[POWERPC] spufs: add support for read/write on cntl

Writing to cntl can be used to stop execution on the
spu and to restart it, reading from cntl gives the
contents of the current status register.

The access is always in ascii, as for most other files.

This was always meant to be there, but we had a little
problem with writing to runctl so it was left out so
far.

Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/powerpc/platforms/cell/spufs/file.c

···
 #define spufs_cntl_mmap NULL
 #endif /* !SPUFS_MMAP_4K */
 
+static u64 spufs_cntl_get(void *data)
+{
+	struct spu_context *ctx = data;
+	u64 val;
+
+	spu_acquire(ctx);
+	val = ctx->ops->status_read(ctx);
+	spu_release(ctx);
+
+	return val;
+}
+
+static void spufs_cntl_set(void *data, u64 val)
+{
+	struct spu_context *ctx = data;
+
+	spu_acquire(ctx);
+	ctx->ops->runcntl_write(ctx, val);
+	spu_release(ctx);
+}
+
 static int spufs_cntl_open(struct inode *inode, struct file *file)
 {
 	struct spufs_inode_info *i = SPUFS_I(inode);
···
 	file->private_data = ctx;
 	file->f_mapping = inode->i_mapping;
 	ctx->cntl = inode->i_mapping;
-	return 0;
-}
-
-static ssize_t
-spufs_cntl_read(struct file *file, char __user *buffer,
-		size_t size, loff_t *pos)
-{
-	/* FIXME: read from spu status */
-	return -EINVAL;
-}
-
-static ssize_t
-spufs_cntl_write(struct file *file, const char __user *buffer,
-		 size_t size, loff_t *pos)
-{
-	/* FIXME: write to runctl bit */
-	return -EINVAL;
+	return simple_attr_open(inode, file, spufs_cntl_get,
+					spufs_cntl_set, "0x%08lx");
 }
 
 static struct file_operations spufs_cntl_fops = {
 	.open = spufs_cntl_open,
-	.read = spufs_cntl_read,
-	.write = spufs_cntl_write,
+	.read = simple_attr_read,
+	.write = simple_attr_write,
 	.mmap = spufs_cntl_mmap,
 };