phandle_args for the result. On success,
* @arg->args[0] will contain the translated ID. If a map entry was
* matched, @arg->np will be set to the target node with a reference
* held that the caller must release with of_node_put().
* @arg->args_count will be set to the number of output specifier cells
* as defined by @cells_name in the target node, and
* @arg->args[0..args_count-1] will contain the translated output
* specifier values. If a map entry was matched, @arg->np will be set
* to the target node with a reference held that the caller must release
* with of_node_put().
*
* Given a device ID, look up the appropriate implementation-defined
* platform ID and/or the target device which receives transactions on that
@@ -2146,19 +2176,21 @@ int of_find_last_cache_level(unsigned int cpu)
* Return: 0 on success or a standard error code on failure.
*/
int of_map_id(const struct device_node *np, u32 id,
const char *map_name, const char *map_mask_name,
const char *map_name, const char *cells_name,
const char *map_mask_name,
struct device_node * const *filter_np, struct of_phandle_args *arg)
{
u32 map_mask, masked_id;
int map_len;
int map_bytes, map_len, offset = 0;
bool bad_map = false;
const __be32 *map = NULL;
if (!np || !map_name || !arg)
if (!np || !map_name || !cells_name || !arg)
return -EINVAL;
/* Ensure bypass/no-match success never returns a stale target node. */
arg->np = NULL;
map = of_get_property(np, map_name, &map_len);
map = of_get_property(np, map_name, &map_bytes);
if (!map) {
if (filter_np)
return -ENODEV;
@@ -2168,11 +2200,9 @@ int of_map_id(const struct device_node *np, u32 id,
return 0;
}
if (!map_len || map_len % (4 * sizeof(*map))) {
pr_err("%pOF: Error: Bad %s length: %d\n", np,
map_name, map_len);
return -EINVAL;
}
if (map_bytes % sizeof(*map))
goto err_map_len;
map_len = map_bytes / sizeof(*map);
/* The default is to select all bits. */
map_mask = 0xffffffff;
@@ -2185,39 +2215,93 @@ int of_map_id(const struct device_node *np, u32 id,
of_property_read_u32(np, map_mask_name, &map_mask);
masked_id = map_mask & id;
for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
while (offset < map_len) {
struct device_node *phandle_node;
u32 id_base = be32_to_cpup(map + 0);
u32 phandle = be32_to_cpup(map + 1);
u32 out_base = be32_to_cpup(map + 2);
u32 id_len = be32_to_cpup(map + 3);
u32 id_base, phandle, id_len, id_off, cells = 0;
const __be32 *out_base;
if (map_len - offset < 2)
goto err_map_len;
id_base = be32_to_cpup(map + offset);
if (id_base & ~map_mask) {
pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
np, map_name, map_name,
map_mask, id_base);
pr_err("%pOF: Invalid %s translation - %s (0x%x) ignores id-base (0x%x)\n",
np, map_name, map_mask_name, map_mask, id_base);
return -EFAULT;
}
if (masked_id < id_base || masked_id >= id_base + id_len)
continue;
phandle = be32_to_cpup(map + offset + 1);
phandle_node = of_find_node_by_phandle(phandle);
if (!phandle_node)
return -ENODEV;
/*
* Assume 1-cell output specifier if the target node lacks the
* #cells property, for backward compatibility with controllers
* that predate the property (e.g. arm,gic-v2m-frame).
*/
if (bad_map || of_property_read_u32(phandle_node, cells_name, &cells))
cells = 1;
if (cells > MAX_PHANDLE_ARGS) {
pr_err("%pOF: %s cell count %d exceeds maximum\n",
phandle_node, cells_name, cells);
of_node_put(phandle_node);
return -EINVAL;
}
if (offset == 0 && cells == 2) {
bad_map = of_check_bad_map(map, map_len);
if (bad_map) {
pr_warn_once("%pOF: %s has 1-cell entries targeting 2-cell %s, treating as 1-cell output\n",
np, map_name, cells_name);
cells = 1;
}
}
if (map_len - offset < 3 + cells) {
of_node_put(phandle_node);
goto err_map_len;
}
out_base = map + offset + 2;
offset += 3 + cells;
id_len = be32_to_cpup(map + offset - 1);
id_off = masked_id - id_base;
if (masked_id < id_base || id_off >= id_len) {
of_node_put(phandle_node);
continue;
}
if (id_len > 1 && cells > 1) {
/*
* With 1 output cell we reasonably assume its value
* has a linear relationship to the input; with more,
* we'd need help from the provider to know what to do.
*/
pr_err("%pOF: Unsupported %s - cannot handle %d-ID range with %d-cell output specifier\n",
np, map_name, id_len, cells);
of_node_put(phandle_node);
return -EINVAL;
}
if (filter_np && *filter_np && *filter_np != phandle_node) {
of_node_put(phandle_node);
continue;
}
arg->np = phandle_node;
arg->args[0] = masked_id - id_base + out_base;
arg->args_count = 1;
for (int i = 0; i < cells; i++)
arg->args[i] = id_off + be32_to_cpu(out_base[i]);
arg->args_count = cells;
pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
np, map_name, map_mask, id_base, out_base,
id_len, id, masked_id - id_base + out_base);
np, map_name, map_mask, id_base,
cells ? be32_to_cpup(out_base) : 0,
id_len, id,
cells ? id_off + be32_to_cpup(out_base) : id_off);
return 0;
}
@@ -2228,6 +2312,10 @@ int of_map_id(const struct device_node *np, u32 id,
arg->args[0] = id;
arg->args_count = 1;
return 0;
err_map_len:
pr_err("%pOF: Error: Bad %s length: %d\n", np, map_name, map_bytes);
return -EINVAL;
}
EXPORT_SYMBOL_GPL(of_map_id);
@@ -2237,18 +2325,21 @@ EXPORT_SYMBOL_GPL(of_map_id);
* @id: Requester ID of the device (e.g. PCI RID/BDF or a platform
* stream/device ID) used as the lookup key in the iommu-map table.
* @arg: pointer to a &struct of_phandle_args for the result. On success,
* @arg->args[0] contains the translated ID. If a map entry was matched,
* @arg->np holds a reference to the target node that the caller must
* release with of_node_put().
* @arg->args_count will be set to the number of output specifier cells
* and @arg->args[0..args_count-1] will contain the translated output
* specifier values. If a map entry was matched, @arg->np holds a
* reference to the target node that the caller must release with
* of_node_put().
*
* Convenience wrapper around of_map_id() using "iommu-map" and "iommu-map-mask".
* Convenience wrapper around of_map_id() using "iommu-map", "#iommu-cells",
* and "iommu-map-mask".
*
* Return: 0 on success or a standard error code on failure.
*/
int of_map_iommu_id(const struct device_node *np, u32 id,
struct of_phandle_args *arg)
{
return of_map_id(np, id, "iommu-map", "iommu-map-mask", NULL, arg);
return of_map_id(np, id, "iommu-map", "#iommu-cells", "iommu-map-mask", NULL, arg);
}
EXPORT_SYMBOL_GPL(of_map_iommu_id);
@@ -2261,17 +2352,20 @@ EXPORT_SYMBOL_GPL(of_map_iommu_id);
* If non-NULL, the map property must exist (-ENODEV if absent). If
* *filter_np is also non-NULL, only entries targeting that node match.
* @arg: pointer to a &struct of_phandle_args for the result. On success,
* @arg->args[0] contains the translated ID. If a map entry was matched,
* @arg->np holds a reference to the target node that the caller must
* release with of_node_put().
* @arg->args_count will be set to the number of output specifier cells
* and @arg->args[0..args_count-1] will contain the translated output
* specifier values. If a map entry was matched, @arg->np holds a
* reference to the target node that the caller must release with
* of_node_put().
*
* Convenience wrapper around of_map_id() using "msi-map" and "msi-map-mask".
* Convenience wrapper around of_map_id() using "msi-map", "#msi-cells",
* and "msi-map-mask".
*
* Return: 0 on success or a standard error code on failure.
*/
int of_map_msi_id(const struct device_node *np, u32 id,
struct device_node * const *filter_np, struct of_phandle_args *arg)
{
return of_map_id(np, id, "msi-map", "msi-map-mask", filter_np, arg);
return of_map_id(np, id, "msi-map", "#msi-cells", "msi-map-mask", filter_np, arg);
}
EXPORT_SYMBOL_GPL(of_map_msi_id);

6
include/linux/of.h
View File

@@ -465,7 +465,8 @@ const char *of_prop_next_string(const struct property *prop, const char *cur);
bool of_console_check(const struct device_node *dn, char *name, int index);
int of_map_id(const struct device_node *np, u32 id,
const char *map_name, const char *map_mask_name,
const char *map_name, const char *cells_name,
const char *map_mask_name,
struct device_node * const *filter_np,
struct of_phandle_args *arg);
@@ -950,7 +951,8 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
}
static inline int of_map_id(const struct device_node *np, u32 id,
const char *map_name, const char *map_mask_name,
const char *map_name, const char *cells_name,
const char *map_mask_name,
struct device_node * const *filter_np,
struct of_phandle_args *arg)
{