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@@ -0,0 +1,219 @@
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+/*
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+ * Device tree helpers for DMA request / controller
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+ *
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+ * Based on of_gpio.c
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+ *
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+ * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/device.h>
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+#include <linux/err.h>
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+#include <linux/module.h>
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+#include <linux/rculist.h>
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+#include <linux/slab.h>
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+#include <linux/of.h>
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+#include <linux/of_dma.h>
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+
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+static LIST_HEAD(of_dma_list);
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+
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+/**
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+ * of_dma_find_controller - Find a DMA controller in DT DMA helpers list
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+ * @np: device node of DMA controller
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+ */
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+static struct of_dma *of_dma_find_controller(struct device_node *np)
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+{
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+ struct of_dma *ofdma;
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+
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+ if (list_empty(&of_dma_list)) {
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+ pr_err("empty DMA controller list\n");
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+ return NULL;
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+ }
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+
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+ list_for_each_entry_rcu(ofdma, &of_dma_list, of_dma_controllers)
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+ if (ofdma->of_node == np)
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+ return ofdma;
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+
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+ return NULL;
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+}
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+
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+/**
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+ * of_dma_controller_register - Register a DMA controller to DT DMA helpers
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+ * @np: device node of DMA controller
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+ * @of_dma_xlate: translation function which converts a phandle
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+ * arguments list into a dma_chan structure
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+ * @data pointer to controller specific data to be used by
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+ * translation function
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+ *
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+ * Returns 0 on success or appropriate errno value on error.
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+ *
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+ * Allocated memory should be freed with appropriate of_dma_controller_free()
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+ * call.
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+ */
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+int of_dma_controller_register(struct device_node *np,
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+ struct dma_chan *(*of_dma_xlate)
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+ (struct of_phandle_args *, struct of_dma *),
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+ void *data)
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+{
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+ struct of_dma *ofdma;
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+ int nbcells;
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+
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+ if (!np || !of_dma_xlate) {
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+ pr_err("%s: not enough information provided\n", __func__);
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+ return -EINVAL;
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+ }
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+
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+ ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
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+ if (!ofdma)
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+ return -ENOMEM;
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+
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+ nbcells = be32_to_cpup(of_get_property(np, "#dma-cells", NULL));
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+ if (!nbcells) {
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+ pr_err("%s: #dma-cells property is missing or invalid\n",
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+ __func__);
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+ return -EINVAL;
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+ }
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+
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+ ofdma->of_node = np;
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+ ofdma->of_dma_nbcells = nbcells;
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+ ofdma->of_dma_xlate = of_dma_xlate;
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+ ofdma->of_dma_data = data;
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+
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+ /* Now queue of_dma controller structure in list */
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+ list_add_tail_rcu(&ofdma->of_dma_controllers, &of_dma_list);
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+
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+ return 0;
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+}
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+EXPORT_SYMBOL_GPL(of_dma_controller_register);
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+
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+/**
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+ * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
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+ * @np: device node of DMA controller
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+ *
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+ * Memory allocated by of_dma_controller_register() is freed here.
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+ */
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+void of_dma_controller_free(struct device_node *np)
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+{
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+ struct of_dma *ofdma;
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+
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+ ofdma = of_dma_find_controller(np);
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+ if (ofdma) {
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+ list_del_rcu(&ofdma->of_dma_controllers);
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+ kfree(ofdma);
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+ }
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+}
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+EXPORT_SYMBOL_GPL(of_dma_controller_free);
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+
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+/**
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+ * of_dma_find_channel - Find a DMA channel by name
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+ * @np: device node to look for DMA channels
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+ * @name: name of desired channel
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+ * @dma_spec: pointer to DMA specifier as found in the device tree
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+ *
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+ * Find a DMA channel by the name. Returns 0 on success or appropriate
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+ * errno value on error.
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+ */
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+static int of_dma_find_channel(struct device_node *np, char *name,
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+ struct of_phandle_args *dma_spec)
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+{
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+ int count, i;
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+ const char *s;
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+
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+ count = of_property_count_strings(np, "dma-names");
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+ if (count < 0)
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+ return count;
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+
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+ for (i = 0; i < count; i++) {
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+ if (of_property_read_string_index(np, "dma-names", i, &s))
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+ continue;
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+
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+ if (strcmp(name, s))
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+ continue;
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+
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+ if (!of_parse_phandle_with_args(np, "dmas", "#dma-cells", i,
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+ dma_spec))
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+ return 0;
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+ }
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+
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+ return -ENODEV;
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+}
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+
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+/**
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+ * of_dma_request_slave_channel - Get the DMA slave channel
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+ * @np: device node to get DMA request from
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+ * @name: name of desired channel
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+ *
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+ * Returns pointer to appropriate dma channel on success or NULL on error.
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+ */
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+struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
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+ char *name)
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+{
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+ struct of_phandle_args dma_spec;
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+ struct of_dma *ofdma;
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+ struct dma_chan *chan;
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+ int r;
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+
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+ if (!np || !name) {
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+ pr_err("%s: not enough information provided\n", __func__);
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+ return NULL;
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+ }
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+
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+ do {
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+ r = of_dma_find_channel(np, name, &dma_spec);
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+ if (r) {
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+ pr_err("%s: can't find DMA channel\n", np->full_name);
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+ return NULL;
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+ }
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+
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+ ofdma = of_dma_find_controller(dma_spec.np);
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+ if (!ofdma) {
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+ pr_debug("%s: can't find DMA controller %s\n",
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+ np->full_name, dma_spec.np->full_name);
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+ continue;
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+ }
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+
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+ if (dma_spec.args_count != ofdma->of_dma_nbcells) {
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+ pr_debug("%s: wrong #dma-cells for %s\n", np->full_name,
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+ dma_spec.np->full_name);
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+ continue;
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+ }
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+
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+ chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
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+
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+ of_node_put(dma_spec.np);
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+
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+ } while (!chan);
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+
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+ return chan;
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+}
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+
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+/**
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+ * of_dma_simple_xlate - Simple DMA engine translation function
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+ * @dma_spec: pointer to DMA specifier as found in the device tree
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+ * @of_dma: pointer to DMA controller data
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+ *
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+ * A simple translation function for devices that use a 32-bit value for the
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+ * filter_param when calling the DMA engine dma_request_channel() function.
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+ * Note that this translation function requires that #dma-cells is equal to 1
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+ * and the argument of the dma specifier is the 32-bit filter_param. Returns
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+ * pointer to appropriate dma channel on success or NULL on error.
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+ */
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+struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
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+ struct of_dma *ofdma)
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+{
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+ int count = dma_spec->args_count;
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+ struct of_dma_filter_info *info = ofdma->of_dma_data;
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+
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+ if (!info || !info->filter_fn)
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+ return NULL;
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+
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+ if (count != 1)
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+ return NULL;
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+
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+ return dma_request_channel(info->dma_cap, info->filter_fn,
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+ &dma_spec->args[0]);
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+}
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+EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
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Jon Hunter