[PATCH v9 3/3] of: Respect #{iommu,msi}-cells in maps

[Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>]

From: Robin Murphy <robin.murphy@xxxxxxx>

So far our parsing of {iommu,msi}-map properites 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.
Added support for that part --charan

Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
Signed-off-by: Charan Teja Kalla <charan.kalla@xxxxxxxxxxxxxxxx>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@xxxxxxxxxxxxxxxx>
---
 drivers/iommu/of_iommu.c |   2 +-
 drivers/of/base.c        | 117 +++++++++++++++++++++++++++++++++++++----------
 include/linux/of.h       |  16 +++----
 3 files changed, 102 insertions(+), 33 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index d255d0f58e8c..a18bb60f6f3d 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -45,7 +45,7 @@ static int of_iommu_configure_dev_id(struct device_node 
*master_np,
                                     struct device *dev,
                                     const u32 *id)
 {
-       struct of_phandle_args iommu_spec = { .args_count = 1 };
+       struct of_phandle_args iommu_spec = {};
        int err;
 
        err = of_map_iommu_id(master_np, *id, &iommu_spec);
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 6c3628255908..596bcf993dcb 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2096,11 +2096,38 @@ 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.
  * @arg: of_phandle_args structure,
  *     which includes:
@@ -2118,18 +2145,19 @@ 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,
-              struct of_phandle_args *arg)
+int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+             const char *cells_name, const char *map_mask_name,
+             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)
                return -EINVAL;
 
-       map = of_get_property(np, map_name, &map_len);
+       map = of_get_property(np, map_name, &map_bytes);
        if (!map) {
                if (arg->np)
                        return -ENODEV;
@@ -2138,11 +2166,9 @@ 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;
@@ -2155,27 +2181,63 @@ 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;
 
+               if (!bad_map && of_property_read_u32(phandle_node, cells_name, 
&cells)) {
+                       pr_err("%pOF: missing %s property\n", phandle_node, 
cells_name);
+                       return -EINVAL;
+               }
+
+               if (map_len - offset < 3 + cells)
+                       goto err_map_len;
+
+               if (offset == 0 && cells == 2) {
+                       bad_map = of_check_bad_map(map, map_len);
+                       if (bad_map) {
+                               pr_warn_once("%pOF: %s mismatches target %s, 
assuming extra cell of 0\n",
+                                            np, map_name, cells_name);
+                               cells = 1;
+                       }
+               }
+
+               out_base = map + offset + 2;
+               offset += 3 + cells;
+
+               id_len = be32_to_cpup(map + offset - 1);
+               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);
+                       return -EINVAL;
+               }
+               id_off = masked_id - id_base;
+               if (masked_id < id_base || id_off >= id_len)
+                       continue;
+
                if (arg->np)
                        of_node_put(phandle_node);
                else
@@ -2184,11 +2246,14 @@ int of_map_id(const struct device_node *np, u32 id,
                if (arg->np != phandle_node)
                        continue;
 
-               arg->args[0] = masked_id - id_base + out_base;
+               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, 
be32_to_cpup(out_base),
+                        id_len, id, id_off + be32_to_cpup(out_base));
                return 0;
        }
 
@@ -2198,5 +2263,9 @@ int of_map_id(const struct device_node *np, u32 id,
        /* Bypasses translation */
        arg->args[0] = id;
        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);
diff --git a/include/linux/of.h b/include/linux/of.h
index 9d72d76f909d..5b5b5dc2d3f3 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -461,9 +461,9 @@ 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,
-              struct of_phandle_args *arg);
+int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+             const char *cells_name, const char *map_mask_name,
+             struct of_phandle_args *arg);
 
 phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
 
@@ -927,9 +927,9 @@ 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,
-                            struct of_phandle_args *arg)
+static inline int of_map_id(const struct device_node *np, u32 id, const char 
*map_name,
+                           const char *cells_name, const char *map_mask_name,
+                           struct of_phandle_args *arg)
 {
        return -EINVAL;
 }
@@ -1460,7 +1460,7 @@ static inline int of_property_read_s32(const struct 
device_node *np,
 static inline 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", arg);
+       return of_map_id(np, id, "iommu-map", "#iommu-cells", "iommu-map-mask", 
arg);
 }
 
 static inline int of_map_msi_id(const struct device_node *np, u32 id,
@@ -1469,7 +1469,7 @@ static inline int of_map_msi_id(const struct device_node 
*np, u32 id,
        struct of_phandle_args msi_spec = { .np = *target, .args_count = 1 };
        int ret;
 
-       ret = of_map_id(np, id, "msi-map", "msi-map-mask", &msi_spec);
+       ret = of_map_id(np, id, "msi-map", "#msi-cells", "msi-map-mask", 
&msi_spec);
        if (!ret) {
                *target = msi_spec.np;
                *id_out = msi_spec.args[0];

-- 
2.34.1