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Message-ID: <1332864670.1820.13.camel@vkoul-udesk3>
Date: Tue, 27 Mar 2012 21:41:10 +0530
From: Vinod Koul <vinod.koul@...ux.intel.com>
To: Alexandre Bounine <alexandre.bounine@....com>
Cc: akpm@...ux-foundation.org, dan.j.williams@...el.com,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
leoli@...escale.com, mporter@...nel.crashing.org,
paul.gortmaker@...driver.com
Subject: Re: [PATCH V2 1/2] rapidio: add DMA engine support for RIO data
transfers
On Mon, 2012-03-26 at 16:45 -0400, Alexandre Bounine wrote:
> Adds DMA Engine framework support into RapidIO subsystem.
> Uses DMA Engine DMA_SLAVE interface to generate data transfers to/from
> remote RapidIO target devices.
> Introduces RapidIO-specific wrapper for prep_slave_sg() interface
> with an extra parameter to pass target specific information.
> Uses scatterlist to describe local data buffer. Address flat data buffer
> on a remote side.
>
> Signed-off-by: Alexandre Bounine <alexandre.bounine@....com>
Acked by: Vinod Koul <vinod.koul@...ux.intel.com>
> ---
>
> This patch is applicable to linux-next-20120326 and after.
>
> v2: Uses updated DMA engine prep_slave_sg() interface.
> See https://lkml.org/lkml/2012/3/8/373 for more details.
>
> drivers/rapidio/Kconfig | 14 ++++++++
> drivers/rapidio/rio.c | 81 +++++++++++++++++++++++++++++++++++++++++++++
> include/linux/dmaengine.h | 12 +++++++
> include/linux/rio.h | 47 ++++++++++++++++++++++++++
> include/linux/rio_drv.h | 9 +++++
> 5 files changed, 163 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/rapidio/Kconfig b/drivers/rapidio/Kconfig
> index bc87192..6194d35 100644
> --- a/drivers/rapidio/Kconfig
> +++ b/drivers/rapidio/Kconfig
> @@ -22,6 +22,20 @@ config RAPIDIO_ENABLE_RX_TX_PORTS
> ports for Input/Output direction to allow other traffic
> than Maintenance transfers.
>
> +config RAPIDIO_DMA_ENGINE
> + bool "DMA Engine support for RapidIO"
> + depends on RAPIDIO
> + select DMADEVICES
> + select DMA_ENGINE
> + help
> + Say Y here if you want to use DMA Engine frameork for RapidIO data
> + transfers to/from target RIO devices. RapidIO uses NREAD and
> + NWRITE (NWRITE_R, SWRITE) requests to transfer data between local
> + memory and memory on remote target device. You need a DMA controller
> + capable to perform data transfers to/from RapidIO.
> +
> + If you are unsure about this, say Y here.
> +
> config RAPIDIO_DEBUG
> bool "RapidIO subsystem debug messages"
> depends on RAPIDIO
> diff --git a/drivers/rapidio/rio.c b/drivers/rapidio/rio.c
> index 86c9a09..c40665a 100644
> --- a/drivers/rapidio/rio.c
> +++ b/drivers/rapidio/rio.c
> @@ -1121,6 +1121,87 @@ int rio_std_route_clr_table(struct rio_mport *mport, u16 destid, u8 hopcount,
> return 0;
> }
>
> +#ifdef CONFIG_RAPIDIO_DMA_ENGINE
> +
> +static bool rio_chan_filter(struct dma_chan *chan, void *arg)
> +{
> + struct rio_dev *rdev = arg;
> +
> + /* Check that DMA device belongs to the right MPORT */
> + return (rdev->net->hport ==
> + container_of(chan->device, struct rio_mport, dma));
> +}
> +
> +/**
> + * rio_request_dma - request RapidIO capable DMA channel that supports
> + * specified target RapidIO device.
> + * @rdev: RIO device control structure
> + *
> + * Returns pointer to allocated DMA channel or NULL if failed.
> + */
> +struct dma_chan *rio_request_dma(struct rio_dev *rdev)
> +{
> + dma_cap_mask_t mask;
> + struct dma_chan *dchan;
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
> + dchan = dma_request_channel(mask, rio_chan_filter, rdev);
> +
> + return dchan;
> +}
> +EXPORT_SYMBOL_GPL(rio_request_dma);
> +
> +/**
> + * rio_release_dma - release specified DMA channel
> + * @dchan: DMA channel to release
> + */
> +void rio_release_dma(struct dma_chan *dchan)
> +{
> + dma_release_channel(dchan);
> +}
> +EXPORT_SYMBOL_GPL(rio_release_dma);
> +
> +/**
> + * rio_dma_prep_slave_sg - RapidIO specific wrapper
> + * for device_prep_slave_sg callback defined by DMAENGINE.
> + * @rdev: RIO device control structure
> + * @dchan: DMA channel to configure
> + * @data: RIO specific data descriptor
> + * @direction: DMA data transfer direction (TO or FROM the device)
> + * @flags: dmaengine defined flags
> + *
> + * Initializes RapidIO capable DMA channel for the specified data transfer.
> + * Uses DMA channel private extension to pass information related to remote
> + * target RIO device.
> + * Returns pointer to DMA transaction descriptor or NULL if failed.
> + */
> +struct dma_async_tx_descriptor *rio_dma_prep_slave_sg(struct rio_dev *rdev,
> + struct dma_chan *dchan, struct rio_dma_data *data,
> + enum dma_transfer_direction direction, unsigned long flags)
> +{
> + struct dma_async_tx_descriptor *txd = NULL;
> + struct rio_dma_ext rio_ext;
> +
> + if (dchan->device->device_prep_slave_sg == NULL) {
> + pr_err("%s: prep_rio_sg == NULL\n", __func__);
> + return NULL;
> + }
> +
> + rio_ext.destid = rdev->destid;
> + rio_ext.rio_addr_u = data->rio_addr_u;
> + rio_ext.rio_addr = data->rio_addr;
> + rio_ext.wr_type = data->wr_type;
> +
> + txd = dmaengine_prep_rio_sg(dchan, data->sg, data->sg_len,
> + direction, flags, &rio_ext);
> +
> + return txd;
> +}
> +EXPORT_SYMBOL_GPL(rio_dma_prep_slave_sg);
> +
> +#endif /* CONFIG_RAPIDIO_DMA_ENGINE */
> +
> static void rio_fixup_device(struct rio_dev *dev)
> {
> }
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index 676f967..3596a3a 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -633,6 +633,18 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
> dir, flags, NULL);
> }
>
> +#ifdef CONFIG_RAPIDIO_DMA_ENGINE
> +struct rio_dma_ext;
> +static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg(
> + struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len,
> + enum dma_transfer_direction dir, unsigned long flags,
> + struct rio_dma_ext *rio_ext)
> +{
> + return chan->device->device_prep_slave_sg(chan, sgl, sg_len,
> + dir, flags, rio_ext);
> +}
> +#endif
> +
> static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic(
> struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
> size_t period_len, enum dma_transfer_direction dir)
> diff --git a/include/linux/rio.h b/include/linux/rio.h
> index 4d50611..a90ebad 100644
> --- a/include/linux/rio.h
> +++ b/include/linux/rio.h
> @@ -20,6 +20,9 @@
> #include <linux/errno.h>
> #include <linux/device.h>
> #include <linux/rio_regs.h>
> +#ifdef CONFIG_RAPIDIO_DMA_ENGINE
> +#include <linux/dmaengine.h>
> +#endif
>
> #define RIO_NO_HOPCOUNT -1
> #define RIO_INVALID_DESTID 0xffff
> @@ -254,6 +257,9 @@ struct rio_mport {
> u32 phys_efptr;
> unsigned char name[40];
> void *priv; /* Master port private data */
> +#ifdef CONFIG_RAPIDIO_DMA_ENGINE
> + struct dma_device dma;
> +#endif
> };
>
> /**
> @@ -395,6 +401,47 @@ union rio_pw_msg {
> u32 raw[RIO_PW_MSG_SIZE/sizeof(u32)];
> };
>
> +#ifdef CONFIG_RAPIDIO_DMA_ENGINE
> +
> +/**
> + * enum rio_write_type - RIO write transaction types used in DMA transfers
> + *
> + * Note: RapidIO specification defines write (NWRITE) and
> + * write-with-response (NWRITE_R) data transfer operations.
> + * Existing DMA controllers that service RapidIO may use one of these operations
> + * for entire data transfer or their combination with only the last data packet
> + * requires response.
> + */
> +enum rio_write_type {
> + RDW_DEFAULT, /* default method used by DMA driver */
> + RDW_ALL_NWRITE, /* all packets use NWRITE */
> + RDW_ALL_NWRITE_R, /* all packets use NWRITE_R */
> + RDW_LAST_NWRITE_R, /* last packet uses NWRITE_R, others - NWRITE */
> +};
> +
> +struct rio_dma_ext {
> + u16 destid;
> + u64 rio_addr; /* low 64-bits of 66-bit RapidIO address */
> + u8 rio_addr_u; /* upper 2-bits of 66-bit RapidIO address */
> + enum rio_write_type wr_type; /* preferred RIO write operation type */
> +};
> +
> +struct rio_dma_data {
> + /* Local data (as scatterlist) */
> + struct scatterlist *sg; /* I/O scatter list */
> + unsigned int sg_len; /* size of scatter list */
> + /* Remote device address (flat buffer) */
> + u64 rio_addr; /* low 64-bits of 66-bit RapidIO address */
> + u8 rio_addr_u; /* upper 2-bits of 66-bit RapidIO address */
> + enum rio_write_type wr_type; /* preferred RIO write operation type */
> +};
> +
> +static inline struct rio_mport *dma_to_mport(struct dma_device *ddev)
> +{
> + return container_of(ddev, struct rio_mport, dma);
> +}
> +#endif /* CONFIG_RAPIDIO_DMA_ENGINE */
> +
> /* Architecture and hardware-specific functions */
> extern int rio_register_mport(struct rio_mport *);
> extern int rio_open_inb_mbox(struct rio_mport *, void *, int, int);
> diff --git a/include/linux/rio_drv.h b/include/linux/rio_drv.h
> index 7f07470..31ad146 100644
> --- a/include/linux/rio_drv.h
> +++ b/include/linux/rio_drv.h
> @@ -377,6 +377,15 @@ void rio_unregister_driver(struct rio_driver *);
> struct rio_dev *rio_dev_get(struct rio_dev *);
> void rio_dev_put(struct rio_dev *);
>
> +#ifdef CONFIG_RAPIDIO_DMA_ENGINE
> +extern struct dma_chan *rio_request_dma(struct rio_dev *rdev);
> +extern void rio_release_dma(struct dma_chan *dchan);
> +extern struct dma_async_tx_descriptor *rio_dma_prep_slave_sg(
> + struct rio_dev *rdev, struct dma_chan *dchan,
> + struct rio_dma_data *data,
> + enum dma_transfer_direction direction, unsigned long flags);
> +#endif
> +
> /**
> * rio_name - Get the unique RIO device identifier
> * @rdev: RIO device
--
~Vinod
--
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