[U-Boot] [PATCH v5 02/15] dma: add channels support

Joe Hershberger
2018-03-07T21:27:30Z

On Mon, Mar 5, 2018 at 2:05 PM, Álvaro Fernández Rojas
<noltari@gmail.com> wrote:
> 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>
> Reviewed-by: Simon Glass <sjg@chromium.org>
> ---
> v5: remove unneeded dma.h include
> v4: no changes
> v3: Introduce changes reported by Simon Glass:
> - Improve dma-uclass.h documentation.
> - Switch to live tree API.
>
> drivers/dma/Kconfig | 7 ++
> drivers/dma/dma-uclass.c | 188 +++++++++++++++++++++++++++++++++++++++++++++--
> include/dma-uclass.h | 78 ++++++++++++++++++++
> include/dma.h | 174 ++++++++++++++++++++++++++++++++++++++++++-
> 4 files changed, 439 insertions(+), 8 deletions(-)
>
> 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 faa27a3a56..b5109aafc9 100644
> --- a/drivers/dma/dma-uclass.c
> +++ b/drivers/dma/dma-uclass.c
> @@ -1,23 +1,199 @@
> /*
> * Direct Memory Access U-Class driver
> *
> - * (C) Copyright 2015
> - * Texas Instruments Incorporated, <www.ti.com>
> - *
> - * Author: Mugunthan V N <mugunthanvnm@ti.com>
> + * Copyright (C) 2018 Álvaro Fernández Rojas <noltari@gmail.com>
> + * Copyright (C) 2015 Texas Instruments Incorporated <www.ti.com>
> + * Written by Mugunthan V N <mugunthanvnm@ti.com>
> *
> * SPDX-License-Identifier: GPL-2.0+
> */
>
> #include <common.h>
> #include <dm.h>
> -#include <dm/uclass-internal.h>
> -#include <dm/device-internal.h>
> +#include <dm/read.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_1_arg *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 ofnode_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 ofnode_phandle_args args;
> + struct udevice *dev_dma;
> + const struct dma_ops *ops;
> +
> + debug("%s(dev=%p, index=%d, dma=%p)\n", __func__, dev, index, dma);
> +
> + assert(dma);
> + dma->dev = NULL;
> +
> + ret = dev_read_phandle_with_args(dev, "dmas", "#dma-cells", 0, index,
> + &args);
> + if (ret) {
> + pr_err("%s: dev_read_phandle_with_args failed: err=%d\n",
> + __func__, ret);
> + return ret;
> + }
> +
> + ret = uclass_get_device_by_ofnode(UCLASS_DMA, args.node, &dev_dma);
> + if (ret) {
> + pr_err("%s: uclass_get_device_by_ofnode 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);
> + dma->dev = NULL;
> +
> + index = dev_read_stringlist_search(dev, "dma-names", name);
> + if (index < 0) {
> + pr_err("dev_read_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;

Isn't there a better error code you could return? Such as -ENOSYS like above?

> +
> + 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;

Same here.

> +
> + 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 3429f65ec4..b334adb68b 100644
> --- a/include/dma-uclass.h
> +++ b/include/dma-uclass.h
> @@ -13,6 +13,8 @@
>
> #include <dma.h>
>
> +struct ofnode_phandle_args;
> +
> /*
> * struct dma_ops - Driver model DMA operations
> *
> @@ -20,6 +22,82 @@
> * 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 ofnode_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.
> + */

I haven't seen any implementation of this. Will it return -EAGAIN in
the case where the packet isn't available?

> + 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 sent (number of bytes).
> + * @return zero on success, or -ve error code.
> + */
> + int (*send)(struct dma *dma, void *src, size_t len);
> +#endif /* CONFIG_DMA_CHANNELS */
> /**
> * transfer() - Issue a DMA transfer. The implementation must
> * wait until the transfer is done.
> diff --git a/include/dma.h b/include/dma.h
> index 89320f10d9..bf8123fa9e 100644
> --- a/include/dma.h
> +++ b/include/dma.h
> @@ -1,6 +1,7 @@
> /*
> - * (C) Copyright 2015
> - * Texas Instruments Incorporated, <www.ti.com>
> + * Copyright (C) 2018 Álvaro Fernández Rojas <noltari@gmail.com>
> + * Copyright (C) 2015 Texas Instruments Incorporated <www.ti.com>
> + * Written by Mugunthan V N <mugunthanvnm@ti.com>
> *
> * SPDX-License-Identifier: GPL-2.0+
> */
> @@ -8,6 +9,9 @@
> #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 +41,172 @@ 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_1_arg;
> +int dma_get_by_index_platdata(struct udevice *dev, int index,
> + struct phandle_1_arg *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 sent (number of bytes).
> + * @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
>
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