linux/drivers/dma/dw/dw.c
Serge Semin 8d2f59dab3 dmaengine: dw: Ignore burst setting for memory peripherals
According to the DW DMA controller Databook 2.18b (page 40 "3.5 Memory
Peripherals") memory peripherals don't have handshaking interface
connected to the controller, therefore they can never be a flow
controller. Since the CTLx.SRC_MSIZE and CTLx.DEST_MSIZE are properties
valid only for peripherals with a handshaking interface, we can freely
zero these fields out if the memory peripheral is selected to be the
source or the destination of the DMA transfers.

Note according to the databook, length of burst transfers to memory is
always equal to the number of data items available in a channel FIFO or
data items required to complete the block transfer, whichever is smaller;
length of burst transfers from memory is always equal to the space
available in a channel FIFO or number of data items required to complete
the block transfer, whichever is smaller.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200731200826.9292-5-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Vinod Koul <vkoul@kernel.org>
2020-08-17 11:58:31 +05:30

138 lines
3.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2007-2008 Atmel Corporation
// Copyright (C) 2010-2011 ST Microelectronics
// Copyright (C) 2013,2018 Intel Corporation
#include <linux/bitops.h>
#include <linux/dmaengine.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/types.h>
#include "internal.h"
static void dw_dma_initialize_chan(struct dw_dma_chan *dwc)
{
struct dw_dma *dw = to_dw_dma(dwc->chan.device);
u32 cfghi = is_slave_direction(dwc->direction) ? 0 : DWC_CFGH_FIFO_MODE;
u32 cfglo = DWC_CFGL_CH_PRIOR(dwc->priority);
bool hs_polarity = dwc->dws.hs_polarity;
cfghi |= DWC_CFGH_DST_PER(dwc->dws.dst_id);
cfghi |= DWC_CFGH_SRC_PER(dwc->dws.src_id);
cfghi |= DWC_CFGH_PROTCTL(dw->pdata->protctl);
/* Set polarity of handshake interface */
cfglo |= hs_polarity ? DWC_CFGL_HS_DST_POL | DWC_CFGL_HS_SRC_POL : 0;
channel_writel(dwc, CFG_LO, cfglo);
channel_writel(dwc, CFG_HI, cfghi);
}
static void dw_dma_suspend_chan(struct dw_dma_chan *dwc, bool drain)
{
u32 cfglo = channel_readl(dwc, CFG_LO);
channel_writel(dwc, CFG_LO, cfglo | DWC_CFGL_CH_SUSP);
}
static void dw_dma_resume_chan(struct dw_dma_chan *dwc, bool drain)
{
u32 cfglo = channel_readl(dwc, CFG_LO);
channel_writel(dwc, CFG_LO, cfglo & ~DWC_CFGL_CH_SUSP);
}
static u32 dw_dma_bytes2block(struct dw_dma_chan *dwc,
size_t bytes, unsigned int width, size_t *len)
{
u32 block;
if ((bytes >> width) > dwc->block_size) {
block = dwc->block_size;
*len = dwc->block_size << width;
} else {
block = bytes >> width;
*len = bytes;
}
return block;
}
static size_t dw_dma_block2bytes(struct dw_dma_chan *dwc, u32 block, u32 width)
{
return DWC_CTLH_BLOCK_TS(block) << width;
}
static u32 dw_dma_prepare_ctllo(struct dw_dma_chan *dwc)
{
struct dma_slave_config *sconfig = &dwc->dma_sconfig;
u8 smsize = (dwc->direction == DMA_DEV_TO_MEM) ? sconfig->src_maxburst : 0;
u8 dmsize = (dwc->direction == DMA_MEM_TO_DEV) ? sconfig->dst_maxburst : 0;
u8 p_master = dwc->dws.p_master;
u8 m_master = dwc->dws.m_master;
u8 dms = (dwc->direction == DMA_MEM_TO_DEV) ? p_master : m_master;
u8 sms = (dwc->direction == DMA_DEV_TO_MEM) ? p_master : m_master;
return DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN |
DWC_CTLL_DST_MSIZE(dmsize) | DWC_CTLL_SRC_MSIZE(smsize) |
DWC_CTLL_DMS(dms) | DWC_CTLL_SMS(sms);
}
static void dw_dma_encode_maxburst(struct dw_dma_chan *dwc, u32 *maxburst)
{
/*
* Fix burst size according to dw_dmac. We need to convert them as:
* 1 -> 0, 4 -> 1, 8 -> 2, 16 -> 3.
*/
*maxburst = *maxburst > 1 ? fls(*maxburst) - 2 : 0;
}
static void dw_dma_set_device_name(struct dw_dma *dw, int id)
{
snprintf(dw->name, sizeof(dw->name), "dw:dmac%d", id);
}
static void dw_dma_disable(struct dw_dma *dw)
{
do_dw_dma_off(dw);
}
static void dw_dma_enable(struct dw_dma *dw)
{
do_dw_dma_on(dw);
}
int dw_dma_probe(struct dw_dma_chip *chip)
{
struct dw_dma *dw;
dw = devm_kzalloc(chip->dev, sizeof(*dw), GFP_KERNEL);
if (!dw)
return -ENOMEM;
/* Channel operations */
dw->initialize_chan = dw_dma_initialize_chan;
dw->suspend_chan = dw_dma_suspend_chan;
dw->resume_chan = dw_dma_resume_chan;
dw->prepare_ctllo = dw_dma_prepare_ctllo;
dw->encode_maxburst = dw_dma_encode_maxburst;
dw->bytes2block = dw_dma_bytes2block;
dw->block2bytes = dw_dma_block2bytes;
/* Device operations */
dw->set_device_name = dw_dma_set_device_name;
dw->disable = dw_dma_disable;
dw->enable = dw_dma_enable;
chip->dw = dw;
return do_dma_probe(chip);
}
EXPORT_SYMBOL_GPL(dw_dma_probe);
int dw_dma_remove(struct dw_dma_chip *chip)
{
return do_dma_remove(chip);
}
EXPORT_SYMBOL_GPL(dw_dma_remove);