Re: [PATCH v2 7/8] dmaengine: add a driver for Intel integrated DMA 64-bit

[Vinod Koul]

On Mon, May 25, 2015 at 07:09:31PM +0300, Andy Shevchenko wrote:
> Intel integrated DMA (iDMA) 64-bit is a specific IP that is used as a part of
> LPSS devices such as HSUART or SPI. The iDMA IP is attached for private
> usage on each host controller independently.
> 
> While it has similarities with Synopsys DesignWare DMA, the following
> distinctions doesn't allow to use the existing driver:
> - 64-bit mode with corresponding changes in Hardware Linked List data structure
> - many slight differences in the channel registers
> 
> Moreover this driver is based on the DMA virtual channels framework that helps
> to make the driver cleaner and easy to understand.
> 
Looking at code and iDMA controllers (if this is the same as I have used), we
have register compatibility with DW controller, so why new driver and why not
use and enhance dw driver ?

-- 
~Vinod

> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
>  drivers/dma/Kconfig  |   5 +
>  drivers/dma/Makefile |   1 +
>  drivers/dma/idma64.c | 749 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/dma/idma64.h | 233 ++++++++++++++++
>  4 files changed, 988 insertions(+)
>  create mode 100644 drivers/dma/idma64.c
>  create mode 100644 drivers/dma/idma64.h
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index bda2cb0..e4257e9 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -85,6 +85,11 @@ config INTEL_IOP_ADMA
>  	help
>  	  Enable support for the Intel(R) IOP Series RAID engines.
>  
> +config IDMA64
> +	tristate "Intel integrated DMA 64-bit support"
> +	select DMA_ENGINE
> +	select DMA_VIRTUAL_CHANNELS
> +
>  source "drivers/dma/dw/Kconfig"
>  
>  config AT_HDMAC
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index 69f77d5..c1fe119 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_HSU_DMA) += hsu/
>  obj-$(CONFIG_MPC512X_DMA) += mpc512x_dma.o
>  obj-$(CONFIG_PPC_BESTCOMM) += bestcomm/
>  obj-$(CONFIG_MV_XOR) += mv_xor.o
> +obj-$(CONFIG_IDMA64) += idma64.o
>  obj-$(CONFIG_DW_DMAC_CORE) += dw/
>  obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
>  obj-$(CONFIG_AT_XDMAC) += at_xdmac.o
> diff --git a/drivers/dma/idma64.c b/drivers/dma/idma64.c
> new file mode 100644
> index 0000000..3119bdf
> --- /dev/null
> +++ b/drivers/dma/idma64.c
> @@ -0,0 +1,749 @@
> +/*
> + * Core driver for the Intel integrated DMA 64-bit
> + *
> + * Copyright (C) 2015 Intel Corporation
> + * Author: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmapool.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/platform_device.h>
> +
> +#include "idma64.h"
> +
> +/* Platform driver name */
> +#define DRV_NAME		"idma64"
> +
> +/* For now we support only two channels */
> +#define IDMA64_NR_CHAN		2
> +
> +/* ---------------------------------------------------------------------- */
> +
> +static struct device *chan2dev(struct dma_chan *chan)
> +{
> +	return &chan->dev->device;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +
> +static void idma64_off(struct idma64 *idma64)
> +{
> +	unsigned short count = 100;
> +
> +	dma_writel(idma64, CFG, 0);
> +
> +	channel_clear_bit(idma64, MASK(XFER), idma64->all_chan_mask);
> +	channel_clear_bit(idma64, MASK(BLOCK), idma64->all_chan_mask);
> +	channel_clear_bit(idma64, MASK(SRC_TRAN), idma64->all_chan_mask);
> +	channel_clear_bit(idma64, MASK(DST_TRAN), idma64->all_chan_mask);
> +	channel_clear_bit(idma64, MASK(ERROR), idma64->all_chan_mask);
> +
> +	do {
> +		cpu_relax();
> +	} while (dma_readl(idma64, CFG) & IDMA64_CFG_DMA_EN && --count);
> +}
> +
> +static void idma64_on(struct idma64 *idma64)
> +{
> +	dma_writel(idma64, CFG, IDMA64_CFG_DMA_EN);
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +
> +static void idma64_chan_init(struct idma64 *idma64, struct idma64_chan *idma64c)
> +{
> +	u32 cfghi = IDMA64C_CFGH_SRC_PER(1) | IDMA64C_CFGH_DST_PER(0);
> +	u32 cfglo = 0;
> +
> +	/* Enforce FIFO drain when channel is suspended */
> +	cfglo |= IDMA64C_CFGL_CH_DRAIN;
> +
> +	/* Set default burst alignment */
> +	cfglo |= IDMA64C_CFGL_DST_BURST_ALIGN | IDMA64C_CFGL_SRC_BURST_ALIGN;
> +
> +	channel_writel(idma64c, CFG_LO, cfglo);
> +	channel_writel(idma64c, CFG_HI, cfghi);
> +
> +	/* Enable interrupts */
> +	channel_set_bit(idma64, MASK(XFER), idma64c->mask);
> +	channel_set_bit(idma64, MASK(ERROR), idma64c->mask);
> +
> +	/*
> +	 * Enforce the controller to be turned on.
> +	 *
> +	 * The iDMA is turned off in ->probe() and looses context during system
> +	 * suspend / resume cycle. That's why we have to enable it each time we
> +	 * use it.
> +	 */
> +	idma64_on(idma64);
> +}
> +
> +static void idma64_chan_stop(struct idma64 *idma64, struct idma64_chan *idma64c)
> +{
> +	channel_clear_bit(idma64, CH_EN, idma64c->mask);
> +}
> +
> +static void idma64_chan_start(struct idma64 *idma64, struct idma64_chan *idma64c)
> +{
> +	struct idma64_desc *desc = idma64c->desc;
> +	struct idma64_hw_desc *hw = &desc->hw[0];
> +
> +	channel_writeq(idma64c, SAR, 0);
> +	channel_writeq(idma64c, DAR, 0);
> +
> +	channel_writel(idma64c, CTL_HI, IDMA64C_CTLH_BLOCK_TS(~0UL));
> +	channel_writel(idma64c, CTL_LO, IDMA64C_CTLL_LLP_S_EN | IDMA64C_CTLL_LLP_D_EN);
> +
> +	channel_writeq(idma64c, LLP, hw->llp);
> +
> +	channel_set_bit(idma64, CH_EN, idma64c->mask);
> +}
> +
> +static void idma64_init_channel(struct idma64_chan *idma64c)
> +{
> +	struct idma64 *idma64 = to_idma64(idma64c->vchan.chan.device);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	idma64_chan_init(idma64, idma64c);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +}
> +
> +static void idma64_stop_channel(struct idma64_chan *idma64c)
> +{
> +	struct idma64 *idma64 = to_idma64(idma64c->vchan.chan.device);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	idma64_chan_stop(idma64, idma64c);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +}
> +
> +static void idma64_start_channel(struct idma64_chan *idma64c)
> +{
> +	struct idma64 *idma64 = to_idma64(idma64c->vchan.chan.device);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	idma64_chan_start(idma64, idma64c);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +}
> +
> +static void idma64_start_transfer(struct idma64_chan *idma64c)
> +{
> +	struct virt_dma_desc *vdesc;
> +
> +	/* Get the next descriptor */
> +	vdesc = vchan_next_desc(&idma64c->vchan);
> +	if (!vdesc) {
> +		idma64c->desc = NULL;
> +		return;
> +	}
> +
> +	list_del(&vdesc->node);
> +	idma64c->desc = to_idma64_desc(vdesc);
> +
> +	/* Configure the channel */
> +	idma64_init_channel(idma64c);
> +
> +	/* Start the channel with a new descriptor */
> +	idma64_start_channel(idma64c);
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +
> +static void idma64_chan_irq(struct idma64 *idma64, unsigned short c,
> +		u32 status_err, u32 status_xfer)
> +{
> +	struct idma64_chan *idma64c = &idma64->chan[c];
> +	struct idma64_desc *desc;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->vchan.lock, flags);
> +	desc = idma64c->desc;
> +	if (desc) {
> +		if (status_err & (1 << c)) {
> +			dma_writel(idma64, CLEAR(ERROR), idma64c->mask);
> +			desc->status = DMA_ERROR;
> +		} else if (status_xfer & (1 << c)) {
> +			dma_writel(idma64, CLEAR(XFER), idma64c->mask);
> +			desc->status = DMA_COMPLETE;
> +			vchan_cookie_complete(&desc->vdesc);
> +			idma64_start_transfer(idma64c);
> +		}
> +
> +		/* idma64_start_transfer() updates idma64c->desc */
> +		if (idma64c->desc == NULL || desc->status == DMA_ERROR)
> +			idma64_stop_channel(idma64c);
> +	}
> +	spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
> +}
> +
> +static irqreturn_t idma64_irq(int irq, void *dev)
> +{
> +	struct idma64 *idma64 = dev;
> +	u32 status = dma_readl(idma64, STATUS_INT);
> +	u32 status_xfer;
> +	u32 status_err;
> +	unsigned short i;
> +
> +	dev_vdbg(idma64->dma.dev, "%s: status=%#x\n", __func__, status);
> +
> +	/* Check if we have any interrupt from the DMA controller */
> +	if (!status)
> +		return IRQ_NONE;
> +
> +	/* Disable interrupts */
> +	channel_clear_bit(idma64, MASK(XFER), idma64->all_chan_mask);
> +	channel_clear_bit(idma64, MASK(ERROR), idma64->all_chan_mask);
> +
> +	status_xfer = dma_readl(idma64, RAW(XFER));
> +	status_err = dma_readl(idma64, RAW(ERROR));
> +
> +	for (i = 0; i < idma64->dma.chancnt; i++)
> +		idma64_chan_irq(idma64, i, status_err, status_xfer);
> +
> +	/* Re-enable interrupts */
> +	channel_set_bit(idma64, MASK(XFER), idma64->all_chan_mask);
> +	channel_set_bit(idma64, MASK(ERROR), idma64->all_chan_mask);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +
> +static struct idma64_desc *idma64_alloc_desc(unsigned int ndesc)
> +{
> +	struct idma64_desc *desc;
> +
> +	desc = kzalloc(sizeof(*desc), GFP_NOWAIT);
> +	if (!desc)
> +		return NULL;
> +
> +	desc->hw = kcalloc(ndesc, sizeof(*desc->hw), GFP_NOWAIT);
> +	if (!desc->hw) {
> +		kfree(desc);
> +		return NULL;
> +	}
> +
> +	return desc;
> +}
> +
> +static void idma64_desc_free(struct idma64_chan *idma64c,
> +		struct idma64_desc *desc)
> +{
> +	struct idma64_hw_desc *hw;
> +
> +	if (desc->ndesc) {
> +		unsigned int i = desc->ndesc;
> +
> +		do {
> +			hw = &desc->hw[--i];
> +			dma_pool_free(idma64c->pool, hw->lli, hw->llp);
> +		} while (i);
> +	}
> +
> +	kfree(desc->hw);
> +	kfree(desc);
> +}
> +
> +static void idma64_vdesc_free(struct virt_dma_desc *vdesc)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(vdesc->tx.chan);
> +
> +	idma64_desc_free(idma64c, to_idma64_desc(vdesc));
> +}
> +
> +static void idma64_hw_desc_fill(struct idma64_hw_desc *hw,
> +		struct dma_slave_config *config,
> +		enum dma_transfer_direction direction, u64 llp)
> +{
> +	struct idma64_lli *lli = hw->lli;
> +	u64 sar, dar;
> +	u32 ctlhi = IDMA64C_CTLH_BLOCK_TS(hw->len);
> +	u32 ctllo = IDMA64C_CTLL_LLP_S_EN | IDMA64C_CTLL_LLP_D_EN;
> +	u32 src_width, dst_width;
> +
> +	if (direction == DMA_MEM_TO_DEV) {
> +		sar = hw->phys;
> +		dar = config->dst_addr;
> +		ctllo |= IDMA64C_CTLL_DST_FIX | IDMA64C_CTLL_SRC_INC |
> +			 IDMA64C_CTLL_FC_M2P;
> +		src_width = min_t(u32, 2, __ffs(sar | hw->len));
> +		dst_width = __fls(config->dst_addr_width);
> +	} else {	/* DMA_DEV_TO_MEM */
> +		sar = config->src_addr;
> +		dar = hw->phys;
> +		ctllo |= IDMA64C_CTLL_DST_INC | IDMA64C_CTLL_SRC_FIX |
> +			 IDMA64C_CTLL_FC_P2M;
> +		src_width = __fls(config->src_addr_width);
> +		dst_width = min_t(u32, 2, __ffs(dar | hw->len));
> +	}
> +
> +	lli->sar = sar;
> +	lli->dar = dar;
> +
> +	lli->ctlhi = ctlhi;
> +	lli->ctllo = ctllo |
> +		     IDMA64C_CTLL_SRC_MSIZE(config->src_maxburst) |
> +		     IDMA64C_CTLL_DST_MSIZE(config->dst_maxburst) |
> +		     IDMA64C_CTLL_DST_WIDTH(dst_width) |
> +		     IDMA64C_CTLL_SRC_WIDTH(src_width);
> +
> +	lli->llp = llp;
> +}
> +
> +static void idma64_desc_fill(struct idma64_chan *idma64c,
> +		struct idma64_desc *desc)
> +{
> +	struct dma_slave_config *config = &idma64c->config;
> +	struct idma64_hw_desc *hw = &desc->hw[desc->ndesc - 1];
> +	struct idma64_lli *lli = hw->lli;
> +	u64 llp = 0;
> +	unsigned int i = desc->ndesc;
> +
> +	/* Fill the hardware descriptors and link them to a list */
> +	do {
> +		hw = &desc->hw[--i];
> +		idma64_hw_desc_fill(hw, config, desc->direction, llp);
> +		llp = hw->llp;
> +	} while (i);
> +
> +	/* Trigger interrupt after last block */
> +	lli->ctllo |= IDMA64C_CTLL_INT_EN;
> +}
> +
> +static struct dma_async_tx_descriptor *idma64_prep_slave_sg(
> +		struct dma_chan *chan, struct scatterlist *sgl,
> +		unsigned int sg_len, enum dma_transfer_direction direction,
> +		unsigned long flags, void *context)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +	struct idma64_desc *desc;
> +	struct scatterlist *sg;
> +	unsigned int i;
> +
> +	desc = idma64_alloc_desc(sg_len);
> +	if (!desc)
> +		return NULL;
> +
> +	for_each_sg(sgl, sg, sg_len, i) {
> +		struct idma64_hw_desc *hw = &desc->hw[i];
> +
> +		/* Allocate DMA capable memory for hardware descriptor */
> +		hw->lli = dma_pool_alloc(idma64c->pool, GFP_NOWAIT, &hw->llp);
> +		if (!hw->lli) {
> +			desc->ndesc = i;
> +			idma64_desc_free(idma64c, desc);
> +			return NULL;
> +		}
> +
> +		hw->phys = sg_dma_address(sg);
> +		hw->len = sg_dma_len(sg);
> +	}
> +
> +	desc->ndesc = sg_len;
> +	desc->direction = direction;
> +	desc->status = DMA_IN_PROGRESS;
> +
> +	idma64_desc_fill(idma64c, desc);
> +	return vchan_tx_prep(&idma64c->vchan, &desc->vdesc, flags);
> +}
> +
> +static void idma64_issue_pending(struct dma_chan *chan)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->vchan.lock, flags);
> +	if (vchan_issue_pending(&idma64c->vchan) && !idma64c->desc)
> +		idma64_start_transfer(idma64c);
> +	spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
> +}
> +
> +static size_t idma64_desc_size(struct idma64_desc *desc, unsigned int active)
> +{
> +	size_t bytes = 0;
> +	unsigned int i;
> +
> +	for (i = active; i < desc->ndesc; i++)
> +		bytes += desc->hw[i].len;
> +
> +	return bytes;
> +}
> +
> +static size_t idma64_pending_desc_size(struct idma64_desc *desc)
> +{
> +	return idma64_desc_size(desc, 0);
> +}
> +
> +static size_t idma64_active_desc_size(struct idma64_chan *idma64c)
> +{
> +	struct idma64_desc *desc = idma64c->desc;
> +	struct idma64_hw_desc *hw;
> +	size_t bytes;
> +	u64 llp;
> +	u32 ctlhi;
> +	unsigned int i = 0;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	llp = channel_readq(idma64c, LLP);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +
> +	do {
> +		hw = &desc->hw[i];
> +	} while (llp != hw->llp && ++i < desc->ndesc);
> +
> +	bytes = idma64_desc_size(desc, i);
> +	if (!i)
> +		return bytes;
> +
> +	hw = &desc->hw[--i];
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	ctlhi = channel_readl(idma64c, CTL_HI);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +
> +	return bytes + hw->len - IDMA64C_CTLH_BLOCK_TS(ctlhi);
> +}
> +
> +static enum dma_status idma64_tx_status(struct dma_chan *chan,
> +		dma_cookie_t cookie, struct dma_tx_state *state)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +	struct virt_dma_desc *vdesc;
> +	enum dma_status status;
> +	size_t bytes;
> +	unsigned long flags;
> +
> +	status = dma_cookie_status(chan, cookie, state);
> +	if (status == DMA_COMPLETE)
> +		return status;
> +
> +	spin_lock_irqsave(&idma64c->vchan.lock, flags);
> +	vdesc = vchan_find_desc(&idma64c->vchan, cookie);
> +	if (idma64c->desc && cookie == idma64c->desc->vdesc.tx.cookie) {
> +		bytes = idma64_active_desc_size(idma64c);
> +		dma_set_residue(state, bytes);
> +		status = idma64c->desc->status;
> +	} else if (vdesc) {
> +		bytes = idma64_pending_desc_size(to_idma64_desc(vdesc));
> +		dma_set_residue(state, bytes);
> +	}
> +	spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
> +
> +	return status;
> +}
> +
> +static void convert_burst(u32 *maxburst)
> +{
> +	if (*maxburst)
> +		*maxburst = __fls(*maxburst);
> +	else
> +		*maxburst = 0;
> +}
> +
> +static int idma64_slave_config(struct dma_chan *chan,
> +		struct dma_slave_config *config)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +
> +	/* Check if chan will be configured for slave transfers */
> +	if (!is_slave_direction(config->direction))
> +		return -EINVAL;
> +
> +	memcpy(&idma64c->config, config, sizeof(idma64c->config));
> +
> +	convert_burst(&idma64c->config.src_maxburst);
> +	convert_burst(&idma64c->config.dst_maxburst);
> +
> +	return 0;
> +}
> +
> +static void idma64_chan_deactivate(struct idma64_chan *idma64c)
> +{
> +	unsigned short count = 100;
> +	u32 cfglo;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	cfglo = channel_readl(idma64c, CFG_LO);
> +	channel_writel(idma64c, CFG_LO, cfglo | IDMA64C_CFGL_CH_SUSP);
> +	do {
> +		udelay(1);
> +		cfglo = channel_readl(idma64c, CFG_LO);
> +	} while (!(cfglo & IDMA64C_CFGL_FIFO_EMPTY) && --count);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +}
> +
> +static void idma64_chan_activate(struct idma64_chan *idma64c)
> +{
> +	u32 cfglo;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->lock, flags);
> +	cfglo = channel_readl(idma64c, CFG_LO);
> +	channel_writel(idma64c, CFG_LO, cfglo & ~IDMA64C_CFGL_CH_SUSP);
> +	spin_unlock_irqrestore(&idma64c->lock, flags);
> +}
> +
> +static int idma64_pause(struct dma_chan *chan)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->vchan.lock, flags);
> +	if (idma64c->desc && idma64c->desc->status == DMA_IN_PROGRESS) {
> +		idma64_chan_deactivate(idma64c);
> +		idma64c->desc->status = DMA_PAUSED;
> +	}
> +	spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
> +
> +	return 0;
> +}
> +
> +static int idma64_resume(struct dma_chan *chan)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&idma64c->vchan.lock, flags);
> +	if (idma64c->desc && idma64c->desc->status == DMA_PAUSED) {
> +		idma64c->desc->status = DMA_IN_PROGRESS;
> +		idma64_chan_activate(idma64c);
> +	}
> +	spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
> +
> +	return 0;
> +}
> +
> +static int idma64_terminate_all(struct dma_chan *chan)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +	unsigned long flags;
> +	LIST_HEAD(head);
> +
> +	spin_lock_irqsave(&idma64c->vchan.lock, flags);
> +	idma64_stop_channel(idma64c);
> +	if (idma64c->desc) {
> +		idma64_vdesc_free(&idma64c->desc->vdesc);
> +		idma64c->desc = NULL;
> +	}
> +	vchan_get_all_descriptors(&idma64c->vchan, &head);
> +	spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
> +
> +	vchan_dma_desc_free_list(&idma64c->vchan, &head);
> +	return 0;
> +}
> +
> +static int idma64_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +
> +	/* Create a pool of consistent memory blocks for hardware descriptors */
> +	idma64c->pool = dma_pool_create(dev_name(chan2dev(chan)),
> +					chan->device->dev,
> +					sizeof(struct idma64_lli), 8, 0);
> +	if (!idma64c->pool) {
> +		dev_err(chan2dev(chan), "No memory for descriptors\n");
> +		return -ENOMEM;
> +	}
> +
> +	return 0;
> +}
> +
> +static void idma64_free_chan_resources(struct dma_chan *chan)
> +{
> +	struct idma64_chan *idma64c = to_idma64_chan(chan);
> +
> +	dma_pool_destroy(idma64c->pool);
> +	vchan_free_chan_resources(to_virt_chan(chan));
> +}
> +
> +static int idma64_probe(struct idma64_chip *chip)
> +{
> +	struct idma64 *idma64;
> +	unsigned short nr_chan = IDMA64_NR_CHAN;
> +	unsigned short i;
> +	int ret;
> +
> +	idma64 = devm_kzalloc(chip->dev, sizeof(*idma64), GFP_KERNEL);
> +	if (!idma64)
> +		return -ENOMEM;
> +
> +	idma64->regs = chip->regs;
> +	chip->idma64 = idma64;
> +
> +	idma64->chan = devm_kcalloc(chip->dev, nr_chan, sizeof(*idma64->chan),
> +				    GFP_KERNEL);
> +	if (!idma64->chan)
> +		return -ENOMEM;
> +
> +	idma64->all_chan_mask = (1 << nr_chan) - 1;
> +
> +	/* Turn off iDMA controller */
> +	idma64_off(idma64);
> +
> +	ret = devm_request_irq(chip->dev, chip->irq, idma64_irq, IRQF_SHARED,
> +			       dev_name(chip->dev), idma64);
> +	if (ret)
> +		return ret;
> +
> +	INIT_LIST_HEAD(&idma64->dma.channels);
> +	for (i = 0; i < nr_chan; i++) {
> +		struct idma64_chan *idma64c = &idma64->chan[i];
> +
> +		idma64c->vchan.desc_free = idma64_vdesc_free;
> +		vchan_init(&idma64c->vchan, &idma64->dma);
> +
> +		idma64c->regs = idma64->regs + i * IDMA64_CH_LENGTH;
> +		idma64c->mask = BIT(i);
> +
> +		spin_lock_init(&idma64c->lock);
> +	}
> +
> +	dma_cap_set(DMA_SLAVE, idma64->dma.cap_mask);
> +	dma_cap_set(DMA_PRIVATE, idma64->dma.cap_mask);
> +
> +	idma64->dma.device_alloc_chan_resources = idma64_alloc_chan_resources;
> +	idma64->dma.device_free_chan_resources = idma64_free_chan_resources;
> +
> +	idma64->dma.device_prep_slave_sg = idma64_prep_slave_sg;
> +
> +	idma64->dma.device_issue_pending = idma64_issue_pending;
> +	idma64->dma.device_tx_status = idma64_tx_status;
> +
> +	idma64->dma.device_config = idma64_slave_config;
> +	idma64->dma.device_pause = idma64_pause;
> +	idma64->dma.device_resume = idma64_resume;
> +	idma64->dma.device_terminate_all = idma64_terminate_all;
> +
> +	idma64->dma.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
> +	idma64->dma.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
> +
> +	idma64->dma.dev = chip->dev;
> +
> +	ret = dma_async_device_register(&idma64->dma);
> +	if (ret)
> +		return ret;
> +
> +	dev_info(chip->dev, "Found Intel integrated DMA 64-bit\n");
> +	return 0;
> +}
> +
> +static int idma64_remove(struct idma64_chip *chip)
> +{
> +	struct idma64 *idma64 = chip->idma64;
> +	unsigned short i;
> +
> +	dma_async_device_unregister(&idma64->dma);
> +
> +	/*
> +	 * Explicitly call devm_request_irq() to avoid the side effects with
> +	 * the scheduled tasklets.
> +	 */
> +	devm_free_irq(chip->dev, chip->irq, idma64);
> +
> +	for (i = 0; i < idma64->dma.chancnt; i++) {
> +		struct idma64_chan *idma64c = &idma64->chan[i];
> +
> +		tasklet_kill(&idma64c->vchan.task);
> +	}
> +
> +	return 0;
> +}
> +
> +/* ---------------------------------------------------------------------- */
> +
> +static int idma64_platform_probe(struct platform_device *pdev)
> +{
> +	struct idma64_chip *chip;
> +	struct device *dev = &pdev->dev;
> +	struct resource *mem;
> +	int ret;
> +
> +	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	chip->irq = platform_get_irq(pdev, 0);
> +	if (chip->irq < 0)
> +		return chip->irq;
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	chip->regs = devm_ioremap_resource(dev, mem);
> +	if (IS_ERR(chip->regs))
> +		return PTR_ERR(chip->regs);
> +
> +	ret = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
> +	if (ret)
> +		return ret;
> +
> +	chip->dev = dev;
> +
> +	ret = idma64_probe(chip);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, chip);
> +	return 0;
> +}
> +
> +static int idma64_platform_remove(struct platform_device *pdev)
> +{
> +	struct idma64_chip *chip = platform_get_drvdata(pdev);
> +
> +	return idma64_remove(chip);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +
> +static int idma64_suspend_late(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct idma64_chip *chip = platform_get_drvdata(pdev);
> +
> +	idma64_off(chip->idma64);
> +	return 0;
> +}
> +
> +static int idma64_resume_early(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct idma64_chip *chip = platform_get_drvdata(pdev);
> +
> +	idma64_on(chip->idma64);
> +	return 0;
> +}
> +
> +#endif /* CONFIG_PM_SLEEP */
> +
> +static const struct dev_pm_ops idma64_dev_pm_ops = {
> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(idma64_suspend_late, idma64_resume_early)
> +};
> +
> +static struct platform_driver idma64_platform_driver = {
> +	.probe		= idma64_platform_probe,
> +	.remove		= idma64_platform_remove,
> +	.driver = {
> +		.name	= DRV_NAME,
> +		.pm	= &idma64_dev_pm_ops,
> +	},
> +};
> +
> +module_platform_driver(idma64_platform_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("iDMA64 core driver");
> +MODULE_AUTHOR("Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>");
> +MODULE_ALIAS("platform:" DRV_NAME);
> diff --git a/drivers/dma/idma64.h b/drivers/dma/idma64.h
> new file mode 100644
> index 0000000..63be77f
> --- /dev/null
> +++ b/drivers/dma/idma64.h
> @@ -0,0 +1,233 @@
> +/*
> + * Driver for the Intel integrated DMA 64-bit
> + *
> + * Copyright (C) 2015 Intel Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef __DMA_IDMA64_H__
> +#define __DMA_IDMA64_H__
> +
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/spinlock.h>
> +#include <linux/types.h>
> +
> +#include "virt-dma.h"
> +
> +/* Channel registers */
> +
> +#define IDMA64_CH_SAR		0x00	/* Source Address Register */
> +#define IDMA64_CH_DAR		0x08	/* Destination Address Register */
> +#define IDMA64_CH_LLP		0x10	/* Linked List Pointer */
> +#define IDMA64_CH_CTL_LO	0x18	/* Control Register Low */
> +#define IDMA64_CH_CTL_HI	0x1c	/* Control Register High */
> +#define IDMA64_CH_SSTAT		0x20
> +#define IDMA64_CH_DSTAT		0x28
> +#define IDMA64_CH_SSTATAR	0x30
> +#define IDMA64_CH_DSTATAR	0x38
> +#define IDMA64_CH_CFG_LO	0x40	/* Configuration Register Low */
> +#define IDMA64_CH_CFG_HI	0x44	/* Configuration Register High */
> +#define IDMA64_CH_SGR		0x48
> +#define IDMA64_CH_DSR		0x50
> +
> +#define IDMA64_CH_LENGTH	0x58
> +
> +/* Bitfields in CTL_LO */
> +#define IDMA64C_CTLL_INT_EN		(1 << 0)	/* irqs enabled? */
> +#define IDMA64C_CTLL_DST_WIDTH(x)	((x) << 1)	/* bytes per element */
> +#define IDMA64C_CTLL_SRC_WIDTH(x)	((x) << 4)
> +#define IDMA64C_CTLL_DST_INC		(0 << 8)	/* DAR update/not */
> +#define IDMA64C_CTLL_DST_FIX		(1 << 8)
> +#define IDMA64C_CTLL_SRC_INC		(0 << 10)	/* SAR update/not */
> +#define IDMA64C_CTLL_SRC_FIX		(1 << 10)
> +#define IDMA64C_CTLL_DST_MSIZE(x)	((x) << 11)	/* burst, #elements */
> +#define IDMA64C_CTLL_SRC_MSIZE(x)	((x) << 14)
> +#define IDMA64C_CTLL_FC_M2P		(1 << 20)	/* mem-to-periph */
> +#define IDMA64C_CTLL_FC_P2M		(2 << 20)	/* periph-to-mem */
> +#define IDMA64C_CTLL_LLP_D_EN		(1 << 27)	/* dest block chain */
> +#define IDMA64C_CTLL_LLP_S_EN		(1 << 28)	/* src block chain */
> +
> +/* Bitfields in CTL_HI */
> +#define IDMA64C_CTLH_BLOCK_TS(x)	((x) & ((1 << 17) - 1))
> +#define IDMA64C_CTLH_DONE		(1 << 17)
> +
> +/* Bitfields in CFG_LO */
> +#define IDMA64C_CFGL_DST_BURST_ALIGN	(1 << 0)	/* dst burst align */
> +#define IDMA64C_CFGL_SRC_BURST_ALIGN	(1 << 1)	/* src burst align */
> +#define IDMA64C_CFGL_CH_SUSP		(1 << 8)
> +#define IDMA64C_CFGL_FIFO_EMPTY		(1 << 9)
> +#define IDMA64C_CFGL_CH_DRAIN		(1 << 10)	/* drain FIFO */
> +#define IDMA64C_CFGL_DST_OPT_BL		(1 << 20)	/* optimize dst burst length */
> +#define IDMA64C_CFGL_SRC_OPT_BL		(1 << 21)	/* optimize src burst length */
> +
> +/* Bitfields in CFG_HI */
> +#define IDMA64C_CFGH_SRC_PER(x)		((x) << 0)	/* src peripheral */
> +#define IDMA64C_CFGH_DST_PER(x)		((x) << 4)	/* dst peripheral */
> +#define IDMA64C_CFGH_RD_ISSUE_THD(x)	((x) << 8)
> +#define IDMA64C_CFGH_RW_ISSUE_THD(x)	((x) << 18)
> +
> +/* Interrupt registers */
> +
> +#define IDMA64_INT_XFER		0x00
> +#define IDMA64_INT_BLOCK	0x08
> +#define IDMA64_INT_SRC_TRAN	0x10
> +#define IDMA64_INT_DST_TRAN	0x18
> +#define IDMA64_INT_ERROR	0x20
> +
> +#define IDMA64_RAW(x)		(0x2c0 + IDMA64_INT_##x)	/* r */
> +#define IDMA64_STATUS(x)	(0x2e8 + IDMA64_INT_##x)	/* r (raw & mask) */
> +#define IDMA64_MASK(x)		(0x310 + IDMA64_INT_##x)	/* rw (set = irq enabled) */
> +#define IDMA64_CLEAR(x)		(0x338 + IDMA64_INT_##x)	/* w (ack, affects "raw") */
> +
> +/* Common registers */
> +
> +#define IDMA64_STATUS_INT	0x360	/* r */
> +#define IDMA64_CFG		0x398
> +#define IDMA64_CH_EN		0x3a0
> +
> +/* Bitfields in CFG */
> +#define IDMA64_CFG_DMA_EN		(1 << 0)
> +
> +/* Hardware descriptor for Linked LIst transfers */
> +struct idma64_lli {
> +	u64		sar;
> +	u64		dar;
> +	u64		llp;
> +	u32		ctllo;
> +	u32		ctlhi;
> +	u32		sstat;
> +	u32		dstat;
> +};
> +
> +struct idma64_hw_desc {
> +	struct idma64_lli *lli;
> +	dma_addr_t llp;
> +	dma_addr_t phys;
> +	unsigned int len;
> +};
> +
> +struct idma64_desc {
> +	struct virt_dma_desc vdesc;
> +	enum dma_transfer_direction direction;
> +	struct idma64_hw_desc *hw;
> +	unsigned int ndesc;
> +	enum dma_status status;
> +};
> +
> +static inline struct idma64_desc *to_idma64_desc(struct virt_dma_desc *vdesc)
> +{
> +	return container_of(vdesc, struct idma64_desc, vdesc);
> +}
> +
> +struct idma64_chan {
> +	struct virt_dma_chan vchan;
> +
> +	void __iomem *regs;
> +	spinlock_t lock;
> +
> +	/* hardware configuration */
> +	enum dma_transfer_direction direction;
> +	unsigned int mask;
> +	struct dma_slave_config config;
> +
> +	void *pool;
> +	struct idma64_desc *desc;
> +};
> +
> +static inline struct idma64_chan *to_idma64_chan(struct dma_chan *chan)
> +{
> +	return container_of(chan, struct idma64_chan, vchan.chan);
> +}
> +
> +#define channel_set_bit(idma64, reg, mask)	\
> +	dma_writel(idma64, reg, ((mask) << 8) | (mask))
> +#define channel_clear_bit(idma64, reg, mask)	\
> +	dma_writel(idma64, reg, ((mask) << 8) | 0)
> +
> +static inline u32 idma64c_readl(struct idma64_chan *idma64c, int offset)
> +{
> +	return readl(idma64c->regs + offset);
> +}
> +
> +static inline void idma64c_writel(struct idma64_chan *idma64c, int offset,
> +				  u32 value)
> +{
> +	writel(value, idma64c->regs + offset);
> +}
> +
> +#define channel_readl(idma64c, reg)		\
> +	idma64c_readl(idma64c, IDMA64_CH_##reg)
> +#define channel_writel(idma64c, reg, value)	\
> +	idma64c_writel(idma64c, IDMA64_CH_##reg, (value))
> +
> +static inline u64 idma64c_readq(struct idma64_chan *idma64c, int offset)
> +{
> +	u64 l, h;
> +
> +	l = idma64c_readl(idma64c, offset);
> +	h = idma64c_readl(idma64c, offset + 4);
> +
> +	return l | (h << 32);
> +}
> +
> +static inline void idma64c_writeq(struct idma64_chan *idma64c, int offset,
> +				  u64 value)
> +{
> +	idma64c_writel(idma64c, offset, value);
> +	idma64c_writel(idma64c, offset + 4, value >> 32);
> +}
> +
> +#define channel_readq(idma64c, reg)		\
> +	idma64c_readq(idma64c, IDMA64_CH_##reg)
> +#define channel_writeq(idma64c, reg, value)	\
> +	idma64c_writeq(idma64c, IDMA64_CH_##reg, (value))
> +
> +struct idma64 {
> +	struct dma_device dma;
> +
> +	void __iomem *regs;
> +
> +	/* channels */
> +	unsigned short all_chan_mask;
> +	struct idma64_chan *chan;
> +};
> +
> +static inline struct idma64 *to_idma64(struct dma_device *ddev)
> +{
> +	return container_of(ddev, struct idma64, dma);
> +}
> +
> +static inline u32 idma64_readl(struct idma64 *idma64, int offset)
> +{
> +	return readl(idma64->regs + offset);
> +}
> +
> +static inline void idma64_writel(struct idma64 *idma64, int offset, u32 value)
> +{
> +	writel(value, idma64->regs + offset);
> +}
> +
> +#define dma_readl(idma64, reg)			\
> +	idma64_readl(idma64, IDMA64_##reg)
> +#define dma_writel(idma64, reg, value)		\
> +	idma64_writel(idma64, IDMA64_##reg, (value))
> +
> +/**
> + * struct idma64_chip - representation of DesignWare DMA controller hardware
> + * @dev:		struct device of the DMA controller
> + * @irq:		irq line
> + * @regs:		memory mapped I/O space
> + * @idma64:		struct idma64 that is filed by idma64_probe()
> + */
> +struct idma64_chip {
> +	struct device	*dev;
> +	int		irq;
> +	void __iomem	*regs;
> +	struct idma64	*idma64;
> +};
> +
> +#endif /* __DMA_IDMA64_H__ */
> -- 
> 2.1.4
> 

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