[U-Boot] [PATCH v2 1/6] dm: implement a DMA uclass
Mugunthan V N
mugunthanvnm at ti.com
Wed Jan 6 07:30:25 CET 2016
On Wednesday 06 January 2016 05:54 AM, Simon Glass wrote:
> 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.
Will fix it in v3
>
>> +{
>> + struct udevice *dev = NULL;
>
> Should be able to drop the assignment.
Okay
>
>> + 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.
Okay, will simplify the code.
>
>> + 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.
Okay, will fix in next version.
>
>> + }
>> +
>> + *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.
Okay.
>
>> + */
>> +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
Will add return documentation in next revision.
Regards
Mugunthan V N
>
>> + */
>> +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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