dw_dmac: add cyclic API to DW DMA driver

This patch adds a cyclic DMA interface to the DW DMA driver. This is
very useful if you want to use the DMA controller in combination with a
sound device which uses cyclic buffers.

Using a DMA channel for cyclic DMA will disable the possibility to use
it as a normal DMA engine until the user calls the cyclic free function
on the DMA channel. Also a cyclic DMA list can not be prepared if the
channel is already active.

Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Hans-Christian Egtvedt 2009-04-01 15:47:02 +02:00 committed by Dan Williams
parent 0f571515c3
commit d9de451989
3 changed files with 356 additions and 2 deletions
drivers/dma
include/linux

View File

@ -363,6 +363,82 @@ static void dwc_handle_error(struct dw_dma *dw, struct dw_dma_chan *dwc)
dwc_descriptor_complete(dwc, bad_desc);
}
/* --------------------- Cyclic DMA API extensions -------------------- */
inline dma_addr_t dw_dma_get_src_addr(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
return channel_readl(dwc, SAR);
}
EXPORT_SYMBOL(dw_dma_get_src_addr);
inline dma_addr_t dw_dma_get_dst_addr(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
return channel_readl(dwc, DAR);
}
EXPORT_SYMBOL(dw_dma_get_dst_addr);
/* called with dwc->lock held and all DMAC interrupts disabled */
static void dwc_handle_cyclic(struct dw_dma *dw, struct dw_dma_chan *dwc,
u32 status_block, u32 status_err, u32 status_xfer)
{
if (status_block & dwc->mask) {
void (*callback)(void *param);
void *callback_param;
dev_vdbg(chan2dev(&dwc->chan), "new cyclic period llp 0x%08x\n",
channel_readl(dwc, LLP));
dma_writel(dw, CLEAR.BLOCK, dwc->mask);
callback = dwc->cdesc->period_callback;
callback_param = dwc->cdesc->period_callback_param;
if (callback) {
spin_unlock(&dwc->lock);
callback(callback_param);
spin_lock(&dwc->lock);
}
}
/*
* Error and transfer complete are highly unlikely, and will most
* likely be due to a configuration error by the user.
*/
if (unlikely(status_err & dwc->mask) ||
unlikely(status_xfer & dwc->mask)) {
int i;
dev_err(chan2dev(&dwc->chan), "cyclic DMA unexpected %s "
"interrupt, stopping DMA transfer\n",
status_xfer ? "xfer" : "error");
dev_err(chan2dev(&dwc->chan),
" SAR: 0x%x DAR: 0x%x LLP: 0x%x CTL: 0x%x:%08x\n",
channel_readl(dwc, SAR),
channel_readl(dwc, DAR),
channel_readl(dwc, LLP),
channel_readl(dwc, CTL_HI),
channel_readl(dwc, CTL_LO));
channel_clear_bit(dw, CH_EN, dwc->mask);
while (dma_readl(dw, CH_EN) & dwc->mask)
cpu_relax();
/* make sure DMA does not restart by loading a new list */
channel_writel(dwc, LLP, 0);
channel_writel(dwc, CTL_LO, 0);
channel_writel(dwc, CTL_HI, 0);
dma_writel(dw, CLEAR.BLOCK, dwc->mask);
dma_writel(dw, CLEAR.ERROR, dwc->mask);
dma_writel(dw, CLEAR.XFER, dwc->mask);
for (i = 0; i < dwc->cdesc->periods; i++)
dwc_dump_lli(dwc, &dwc->cdesc->desc[i]->lli);
}
}
/* ------------------------------------------------------------------------- */
static void dw_dma_tasklet(unsigned long data)
{
struct dw_dma *dw = (struct dw_dma *)data;
@ -382,7 +458,10 @@ static void dw_dma_tasklet(unsigned long data)
for (i = 0; i < dw->dma.chancnt; i++) {
dwc = &dw->chan[i];
spin_lock(&dwc->lock);
if (status_err & (1 << i))
if (test_bit(DW_DMA_IS_CYCLIC, &dwc->flags))
dwc_handle_cyclic(dw, dwc, status_block, status_err,
status_xfer);
else if (status_err & (1 << i))
dwc_handle_error(dw, dwc);
else if ((status_block | status_xfer) & (1 << i))
dwc_scan_descriptors(dw, dwc);
@ -883,6 +962,257 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
dev_vdbg(chan2dev(chan), "free_chan_resources done\n");
}
/* --------------------- Cyclic DMA API extensions -------------------- */
/**
* dw_dma_cyclic_start - start the cyclic DMA transfer
* @chan: the DMA channel to start
*
* Must be called with soft interrupts disabled. Returns zero on success or
* -errno on failure.
*/
int dw_dma_cyclic_start(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
struct dw_dma *dw = to_dw_dma(dwc->chan.device);
if (!test_bit(DW_DMA_IS_CYCLIC, &dwc->flags)) {
dev_err(chan2dev(&dwc->chan), "missing prep for cyclic DMA\n");
return -ENODEV;
}
spin_lock(&dwc->lock);
/* assert channel is idle */
if (dma_readl(dw, CH_EN) & dwc->mask) {
dev_err(chan2dev(&dwc->chan),
"BUG: Attempted to start non-idle channel\n");
dev_err(chan2dev(&dwc->chan),
" SAR: 0x%x DAR: 0x%x LLP: 0x%x CTL: 0x%x:%08x\n",
channel_readl(dwc, SAR),
channel_readl(dwc, DAR),
channel_readl(dwc, LLP),
channel_readl(dwc, CTL_HI),
channel_readl(dwc, CTL_LO));
spin_unlock(&dwc->lock);
return -EBUSY;
}
dma_writel(dw, CLEAR.BLOCK, dwc->mask);
dma_writel(dw, CLEAR.ERROR, dwc->mask);
dma_writel(dw, CLEAR.XFER, dwc->mask);
/* setup DMAC channel registers */
channel_writel(dwc, LLP, dwc->cdesc->desc[0]->txd.phys);
channel_writel(dwc, CTL_LO, DWC_CTLL_LLP_D_EN | DWC_CTLL_LLP_S_EN);
channel_writel(dwc, CTL_HI, 0);
channel_set_bit(dw, CH_EN, dwc->mask);
spin_unlock(&dwc->lock);
return 0;
}
EXPORT_SYMBOL(dw_dma_cyclic_start);
/**
* dw_dma_cyclic_stop - stop the cyclic DMA transfer
* @chan: the DMA channel to stop
*
* Must be called with soft interrupts disabled.
*/
void dw_dma_cyclic_stop(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
struct dw_dma *dw = to_dw_dma(dwc->chan.device);
spin_lock(&dwc->lock);
channel_clear_bit(dw, CH_EN, dwc->mask);
while (dma_readl(dw, CH_EN) & dwc->mask)
cpu_relax();
spin_unlock(&dwc->lock);
}
EXPORT_SYMBOL(dw_dma_cyclic_stop);
/**
* dw_dma_cyclic_prep - prepare the cyclic DMA transfer
* @chan: the DMA channel to prepare
* @buf_addr: physical DMA address where the buffer starts
* @buf_len: total number of bytes for the entire buffer
* @period_len: number of bytes for each period
* @direction: transfer direction, to or from device
*
* Must be called before trying to start the transfer. Returns a valid struct
* dw_cyclic_desc if successful or an ERR_PTR(-errno) if not successful.
*/
struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,
dma_addr_t buf_addr, size_t buf_len, size_t period_len,
enum dma_data_direction direction)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
struct dw_cyclic_desc *cdesc;
struct dw_cyclic_desc *retval = NULL;
struct dw_desc *desc;
struct dw_desc *last = NULL;
struct dw_dma_slave *dws = chan->private;
unsigned long was_cyclic;
unsigned int reg_width;
unsigned int periods;
unsigned int i;
spin_lock_bh(&dwc->lock);
if (!list_empty(&dwc->queue) || !list_empty(&dwc->active_list)) {
spin_unlock_bh(&dwc->lock);
dev_dbg(chan2dev(&dwc->chan),
"queue and/or active list are not empty\n");
return ERR_PTR(-EBUSY);
}
was_cyclic = test_and_set_bit(DW_DMA_IS_CYCLIC, &dwc->flags);
spin_unlock_bh(&dwc->lock);
if (was_cyclic) {
dev_dbg(chan2dev(&dwc->chan),
"channel already prepared for cyclic DMA\n");
return ERR_PTR(-EBUSY);
}
retval = ERR_PTR(-EINVAL);
reg_width = dws->reg_width;
periods = buf_len / period_len;
/* Check for too big/unaligned periods and unaligned DMA buffer. */
if (period_len > (DWC_MAX_COUNT << reg_width))
goto out_err;
if (unlikely(period_len & ((1 << reg_width) - 1)))
goto out_err;
if (unlikely(buf_addr & ((1 << reg_width) - 1)))
goto out_err;
if (unlikely(!(direction & (DMA_TO_DEVICE | DMA_FROM_DEVICE))))
goto out_err;
retval = ERR_PTR(-ENOMEM);
if (periods > NR_DESCS_PER_CHANNEL)
goto out_err;
cdesc = kzalloc(sizeof(struct dw_cyclic_desc), GFP_KERNEL);
if (!cdesc)
goto out_err;
cdesc->desc = kzalloc(sizeof(struct dw_desc *) * periods, GFP_KERNEL);
if (!cdesc->desc)
goto out_err_alloc;
for (i = 0; i < periods; i++) {
desc = dwc_desc_get(dwc);
if (!desc)
goto out_err_desc_get;
switch (direction) {
case DMA_TO_DEVICE:
desc->lli.dar = dws->tx_reg;
desc->lli.sar = buf_addr + (period_len * i);
desc->lli.ctllo = (DWC_DEFAULT_CTLLO
| DWC_CTLL_DST_WIDTH(reg_width)
| DWC_CTLL_SRC_WIDTH(reg_width)
| DWC_CTLL_DST_FIX
| DWC_CTLL_SRC_INC
| DWC_CTLL_FC_M2P
| DWC_CTLL_INT_EN);
break;
case DMA_FROM_DEVICE:
desc->lli.dar = buf_addr + (period_len * i);
desc->lli.sar = dws->rx_reg;
desc->lli.ctllo = (DWC_DEFAULT_CTLLO
| DWC_CTLL_SRC_WIDTH(reg_width)
| DWC_CTLL_DST_WIDTH(reg_width)
| DWC_CTLL_DST_INC
| DWC_CTLL_SRC_FIX
| DWC_CTLL_FC_P2M
| DWC_CTLL_INT_EN);
break;
default:
break;
}
desc->lli.ctlhi = (period_len >> reg_width);
cdesc->desc[i] = desc;
if (last) {
last->lli.llp = desc->txd.phys;
dma_sync_single_for_device(chan2parent(chan),
last->txd.phys, sizeof(last->lli),
DMA_TO_DEVICE);
}
last = desc;
}
/* lets make a cyclic list */
last->lli.llp = cdesc->desc[0]->txd.phys;
dma_sync_single_for_device(chan2parent(chan), last->txd.phys,
sizeof(last->lli), DMA_TO_DEVICE);
dev_dbg(chan2dev(&dwc->chan), "cyclic prepared buf 0x%08x len %zu "
"period %zu periods %d\n", buf_addr, buf_len,
period_len, periods);
cdesc->periods = periods;
dwc->cdesc = cdesc;
return cdesc;
out_err_desc_get:
while (i--)
dwc_desc_put(dwc, cdesc->desc[i]);
out_err_alloc:
kfree(cdesc);
out_err:
clear_bit(DW_DMA_IS_CYCLIC, &dwc->flags);
return (struct dw_cyclic_desc *)retval;
}
EXPORT_SYMBOL(dw_dma_cyclic_prep);
/**
* dw_dma_cyclic_free - free a prepared cyclic DMA transfer
* @chan: the DMA channel to free
*/
void dw_dma_cyclic_free(struct dma_chan *chan)
{
struct dw_dma_chan *dwc = to_dw_dma_chan(chan);
struct dw_dma *dw = to_dw_dma(dwc->chan.device);
struct dw_cyclic_desc *cdesc = dwc->cdesc;
int i;
dev_dbg(chan2dev(&dwc->chan), "cyclic free\n");
if (!cdesc)
return;
spin_lock_bh(&dwc->lock);
channel_clear_bit(dw, CH_EN, dwc->mask);
while (dma_readl(dw, CH_EN) & dwc->mask)
cpu_relax();
dma_writel(dw, CLEAR.BLOCK, dwc->mask);
dma_writel(dw, CLEAR.ERROR, dwc->mask);
dma_writel(dw, CLEAR.XFER, dwc->mask);
spin_unlock_bh(&dwc->lock);
for (i = 0; i < cdesc->periods; i++)
dwc_desc_put(dwc, cdesc->desc[i]);
kfree(cdesc->desc);
kfree(cdesc);
clear_bit(DW_DMA_IS_CYCLIC, &dwc->flags);
}
EXPORT_SYMBOL(dw_dma_cyclic_free);
/*----------------------------------------------------------------------*/
static void dw_dma_off(struct dw_dma *dw)

View File

@ -126,6 +126,10 @@ struct dw_dma_regs {
#define DW_REGLEN 0x400
enum dw_dmac_flags {
DW_DMA_IS_CYCLIC = 0,
};
struct dw_dma_chan {
struct dma_chan chan;
void __iomem *ch_regs;
@ -134,10 +138,12 @@ struct dw_dma_chan {
spinlock_t lock;
/* these other elements are all protected by lock */
unsigned long flags;
dma_cookie_t completed;
struct list_head active_list;
struct list_head queue;
struct list_head free_list;
struct dw_cyclic_desc *cdesc;
unsigned int descs_allocated;
};
@ -158,7 +164,6 @@ static inline struct dw_dma_chan *to_dw_dma_chan(struct dma_chan *chan)
return container_of(chan, struct dw_dma_chan, chan);
}
struct dw_dma {
struct dma_device dma;
void __iomem *regs;

View File

@ -74,4 +74,23 @@ struct dw_dma_slave {
#define DWC_CFGL_HS_DST_POL (1 << 18) /* dst handshake active low */
#define DWC_CFGL_HS_SRC_POL (1 << 19) /* src handshake active low */
/* DMA API extensions */
struct dw_cyclic_desc {
struct dw_desc **desc;
unsigned long periods;
void (*period_callback)(void *param);
void *period_callback_param;
};
struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,
dma_addr_t buf_addr, size_t buf_len, size_t period_len,
enum dma_data_direction direction);
void dw_dma_cyclic_free(struct dma_chan *chan);
int dw_dma_cyclic_start(struct dma_chan *chan);
void dw_dma_cyclic_stop(struct dma_chan *chan);
dma_addr_t dw_dma_get_src_addr(struct dma_chan *chan);
dma_addr_t dw_dma_get_dst_addr(struct dma_chan *chan);
#endif /* DW_DMAC_H */