[U-Boot] [PATCH 1/6] dm: implement a DMA uclass

[Simon Glass <sjg@chromium.org>]

Hi Mugunthan,

On 1 December 2015 at 04:13, Mugunthan V N <mugunthanvnm@ti.com> wrote:
> Implement a DMA uclass so that the devices like ethernet, spi,
> mmc etc can offload the data transfers from/to the device and
> memory.
>
> Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
> ---
>  drivers/dma/Kconfig      | 15 ++++++++++++
>  drivers/dma/Makefile     |  2 ++
>  drivers/dma/dma-uclass.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/dm/uclass-id.h   |  1 +
>  include/dma.h            | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 145 insertions(+)
>  create mode 100644 drivers/dma/dma-uclass.c
>  create mode 100644 include/dma.h
>
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index e69de29..af15199 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -0,0 +1,15 @@
> +menu "DMA Support"
> +
> +config DM_DMA
> +       bool "Enable Driver Model for DMA drivers"
> +       depends on DM
> +       help
> +         Enable driver model for DMA. DMA engines can do
> +         asynchronous data transfers without involving the host
> +         CPU. Currently, this framework can be used to offload
> +         memory copies to and from devices like qspi, ethernet
> +         etc Drivers provide methods to access the DMA devices
> +         buses that is used to transfer data to and from memory.
> +         The uclass interface is defined in include/dma.h.
> +
> +endmenu # menu "DMA Support"
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index f95fe70..4ff22aa 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -5,6 +5,8 @@
>  # SPDX-License-Identifier:     GPL-2.0+
>  #
>
> +obj-$(CONFIG_DM_DMA) += dma-uclass.o

You can just use CONFIG_DMA. The DM_ prefix is for when we have an
existing pre-DM interface. Eventually all the CONFIG_DM_... options
will be removed. Unless you have a special reason?

> +
>  obj-$(CONFIG_FSLDMAFEC) += MCD_tasksInit.o MCD_dmaApi.o MCD_tasks.o
>  obj-$(CONFIG_APBH_DMA) += apbh_dma.o
>  obj-$(CONFIG_FSL_DMA) += fsl_dma.o
> diff --git a/drivers/dma/dma-uclass.c b/drivers/dma/dma-uclass.c
> new file mode 100644
> index 0000000..1afcbaa4
> --- /dev/null
> +++ b/drivers/dma/dma-uclass.c
> @@ -0,0 +1,63 @@
> +/*
> + * Direct Memory Access U-Class driver
> + *
> + * (C) Copyright 2015
> + *     Texas Instruments Incorporated, <www.ti.com>
> + *
> + * Author: Mugunthan V N <mugunthanvnm@ti.com>
> + *
> + * SPDX-License-Identifier:     GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <dma.h>
> +#include <dm.h>
> +#include <dm/uclass-internal.h>
> +#include <errno.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +int dma_memcpy(void *dst, void *src, size_t len)
> +{
> +       struct udevice *dev;
> +       const struct dma_ops *ops;
> +       int ret;
> +
> +       for (ret = uclass_find_first_device(UCLASS_DMA, &dev); dev && !ret;
> +            ret = uclass_find_next_device(&dev)) {
> +               struct dma_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> +
> +               if (uc_priv->supported & SUPPORTS_MEM_TO_MEM)
> +                       break;
> +       }
> +
> +       if (!dev) {
> +               printf("No DMA device found that supports mem to mem transfers\n");
> +               return -ENODEV;
> +       }

Can you put the above code in a separate function like:

static int get_dma_device(struct udevice **devp)

also also please call device_probe() on it before returning it.

> +
> +       ops = device_get_ops(dev);
> +       if (!ops->transfer)
> +               return -ENOSYS;
> +
> +       /* Invalidate the area, so no writeback into the RAM races with DMA */
> +       invalidate_dcache_range((unsigned long)dst, (unsigned long)dst +
> +                               roundup(len, ARCH_DMA_MINALIGN));
> +
> +       return ops->transfer(dev, DMA_MEM_TO_MEM, dst, src, len);
> +}
> +
> +int dma_post_bind(struct udevice *dev)
> +{
> +       struct udevice *devp;
> +       uclass_get_device_by_of_offset(UCLASS_DMA, dev->of_offset, &devp);

You are not allowed to do this in the post_bind() method. See above
for how it should get probed.

> +       return 0;
> +}
> +
> +UCLASS_DRIVER(dma) = {
> +       .id             = UCLASS_DMA,
> +       .name           = "dma",
> +       .flags          = DM_UC_FLAG_SEQ_ALIAS,
> +       .per_device_auto_alloc_size = sizeof(struct dma_dev_priv),
> +       .post_bind      = dma_post_bind,
> +};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index 27fa0b6..9f5fcae 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -30,6 +30,7 @@ enum uclass_id {
>         UCLASS_CPU,             /* CPU, typically part of an SoC */
>         UCLASS_CROS_EC,         /* Chrome OS EC */
>         UCLASS_DISPLAY_PORT,    /* Display port video */
> +       UCLASS_DMA,             /* Direct Memory Access */
>         UCLASS_RAM,             /* RAM controller */
>         UCLASS_ETH,             /* Ethernet device */
>         UCLASS_GPIO,            /* Bank of general-purpose I/O pins */
> diff --git a/include/dma.h b/include/dma.h
> new file mode 100644
> index 0000000..d53e435
> --- /dev/null
> +++ b/include/dma.h
> @@ -0,0 +1,64 @@
> +/*
> + * (C) Copyright 2015
> + *     Texas Instruments Incorporated, <www.ti.com>
> + *
> + * SPDX-License-Identifier:     GPL-2.0+
> + */
> +
> +#ifndef _DMA_H_
> +#define _DMA_H_
> +
> +/*
> + * enum dma_direction - dma transfer direction indicator
> + * @DMA_MEM_TO_MEM: Memcpy mode
> + * @DMA_MEM_TO_DEV: From Memory to Device
> + * @DMA_DEV_TO_MEM: From Device to Memory
> + * @DMA_DEV_TO_DEV: From Device to Device
> + */
> +enum dma_direction {
> +       DMA_MEM_TO_MEM,
> +       DMA_MEM_TO_DEV,
> +       DMA_DEV_TO_MEM,
> +       DMA_DEV_TO_DEV,
> +       DMA_TRANS_NONE,

What does that mean?

> +};
> +
> +#define SUPPORTS_MEM_TO_MEM    BIT(0)
> +#define SUPPORTS_MEM_TO_DEV    BIT(1)
> +#define SUPPORTS_DEV_TO_MEM    BIT(2)
> +#define SUPPORTS_DEV_TO_DEV    BIT(3)

DMA_ prefix on these. Also you could put them in an enum so they are grouped.

> +
> +/*
> + * struct dma_ops - Driver model DMA operations
> + *
> + * The uclass interface is implemented by all DMA devices which use
> + * driver model.
> + */
> +struct dma_ops {
> +       /*
> +        * Get the current timer count

Incorrect comment.

> +        *
> +        * @dev: The DMA device
> +        * @direction: direction of data transfer should be one from
> +                      enum dma_direction
> +        * @dst: Destination pointer
> +        * @src: Source pointer

Any alignment restructions?

> +        * @len: Length of the data to be copied.

In bytes?

> +        * @return: 0 if OK, -ve on error
> +        */
> +       int (*transfer)(struct udevice *dev, int direction, void *dst,

s/int direction/enum dma_direction direction/

> +                       void *src, size_t len);
> +};
> +
> +/*
> + * struct dma_dev_priv - information about a device used by the uclass
> + *
> + * @supported: mode of transfers that DMA can support

Please reference where these flags come from.

> + */
> +struct dma_dev_priv {
> +       unsigned long supported;

int or uint should be enough.

> +};
> +
> +int dma_memcpy(void *dst, void *src, size_t len);
> +
> +#endif /* _DMA_H_ */
> --
> 2.6.3.368.gf34be46
>

Regards,
Simon