4 files changed, 346 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/dma/dma.txt b/Documentation/devicetree/bindings/dma/dma.txt
new file mode 100644
index 000000000000..a4f59a5967d4
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/dma.txt
@@ -0,0 +1,81 @@
+* Generic DMA Controller and DMA request bindings
+
+Generic binding to provide a way for a driver using DMA Engine to retrieve the
+DMA request or channel information that goes from a hardware device to a DMA
+controller.
+
+
+* DMA controller
+
+Required property:
+- #dma-cells:           Must be at least 1. Used to provide DMA controller
+                        specific information. See DMA client binding below for
+                        more details.
+
+Optional properties:
+- #dma-channels:        Number of DMA channels supported by the controller.
+- #dma-requests:        Number of DMA requests signals supported by the
+                        controller.
+
+Example:
+
+        dma: dma@48000000 {
+                compatible = "ti,omap-sdma"
+                reg = <0x48000000 0x1000>;
+                interrupts = <0 12 0x4
+                              0 13 0x4
+                              0 14 0x4
+                              0 15 0x4>;
+                #dma-cells = <1>;
+                #dma-channels = <32>;
+                #dma-requests = <127>;
+        };
+
+
+* DMA client
+
+Client drivers should specify the DMA property using a phandle to the controller
+followed by DMA controller specific data.
+
+Required property:
+- dmas:                 List of one or more DMA specifiers, each consisting of
+                        - A phandle pointing to DMA controller node
+                        - A number of integer cells, as determined by the
+                          #dma-cells property in the node referenced by phandle
+                          containing DMA controller specific information. This
+                          typically contains a DMA request line number or a
+                          channel number, but can contain any data that is used
+                          required for configuring a channel.
+- dma-names:            Contains one identifier string for each DMA specifier in
+                        the dmas property. The specific strings that can be used
+                        are defined in the binding of the DMA client device.
+                        Multiple DMA specifiers can be used to represent
+                        alternatives and in this case the dma-names for those
+                        DMA specifiers must be identical (see examples).
+
+Examples:
+
+1. A device with one DMA read channel, one DMA write channel:
+
+        i2c1: i2c@1 {
+                ...
+                dmas = <&dma 2          /* read channel */
+                        &dma 3>;        /* write channel */
+                dma-names = "rx", "tx"
+                ...
+        };
+
+2. A single read-write channel with three alternative DMA controllers:
+
+        dmas = <&dma1 5
+                &dma2 7
+                &dma3 2>;
+        dma-names = "rx-tx", "rx-tx", "rx-tx"
+
+3. A device with three channels, one of which has two alternatives:
+
+        dmas = <&dma1 2                 /* read channel */
+                &dma1 3                 /* write channel */
+                &dma2 0                 /* error read */
+                &dma3 0>;               /* alternative error read */
+        dma-names = "rx", "tx", "error", "error";
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index e027f444d10c..eafa107aed40 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -1,4 +1,4 @@
-obj-y = base.o
+obj-y = base.o dma.o
 obj-$(CONFIG_OF_FLATTREE) += fdt.o
 obj-$(CONFIG_OF_PROMTREE) += pdt.o
 obj-$(CONFIG_OF_ADDRESS)  += address.o
diff --git a/drivers/of/dma.c b/drivers/of/dma.c
new file mode 100644
index 000000000000..19ad37c066f5
--- /dev/null
+++ b/drivers/of/dma.c
@@ -0,0 +1,219 @@
+/*
+ * 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);
+
+/**
+ * of_dma_find_controller - Find a DMA controller in DT DMA helpers list
+ * @np:         device node of DMA controller
+ */
+static struct of_dma *of_dma_find_controller(struct device_node *np)
+{
+        struct of_dma *ofdma;
+
+        if (list_empty(&of_dma_list)) {
+                pr_err("empty DMA controller list\n");
+                return NULL;
+        }
+
+        list_for_each_entry_rcu(ofdma, &of_dma_list, of_dma_controllers)
+                if (ofdma->of_node == np)
+                        return ofdma;
+
+        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;
+        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__);
+                return -EINVAL;
+        }
+
+        ofdma->of_node = np;
+        ofdma->of_dma_nbcells = nbcells;
+        ofdma->of_dma_xlate = of_dma_xlate;
+        ofdma->of_dma_data = data;
+
+        /* Now queue of_dma controller structure in list */
+        list_add_tail_rcu(&ofdma->of_dma_controllers, &of_dma_list);
+
+        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;
+
+        ofdma = of_dma_find_controller(np);
+        if (ofdma) {
+                list_del_rcu(&ofdma->of_dma_controllers);
+                kfree(ofdma);
+        }
+}
+EXPORT_SYMBOL_GPL(of_dma_controller_free);
+
+/**
+ * of_dma_find_channel - Find a DMA channel by name
+ * @np:         device node to look for DMA channels
+ * @name:       name of desired channel
+ * @dma_spec:   pointer to DMA specifier as found in the device tree
+ *
+ * Find a DMA channel by the name. Returns 0 on success or appropriate
+ * errno value on error.
+ */
+static int of_dma_find_channel(struct device_node *np, char *name,
+                               struct of_phandle_args *dma_spec)
+{
+        int count, i;
+        const char *s;
+
+        count = of_property_count_strings(np, "dma-names");
+        if (count < 0)
+                return count;
+
+        for (i = 0; i < count; i++) {
+                if (of_property_read_string_index(np, "dma-names", i, &s))
+                        continue;
+
+                if (strcmp(name, s))
+                        continue;
+
+                if (!of_parse_phandle_with_args(np, "dmas", "#dma-cells", i,
+                                                dma_spec))
+                        return 0;
+        }
+
+        return -ENODEV;
+}
+
+/**
+ * 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                     r;
+
+        if (!np || !name) {
+                pr_err("%s: not enough information provided\n", __func__);
+                return NULL;
+        }
+
+        do {
+                r = of_dma_find_channel(np, name, &dma_spec);
+                if (r) {
+                        pr_err("%s: can't find DMA channel\n", np->full_name);
+                        return NULL;
+                }
+
+                ofdma = of_dma_find_controller(dma_spec.np);
+                if (!ofdma) {
+                        pr_debug("%s: can't find DMA controller %s\n",
+                                 np->full_name, dma_spec.np->full_name);
+                        continue;
+                }
+
+                if (dma_spec.args_count != ofdma->of_dma_nbcells) {
+                        pr_debug("%s: wrong #dma-cells for %s\n", np->full_name,
+                                 dma_spec.np->full_name);
+                        continue;
+                }
+
+                chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
+
+                of_node_put(dma_spec.np);
+
+        } while (!chan);
+
+        return chan;
+}
+
+/**
+ * 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);
diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h
new file mode 100644
index 000000000000..337823dc6b90
--- /dev/null
+++ b/include/linux/of_dma.h
@@ -0,0 +1,45 @@
+/*
+ * OF helpers for DMA request / controller
+ *
+ * Based on of_gpio.h
+ *
+ * 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.
+ */
+
+#ifndef __LINUX_OF_DMA_H
+#define __LINUX_OF_DMA_H
+
+#include <linux/of.h>
+#include <linux/dmaengine.h>
+
+struct device_node;
+
+struct of_dma {
+        struct list_head        of_dma_controllers;
+        struct device_node      *of_node;
+        int                     of_dma_nbcells;
+        struct dma_chan         *(*of_dma_xlate)
+                                (struct of_phandle_args *, struct of_dma *);
+        void                    *of_dma_data;
+};
+
+struct of_dma_filter_info {
+        dma_cap_mask_t  dma_cap;
+        dma_filter_fn   filter_fn;
+};
+
+extern int of_dma_controller_register(struct device_node *np,
+                struct dma_chan *(*of_dma_xlate)
+                (struct of_phandle_args *, struct of_dma *),
+                void *data);
+extern void of_dma_controller_free(struct device_node *np);
+extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
+                                                     char *name);
+extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
+                struct of_dma *ofdma);
+
+#endif /* __LINUX_OF_DMA_H */