[U-Boot] [RFC v2 02/15] dma: add channels support

["Álvaro Fernández Rojas" <noltari@gmail.com>]

This adds channels support for dma controllers that have multiple channels
which can transfer data to/from different devices (enet, usb...).

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---
 v2: Introduce changes reported by Vignesh:
  - Respect current dma implementation.
  - Let dma_memcpy find a compatible dma device.

 drivers/dma/Kconfig      |   7 ++
 drivers/dma/dma-uclass.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++
 include/dma-uclass.h     |  77 +++++++++++++++++++++
 include/dma.h            | 169 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 430 insertions(+)

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 1b92c7789d..21b2c0dcaa 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -12,6 +12,13 @@ config DMA
 	  buses that is used to transfer data to and from memory.
 	  The uclass interface is defined in include/dma.h.
 
+config DMA_CHANNELS
+	bool "Enable DMA channels support"
+	depends on DMA
+	help
+	  Enable channels support for DMA. Some DMA controllers have multiple
+	  channels which can either transfer data to/from different devices.
+
 config TI_EDMA3
 	bool "TI EDMA3 driver"
 	help
diff --git a/drivers/dma/dma-uclass.c b/drivers/dma/dma-uclass.c
index 6fd4e1b35d..a16c3a786c 100644
--- a/drivers/dma/dma-uclass.c
+++ b/drivers/dma/dma-uclass.c
@@ -15,10 +15,187 @@
 #include <dm/device-internal.h>
 #include <dma.h>
 #include <dma-uclass.h>
+#include <dt-structs.h>
 #include <errno.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#ifdef CONFIG_DMA_CHANNELS
+static inline struct dma_ops *dma_dev_ops(struct udevice *dev)
+{
+	return (struct dma_ops *)dev->driver->ops;
+}
+
+# if CONFIG_IS_ENABLED(OF_CONTROL)
+#  if CONFIG_IS_ENABLED(OF_PLATDATA)
+int dma_get_by_index_platdata(struct udevice *dev, int index,
+			      struct phandle_2_cell *cells, struct dma *dma)
+{
+	int ret;
+
+	if (index != 0)
+		return -ENOSYS;
+	ret = uclass_get_device(UCLASS_DMA, 0, &dma->dev);
+	if (ret)
+		return ret;
+	dma->id = cells[0].id;
+
+	return 0;
+}
+#  else
+static int dma_of_xlate_default(struct dma *dma,
+				struct fdtdec_phandle_args *args)
+{
+	debug("%s(dma=%p)\n", __func__, dma);
+
+	if (args->args_count > 1) {
+		pr_err("Invaild args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	if (args->args_count)
+		dma->id = args->args[0];
+	else
+		dma->id = 0;
+
+	return 0;
+}
+
+int dma_get_by_index(struct udevice *dev, int index, struct dma *dma)
+{
+	int ret;
+	struct fdtdec_phandle_args args;
+	struct udevice *dev_dma;
+	struct dma_ops *ops;
+
+	debug("%s(dev=%p, index=%d, dma=%p)\n", __func__, dev, index, dma);
+
+	assert(dma);
+	ret = fdtdec_parse_phandle_with_args(gd->fdt_blob, dev_of_offset(dev),
+					     "dmas", "#dma-cells", 0, index,
+					     &args);
+	if (ret) {
+		pr_err("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	ret = uclass_get_device_by_of_offset(UCLASS_DMA, args.node, &dev_dma);
+	if (ret) {
+		pr_err("%s: uclass_get_device_by_of_offset failed: err=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	dma->dev = dev_dma;
+
+	ops = dma_dev_ops(dev_dma);
+
+	if (ops->of_xlate)
+		ret = ops->of_xlate(dma, &args);
+	else
+		ret = dma_of_xlate_default(dma, &args);
+	if (ret) {
+		pr_err("of_xlate() failed: %d\n", ret);
+		return ret;
+	}
+
+	return dma_request(dev_dma, dma);
+}
+#  endif /* OF_PLATDATA */
+
+int dma_get_by_name(struct udevice *dev, const char *name, struct dma *dma)
+{
+	int index;
+
+	debug("%s(dev=%p, name=%s, dma=%p)\n", __func__, dev, name, dma);
+
+	index = fdt_stringlist_search(gd->fdt_blob, dev_of_offset(dev),
+				      "dma-names", name);
+	if (index < 0) {
+		pr_err("fdt_stringlist_search() failed: %d\n", index);
+		return index;
+	}
+
+	return dma_get_by_index(dev, index, dma);
+}
+# endif /* OF_CONTROL */
+
+int dma_request(struct udevice *dev, struct dma *dma)
+{
+	struct dma_ops *ops = dma_dev_ops(dev);
+
+	debug("%s(dev=%p, dma=%p)\n", __func__, dev, dma);
+
+	dma->dev = dev;
+
+	if (!ops->request)
+		return 0;
+
+	return ops->request(dma);
+}
+
+int dma_free(struct dma *dma)
+{
+	struct dma_ops *ops = dma_dev_ops(dma->dev);
+
+	debug("%s(dma=%p)\n", __func__, dma);
+
+	if (!ops->free)
+		return 0;
+
+	return ops->free(dma);
+}
+
+int dma_enable(struct dma *dma)
+{
+	struct dma_ops *ops = dma_dev_ops(dma->dev);
+
+	debug("%s(dma=%p)\n", __func__, dma);
+
+	if (!ops->enable)
+		return -ENOSYS;
+
+	return ops->enable(dma);
+}
+
+int dma_disable(struct dma *dma)
+{
+	struct dma_ops *ops = dma_dev_ops(dma->dev);
+
+	debug("%s(dma=%p)\n", __func__, dma);
+
+	if (!ops->disable)
+		return -ENOSYS;
+
+	return ops->disable(dma);
+}
+
+int dma_receive(struct dma *dma, void **dst)
+{
+	struct dma_ops *ops = dma_dev_ops(dma->dev);
+
+	debug("%s(dma=%p)\n", __func__, dma);
+
+	if (!ops->receive)
+		return -1;
+
+	return ops->receive(dma, dst);
+}
+
+int dma_send(struct dma *dma, void *src, size_t len)
+{
+	struct dma_ops *ops = dma_dev_ops(dma->dev);
+
+	debug("%s(dma=%p)\n", __func__, dma);
+
+	if (!ops->send)
+		return -1;
+
+	return ops->send(dma, src, len);
+}
+#endif /* CONFIG_DMA_CHANNELS */
+
 int dma_get_device(u32 transfer_type, struct udevice **devp)
 {
 	struct udevice *dev;
diff --git a/include/dma-uclass.h b/include/dma-uclass.h
index e29ad103f2..5faec69207 100644
--- a/include/dma-uclass.h
+++ b/include/dma-uclass.h
@@ -12,6 +12,7 @@
 /* See dma.h for background documentation. */
 
 #include <dma.h>
+#include <fdtdec.h>
 
 /*
  * struct dma_ops - Driver model DMA operations
@@ -20,6 +21,82 @@
  * driver model.
  */
 struct dma_ops {
+#ifdef CONFIG_DMA_CHANNELS
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) DMA specifier.
+	 *
+	 * The DMA core calls this function as the first step in implementing
+	 * a client's dma_get_by_*() call.
+	 *
+	 * If this function pointer is set to NULL, the DMA core will use a
+	 * default implementation, which assumes #dma-cells = <1>, and that
+	 * the DT cell contains a simple integer DMA Channel.
+	 *
+	 * At present, the DMA API solely supports device-tree. If this
+	 * changes, other xxx_xlate() functions may be added to support those
+	 * other mechanisms.
+	 *
+	 * @dma: The dma struct to hold the translation result.
+	 * @args:	The dma specifier values from device tree.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*of_xlate)(struct dma *dma,
+			struct fdtdec_phandle_args *args);
+	/**
+	 * request - Request a translated DMA.
+	 *
+	 * The DMA core calls this function as the second step in
+	 * implementing a client's dma_get_by_*() call, following a successful
+	 * xxx_xlate() call, or as the only step in implementing a client's
+	 * dma_request() call.
+	 *
+	 * @dma: The DMA struct to request; this has been filled in by
+	 *   a previoux xxx_xlate() function call, or by the caller of
+	 *   dma_request().
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*request)(struct dma *dma);
+	/**
+	 * free - Free a previously requested dma.
+	 *
+	 * This is the implementation of the client dma_free() API.
+	 *
+	 * @dma: The DMA to free.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*free)(struct dma *dma);
+	/**
+	 * enable() - Enable a DMA Channel.
+	 *
+	 * @dma: The DMA Channel to manipulate.
+	 * @return zero on success, or -ve error code.
+	 */
+	int (*enable)(struct dma *dma);
+	/**
+	 * disable() - Disable a DMA Channel.
+	 *
+	 * @dma: The DMA Channel to manipulate.
+	 * @return zero on success, or -ve error code.
+	 */
+	int (*disable)(struct dma *dma);
+	/**
+	 * receive() - Receive a DMA transfer.
+	 *
+	 * @dma: The DMA Channel to manipulate.
+	 * @dst: The destination pointer.
+	 * @return zero on success, or -ve error code.
+	 */
+	int (*receive)(struct dma *dma, void **dst);
+	/**
+	 * send() - Send a DMA transfer.
+	 *
+	 * @dma: The DMA Channel to manipulate.
+	 * @src: The source pointer.
+	 * @len: Length of the data to be copied.
+	 * @return zero on success, or -ve error code.
+	 */
+	int (*send)(struct dma *dma, void *src, size_t len);
+#endif /* CONFIG_DMA_CHANNELS */
 	/*
 	 * Get the current timer count
 	 *
diff --git a/include/dma.h b/include/dma.h
index 89320f10d9..d9d8567b93 100644
--- a/include/dma.h
+++ b/include/dma.h
@@ -8,6 +8,9 @@
 #ifndef _DMA_H_
 #define _DMA_H_
 
+#include <linux/errno.h>
+#include <linux/types.h>
+
 /*
  * enum dma_direction - dma transfer direction indicator
  * @DMA_MEM_TO_MEM: Memcpy mode
@@ -37,6 +40,172 @@ struct dma_dev_priv {
 	u32 supported;
 };
 
+#ifdef CONFIG_DMA_CHANNELS
+/**
+ * A DMA is a feature of computer systems that allows certain hardware
+ * subsystems to access main system memory, independent of the CPU.
+ * DMA channels are typically generated externally to the HW module
+ * consuming them, by an entity this API calls a DMA provider. This API
+ * provides a standard means for drivers to enable and disable DMAs, and to
+ * copy, send and receive data using DMA.
+ *
+ * A driver that implements UCLASS_DMA is a DMA provider. A provider will
+ * often implement multiple separate DMAs, since the hardware it manages
+ * often has this capability. dma_uclass.h describes the interface which
+ * DMA providers must implement.
+ *
+ * DMA consumers/clients are the HW modules driven by the DMA channels. This
+ * header file describes the API used by drivers for those HW modules.
+ */
+
+struct udevice;
+
+/**
+ * struct dma - A handle to (allowing control of) a single DMA.
+ *
+ * Clients provide storage for DMA handles. The content of the structure is
+ * managed solely by the DMA API and DMA drivers. A DMA struct is
+ * initialized by "get"ing the DMA struct. The DMA struct is passed to all
+ * other DMA APIs to identify which DMA channel to operate upon.
+ *
+ * @dev: The device which implements the DMA channel.
+ * @id: The DMA channel ID within the provider.
+ *
+ * Currently, the DMA API assumes that a single integer ID is enough to
+ * identify and configure any DMA channel for any DMA provider. If this
+ * assumption becomes invalid in the future, the struct could be expanded to
+ * either (a) add more fields to allow DMA providers to store additional
+ * information, or (b) replace the id field with an opaque pointer, which the
+ * provider would dynamically allocated during its .of_xlate op, and process
+ * during is .request op. This may require the addition of an extra op to clean
+ * up the allocation.
+ */
+struct dma {
+	struct udevice *dev;
+	/*
+	 * Written by of_xlate. We assume a single id is enough for now. In the
+	 * future, we might add more fields here.
+	 */
+	unsigned long id;
+};
+
+# if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(DMA)
+struct phandle_2_cell;
+int dma_get_by_index_platdata(struct udevice *dev, int index,
+			      struct phandle_2_cell *cells, struct dma *dma);
+
+/**
+ * dma_get_by_index - Get/request a DMA by integer index.
+ *
+ * This looks up and requests a DMA. The index is relative to the client
+ * device; each device is assumed to have n DMAs associated with it somehow,
+ * and this function finds and requests one of them. The mapping of client
+ * device DMA indices to provider DMAs may be via device-tree properties,
+ * board-provided mapping tables, or some other mechanism.
+ *
+ * @dev:	The client device.
+ * @index:	The index of the DMA to request, within the client's list of
+ *		DMA channels.
+ * @dma:	A pointer to a DMA struct to initialize.
+ * @return 0 if OK, or a negative error code.
+ */
+int dma_get_by_index(struct udevice *dev, int index, struct dma *dma);
+
+/**
+ * dma_get_by_name - Get/request a DMA by name.
+ *
+ * This looks up and requests a DMA. The name is relative to the client
+ * device; each device is assumed to have n DMAs associated with it somehow,
+ * and this function finds and requests one of them. The mapping of client
+ * device DMA names to provider DMAs may be via device-tree properties,
+ * board-provided mapping tables, or some other mechanism.
+ *
+ * @dev:	The client device.
+ * @name:	The name of the DMA to request, within the client's list of
+ *		DMA channels.
+ * @dma:	A pointer to a DMA struct to initialize.
+ * @return 0 if OK, or a negative error code.
+ */
+int dma_get_by_name(struct udevice *dev, const char *name, struct dma *dma);
+# else
+static inline int dma_get_by_index(struct udevice *dev, int index,
+				   struct dma *dma)
+{
+	return -ENOSYS;
+}
+
+static inline int dma_get_by_name(struct udevice *dev, const char *name,
+			   struct dma *dma)
+{
+	return -ENOSYS;
+}
+# endif
+
+/**
+ * dma_request - Request a DMA by provider-specific ID.
+ *
+ * This requests a DMA using a provider-specific ID. Generally, this function
+ * should not be used, since dma_get_by_index/name() provide an interface that
+ * better separates clients from intimate knowledge of DMA providers.
+ * However, this function may be useful in core SoC-specific code.
+ *
+ * @dev: The DMA provider device.
+ * @dma: A pointer to a DMA struct to initialize. The caller must
+ *	 have already initialized any field in this struct which the
+ *	 DMA provider uses to identify the DMA channel.
+ * @return 0 if OK, or a negative error code.
+ */
+int dma_request(struct udevice *dev, struct dma *dma);
+
+/**
+ * dma_free - Free a previously requested DMA.
+ *
+ * @dma: A DMA struct that was previously successfully requested by
+ *	 dma_request/get_by_*().
+ * @return 0 if OK, or a negative error code.
+ */
+int dma_free(struct dma *dma);
+
+/**
+ * dma_enable() - Enable (turn on) a DMA channel.
+ *
+ * @dma: A DMA struct that was previously successfully requested by
+ *	 dma_request/get_by_*().
+ * @return zero on success, or -ve error code.
+ */
+int dma_enable(struct dma *dma);
+
+/**
+ * dma_disable() - Disable (turn off) a DMA channel.
+ *
+ * @dma: A DMA struct that was previously successfully requested by
+ *	 dma_request/get_by_*().
+ * @return zero on success, or -ve error code.
+ */
+int dma_disable(struct dma *dma);
+
+/**
+ * dma_receive() - Receive a DMA transfer.
+ *
+ * @dma: A DMA struct that was previously successfully requested by
+ *	 dma_request/get_by_*().
+ * @dst: The destination pointer.
+ * @return zero on success, or -ve error code.
+ */
+int dma_receive(struct dma *dma, void **dst);
+
+/**
+ * dma_send() - Send a DMA transfer.
+ *
+ * @dma: A DMA struct that was previously successfully requested by
+ *	 dma_request/get_by_*().
+ * @src: The source pointer.
+ * @len: Length of the data to be copied.
+ * @return zero on success, or -ve error code.
+ */
+int dma_send(struct dma *dma, void *src, size_t len);
+#endif /* CONFIG_DMA_CHANNELS */
+
 /*
  * dma_get_device - get a DMA device which supports transfer
  * type of transfer_type
-- 
2.11.0