[PATCH] spufs: implement mfc access for PPE-side DMA

This patch adds a new file called 'mfc' to each spufs directory.
The file accepts DMA commands that are a subset of what would
be legal DMA commands for problem state register access. Upon
reading the file, a bitmask is returned with the completed
tag groups set.

The file is meant to be used from an abstraction in libspe
that is added by a different patch.

From the kernel perspective, this means a process can now
offload a memory copy from or into an SPE local store
without having to run code on the SPE itself.

The transfer will only be performed while the SPE is owned
by one thread that is waiting in the spu_run system call
and the data will be transferred into that thread's
address space, independent of which thread started the
transfer.

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

1 files changed, 57 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/cell/spufs/hw_ops.c b/arch/powerpc/platforms/cell/spufs/hw_ops.c
index 5445719bff79..a13a8b5a014d 100644
--- a/arch/powerpc/platforms/cell/spufs/hw_ops.c
+++ b/arch/powerpc/platforms/cell/spufs/hw_ops.c
@@ -232,6 +232,59 @@ static void spu_hw_runcntl_stop(struct spu_context *ctx)
 	spin_unlock_irq(&ctx->spu->register_lock);
 }
 
+static int spu_hw_set_mfc_query(struct spu_context * ctx, u32 mask, u32 mode)
+{
+	struct spu_problem *prob = ctx->spu->problem;
+	int ret;
+
+	spin_lock_irq(&ctx->spu->register_lock);
+	ret = -EAGAIN;
+	if (in_be32(&prob->dma_querytype_RW))
+		goto out;
+	ret = 0;
+	out_be32(&prob->dma_querymask_RW, mask);
+	out_be32(&prob->dma_querytype_RW, mode);
+out:
+	spin_unlock_irq(&ctx->spu->register_lock);
+	return ret;
+}
+
+static u32 spu_hw_read_mfc_tagstatus(struct spu_context * ctx)
+{
+	return in_be32(&ctx->spu->problem->dma_tagstatus_R);
+}
+
+static u32 spu_hw_get_mfc_free_elements(struct spu_context *ctx)
+{
+	return in_be32(&ctx->spu->problem->dma_qstatus_R);
+}
+
+static int spu_hw_send_mfc_command(struct spu_context *ctx,
+					struct mfc_dma_command *cmd)
+{
+	u32 status;
+	struct spu_problem *prob = ctx->spu->problem;
+
+	spin_lock_irq(&ctx->spu->register_lock);
+	out_be32(&prob->mfc_lsa_W, cmd->lsa);
+	out_be64(&prob->mfc_ea_W, cmd->ea);
+	out_be32(&prob->mfc_union_W.by32.mfc_size_tag32,
+				cmd->size << 16 | cmd->tag);
+	out_be32(&prob->mfc_union_W.by32.mfc_class_cmd32,
+				cmd->class << 16 | cmd->cmd);
+	status = in_be32(&prob->mfc_union_W.by32.mfc_class_cmd32);
+	spin_unlock_irq(&ctx->spu->register_lock);
+
+	switch (status & 0xffff) {
+	case 0:
+		return 0;
+	case 2:
+		return -EAGAIN;
+	default:
+		return -EINVAL;
+	}
+}
+
 struct spu_context_ops spu_hw_ops = {
 	.mbox_read = spu_hw_mbox_read,
 	.mbox_stat_read = spu_hw_mbox_stat_read,
@@ -252,4 +305,8 @@ struct spu_context_ops spu_hw_ops = {
 	.get_ls = spu_hw_get_ls,
 	.runcntl_write = spu_hw_runcntl_write,
 	.runcntl_stop = spu_hw_runcntl_stop,
+	.set_mfc_query = spu_hw_set_mfc_query,
+	.read_mfc_tagstatus = spu_hw_read_mfc_tagstatus,
+	.get_mfc_free_elements = spu_hw_get_mfc_free_elements,
+	.send_mfc_command = spu_hw_send_mfc_command,
 };