[U-Boot] [PATCH v2 1/6] dm: implement a DMA uclass
Simon Glass
sjg at chromium.org
Wed Jan 6 01:24:54 CET 2016
Hi Mugunthan,
On 23 December 2015 at 09:42, Mugunthan V N <mugunthanvnm at 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 at ti.com>
> ---
> drivers/dma/Kconfig | 15 +++++++++
> drivers/dma/Makefile | 2 ++
> drivers/dma/dma-uclass.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++
> include/dm/uclass-id.h | 1 +
> include/dma.h | 81 ++++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 177 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..58cb6e9 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -0,0 +1,15 @@
> +menu "DMA Support"
> +
> +config 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..39b78b2 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -5,6 +5,8 @@
> # SPDX-License-Identifier: GPL-2.0+
> #
>
> +obj-$(CONFIG_DMA) += dma-uclass.o
> +
> obj-$(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..0b3044e
> --- /dev/null
> +++ b/drivers/dma/dma-uclass.c
> @@ -0,0 +1,78 @@
> +/*
> + * Direct Memory Access U-Class driver
> + *
> + * (C) Copyright 2015
> + * Texas Instruments Incorporated, <www.ti.com>
> + *
> + * Author: Mugunthan V N <mugunthanvnm at ti.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0+
> + */
> +
> +#include <common.h>
> +#include <dma.h>
> +#include <dm.h>
> +#include <dm/uclass-internal.h>
> +#include <dm/device-internal.h>
> +#include <errno.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +int dma_get_device(struct udevice **devp, u32 transfer_type)
nit: can you please put devp last? That's the way most of the DM code is.
> +{
> + struct udevice *dev = NULL;
Should be able to drop the assignment.
> + 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;
> +
> + ret = device_probe(dev);
If you are probing it anyway, why not just do:
for (ret = uclass_first_device(...) ... uclass_next_device(...) )
It does the probe for you.
> + if (ret) {
> + error("device probe error\n");
> + continue;
> + }
> +
> + uc_priv = dev_get_uclass_priv(dev);
> + if (uc_priv->supported & transfer_type)
> + break;
> + }
> +
> + if (!dev) {
> + error("No DMA device found that supports %x type\n",
> + transfer_type);
> + return -ENODEV;
-ENOPROTOSUPPORT?
-ENODEV means no device was found. It might be nice to distinguish
between having no devices at all, and not having one that suits.
> + }
> +
> + *devp = dev;
> +
> + return ret;
> +}
> +
> +int dma_memcpy(void *dst, void *src, size_t len)
> +{
> + struct udevice *dev;
> + const struct dma_ops *ops;
> + int ret;
> +
> + ret = dma_get_device(&dev, DMA_SUPPORTS_MEM_TO_MEM);
> + if (ret < 0)
> + return ret;
> +
> + 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);
> +}
> +
> +UCLASS_DRIVER(dma) = {
> + .id = UCLASS_DMA,
> + .name = "dma",
> + .flags = DM_UC_FLAG_SEQ_ALIAS,
> + .per_device_auto_alloc_size = sizeof(struct dma_dev_priv),
> +};
> 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..4b7016f
> --- /dev/null
> +++ b/include/dma.h
> @@ -0,0 +1,81 @@
> +/*
> + * (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,
> +};
> +
> +#define DMA_SUPPORTS_MEM_TO_MEM BIT(0)
> +#define DMA_SUPPORTS_MEM_TO_DEV BIT(1)
> +#define DMA_SUPPORTS_DEV_TO_MEM BIT(2)
> +#define DMA_SUPPORTS_DEV_TO_DEV BIT(3)
> +
> +/*
> + * 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
> + *
> + * @dev: The DMA device
> + * @direction: direction of data transfer should be one from
> + enum dma_direction
> + * @dst: Destination pointer
> + * @src: Source pointer
> + * @len: Length of the data to be copied.
> + * @return: 0 if OK, -ve on error
> + */
> + int (*transfer)(struct udevice *dev, int direction, void *dst,
> + 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
Reference the DMA_SUPPORTS thing above.
> + */
> +struct dma_dev_priv {
> + u32 supported;
> +};
> +
> +/*
> + * dma_get_device - get a DMA device which supports transfer
> + * type of transfer_type
> + *
> + * @devp - udevice pointer to return the found device
> + * @transfer_type - transfer type should be one/multiple of
> + * DMA_SUPPORTS_*
@return
> + */
> +int dma_get_device(struct udevice **devp, u32 transfer_type);
> +
> +/*
> + * dma_memcpy - try to use DMA to do a mem copy which will be
> + * much faster than CPU mem copy
> + *
> + * @dst - destination pointer
> + * @src - souce pointer
> + * @len - data length to be copied
@return
> + */
> +int dma_memcpy(void *dst, void *src, size_t len);
> +
> +#endif /* _DMA_H_ */
> --
> 2.7.0.rc1.5.gf3adf45
>
Regards,
Simon
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