[Xen-devel] [PATCH v6 5/6] xen: arm: Import of_bus PCI entry from Linux (as a dt_bus entry)

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

This provides specific handlers for the PCI bus relating to matching
and translating. It's mostly similar to the defaults but includes some
additional error checks and other PCI specific bits.

There are some subtle differences in how the generic code vs. the pci
specific code here will handle buggy DTs (i.e. #*-cells which are not
as required by the pci bindings). This will mean we tolerate such
device trees better.

I say "buggy", but actually it's not clear to me from reading "PCI Bus
Binding to Open Firmware" that when the device_type is "pci" that
e.g. the text says "The value of "#address-cells" for PCI Bus Nodes is
3." and not "A PCI Bus Node must contain a #address-cells property
containing 3", iow the #address-cells might validly be implicit rather
than an actual property. Maybe that interpretation is bogus, but with
this patch we are are able to cope with DTs written by people who do
read it like that.

It also gets us the ability to parse the flags (cacheability),
although at the moment we only check them for validity rather than use
them.

Functions/types renamed and reindented (because apparently we do
that for these).

Needs a selection of IORESOURCE_* defines, which I've taken from Linux
and have included locally for now until we figure out where else they
might be needed.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v5: Expanded commit message.
v3: New patch
---
 xen/common/device_tree.c |  108 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 105 insertions(+), 3 deletions(-)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index ce2ff66..323c3be 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -417,6 +417,26 @@ int dt_n_size_cells(const struct dt_device_node *np)
 }
 
 /*
+ * These are defined in Linux where much of this code comes from, but
+ * are currently unused outside this file in the context of Xen.
+ */
+#define IORESOURCE_BITS         0x000000ff      /* Bus-specific bits */
+
+#define IORESOURCE_TYPE_BITS    0x00001f00      /* Resource type */
+#define IORESOURCE_IO           0x00000100      /* PCI/ISA I/O ports */
+#define IORESOURCE_MEM          0x00000200
+#define IORESOURCE_REG          0x00000300      /* Register offsets */
+#define IORESOURCE_IRQ          0x00000400
+#define IORESOURCE_DMA          0x00000800
+#define IORESOURCE_BUS          0x00001000
+
+#define IORESOURCE_PREFETCH     0x00002000      /* No side effects */
+#define IORESOURCE_READONLY     0x00004000
+#define IORESOURCE_CACHEABLE    0x00008000
+#define IORESOURCE_RANGELENGTH  0x00010000
+#define IORESOURCE_SHADOWABLE   0x00020000
+
+/*
  * Default translator (generic bus)
  */
 static bool_t dt_bus_default_match(const struct dt_device_node *node)
@@ -480,9 +500,81 @@ static int dt_bus_default_translate(__be32 *addr, u64 
offset, int na)
 }
 static unsigned int dt_bus_default_get_flags(const __be32 *addr)
 {
-    /* TODO: Return the type of memory (device, ...) for caching
-     * attribute during mapping */
-    return 0;
+    return IORESOURCE_MEM;
+}
+
+/*
+ * PCI bus specific translator
+ */
+
+static bool_t dt_bus_pci_match(const struct dt_device_node *np)
+{
+    /*
+     * "pciex" is PCI Express "vci" is for the /chaos bridge on 1st-gen PCI
+     * powermacs "ht" is hypertransport
+     */
+    return !strcmp(np->type, "pci") || !strcmp(np->type, "pciex") ||
+        !strcmp(np->type, "vci") || !strcmp(np->type, "ht");
+}
+
+static void dt_bus_pci_count_cells(const struct dt_device_node *np,
+                                  int *addrc, int *sizec)
+{
+    if (addrc)
+        *addrc = 3;
+    if (sizec)
+        *sizec = 2;
+}
+
+static unsigned int dt_bus_pci_get_flags(const __be32 *addr)
+{
+    unsigned int flags = 0;
+    u32 w = be32_to_cpup(addr);
+
+    switch((w >> 24) & 0x03) {
+    case 0x01:
+        flags |= IORESOURCE_IO;
+        break;
+    case 0x02: /* 32 bits */
+    case 0x03: /* 64 bits */
+        flags |= IORESOURCE_MEM;
+        break;
+    }
+    if (w & 0x40000000)
+        flags |= IORESOURCE_PREFETCH;
+    return flags;
+}
+
+static u64 dt_bus_pci_map(__be32 *addr, const __be32 *range, int na, int ns,
+               int pna)
+{
+    u64 cp, s, da;
+    unsigned int af, rf;
+
+    af = dt_bus_pci_get_flags(addr);
+    rf = dt_bus_pci_get_flags(range);
+
+    /* Check address type match */
+    if ((af ^ rf) & (IORESOURCE_MEM | IORESOURCE_IO))
+        return DT_BAD_ADDR;
+
+    /* Read address values, skipping high cell */
+    cp = dt_read_number(range + 1, na - 1);
+    s  = dt_read_number(range + na + pna, ns);
+    da = dt_read_number(addr + 1, na - 1);
+
+    dt_dprintk("DT: PCI map, cp=%llx, s=%llx, da=%llx\n",
+               (unsigned long long)cp, (unsigned long long)s,
+               (unsigned long long)da);
+
+    if (da < cp || da >= (cp + s))
+        return DT_BAD_ADDR;
+    return da - cp;
+}
+
+static int dt_bus_pci_translate(__be32 *addr, u64 offset, int na)
+{
+    return dt_bus_default_translate(addr + 1, offset, na - 1);
 }
 
 /*
@@ -490,6 +582,16 @@ static unsigned int dt_bus_default_get_flags(const __be32 
*addr)
  */
 static const struct dt_bus dt_busses[] =
 {
+    /* PCI */
+    {
+        .name = "pci",
+        .addresses = "assigned-addresses",
+        .match = dt_bus_pci_match,
+        .count_cells = dt_bus_pci_count_cells,
+        .map = dt_bus_pci_map,
+        .translate = dt_bus_pci_translate,
+        .get_flags = dt_bus_pci_get_flags,
+    },
     /* Default */
     {
         .name = "default",
-- 
1.7.10.4


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