--- /dev/null
+/*
+ * 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/mutex.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+
+static LIST_HEAD(of_dma_list);
+static DEFINE_MUTEX(of_dma_lock);
+
+/**
+ * of_dma_find_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 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_find_controller(struct of_phandle_args *dma_spec)
+{
+ struct of_dma *ofdma;
+
+ list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
+ if (ofdma->of_node == dma_spec->np)
+ return ofdma;
+
+ pr_debug("%s: can't find DMA controller %s\n", __func__,
+ dma_spec->np->full_name);
+
+ return NULL;
+}
+
+/**
+ * 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;
+
+ 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;
+
+ ofdma->of_node = np;
+ ofdma->of_dma_xlate = of_dma_xlate;
+ ofdma->of_dma_data = data;
+
+ /* Now queue of_dma controller structure in list */
+ mutex_lock(&of_dma_lock);
+ list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
+ mutex_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.
+ */
+void of_dma_controller_free(struct device_node *np)
+{
+ struct of_dma *ofdma;
+
+ mutex_lock(&of_dma_lock);
+
+ list_for_each_entry(ofdma, &of_dma_list, of_dma_controllers)
+ if (ofdma->of_node == np) {
+ list_del(&ofdma->of_dma_controllers);
+ kfree(ofdma);
+ break;
+ }
+
+ mutex_unlock(&of_dma_lock);
+}
+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, const 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 an error pointer.
+ */
+struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
+ const char *name)
+{
+ struct of_phandle_args dma_spec;
+ struct of_dma *ofdma;
+ struct dma_chan *chan;
+ int count, i;
+ int ret_no_channel = -ENODEV;
+
+ if (!np || !name) {
+ pr_err("%s: not enough information provided\n", __func__);
+ return ERR_PTR(-ENODEV);
+ }
+
+ /* Silently fail if there is not even the "dmas" property */
+ if (!of_find_property(np, "dmas", NULL))
+ return ERR_PTR(-ENODEV);
+
+ count = of_property_count_strings(np, "dma-names");
+ if (count < 0) {
+ pr_err("%s: dma-names property of node '%s' missing or empty\n",
+ __func__, np->full_name);
+ return ERR_PTR(-ENODEV);
+ }
+
+ for (i = 0; i < count; i++) {
+ if (of_dma_match_channel(np, name, i, &dma_spec))
+ continue;
+
+ mutex_lock(&of_dma_lock);
+ ofdma = of_dma_find_controller(&dma_spec);
+
+ if (ofdma) {
+ chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
+ } else {
+ ret_no_channel = -EPROBE_DEFER;
+ chan = NULL;
+ }
+
+ mutex_unlock(&of_dma_lock);
+
+ of_node_put(dma_spec.np);
+
+ if (chan)
+ return chan;
+ }
+
+ return ERR_PTR(ret_no_channel);
+}
+EXPORT_SYMBOL_GPL(of_dma_request_slave_channel);
+
+/**
+ * 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);
+
+/**
+ * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
+ * @dma_spec: pointer to DMA specifier as found in the device tree
+ * @of_dma: pointer to DMA controller data
+ *
+ * This function can be used as the of xlate callback for DMA driver which wants
+ * to match the channel based on the channel id. When using this xlate function
+ * the #dma-cells propety of the DMA controller dt node needs to be set to 1.
+ * The data parameter of of_dma_controller_register must be a pointer to the
+ * dma_device struct the function should match upon.
+ *
+ * Returns pointer to appropriate dma channel on success or NULL on error.
+ */
+struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma)
+{
+ struct dma_device *dev = ofdma->of_dma_data;
+ struct dma_chan *chan, *candidate = NULL;
+
+ if (!dev || dma_spec->args_count != 1)
+ return NULL;
+
+ list_for_each_entry(chan, &dev->channels, device_node)
+ if (chan->chan_id == dma_spec->args[0]) {
+ candidate = chan;
+ break;
+ }
+
+ if (!candidate)
+ return NULL;
+
+ return dma_get_slave_channel(candidate);
+}
+EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);
Code Review / kvmfornfv.git / blobdiff