dma: acpi-dma: introduce ACPI DMA helpers

There is a new generic API to get a DMA channel for a slave device (commit
9a6cecc8 "dmaengine: add helper function to request a slave DMA channel"). In
similar fashion to the DT case (commit aa3da644 "of: Add generic device tree
DMA helpers") we introduce helpers to the DMAC drivers which are enumerated by
ACPI.

The proposed extension provides the following API calls:
	acpi_dma_controller_register(), devm_acpi_dma_controller_register()
	acpi_dma_controller_free(), devm_acpi_dma_controller_free()
	acpi_dma_simple_xlate()
	acpi_dma_request_slave_chan_by_index()
	acpi_dma_request_slave_chan_by_name()

The first two should be used, for example, at probe() and remove() of the
corresponding DMAC driver. At the register stage the DMAC driver supplies a
custom xlate() function to translate a struct dma_spec into struct dma_chan.

Accordingly to the ACPI Fixed DMA resource specification the only two pieces of
information the slave device has are the channel id and the request line (slave
id). Those two are represented by struct dma_spec. The
acpi_dma_request_slave_chan_by_index() provides access to the specifix FixedDMA
resource by its index. Whereas dma_request_slave_channel() takes a string
parameter to identify the DMA resources required by the slave device. To make a
slave device driver work with both DeviceTree and ACPI enumeration a simple
convention is established: "tx" corresponds to the index 0 and "rx" to the
index 1. In case of robust configuration the slave device driver unfortunately
needs to call acpi_dma_request_slave_chan_by_index() directly.

Additionally the patch provides "managed" version of the register/free pair
i.e. devm_acpi_dma_controller_register() and devm_acpi_dma_controller_free().
Usually, the driver uses only devm_acpi_dma_controller_register().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 116 insertions, 0 deletions

diff --git a/include/linux/acpi_dma.h b/include/linux/acpi_dma.h
new file mode 100644
index 0000000..d09deab
--- /dev/null
+++ b/include/linux/acpi_dma.h
@@ -0,0 +1,116 @@
+/*
+ * ACPI helpers for DMA request / controller
+ *
+ * Based on of_dma.h
+ *
+ * Copyright (C) 2013, Intel Corporation
+ * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __LINUX_ACPI_DMA_H
+#define __LINUX_ACPI_DMA_H
+
+#include <linux/list.h>
+#include <linux/device.h>
+#include <linux/dmaengine.h>
+
+/**
+ * struct acpi_dma_spec - slave device DMA resources
+ * @chan_id:	channel unique id
+ * @slave_id:	request line unique id
+ * @dev:	struct device of the DMA controller to be used in the filter
+ *		function
+ */
+struct acpi_dma_spec {
+	int		chan_id;
+	int		slave_id;
+	struct device	*dev;
+};
+
+/**
+ * struct acpi_dma - representation of the registered DMAC
+ * @dma_controllers:	linked list node
+ * @dev:		struct device of this controller
+ * @acpi_dma_xlate:	callback function to find a suitable channel
+ * @data:		private data used by a callback function
+ */
+struct acpi_dma {
+	struct list_head	dma_controllers;
+	struct device		*dev;
+	struct dma_chan		*(*acpi_dma_xlate)
+				(struct acpi_dma_spec *, struct acpi_dma *);
+	void			*data;
+};
+
+/* Used with acpi_dma_simple_xlate() */
+struct acpi_dma_filter_info {
+	dma_cap_mask_t	dma_cap;
+	dma_filter_fn	filter_fn;
+};
+
+#ifdef CONFIG_DMA_ACPI
+
+int acpi_dma_controller_register(struct device *dev,
+		struct dma_chan *(*acpi_dma_xlate)
+		(struct acpi_dma_spec *, struct acpi_dma *),
+		void *data);
+int acpi_dma_controller_free(struct device *dev);
+int devm_acpi_dma_controller_register(struct device *dev,
+		struct dma_chan *(*acpi_dma_xlate)
+		(struct acpi_dma_spec *, struct acpi_dma *),
+		void *data);
+void devm_acpi_dma_controller_free(struct device *dev);
+
+struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
+						      size_t index);
+struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev,
+						     const char *name);
+
+struct dma_chan *acpi_dma_simple_xlate(struct acpi_dma_spec *dma_spec,
+				       struct acpi_dma *adma);
+#else
+
+static inline int acpi_dma_controller_register(struct device *dev,
+		struct dma_chan *(*acpi_dma_xlate)
+		(struct acpi_dma_spec *, struct acpi_dma *),
+		void *data)
+{
+	return -ENODEV;
+}
+static inline int acpi_dma_controller_free(struct device *dev)
+{
+	return -ENODEV;
+}
+static inline int devm_acpi_dma_controller_register(struct device *dev,
+		struct dma_chan *(*acpi_dma_xlate)
+		(struct acpi_dma_spec *, struct acpi_dma *),
+		void *data)
+{
+	return -ENODEV;
+}
+static inline void devm_acpi_dma_controller_free(struct device *dev)
+{
+}
+
+static inline struct dma_chan *acpi_dma_request_slave_chan_by_index(
+		struct device *dev, size_t index)
+{
+	return NULL;
+}
+static inline struct dma_chan *acpi_dma_request_slave_chan_by_name(
+		struct device *dev, const char *name)
+{
+	return NULL;
+}
+
+#define acpi_dma_simple_xlate	NULL
+
+#endif
+
+#define acpi_dma_request_slave_channel	acpi_dma_request_slave_chan_by_index
+
+#endif /* __LINUX_ACPI_DMA_H */