/*
* Enable a DMA channel.
*
* If the given channel has any DMA descriptors on its active list, this
* function causes the DMA hardware to begin processing them.
*
* This function marks the DMA channel as "busy," whether or not there are any
* descriptors to process.
*/
static int mxs_dma_enable(int channel)
{
struct apbh_dma *apbh = apbh_dma;
unsigned int sem;
struct mxs_dma_chan *pchan;
struct mxs_dma_desc *pdesc;
int channel_bit, ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
if (pchan->pending_num == 0) {
pchan->flags |= MXS_DMA_FLAGS_BUSY;
return 0;
}
pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node);
if (pdesc == NULL)
return -EFAULT;
if (pchan->flags & MXS_DMA_FLAGS_BUSY) {
if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN))
return 0;
sem = mxs_dma_read_semaphore(channel);
if (sem == 0)
return 0;
if (sem == 1) {
pdesc = list_entry(pdesc->node.next,
struct mxs_dma_desc, node);
if (apbh_dma_is_imx23(apbh))
writel(mxs_dma_cmd_address(pdesc),
apbh->regs + HW_APBHX_CHn_NXTCMDAR_MX23(channel));
else
writel(mxs_dma_cmd_address(pdesc),
apbh->regs + HW_APBHX_CHn_NXTCMDAR_MX28(channel));
}
if (apbh_dma_is_imx23(apbh))
writel(pchan->pending_num,
apbh->regs + HW_APBHX_CHn_SEMA_MX23(channel));
else
writel(pchan->pending_num,
apbh->regs + HW_APBHX_CHn_SEMA_MX28(channel));
pchan->active_num += pchan->pending_num;
pchan->pending_num = 0;
} else {
/*
* Read a DMA channel's hardware semaphore.
*
* As used by the MXS platform's DMA software, the DMA channel's hardware
* semaphore reflects the number of DMA commands the hardware will process, but
* has not yet finished. This is a volatile value read directly from hardware,
* so it must be be viewed as immediately stale.
*
* If the channel is not marked busy, or has finished processing all its
* commands, this value should be zero.
*
* See mxs_dma_append() for details on how DMA command blocks must be configured
* to maintain the expected behavior of the semaphore's value.
*/
static int mxs_dma_read_semaphore(int channel)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
uint32_t tmp;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
tmp = readl(&apbh_regs->ch[channel].hw_apbh_ch_sema);
tmp &= APBH_CHn_SEMA_PHORE_MASK;
tmp >>= APBH_CHn_SEMA_PHORE_OFFSET;
return tmp;
}
/*
* Enable a DMA channel.
*
* If the given channel has any DMA descriptors on its active list, this
* function causes the DMA hardware to begin processing them.
*
* This function marks the DMA channel as "busy," whether or not there are any
* descriptors to process.
*/
static int mxs_dma_enable(int channel)
{
struct mxs_apbh_regs *apbh_regs =
(struct mxs_apbh_regs *)MXS_APBH_BASE;
unsigned int sem;
struct mxs_dma_chan *pchan;
struct mxs_dma_desc *pdesc;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
pchan = mxs_dma_channels + channel;
if (pchan->pending_num == 0) {
pchan->flags |= MXS_DMA_FLAGS_BUSY;
return 0;
}
pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node);
if (pdesc == NULL)
return -EFAULT;
if (pchan->flags & MXS_DMA_FLAGS_BUSY) {
if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN))
return 0;
sem = mxs_dma_read_semaphore(channel);
if (sem == 0)
return 0;
if (sem == 1) {
pdesc = list_entry(pdesc->node.next,
struct mxs_dma_desc, node);
writel(mxs_dma_cmd_address(pdesc),
&apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
}
writel(pchan->pending_num,
&apbh_regs->ch[channel].hw_apbh_ch_sema);
pchan->active_num += pchan->pending_num;
pchan->pending_num = 0;
} else {
/*
* Read a DMA channel's hardware semaphore.
*
* As used by the MXS platform's DMA software, the DMA channel's hardware
* semaphore reflects the number of DMA commands the hardware will process, but
* has not yet finished. This is a volatile value read directly from hardware,
* so it must be be viewed as immediately stale.
*
* If the channel is not marked busy, or has finished processing all its
* commands, this value should be zero.
*
* See mxs_dma_append() for details on how DMA command blocks must be configured
* to maintain the expected behavior of the semaphore's value.
*/
static int mxs_dma_read_semaphore(int channel)
{
struct apbh_dma *apbh = apbh_dma;
uint32_t tmp;
int ret;
ret = mxs_dma_validate_chan(channel);
if (ret)
return ret;
if (apbh_dma_is_imx23(apbh))
tmp = readl(apbh->regs + HW_APBHX_CHn_SEMA_MX23(channel));
else
tmp = readl(apbh->regs + HW_APBHX_CHn_SEMA_MX28(channel));
tmp &= BM_APBHX_CHn_SEMA_PHORE;
tmp >>= BP_APBHX_CHn_SEMA_PHORE;
return tmp;
}
