1 files changed, 267 insertions, 0 deletions
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
new file mode 100644
index 000000000000..69d04d28b1ef
--- /dev/null
+++ b/drivers/dma/of-dma.c
@@ -0,0 +1,267 @@
+/*
+ * Device tree helpers for DMA request / controller
+ *
+ * Based on of_gpio.c
+ *
+ * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.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.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/rculist.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+
+static LIST_HEAD(of_dma_list);
+static DEFINE_SPINLOCK(of_dma_lock);
+
+/**
+ * of_dma_get_controller - Get a DMA controller in DT DMA helpers list
+ * @dma_spec:	pointer to DMA specifier as found in the device tree
+ *
+ * Finds a DMA controller with matching device node and number for dma cells
+ * in a list of registered DMA controllers. If a match is found the use_count
+ * variable is increased and a valid pointer to the DMA data stored is retuned.
+ * A NULL pointer is returned if no match is found.
+ */
+static struct of_dma *of_dma_get_controller(struct of_phandle_args *dma_spec)
+{
+	struct of_dma *ofdma;
+
+	spin_lock(&of_dma_lock);
+
+	if (list_empty(&of_dma_list)) {
+		spin_unlock(&of_dma_lock);
+		return NULL;
+	}
+
+	list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
+		if ((ofdma->of_node == dma_spec->np) &&
+		    (ofdma->of_dma_nbcells == dma_spec->args_count)) {
+			ofdma->use_count++;
+			spin_unlock(&of_dma_lock);
+			return ofdma;
+		}
+
+	spin_unlock(&of_dma_lock);
+
+	pr_debug("%s: can't find DMA controller %s\n", __func__,
+		 dma_spec->np->full_name);
+
+	return NULL;
+}
+
+/**
+ * of_dma_put_controller - Decrement use count for a registered DMA controller
+ * @of_dma:	pointer to DMA controller data
+ *
+ * Decrements the use_count variable in the DMA data structure. This function
+ * should be called only when a valid pointer is returned from
+ * of_dma_get_controller() and no further accesses to data referenced by that
+ * pointer are needed.
+ */
+static void of_dma_put_controller(struct of_dma *ofdma)
+{
+	spin_lock(&of_dma_lock);
+	ofdma->use_count--;
+	spin_unlock(&of_dma_lock);
+}
+
+/**
+ * of_dma_controller_register - Register a DMA controller to DT DMA helpers
+ * @np:			device node of DMA controller
+ * @of_dma_xlate:	translation function which converts a phandle
+ *			arguments list into a dma_chan structure
+ * @data		pointer to controller specific data to be used by
+ *			translation function
+ *
+ * Returns 0 on success or appropriate errno value on error.
+ *
+ * Allocated memory should be freed with appropriate of_dma_controller_free()
+ * call.
+ */
+int of_dma_controller_register(struct device_node *np,
+				struct dma_chan *(*of_dma_xlate)
+				(struct of_phandle_args *, struct of_dma *),
+				void *data)
+{
+	struct of_dma	*ofdma;
+	int		nbcells;
+
+	if (!np || !of_dma_xlate) {
+		pr_err("%s: not enough information provided\n", __func__);
+		return -EINVAL;
+	}
+
+	ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
+	if (!ofdma)
+		return -ENOMEM;
+
+	nbcells = be32_to_cpup(of_get_property(np, "#dma-cells", NULL));
+	if (!nbcells) {
+		pr_err("%s: #dma-cells property is missing or invalid\n",
+		       __func__);
+		kfree(ofdma);
+		return -EINVAL;
+	}
+
+	ofdma->of_node = np;
+	ofdma->of_dma_nbcells = nbcells;
+	ofdma->of_dma_xlate = of_dma_xlate;
+	ofdma->of_dma_data = data;
+	ofdma->use_count = 0;
+
+	/* Now queue of_dma controller structure in list */
+	spin_lock(&of_dma_lock);
+	list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
+	spin_unlock(&of_dma_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_dma_controller_register);
+
+/**
+ * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
+ * @np:		device node of DMA controller
+ *
+ * Memory allocated by of_dma_controller_register() is freed here.
+ */
+int of_dma_controller_free(struct device_node *np)
+{
+	struct of_dma *ofdma;
+
+	spin_lock(&of_dma_lock);
+
+	if (list_empty(&of_dma_list)) {
+		spin_unlock(&of_dma_lock);
+		return -ENODEV;
+	}
+
+	list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
+		if (ofdma->of_node == np) {
+			if (ofdma->use_count) {
+				spin_unlock(&of_dma_lock);
+				return -EBUSY;
+			}
+
+			list_del(&ofdma->of_dma_controllers);
+			spin_unlock(&of_dma_lock);
+			kfree(ofdma);
+			return 0;
+		}
+
+	spin_unlock(&of_dma_lock);
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(of_dma_controller_free);
+
+/**
+ * of_dma_match_channel - Check if a DMA specifier matches name
+ * @np:		device node to look for DMA channels
+ * @name:	channel name to be matched
+ * @index:	index of DMA specifier in list of DMA specifiers
+ * @dma_spec:	pointer to DMA specifier as found in the device tree
+ *
+ * Check if the DMA specifier pointed to by the index in a list of DMA
+ * specifiers, matches the name provided. Returns 0 if the name matches and
+ * a valid pointer to the DMA specifier is found. Otherwise returns -ENODEV.
+ */
+static int of_dma_match_channel(struct device_node *np, char *name, int index,
+				struct of_phandle_args *dma_spec)
+{
+	const char *s;
+
+	if (of_property_read_string_index(np, "dma-names", index, &s))
+		return -ENODEV;
+
+	if (strcmp(name, s))
+		return -ENODEV;
+
+	if (of_parse_phandle_with_args(np, "dmas", "#dma-cells", index,
+				       dma_spec))
+		return -ENODEV;
+
+	return 0;
+}
+
+/**
+ * of_dma_request_slave_channel - Get the DMA slave channel
+ * @np:		device node to get DMA request from
+ * @name:	name of desired channel
+ *
+ * Returns pointer to appropriate dma channel on success or NULL on error.
+ */
+struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
+					      char *name)
+{
+	struct of_phandle_args	dma_spec;
+	struct of_dma		*ofdma;
+	struct dma_chan		*chan;
+	int			count, i;
+
+	if (!np || !name) {
+		pr_err("%s: not enough information provided\n", __func__);
+		return NULL;
+	}
+
+	count = of_property_count_strings(np, "dma-names");
+	if (count < 0) {
+		pr_err("%s: dma-names property missing or empty\n", __func__);
+		return NULL;
+	}
+
+	for (i = 0; i < count; i++) {
+		if (of_dma_match_channel(np, name, i, &dma_spec))
+			continue;
+
+		ofdma = of_dma_get_controller(&dma_spec);
+
+		if (!ofdma)
+			continue;
+
+		chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
+
+		of_dma_put_controller(ofdma);
+
+		of_node_put(dma_spec.np);
+
+		if (chan)
+			return chan;
+	}
+
+	return NULL;
+}
+
+/**
+ * of_dma_simple_xlate - Simple DMA engine translation function
+ * @dma_spec:	pointer to DMA specifier as found in the device tree
+ * @of_dma:	pointer to DMA controller data
+ *
+ * A simple translation function for devices that use a 32-bit value for the
+ * filter_param when calling the DMA engine dma_request_channel() function.
+ * Note that this translation function requires that #dma-cells is equal to 1
+ * and the argument of the dma specifier is the 32-bit filter_param. Returns
+ * pointer to appropriate dma channel on success or NULL on error.
+ */
+struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
+						struct of_dma *ofdma)
+{
+	int count = dma_spec->args_count;
+	struct of_dma_filter_info *info = ofdma->of_dma_data;
+
+	if (!info || !info->filter_fn)
+		return NULL;
+
+	if (count != 1)
+		return NULL;
+
+	return dma_request_channel(info->dma_cap, info->filter_fn,
+			&dma_spec->args[0]);
+}
+EXPORT_SYMBOL_GPL(of_dma_simple_xlate);