of: property: Fix fw_devlink handling of interrupt-map

Commit d976c6f4b32c ("of: property: Add fw_devlink support for
interrupt-map property") tried to do what it says on the tin,
but failed on a couple of points:

- it confuses bytes and cells. Not a huge deal, except when it
  comes to pointer arithmetic

- it doesn't really handle anything but interrupt-maps that have
  their parent #address-cells set to 0

The combinations of the two leads to some serious fun on my M1
box, with plenty of WARN-ON() firing all over the shop, and
amusing values being generated for interrupt specifiers.

Having 2 versions of parsing code for "interrupt-map" was a bad
idea. Now that the common parsing parts have been refactored
into of_irq_parse_imap_parent(), rework the code here to use it
instead and fix the pointer arithmetic.

Note that the dependency will be a bit different than the original code
when the interrupt-map points to another interrupt-map. In this case,
the original code would resolve to the final interrupt controller. Now
the dependency is the parent interrupt-map (which itself should have a
dependency to the parent). It is possible that a node with an
interrupt-map has no driver.

Fixes: d976c6f4b32c ("of: property: Add fw_devlink support for interrupt-map property")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Co-developed-by: Rob Herring (Arm) <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Tested-by: Anup Patel <apatel@ventanamicro.com>
Link: https://lore.kernel.org/r/20240529-dt-interrupt-map-fix-v2-2-ef86dc5bcd2a@kernel.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

diff --git a/drivers/of/property.c b/drivers/of/property.c
index 1c83e68f805baa50af98da953a6434740e8892c9..164d77cb944585d6da7d4931a9fe5a121892841e 100644 (file)
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1306,10 +1306,10 @@ static struct device_node *parse_interrupts(struct device_node *np,
 static struct device_node *parse_interrupt_map(struct device_node *np,
                                               const char *prop_name, int index)
 {
-       const __be32 *imap, *imap_end, *addr;
+       const __be32 *imap, *imap_end;
        struct of_phandle_args sup_args;
        u32 addrcells, intcells;
-       int i, imaplen;
+       int imaplen;
 
        if (!IS_ENABLED(CONFIG_OF_IRQ))
                return NULL;
@@ -1322,33 +1322,23 @@ static struct device_node *parse_interrupt_map(struct device_node *np,
        addrcells = of_bus_n_addr_cells(np);
 
        imap = of_get_property(np, "interrupt-map", &imaplen);
-       if (!imap || imaplen <= (addrcells + intcells))
+       imaplen /= sizeof(*imap);
+       if (!imap)
                return NULL;
-       imap_end = imap + imaplen;
 
-       while (imap < imap_end) {
-               addr = imap;
-               imap += addrcells;
+       imap_end = imap + imaplen;
 
-               sup_args.np = np;
-               sup_args.args_count = intcells;
-               for (i = 0; i < intcells; i++)
-                       sup_args.args[i] = be32_to_cpu(imap[i]);
-               imap += intcells;
+       for (int i = 0; imap + addrcells + intcells + 1 < imap_end; i++) {
+               imap += addrcells + intcells;
 
-               /*
-                * Upon success, the function of_irq_parse_raw() returns
-                * interrupt controller DT node pointer in sup_args.np.
-                */
-               if (of_irq_parse_raw(addr, &sup_args))
+               imap = of_irq_parse_imap_parent(imap, imap_end - imap, &sup_args);
+               if (!imap)
                        return NULL;
 
-               if (!index)
+               if (i == index)
                        return sup_args.np;
 
                of_node_put(sup_args.np);
-               imap += sup_args.args_count + 1;
-               index--;
        }
 
        return NULL;