[Xen-devel] [PATCH v2 1/3] xen: dt: add dt_for_each_irq_map helper

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

This function iterates over a nodes interrupt-map property and calls a
callback for each interrupt. For now it only supplies the raw IRQ
since my use case has no need of e.g. child unit address. These can be
added as needed by any future users.

This follows much the same logic as dt_irq_map_raw when parsing the
interrupt-map, but doesn't walk up the tree doing the actual
translation and it iterates over all entries instead of just looking
for the first match.

I looked into refactoring dt_irq_map_raw but I couldn't find a way
which I was confident in, plus I was reluctant to diverge from the
Linux roots of this function any further.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/common/device_tree.c      |  140 +++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/device_tree.h |   12 ++++
 2 files changed, 152 insertions(+)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 89491b2..ecc67da 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -816,6 +816,146 @@ unsigned int dt_number_of_address(const struct 
dt_device_node *dev)
     return (psize / onesize);
 }
 
+int dt_for_each_irq_map(const struct dt_device_node *dev,
+                        int (*cb)(const struct dt_device_node *,
+                                  const struct dt_raw_irq *,
+                                  void *),
+                        void *data)
+{
+    const struct dt_device_node *ipar, *tnode, *old = NULL;
+    const __be32 *tmp, *imap;
+    u32 intsize = 1, addrsize, pintsize = 0, paddrsize = 0;
+    u32 imaplen;
+    int i, ret;
+
+    struct dt_raw_irq dt_raw_irq;
+
+    dt_dprintk("%s: par=%s cb=%p data=%p\n", __func__,
+               dev->full_name, cb, data);
+
+    ipar = dev;
+
+    /* First get the #interrupt-cells property of the current cursor
+     * that tells us how to interpret the passed-in intspec. If there
+     * is none, we are nice and just walk up the tree
+     */
+    do {
+        tmp = dt_get_property(ipar, "#interrupt-cells", NULL);
+        if ( tmp != NULL )
+        {
+            intsize = be32_to_cpu(*tmp);
+            break;
+        }
+        tnode = ipar;
+        ipar = dt_irq_find_parent(ipar);
+    } while ( ipar );
+    if ( ipar == NULL )
+    {
+        dt_dprintk(" -> no parent found !\n");
+        goto fail;
+    }
+
+    dt_dprintk("%s: ipar=%s, size=%d\n", __func__, ipar->full_name, intsize);
+
+    if ( intsize > DT_MAX_IRQ_SPEC )
+    {
+        dt_dprintk(" -> too many irq specifier cells\n");
+        goto fail;
+    }
+
+    /* Look for this #address-cells. We have to implement the old linux
+     * trick of looking for the parent here as some device-trees rely on it
+     */
+    old = ipar;
+    do {
+        tmp = dt_get_property(old, "#address-cells", NULL);
+        tnode = dt_get_parent(old);
+        old = tnode;
+    } while ( old && tmp == NULL );
+
+    old = NULL;
+    addrsize = (tmp == NULL) ? 2 : be32_to_cpu(*tmp);
+
+    dt_dprintk(" -> addrsize=%d\n", addrsize);
+
+    /* Now look for an interrupt-map */
+    imap = dt_get_property(dev, "interrupt-map", &imaplen);
+    /* No interrupt map, check for an interrupt parent */
+    if ( imap == NULL )
+    {
+        dt_dprintk(" -> no map, ignoring\n");
+        goto fail;
+    }
+    imaplen /= sizeof(u32);
+
+    /* Parse interrupt-map */
+    while ( imaplen > (addrsize + intsize + 1) )
+    {
+        /* skip child unit address and child interrupt specifier */
+        imap += addrsize + intsize;
+        imaplen -= addrsize + intsize;
+
+        /* Get the interrupt parent */
+        ipar = dt_find_node_by_phandle(be32_to_cpup(imap));
+        imap++;
+        --imaplen;
+
+        /* Check if not found */
+        if ( ipar == NULL )
+        {
+            dt_dprintk(" -> imap parent not found !\n");
+            goto fail;
+        }
+
+        dt_dprintk(" -> ipar %s\n", dt_node_name(ipar));
+
+        /* Get #interrupt-cells and #address-cells of new
+         * parent
+         */
+        tmp = dt_get_property(ipar, "#interrupt-cells", NULL);
+        if ( tmp == NULL )
+        {
+            dt_dprintk(" -> parent lacks #interrupt-cells!\n");
+            goto fail;
+        }
+        pintsize = be32_to_cpu(*tmp);
+        tmp = dt_get_property(ipar, "#address-cells", NULL);
+        paddrsize = (tmp == NULL) ? 0 : be32_to_cpu(*tmp);
+
+        dt_dprintk(" -> pintsize=%d, paddrsize=%d\n",
+                   pintsize, paddrsize);
+
+        /* Check for malformed properties */
+        if ( imaplen < (paddrsize + pintsize) )
+            goto fail;
+
+        imap += paddrsize;
+        imaplen -= paddrsize;
+
+        dt_raw_irq.controller = ipar;
+        dt_raw_irq.size = pintsize;
+        for ( i = 0; i < pintsize; i++ )
+            dt_raw_irq.specifier[i] = dt_read_number(imap + i, 1);
+
+        ret = cb(dev, &dt_raw_irq, data);
+        if ( ret < 0 )
+        {
+            dt_dprintk(" -> callback failed=%d\n", ret);
+            return ret;
+        }
+
+        imap += pintsize;
+        imaplen -= pintsize;
+
+        dt_dprintk(" -> imaplen=%d\n", imaplen);
+    }
+
+    return 0;
+
+fail:
+    return -EINVAL;
+}
+
 /**
  * dt_irq_map_raw - Low level interrupt tree parsing
  * @parent:     the device interrupt parent
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index b7455cd..93e313d 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -529,6 +529,18 @@ int dt_device_get_raw_irq(const struct dt_device_node 
*device, int index,
 int dt_irq_translate(const struct dt_raw_irq *raw, struct dt_irq *out_irq);
 
 /**
+ * dt_for_each_irq_map - Iterate over a nodes interrupt-map property
+ * @dev: The node whose interrupt-map property should be iterated over
+ * @cb: Call back to call for each entry
+ * @data: Caller data passed to callback
+ */
+int dt_for_each_irq_map(const struct dt_device_node *dev,
+                        int (*cb)(const struct dt_device_node *,
+                                  const struct dt_raw_irq *,
+                                  void *),
+                        void *data);
+
+/**
  * dt_n_size_cells - Helper to retrieve the number of cell for the size
  * @np: node to get the value
  *
-- 
1.7.10.4


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