spi-pxa2xx-dma.c
/*
* PXA2xx SPI DMA engine support.
*
* Copyright (C) 2013, Intel Corporation
* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
*
* 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/device.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/pxa2xx_ssp.h>
#include <linux/scatterlist.h>
#include <linux/sizes.h>
#include <linux/spi/spi.h>
#include <linux/spi/pxa2xx_spi.h>
#include "spi-pxa2xx.h"
static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
enum dma_data_direction dir)
{
int i, nents, len = drv_data->len;
struct scatterlist *sg;
struct device *dmadev;
struct sg_table *sgt;
void *buf, *pbuf;
/*
* Some DMA controllers have problems transferring buffers that are
* not multiple of 4 bytes. So we truncate the transfer so that it
* is suitable for such controllers, and handle the trailing bytes
* manually after the DMA completes.
*
* REVISIT: It would be better if this information could be
* retrieved directly from the DMA device in a similar way than
* ->copy_align etc. is done.
*/
len = ALIGN(drv_data->len, 4);
if (dir == DMA_TO_DEVICE) {
dmadev = drv_data->tx_chan->device->dev;
sgt = &drv_data->tx_sgt;
buf = drv_data->tx;
drv_data->tx_map_len = len;
} else {
dmadev = drv_data->rx_chan->device->dev;
sgt = &drv_data->rx_sgt;
buf = drv_data->rx;
drv_data->rx_map_len = len;
}
nents = DIV_ROUND_UP(len, SZ_2K);
if (nents != sgt->nents) {
int ret;
sg_free_table(sgt);
ret = sg_alloc_table(sgt, nents, GFP_ATOMIC);
if (ret)
return ret;
}
pbuf = buf;
for_each_sg(sgt->sgl, sg, sgt->nents, i) {
size_t bytes = min_t(size_t, len, SZ_2K);
if (buf)
sg_set_buf(sg, pbuf, bytes);
else
sg_set_buf(sg, drv_data->dummy, bytes);
pbuf += bytes;
len -= bytes;
}
nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
if (!nents)
return -ENOMEM;
return nents;
}
static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
enum dma_data_direction dir)
{
struct device *dmadev;
struct sg_table *sgt;
if (dir == DMA_TO_DEVICE) {
dmadev = drv_data->tx_chan->device->dev;
sgt = &drv_data->tx_sgt;
} else {
dmadev = drv_data->rx_chan->device->dev;
sgt = &drv_data->rx_sgt;
}
dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
}
static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
{
if (!drv_data->dma_mapped)
return;
pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
drv_data->dma_mapped = 0;
}
static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
bool error)
{
struct spi_message *msg = drv_data->cur_msg;
/*
* It is possible that one CPU is handling ROR interrupt and other
* just gets DMA completion. Calling pump_transfers() twice for the
* same transfer leads to problems thus we prevent concurrent calls
* by using ->dma_running.
*/
if (atomic_dec_and_test(&drv_data->dma_running)) {
void __iomem *reg = drv_data->ioaddr;
/*
* If the other CPU is still handling the ROR interrupt we
* might not know about the error yet. So we re-check the
* ROR bit here before we clear the status register.
*/
if (!error) {
u32 status = read_SSSR(reg) & drv_data->mask_sr;
error = status & SSSR_ROR;
}
/* Clear status & disable interrupts */
write_SSCR1(read_SSCR1(reg) & ~drv_data->dma_cr1, reg);
write_SSSR_CS(drv_data, drv_data->clear_sr);
if (!pxa25x_ssp_comp(drv_data))
write_SSTO(0, reg);
if (!error) {
pxa2xx_spi_unmap_dma_buffers(drv_data);
/* Handle the last bytes of unaligned transfer */
drv_data->tx += drv_data->tx_map_len;
drv_data->write(drv_data);
drv_data->rx += drv_data->rx_map_len;
drv_data->read(drv_data);
msg->actual_length += drv_data->len;
msg->state = pxa2xx_spi_next_transfer(drv_data);
} else {
/* In case we got an error we disable the SSP now */
write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg);
msg->state = ERROR_STATE;
}
tasklet_schedule(&drv_data->pump_transfers);
}
}
static void pxa2xx_spi_dma_callback(void *data)
{
pxa2xx_spi_dma_transfer_complete(data, false);
}
static struct dma_async_tx_descriptor *
pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
enum dma_transfer_direction dir)
{
struct pxa2xx_spi_master *pdata = drv_data->master_info;
struct chip_data *chip = drv_data->cur_chip;
enum dma_slave_buswidth width;
struct dma_slave_config cfg;
struct dma_chan *chan;
struct sg_table *sgt;
int nents, ret;
switch (drv_data->n_bytes) {
case 1:
width = DMA_SLAVE_BUSWIDTH_1_BYTE;
break;
case 2:
width = DMA_SLAVE_BUSWIDTH_2_BYTES;
break;
default:
width = DMA_SLAVE_BUSWIDTH_4_BYTES;
break;
}
memset(&cfg, 0, sizeof(cfg));
cfg.direction = dir;
if (dir == DMA_MEM_TO_DEV) {
cfg.dst_addr = drv_data->ssdr_physical;
cfg.dst_addr_width = width;
cfg.dst_maxburst = chip->dma_burst_size;
cfg.slave_id = pdata->tx_slave_id;
sgt = &drv_data->tx_sgt;
nents = drv_data->tx_nents;
chan = drv_data->tx_chan;
} else {
cfg.src_addr = drv_data->ssdr_physical;
cfg.src_addr_width = width;
cfg.src_maxburst = chip->dma_burst_size;
cfg.slave_id = pdata->rx_slave_id;
sgt = &drv_data->rx_sgt;
nents = drv_data->rx_nents;
chan = drv_data->rx_chan;
}
ret = dmaengine_slave_config(chan, &cfg);
if (ret) {
dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
return NULL;
}
return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
}
static bool pxa2xx_spi_dma_filter(struct dma_chan *chan, void *param)
{
const struct pxa2xx_spi_master *pdata = param;
return chan->chan_id == pdata->tx_chan_id ||
chan->chan_id == pdata->rx_chan_id;
}
bool pxa2xx_spi_dma_is_possible(size_t len)
{
return len <= MAX_DMA_LEN;
}
int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
{
const struct chip_data *chip = drv_data->cur_chip;
int ret;
if (!chip->enable_dma)
return 0;
/* Don't bother with DMA if we can't do even a single burst */
if (drv_data->len < chip->dma_burst_size)
return 0;
ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
if (ret <= 0) {
dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
return 0;
}
drv_data->tx_nents = ret;
ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
if (ret <= 0) {
pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
return 0;
}
drv_data->rx_nents = ret;
return 1;
}
irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
{
u32 status;
status = read_SSSR(drv_data->ioaddr) & drv_data->mask_sr;
if (status & SSSR_ROR) {
dev_err(&drv_data->pdev->dev, "FIFO overrun\n");
dmaengine_terminate_all(drv_data->rx_chan);
dmaengine_terminate_all(drv_data->tx_chan);
pxa2xx_spi_dma_transfer_complete(drv_data, true);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
{
struct dma_async_tx_descriptor *tx_desc, *rx_desc;
tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
if (!tx_desc) {
dev_err(&drv_data->pdev->dev,
"failed to get DMA TX descriptor\n");
return -EBUSY;
}
rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
if (!rx_desc) {
dev_err(&drv_data->pdev->dev,
"failed to get DMA RX descriptor\n");
return -EBUSY;
}
/* We are ready when RX completes */
rx_desc->callback = pxa2xx_spi_dma_callback;
rx_desc->callback_param = drv_data;
dmaengine_submit(rx_desc);
dmaengine_submit(tx_desc);
return 0;
}
void pxa2xx_spi_dma_start(struct driver_data *drv_data)
{
dma_async_issue_pending(drv_data->rx_chan);
dma_async_issue_pending(drv_data->tx_chan);
atomic_set(&drv_data->dma_running, 1);
}
int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
{
struct pxa2xx_spi_master *pdata = drv_data->master_info;
struct device *dev = &drv_data->pdev->dev;
dma_cap_mask_t mask;
dma_cap_zero(mask);
dma_cap_set(DMA_SLAVE, mask);
drv_data->dummy = devm_kzalloc(dev, SZ_2K, GFP_KERNEL);
if (!drv_data->dummy)
return -ENOMEM;
drv_data->tx_chan = dma_request_slave_channel_compat(mask,
pxa2xx_spi_dma_filter, pdata, dev, "tx");
if (!drv_data->tx_chan)
return -ENODEV;
drv_data->rx_chan = dma_request_slave_channel_compat(mask,
pxa2xx_spi_dma_filter, pdata, dev, "rx");
if (!drv_data->rx_chan) {
dma_release_channel(drv_data->tx_chan);
drv_data->tx_chan = NULL;
return -ENODEV;
}
return 0;
}
void pxa2xx_spi_dma_release(struct driver_data *drv_data)
{
if (drv_data->rx_chan) {
dmaengine_terminate_all(drv_data->rx_chan);
dma_release_channel(drv_data->rx_chan);
sg_free_table(&drv_data->rx_sgt);
drv_data->rx_chan = NULL;
}
if (drv_data->tx_chan) {
dmaengine_terminate_all(drv_data->tx_chan);
dma_release_channel(drv_data->tx_chan);
sg_free_table(&drv_data->tx_sgt);
drv_data->tx_chan = NULL;
}
}
void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
{
}
int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
struct spi_device *spi,
u8 bits_per_word, u32 *burst_code,
u32 *threshold)
{
struct pxa2xx_spi_chip *chip_info = spi->controller_data;
/*
* If the DMA burst size is given in chip_info we use that,
* otherwise we use the default. Also we use the default FIFO
* thresholds for now.
*/
*burst_code = chip_info ? chip_info->dma_burst_size : 16;
*threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
| SSCR1_TxTresh(TX_THRESH_DFLT);
return 0;
}