powerpc/spufs: provide context debug file

Add a ctxt file to spufs that shows spu context information that is used
in scheduling. This info can be used for debugging spufs scheduler
issues, and to isolate between application and spufs problems as it
shows a lot of state such as priorities and dispatch counts.

This file contains internal spufs state and is subject to change at any
time, and therefore no applications should depend on it.  The file is
intended for the use of spufs kernel developers.

Signed-off-by: Luke Browning <lukebrowning@us.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

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

@@ -2555,6 +2555,58 @@ void spu_switch_log_notify(struct spu *spu, struct spu_context *ctx,
 	wake_up(&ctx->switch_log->wait);
 }
 
+static int spufs_show_ctx(struct seq_file *s, void *private)
+{
+	struct spu_context *ctx = s->private;
+	u64 mfc_control_RW;
+
+	mutex_lock(&ctx->state_mutex);
+	if (ctx->spu) {
+		struct spu *spu = ctx->spu;
+		struct spu_priv2 __iomem *priv2 = spu->priv2;
+
+		spin_lock_irq(&spu->register_lock);
+		mfc_control_RW = in_be64(&priv2->mfc_control_RW);
+		spin_unlock_irq(&spu->register_lock);
+	} else {
+		struct spu_state *csa = &ctx->csa;
+
+		mfc_control_RW = csa->priv2.mfc_control_RW;
+	}
+
+	seq_printf(s, "%c flgs(%lx) sflgs(%lx) pri(%d) ts(%d) spu(%02d)"
+		" %c %lx %lx %lx %lx %x %x\n",
+		ctx->state == SPU_STATE_SAVED ? 'S' : 'R',
+		ctx->flags,
+		ctx->sched_flags,
+		ctx->prio,
+		ctx->time_slice,
+		ctx->spu ? ctx->spu->number : -1,
+		!list_empty(&ctx->rq) ? 'q' : ' ',
+		ctx->csa.class_0_pending,
+		ctx->csa.class_0_dar,
+		ctx->csa.class_1_dsisr,
+		mfc_control_RW,
+		ctx->ops->runcntl_read(ctx),
+		ctx->ops->status_read(ctx));
+
+	mutex_unlock(&ctx->state_mutex);
+
+	return 0;
+}
+
+static int spufs_ctx_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, spufs_show_ctx, SPUFS_I(inode)->i_ctx);
+}
+
+static const struct file_operations spufs_ctx_fops = {
+	.open           = spufs_ctx_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = single_release,
+};
+
 struct tree_descr spufs_dir_contents[] = {
 	{ "capabilities", &spufs_caps_fops, 0444, },
 	{ "mem",  &spufs_mem_fops,  0666, },
@@ -2591,6 +2643,7 @@ struct tree_descr spufs_dir_contents[] = {
 	{ "tid", &spufs_tid_fops, 0444, },
 	{ "stat", &spufs_stat_fops, 0444, },
 	{ "switch_log", &spufs_switch_log_fops, 0444 },
+	{ ".ctx", &spufs_ctx_fops, 0444, },
 	{},
 };
 
@@ -2616,6 +2669,7 @@ struct tree_descr spufs_dir_nosched_contents[] = {
 	{ "object-id", &spufs_object_id_ops, 0666, },
 	{ "tid", &spufs_tid_fops, 0444, },
 	{ "stat", &spufs_stat_fops, 0444, },
+	{ ".ctx", &spufs_ctx_fops, 0444, },
 	{},
 };