[POWERPC] spufs: restore mapping of mssync register

A recent change to the way that the mfc file gets mapped made it
impossible to map the SPE Multi-Source Synchronization register
into user space, but that may be needed by some applications.

This restores the missing functionality.

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 366185e92667..3bc00913fe18 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -825,6 +825,55 @@ DEFINE_SIMPLE_ATTRIBUTE(spufs_signal2_type, spufs_signal2_type_get,
                                         spufs_signal2_type_set, "%llu");
 
 #ifdef CONFIG_SPUFS_MMAP
+static struct page *spufs_mss_mmap_nopage(struct vm_area_struct *vma,
+                                           unsigned long address, int *type)
+{
+        return spufs_ps_nopage(vma, address, type, 0x0000);
+}
+
+static struct vm_operations_struct spufs_mss_mmap_vmops = {
+        .nopage = spufs_mss_mmap_nopage,
+};
+
+/*
+ * mmap support for problem state MFC DMA area [0x0000 - 0x0fff].
+ * Mapping this area requires that the application have CAP_SYS_RAWIO,
+ * as these registers require special care when read/writing.
+ */
+static int spufs_mss_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        if (!(vma->vm_flags & VM_SHARED))
+                return -EINVAL;
+
+        if (!capable(CAP_SYS_RAWIO))
+                return -EPERM;
+
+        vma->vm_flags |= VM_RESERVED;
+        vma->vm_page_prot = __pgprot(pgprot_val(vma->vm_page_prot)
+                                     | _PAGE_NO_CACHE);
+
+        vma->vm_ops = &spufs_mss_mmap_vmops;
+        return 0;
+}
+#endif
+
+static int spufs_mss_open(struct inode *inode, struct file *file)
+{
+        struct spufs_inode_info *i = SPUFS_I(inode);
+
+        file->private_data = i->i_ctx;
+        return nonseekable_open(inode, file);
+}
+
+static struct file_operations spufs_mss_fops = {
+        .open    = spufs_mss_open,
+#ifdef CONFIG_SPUFS_MMAP
+        .mmap    = spufs_mss_mmap,
+#endif
+};
+
+
+#ifdef CONFIG_SPUFS_MMAP
 static struct page *spufs_mfc_mmap_nopage(struct vm_area_struct *vma,
                                            unsigned long address, int *type)
 {
@@ -1292,6 +1341,7 @@ struct tree_descr spufs_dir_contents[] = {
         { "signal2", &spufs_signal2_fops, 0666, },
         { "signal1_type", &spufs_signal1_type, 0666, },
         { "signal2_type", &spufs_signal2_type, 0666, },
+        { "mss", &spufs_mss_fops, 0666, },
         { "mfc", &spufs_mfc_fops, 0666, },
         { "cntl", &spufs_cntl_fops,  0666, },
         { "npc", &spufs_npc_ops, 0666, },