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

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