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SubjectRe: [PATCH V1] dmaengine: tegra: add dma driver
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On Fri, 2012-04-20 at 14:38 +0530, Laxman Dewangan wrote:
> Adding dmaengine based NVIDIA's Tegra APB dma driver.
> This driver support the slave mode of data transfer from
> peripheral to memory and vice versa.
> The driver supports for the cyclic and non-cyclic mode
> of data transfer.
>
> Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
> ---
> This is NVIDIA Tegra's APB dma controller driver based on dmaengine.
> There is already old driver in mach-tegra/dma.c and we want to get rid
> of this old style driver which exposes private apis.
> Once this driver get through, there will be series of patches to move all
> existing driver to use the dmaengine based driver and old mach-tegra/dma.c
> will get deleted. This driver has following feature than old one:
> - better queue managment.
> - Cyclic transfer supports.
> - Platform driver.
> - Full support for device tree.
> - Uses regmap mmio interface for debugfs/ context restore.
> - Multiple bug fixes over old driver.
[snip]
> + * dma_transfer_mode: Different dma transfer mode.
> + * DMA_MODE_ONCE: Dma transfer the configured buffer once and at the end of
> + * transfer, dma stops automatically and generates interrupt
> + * if enabled. SW need to reprogram dma for next transfer.
> + * DMA_MODE_CYCLE: Dma keeps transferring the same buffer again and again
> + * until dma stopped explicitly by SW or another buffer configured.
> + * After transfer completes, dma again starts transfer from
> + * beginning of buffer without sw intervention. If any new
> + * address/size is configured during buffer transfer then
> + * dma start transfer with new configuration otherwise it
> + * will keep transferring with old configuration. It also
> + * generates the interrupt after buffer transfer completes.
why do you need to define this? use the cyclic api to convey this
> + * DMA_MODE_CYCLE_HALF_NOTIFY: In this mode dma keeps transferring the buffer
> + * into two folds. This is kind of ping-pong buffer where both
> + * buffer size should be same. Dma completes the one buffer,
> + * generates interrupt and keep transferring the next buffer
> + * whose address start just next to first buffer. At the end of
> + * second buffer transfer, dma again generates interrupt and
> + * keep transferring of the data from starting of first buffer.
> + * If sw wants to change the address/size of the buffer then
> + * it needs to change only when dma transferring the second
> + * half of buffer. In dma configuration, it only need to
> + * configure starting of first buffer and size of first buffer.
> + * Dma hw assumes that striating address of second buffer is just
> + * next to end of first buffer and size is same as the first
> + * buffer.
isnt this a specifc example of cylci and frankly why should dmaengine
care about this. This one of the configurations you are passing for a
cyclic dma operation
> + */
> +enum dma_transfer_mode {
> + DMA_MODE_NONE,
> + DMA_MODE_ONCE,
> + DMA_MODE_CYCLE,
> + DMA_MODE_CYCLE_HALF_NOTIFY,
> +};
> +
> +/* List of memory allocated for that channel */
> +struct tegra_dma_chan_mem_alloc {
> + struct list_head node;
> +};
this seems questionable too...
> +
> +/* Dma channel registers */
> +struct tegra_dma_channel_regs {
> + unsigned long csr;
> + unsigned long ahb_ptr;
> + unsigned long apb_ptr;
> + unsigned long ahb_seq;
> + unsigned long apb_seq;
> +};
> +
> +/*
> + * tegra_dma_sg_req: Dma request details to configure hardware. This
> + * contains the details for one transfer to configure dma hw.
> + * The client's request for data transfer can be broken into multiple
> + * sub-transfer as per requestor details and hw support.
typo ^^^^^^^^^
> + * This sub transfer get added in the list of transfer and point to Tegra
> + * dma descriptor which manages the transfer details.
> + */
> +struct tegra_dma_sg_req {
> + struct tegra_dma_channel_regs ch_regs;
> + int req_len;
> + bool configured;
> + bool last_sg;
> + bool half_done;
> + struct list_head node;
> + struct tegra_dma_desc *dma_desc;
> +};
> +
> +/*
> + * tegra_dma_desc: Tegra dma descriptors which manages the client requests.
> + * This de scripts keep track of transfer status, callbacks, transfer and
again ^^^^
> + * request counts etc.
> + */
> +struct tegra_dma_desc {
> + int bytes_requested;
> + int bytes_transferred;
> + enum dma_status dma_status;
> + struct dma_async_tx_descriptor txd;
> + struct list_head node;
> + struct list_head tx_list;
> + struct list_head cb_node;
> + bool ack_reqd;
> + bool cb_due;
> + dma_cookie_t cookie;
> +};
> +
> +struct tegra_dma_channel;
> +
> +typedef void (*dma_isr_handler)(struct tegra_dma_channel *tdc,
> + bool to_terminate);
> +
> +/* tegra_dma_channel: Channel specific information */
> +struct tegra_dma_channel {
> + bool config_init;
> + int id;
> + int irq;
> + unsigned long chan_base_offset;
> + spinlock_t lock;
> + bool busy;
> + enum dma_transfer_mode dma_mode;
> + int descs_allocated;
> + struct dma_chan dma_chan;
> + struct tegra_dma *tdma;
> +
> + /* Different lists for managing the requests */
> + struct list_head free_sg_req;
> + struct list_head pending_sg_req;
> + struct list_head free_dma_desc;
> + struct list_head wait_ack_dma_desc;
> + struct list_head cb_desc;
> +
> + /* isr handler and tasklet for bottom half of isr handling */
> + dma_isr_handler isr_handler;
> + struct tasklet_struct tasklet;
> + dma_async_tx_callback callback;
> + void *callback_param;
> +
> + /* Channel-slave specific configuration */
> + struct dma_slave_config dma_sconfig;
> + struct tegra_dma_slave dma_slave;
> +
> + /* Allocated memory pointer list for this channel */
> + struct list_head alloc_ptr_list;
> +};
> +
> +/* tegra_dma: Tegra dma specific information */
> +struct tegra_dma {
> + struct dma_device dma_dev;
> + struct device *dev;
> + struct clk *dma_clk;
> + spinlock_t global_lock;
> + void __iomem *base_addr;
> + struct regmap *regmap_dma;
> + struct tegra_dma_chip_data chip_data;
> +
> + /* Last member of the structure */
> + struct tegra_dma_channel channels[0];
> +};
> +
> +static inline void tdma_write(struct tegra_dma *tdma, u32 reg, u32 val)
> +{
> + regmap_write(tdma->regmap_dma, reg, val);
> +}
> +
> +static inline u32 tdma_read(struct tegra_dma *tdma, u32 reg)
> +{
> + u32 val;
> + regmap_read(tdma->regmap_dma, reg, &val);
> + return val;
> +}
> +
> +static inline void tdc_write(struct tegra_dma_channel *tdc,
> + u32 reg, u32 val)
> +{
> + regmap_write(tdc->tdma->regmap_dma, tdc->chan_base_offset + reg, val);
> +}
> +
> +static inline u32 tdc_read(struct tegra_dma_channel *tdc, u32 reg)
> +{
> + u32 val;
> + regmap_read(tdc->tdma->regmap_dma, tdc->chan_base_offset + reg, &val);
> + return val;
> +}
> +
> +static inline struct tegra_dma_channel *to_tegra_dma_chan(struct dma_chan *dc)
> +{
> + return container_of(dc, struct tegra_dma_channel, dma_chan);
> +}
> +
> +static inline struct tegra_dma_desc *txd_to_tegra_dma_desc(
> + struct dma_async_tx_descriptor *td)
> +{
> + return container_of(td, struct tegra_dma_desc, txd);
> +}
> +
> +static inline struct device *tdc2dev(struct tegra_dma_channel *tdc)
> +{
> + return &tdc->dma_chan.dev->device;
> +}
> +
> +static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *tx);
> +
> +static int allocate_tegra_desc(struct tegra_dma_channel *tdc,
> + int ndma_desc, int nsg_req)
what does the last arg mean?
> +{
> + int i;
> + struct tegra_dma_desc *dma_desc;
> + struct tegra_dma_sg_req *sg_req;
> + struct dma_chan *dc = &tdc->dma_chan;
> + struct list_head dma_desc_list;
> + struct list_head sg_req_list;
> + struct tegra_dma_chan_mem_alloc *chan_mem;
> + void *memptr;
> + size_t dma_desc_size;
> + size_t sg_req_size;
> + size_t chan_mem_size;
> + size_t total_size;
> + unsigned long flags;
> +
> + INIT_LIST_HEAD(&dma_desc_list);
> + INIT_LIST_HEAD(&sg_req_list);
> +
> + /* Calculate total require size of memory and then allocate */
> + dma_desc_size = sizeof(struct tegra_dma_desc) * ndma_desc;
> + sg_req_size = sizeof(struct tegra_dma_sg_req) * nsg_req;
> + chan_mem_size = sizeof(struct tegra_dma_chan_mem_alloc);
> + total_size = chan_mem_size + dma_desc_size + sg_req_size;

why cant you simply allocate three structs you need?
> +
> + memptr = kzalloc(total_size, GFP_KERNEL);
> + if (!memptr) {
> + dev_err(tdc2dev(tdc),
> + "%s(): Memory allocation fails\n", __func__);
> + return -ENOMEM;
> + }
> + chan_mem = memptr;
> +
> + /* Initialize dma descriptors */
> + dma_desc = memptr + chan_mem_size;
> + for (i = 0; i < ndma_desc; ++i, dma_desc++) {
> + dma_async_tx_descriptor_init(&dma_desc->txd, dc);
> + dma_desc->txd.tx_submit = tegra_dma_tx_submit;
> + dma_desc->txd.flags = DMA_CTRL_ACK;
> + list_add_tail(&dma_desc->node, &dma_desc_list);
> + }
> +
> + /* Initialize req descriptors */
> + sg_req = memptr + chan_mem_size + dma_desc_size;
> + for (i = 0; i < nsg_req; ++i, sg_req++)
> + list_add_tail(&sg_req->node, &sg_req_list);
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> + list_add_tail(&chan_mem->node, &tdc->alloc_ptr_list);
> +
> + if (ndma_desc) {
> + tdc->descs_allocated += ndma_desc;
> + list_splice(&dma_desc_list, &tdc->free_dma_desc);
> + }
> +
> + if (nsg_req)
> + list_splice(&sg_req_list, &tdc->free_sg_req);
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return tdc->descs_allocated;
> +}
> +
> +/* Get dma desc from free list, if not there then allocate it */
> +static struct tegra_dma_desc *tegra_dma_desc_get(struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma_desc *dma_desc = NULL;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> +
> + /* Check from free list desc */
> + if (!list_empty(&tdc->free_dma_desc)) {
> + dma_desc = list_first_entry(&tdc->free_dma_desc,
> + typeof(*dma_desc), node);
> + list_del(&dma_desc->node);
> + goto end;
> + }
> +
> + /*
> + * Check list with desc which are waiting for ack, may be it
> + * got acked from client.
> + */
> + if (!list_empty(&tdc->wait_ack_dma_desc)) {
> + list_for_each_entry(dma_desc, &tdc->wait_ack_dma_desc, node) {
> + if (async_tx_test_ack(&dma_desc->txd)) {
> + list_del(&dma_desc->node);
> + goto end;
> + }
> + }
> + }
> +
> + /* There is no free desc, allocate it */
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + dev_dbg(tdc2dev(tdc),
> + "Allocating more descriptors for channel %d\n", tdc->id);
> + allocate_tegra_desc(tdc, DMA_NR_DESCS_PER_CHANNEL,
> + DMA_NR_DESCS_PER_CHANNEL * DMA_NR_REQ_PER_DESC);
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (list_empty(&tdc->free_dma_desc))
> + goto end;
> +
> + dma_desc = list_first_entry(&tdc->free_dma_desc,
> + typeof(*dma_desc), node);
> + list_del(&dma_desc->node);
> +end:
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return dma_desc;
> +}
> +
> +static void tegra_dma_desc_put(struct tegra_dma_channel *tdc,
> + struct tegra_dma_desc *dma_desc)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (!list_empty(&dma_desc->tx_list))
> + list_splice_init(&dma_desc->tx_list, &tdc->free_sg_req);
> + list_add_tail(&dma_desc->node, &tdc->free_dma_desc);
> + spin_unlock_irqrestore(&tdc->lock, flags);
> +}
> +
> +static void tegra_dma_desc_done_locked(struct tegra_dma_channel *tdc,
> + struct tegra_dma_desc *dma_desc)
> +{
> + if (dma_desc->ack_reqd)
> + list_add_tail(&dma_desc->node, &tdc->wait_ack_dma_desc);
> + else
> + list_add_tail(&dma_desc->node, &tdc->free_dma_desc);
> +}
> +
> +static struct tegra_dma_sg_req *tegra_dma_sg_req_get(
> + struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma_sg_req *sg_req = NULL;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (list_empty(&tdc->free_sg_req)) {
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + dev_dbg(tdc2dev(tdc),
> + "Reallocating sg_req for channel %d\n", tdc->id);
> + allocate_tegra_desc(tdc, 0,
> + DMA_NR_DESCS_PER_CHANNEL * DMA_NR_REQ_PER_DESC);
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (list_empty(&tdc->free_sg_req)) {
> + dev_dbg(tdc2dev(tdc),
> + "Not found free sg_req for channel %d\n", tdc->id);
> + goto end;
> + }
> + }
> +
> + sg_req = list_first_entry(&tdc->free_sg_req, typeof(*sg_req), node);
> + list_del(&sg_req->node);
> +end:
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return sg_req;
> +}
> +
> +static int tegra_dma_slave_config(struct dma_chan *dc,
> + struct dma_slave_config *sconfig)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> +
> + if (!list_empty(&tdc->pending_sg_req)) {
> + dev_err(tdc2dev(tdc),
> + "dma requests are pending, cannot take new configuration");
> + return -EBUSY;
> + }
> +
> + /* Slave specific configuration is must for channel configuration */
> + if (!dc->private) {
private is deprecated, pls dont use that
> + dev_err(tdc2dev(tdc),
> + "Slave specific private data not found for chan %d\n",
> + tdc->id);
> + return -EINVAL;
> + }
> +
> + memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
> + memcpy(&tdc->dma_slave, dc->private, sizeof(tdc->dma_slave));
> + tdc->config_init = true;
> + return 0;
> +}
> +
> +static void tegra_dma_pause(struct tegra_dma_channel *tdc,
> + bool wait_for_burst_complete)
> +{
> + struct tegra_dma *tdma = tdc->tdma;
> + spin_lock(&tdma->global_lock);
> + tdma_write(tdma, APB_DMA_GEN, 0);
> + if (wait_for_burst_complete)
> + udelay(DMA_BUSRT_COMPLETE_TIME);
> +}
> +
> +static void tegra_dma_resume(struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma *tdma = tdc->tdma;
> + tdma_write(tdma, APB_DMA_GEN, GEN_ENABLE);
> + spin_unlock(&tdma->global_lock);
> +}
> +
> +static void tegra_dma_stop(struct tegra_dma_channel *tdc)
> +{
> + u32 csr;
> + u32 status;
> +
> + /* Disable interrupts */
> + csr = tdc_read(tdc, APB_DMA_CHAN_CSR);
> + csr &= ~CSR_IE_EOC;
> + tdc_write(tdc, APB_DMA_CHAN_CSR, csr);
> +
> + /* Disable dma */
> + csr &= ~CSR_ENB;
> + tdc_write(tdc, APB_DMA_CHAN_CSR, csr);
> +
> + /* Clear interrupt status if it is there */
> + status = tdc_read(tdc, APB_DMA_CHAN_STA);
> + if (status & STA_ISE_EOC) {
> + dev_dbg(tdc2dev(tdc), "%s():clearing interrupt\n", __func__);
> + tdc_write(tdc, APB_DMA_CHAN_STA, status);
> + }
> + tdc->busy = false;
> +}
> +
> +static void tegra_dma_start(struct tegra_dma_channel *tdc,
> + struct tegra_dma_sg_req *sg_req)
> +{
> + struct tegra_dma_channel_regs *ch_regs = &sg_req->ch_regs;
> + unsigned long csr = ch_regs->csr;
> +
> + tdc_write(tdc, APB_DMA_CHAN_CSR, csr);
> + tdc_write(tdc, APB_DMA_CHAN_APB_SEQ, ch_regs->apb_seq);
> + tdc_write(tdc, APB_DMA_CHAN_APB_PTR, ch_regs->apb_ptr);
> + tdc_write(tdc, APB_DMA_CHAN_AHB_SEQ, ch_regs->ahb_seq);
> + tdc_write(tdc, APB_DMA_CHAN_AHB_PTR, ch_regs->ahb_ptr);
> +
> + /* Dump the configuration register if verbose mode enabled */
> + dev_vdbg(tdc2dev(tdc),
> + "%s(): csr: 0x%08lx\n", __func__, ch_regs->csr);
> + dev_vdbg(tdc2dev(tdc),
> + "%s(): apbseq: 0x%08lx\n", __func__, ch_regs->apb_seq);
> + dev_vdbg(tdc2dev(tdc),
> + "%s(): apbptr: 0x%08lx\n", __func__, ch_regs->apb_ptr);
> + dev_vdbg(tdc2dev(tdc),
> + "%s(): ahbseq: 0x%08lx\n", __func__, ch_regs->ahb_seq);
> + dev_vdbg(tdc2dev(tdc),
> + "%s(): ahbptr: 0x%08lx\n", __func__, ch_regs->ahb_ptr);
> +
> + /* Start dma */
> + csr |= CSR_ENB;
> + tdc_write(tdc, APB_DMA_CHAN_CSR, csr);
> +}
> +
> +static void tegra_dma_configure_for_next(struct tegra_dma_channel *tdc,
> + struct tegra_dma_sg_req *nsg_req)
> +{
> + unsigned long status;
> +
> + /*
> + * The dma controller reloads the new configuration for next transfer
> + * after last burst of current transfer completes.
> + * If there is no IEC status then this makes sure that last burst
> + * has not be completed. There may be case that last burst is on
> + * flight and so it can complete but because dma is paused, it
> + * will not generates interrupt as well as not reload the new
> + * configuration.
> + * If there is already IEC status then interrupt handler need to
> + * load new configuration.
> + */
> + tegra_dma_pause(tdc, false);
> + status = tdc_read(tdc, APB_DMA_CHAN_STA);
> +
> + /*
> + * If interrupt is pending then do nothing as the ISR will handle
> + * the programing for new request.
> + */
> + if (status & STA_ISE_EOC) {
> + dev_err(tdc2dev(tdc),
> + "Skipping new configuration as interrupt is pending\n");
> + goto exit_config;
> + }
> +
> + /* Safe to program new configuration */
> + tdc_write(tdc, APB_DMA_CHAN_APB_PTR, nsg_req->ch_regs.apb_ptr);
> + tdc_write(tdc, APB_DMA_CHAN_AHB_PTR, nsg_req->ch_regs.ahb_ptr);
> + tdc_write(tdc, APB_DMA_CHAN_CSR, nsg_req->ch_regs.csr | CSR_ENB);
> + nsg_req->configured = true;
> +
> +exit_config:
> + tegra_dma_resume(tdc);
> +}
> +
> +static void tdc_start_head_req(struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma_sg_req *sg_req;
> +
> + if (list_empty(&tdc->pending_sg_req))
> + return;
> +
> + sg_req = list_first_entry(&tdc->pending_sg_req,
> + typeof(*sg_req), node);
> + tegra_dma_start(tdc, sg_req);
> + sg_req->configured = true;
> + tdc->busy = true;
> +}
> +
> +static void tdc_configure_next_head_desc(struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma_sg_req *hsgreq;
> + struct tegra_dma_sg_req *hnsgreq;
> +
> + if (list_empty(&tdc->pending_sg_req))
> + return;
> +
> + hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
> + if (!list_is_last(&hsgreq->node, &tdc->pending_sg_req)) {
> + hnsgreq = list_first_entry(&hsgreq->node,
> + typeof(*hnsgreq), node);
> + tegra_dma_configure_for_next(tdc, hnsgreq);
> + }
> +}
> +
> +static inline int get_current_xferred_count(struct tegra_dma_channel *tdc,
> + struct tegra_dma_sg_req *sg_req, unsigned long status)
> +{
> + return sg_req->req_len - ((status & STA_COUNT_MASK) + 4);
> +}
> +
> +static void tegra_dma_abort_all(struct tegra_dma_channel *tdc)
> +{
> + struct tegra_dma_sg_req *sgreq;
> + struct tegra_dma_desc *dma_desc;
> + while (!list_empty(&tdc->pending_sg_req)) {
> + sgreq = list_first_entry(&tdc->pending_sg_req,
> + typeof(*sgreq), node);
> + list_del(&sgreq->node);
> + list_add_tail(&sgreq->node, &tdc->free_sg_req);
> + if (sgreq->last_sg) {
> + dma_desc = sgreq->dma_desc;
> + dma_desc->dma_status = DMA_ERROR;
> + tegra_dma_desc_done_locked(tdc, dma_desc);
> +
> + /* Add in cb list if it is not there. */
> + if (!dma_desc->cb_due) {
> + list_add_tail(&dma_desc->cb_node,
> + &tdc->cb_desc);
> + dma_desc->cb_due = true;
> + }
> + dma_cookie_complete(&dma_desc->txd);
> + }
> + }
> + tdc->dma_mode = DMA_MODE_NONE;
> +}
> +
> +static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
> + struct tegra_dma_sg_req *last_sg_req, bool to_terminate)
> +{
> + struct tegra_dma_sg_req *hsgreq = NULL;
> +
> + if (list_empty(&tdc->pending_sg_req)) {
> + dev_err(tdc2dev(tdc),
> + "%s(): Dma is running without any req list\n",
> + __func__);
> + tegra_dma_stop(tdc);
> + return false;
> + }
> +
> + /*
> + * Check that head req on list should be in flight.
> + * If it is not in flight then abort transfer as
> + * transfer looping can not continue.
> + */
> + hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
> + if (!hsgreq->configured) {
> + tegra_dma_stop(tdc);
> + dev_err(tdc2dev(tdc),
> + "Error in dma transfer loop, aborting dma\n");
> + tegra_dma_abort_all(tdc);
> + return false;
> + }
> +
> + /* Configure next request in single buffer mode */
> + if (!to_terminate && (tdc->dma_mode == DMA_MODE_CYCLE))
> + tdc_configure_next_head_desc(tdc);
> + return true;
> +}
> +
> +static void handle_once_dma_done(struct tegra_dma_channel *tdc,
> + bool to_terminate)
> +{
> + struct tegra_dma_sg_req *sgreq;
> + struct tegra_dma_desc *dma_desc;
> +
> + tdc->busy = false;
> + sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node);
> + dma_desc = sgreq->dma_desc;
> + dma_desc->bytes_transferred += sgreq->req_len;
> +
> + list_del(&sgreq->node);
> + if (sgreq->last_sg) {
> + dma_cookie_complete(&dma_desc->txd);
> + list_add_tail(&dma_desc->cb_node, &tdc->cb_desc);
> + dma_desc->cb_due = true;
> + tegra_dma_desc_done_locked(tdc, dma_desc);
> + }
> + list_add_tail(&sgreq->node, &tdc->free_sg_req);
> +
> + /* Do not start dma if it is going to be terminate */
> + if (to_terminate || list_empty(&tdc->pending_sg_req))
> + return;
> +
> + tdc_start_head_req(tdc);
> + return;
> +}
> +
> +static void handle_cont_sngl_cycle_dma_done(struct tegra_dma_channel *tdc,
> + bool to_terminate)
> +{
> + struct tegra_dma_sg_req *sgreq;
> + struct tegra_dma_desc *dma_desc;
> + bool st;
> +
> + sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node);
> + dma_desc = sgreq->dma_desc;
> + dma_desc->bytes_transferred += sgreq->req_len;
> +
> + /* Callback need to be call */
> + list_add_tail(&dma_desc->cb_node, &tdc->cb_desc);
> + dma_desc->cb_due = true;
> +
> + /* If not last req then put at end of pending list */
> + if (!list_is_last(&sgreq->node, &tdc->pending_sg_req)) {
> + list_del(&sgreq->node);
> + list_add_tail(&sgreq->node, &tdc->pending_sg_req);
> + sgreq->configured = false;
> + st = handle_continuous_head_request(tdc, sgreq, to_terminate);
> + if (!st)
> + dma_desc->dma_status = DMA_ERROR;
> + }
> + return;
> +}
> +
> +static void handle_cont_dbl_cycle_dma_done(struct tegra_dma_channel *tdc,
> + bool to_terminate)
> +{
> + struct tegra_dma_sg_req *hsgreq;
> + struct tegra_dma_sg_req *hnsgreq;
> + struct tegra_dma_desc *dma_desc;
> +
> + hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
> + dma_desc = hsgreq->dma_desc;
> + dma_desc->bytes_transferred += hsgreq->req_len;
> +
> + if (!hsgreq->half_done) {
> + if (!list_is_last(hsgreq->node.next, &tdc->pending_sg_req) &&
> + !to_terminate) {
> + hnsgreq = list_first_entry(&hsgreq->node,
> + typeof(*hnsgreq), node);
> + tegra_dma_configure_for_next(tdc, hnsgreq);
> + }
> + hsgreq->half_done = true;
> + list_add_tail(&dma_desc->cb_node, &tdc->cb_desc);
> + dma_desc->cb_due = true;
> + } else {
> + hsgreq->half_done = false;
> + list_add_tail(&dma_desc->cb_node, &tdc->cb_desc);
> + dma_desc->cb_due = true;
> +
> + /*
> + * If this is not last entry then put the req in end of
> + * list for next cycle.
> + */
> + if (!list_is_last(hsgreq->node.next, &tdc->pending_sg_req)) {
> + list_del(&hsgreq->node);
> + list_add_tail(&hsgreq->node, &tdc->pending_sg_req);
> + hsgreq->configured = false;
> + }
> + }
> + return;
> +}
> +
> +static void tegra_dma_tasklet(unsigned long data)
> +{
> + struct tegra_dma_channel *tdc = (struct tegra_dma_channel *)data;
> + unsigned long flags;
> + dma_async_tx_callback callback = NULL;
> + void *callback_param = NULL;
> + struct tegra_dma_desc *dma_desc;
> + struct list_head cb_dma_desc_list;
> +
> + INIT_LIST_HEAD(&cb_dma_desc_list);
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (list_empty(&tdc->cb_desc)) {
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return;
> + }
> + list_splice_init(&tdc->cb_desc, &cb_dma_desc_list);
> + spin_unlock_irqrestore(&tdc->lock, flags);
> +
> + while (!list_empty(&cb_dma_desc_list)) {
> + dma_desc = list_first_entry(&cb_dma_desc_list,
> + typeof(*dma_desc), cb_node);
> + list_del(&dma_desc->cb_node);
> +
> + callback = dma_desc->txd.callback;
> + callback_param = dma_desc->txd.callback_param;
> + dma_desc->cb_due = false;
> + if (callback)
> + callback(callback_param);
> + }
> +}
> +
> +static irqreturn_t tegra_dma_isr(int irq, void *dev_id)
> +{
> + struct tegra_dma_channel *tdc = dev_id;
> + unsigned long status;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> +
> + status = tdc_read(tdc, APB_DMA_CHAN_STA);
> + if (status & STA_ISE_EOC) {
> + tdc_write(tdc, APB_DMA_CHAN_STA, status);
> + if (!list_empty(&tdc->cb_desc)) {
> + dev_err(tdc2dev(tdc),
> + "Int before tasklet handled, Stopping DMA %d\n",
> + tdc->id);
> + tegra_dma_stop(tdc);
> + tdc->isr_handler(tdc, true);
> + tegra_dma_abort_all(tdc);
> + /* Schedule tasklet to make callback */
> + tasklet_schedule(&tdc->tasklet);
> + goto end;
> + }
> + tdc->isr_handler(tdc, false);
> + tasklet_schedule(&tdc->tasklet);
> + } else {
> + dev_info(tdc2dev(tdc),
> + "Interrupt is already handled %d status 0x%08lx\n",
> + tdc->id, status);
> + }
> +
> +end:
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return IRQ_HANDLED;
> +}
> +
> +static dma_cookie_t tegra_dma_tx_submit(struct dma_async_tx_descriptor *txd)
> +{
> + struct tegra_dma_desc *dma_desc = txd_to_tegra_dma_desc(txd);
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(txd->chan);
> + unsigned long flags;
> + dma_cookie_t cookie;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> + dma_desc->dma_status = DMA_IN_PROGRESS;
> + cookie = dma_cookie_assign(&dma_desc->txd);
> + dma_desc->cookie = dma_desc->txd.cookie;
> + list_splice_tail_init(&dma_desc->tx_list, &tdc->pending_sg_req);
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return cookie;
> +}
> +
> +static void tegra_dma_issue_pending(struct dma_chan *dc)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (list_empty(&tdc->pending_sg_req)) {
> + dev_err(tdc2dev(tdc),
> + "No requests for channel %d\n", tdc->id);
> + goto end;
> + }
> + if (!tdc->busy) {
> + tdc_start_head_req(tdc);
> +
> + /* Continuous single mode: Configure next req */
> + if (DMA_MODE_CYCLE) {
> + /*
> + * Wait for 1 burst time for configure dma for
> + * next transfer.
> + */
> + udelay(DMA_BUSRT_COMPLETE_TIME);
> + tdc_configure_next_head_desc(tdc);
> + }
> + }
> +end:
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return;
> +}
> +
> +static void tegra_dma_terminate_all(struct dma_chan *dc)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + struct tegra_dma_sg_req *sgreq;
> + struct tegra_dma_desc *dma_desc;
> + unsigned long flags;
> + unsigned long status;
> + struct list_head new_list;
> + dma_async_tx_callback callback = NULL;
> + void *callback_param = NULL;
> + struct list_head cb_dma_desc_list;
> + bool was_busy;
> +
> + INIT_LIST_HEAD(&new_list);
> + INIT_LIST_HEAD(&cb_dma_desc_list);
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> + if (list_empty(&tdc->pending_sg_req)) {
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return;
> + }
> +
> + if (!tdc->busy) {
> + list_splice_init(&tdc->cb_desc, &cb_dma_desc_list);
> + goto skip_dma_stop;
> + }
> +
> + /* Pause dma before checking the queue status */
> + tegra_dma_pause(tdc, true);
> +
> + status = tdc_read(tdc, APB_DMA_CHAN_STA);
> + if (status & STA_ISE_EOC) {
> + dev_dbg(tdc2dev(tdc), "%s():handling isr\n", __func__);
> + tdc->isr_handler(tdc, true);
> + status = tdc_read(tdc, APB_DMA_CHAN_STA);
> + }
> + list_splice_init(&tdc->cb_desc, &cb_dma_desc_list);
> +
> + was_busy = tdc->busy;
> + tegra_dma_stop(tdc);
> + if (!list_empty(&tdc->pending_sg_req) && was_busy) {
> + sgreq = list_first_entry(&tdc->pending_sg_req,
> + typeof(*sgreq), node);
> + sgreq->dma_desc->bytes_transferred +=
> + get_current_xferred_count(tdc, sgreq, status);
> + }
> + tegra_dma_resume(tdc);
> +
> +skip_dma_stop:
> + tegra_dma_abort_all(tdc);
> + /* Ignore callbacks pending list */
> + INIT_LIST_HEAD(&tdc->cb_desc);
> + spin_unlock_irqrestore(&tdc->lock, flags);
> +
> + /* Call callbacks if was pending before aborting requests */
> + while (!list_empty(&cb_dma_desc_list)) {
> + dma_desc = list_first_entry(&cb_dma_desc_list,
> + typeof(*dma_desc), cb_node);
> + list_del(&dma_desc->cb_node);
> + callback = dma_desc->txd.callback;
> + callback_param = dma_desc->txd.callback_param;
> + if (callback)
> + callback(callback_param);
> + }
> +}
> +
> +static enum dma_status tegra_dma_tx_status(struct dma_chan *dc,
> + dma_cookie_t cookie, struct dma_tx_state *txstate)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + struct tegra_dma_desc *dma_desc;
> + struct tegra_dma_sg_req *sg_req;
> + enum dma_status ret;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&tdc->lock, flags);
> +
> + ret = dma_cookie_status(dc, cookie, txstate);
> + if (ret != DMA_SUCCESS)
> + goto check_pending_q;
> +
> + if (list_empty(&tdc->wait_ack_dma_desc))
> + goto check_pending_q;
> +
> + /* Check on wait_ack desc status */
> + list_for_each_entry(dma_desc, &tdc->wait_ack_dma_desc, node) {
> + if (dma_desc->cookie == cookie) {
> + dma_set_residue(txstate,
> + dma_desc->bytes_requested -
> + dma_desc->bytes_transferred);
> + ret = dma_desc->dma_status;
> + goto end;
> + }
> + }
> +
> +check_pending_q:
> + if (list_empty(&tdc->pending_sg_req))
> + goto end;
> +
> + /* May be this is in head list of pending list */
> + list_for_each_entry(sg_req, &tdc->pending_sg_req, node) {
> + dma_desc = sg_req->dma_desc;
> + if (dma_desc->txd.cookie == cookie) {
> + dma_set_residue(txstate,
> + dma_desc->bytes_requested -
> + dma_desc->bytes_transferred);
> + ret = dma_desc->dma_status;
> + goto end;
> + }
> + }
> + dev_info(tdc2dev(tdc), "%s(): cookie does not found\n", __func__);
> +end:
> + spin_unlock_irqrestore(&tdc->lock, flags);
> + return ret;
> +}
> +
> +static int tegra_dma_device_control(struct dma_chan *dc, enum dma_ctrl_cmd cmd,
> + unsigned long arg)
> +{
> + switch (cmd) {
> + case DMA_SLAVE_CONFIG:
> + return tegra_dma_slave_config(dc,
> + (struct dma_slave_config *)arg);
> +
> + case DMA_TERMINATE_ALL:
> + tegra_dma_terminate_all(dc);
> + return 0;
> + default:
> + break;
> + }
> +
> + return -ENXIO;
> +}
> +
> +static inline int get_bus_width(enum dma_slave_buswidth slave_bw)
> +{
> + BUG_ON(!slave_bw);
> + switch (slave_bw) {
> + case DMA_SLAVE_BUSWIDTH_1_BYTE:
> + return APB_SEQ_BUS_WIDTH_8;
> + case DMA_SLAVE_BUSWIDTH_2_BYTES:
> + return APB_SEQ_BUS_WIDTH_16;
> + case DMA_SLAVE_BUSWIDTH_4_BYTES:
> + return APB_SEQ_BUS_WIDTH_32;
> + case DMA_SLAVE_BUSWIDTH_8_BYTES:
> + return APB_SEQ_BUS_WIDTH_64;
> + default:
> + BUG();
> + }
> +}
> +
> +static inline int get_burst_size(struct tegra_dma_channel *tdc, int len)
> +{
> + switch (tdc->dma_slave.burst_size) {
> + case TEGRA_DMA_BURST_1:
> + return AHB_SEQ_BURST_1;
> + case TEGRA_DMA_BURST_4:
> + return AHB_SEQ_BURST_4;
> + case TEGRA_DMA_BURST_8:
> + return AHB_SEQ_BURST_8;
> + case TEGRA_DMA_AUTO:
> + if (len & 0xF)
> + return AHB_SEQ_BURST_1;
> + else if ((len >> 4) & 0x1)
> + return AHB_SEQ_BURST_4;
> + else
> + return AHB_SEQ_BURST_8;
> + }
> + WARN(1, KERN_WARNING "Invalid burst option\n");
> + return AHB_SEQ_BURST_1;
> +}
> +
> +static bool init_dma_mode(struct tegra_dma_channel *tdc,
> + enum dma_transfer_mode new_mode)
> +{
> + if (tdc->dma_mode == DMA_MODE_NONE) {
> + tdc->dma_mode = new_mode;
> + switch (new_mode) {
> + case DMA_MODE_ONCE:
> + tdc->isr_handler = handle_once_dma_done;
> + break;
> + case DMA_MODE_CYCLE:
> + tdc->isr_handler = handle_cont_sngl_cycle_dma_done;
> + break;
> + case DMA_MODE_CYCLE_HALF_NOTIFY:
> + tdc->isr_handler = handle_cont_dbl_cycle_dma_done;
> + break;
> + default:
> + break;
> + }
> + } else {
> + if (new_mode != tdc->dma_mode)
> + return false;
> + }
> + return true;
> +}
> +
> +static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
> + struct dma_chan *dc, struct scatterlist *sgl, unsigned int sg_len,
> + enum dma_transfer_direction direction, unsigned long flags,
> + void *context)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + struct tegra_dma_desc *dma_desc;
> + unsigned int i;
> + struct scatterlist *sg;
> + unsigned long csr, ahb_seq, apb_ptr, apb_seq;
> + struct list_head req_list;
> + struct tegra_dma_sg_req *sg_req = NULL;
> +
> + if (!tdc->config_init) {
> + dev_err(tdc2dev(tdc), "dma channel is not configured\n");
> + return NULL;
> + }
> + if (sg_len < 1) {
> + dev_err(tdc2dev(tdc), "Invalid segment length %d\n", sg_len);
> + return NULL;
> + }
> +
> + INIT_LIST_HEAD(&req_list);
> +
> + ahb_seq = AHB_SEQ_INTR_ENB;
> + ahb_seq |= AHB_SEQ_WRAP_NONE << AHB_SEQ_WRAP_SHIFT;
> + ahb_seq |= AHB_SEQ_BUS_WIDTH_32;
> +
> + csr = CSR_ONCE | CSR_FLOW;
> + csr |= tdc->dma_slave.dma_req_id << CSR_REQ_SEL_SHIFT;
> + if (flags & DMA_PREP_INTERRUPT)
> + csr |= CSR_IE_EOC;
> +
> + apb_seq = APB_SEQ_WRAP_WORD_1;
> +
> + switch (direction) {
> + case DMA_MEM_TO_DEV:
> + apb_ptr = tdc->dma_sconfig.dst_addr;
> + apb_seq |= get_bus_width(tdc->dma_sconfig.dst_addr_width);
> + csr |= CSR_DIR;
> + break;
> +
> + case DMA_DEV_TO_MEM:
> + apb_ptr = tdc->dma_sconfig.src_addr;
> + apb_seq |= get_bus_width(tdc->dma_sconfig.src_addr_width);
> + break;
you dont support DMA_MEM_TO_DEV?

> + default:
> + dev_err(tdc2dev(tdc), "Dma direction is not supported\n");
> + return NULL;
> + }
> +
> + dma_desc = tegra_dma_desc_get(tdc);
> + if (!dma_desc) {
> + dev_err(tdc2dev(tdc), "Dma descriptors not available\n");
> + goto fail;
> + }
> + INIT_LIST_HEAD(&dma_desc->tx_list);
> + INIT_LIST_HEAD(&dma_desc->cb_node);
> + dma_desc->bytes_requested = 0;
> + dma_desc->bytes_transferred = 0;
> + dma_desc->dma_status = DMA_IN_PROGRESS;
> +
> + /* Make transfer requests */
> + for_each_sg(sgl, sg, sg_len, i) {
> + u32 len, mem;
> +
> + mem = sg_phys(sg);
> + len = sg_dma_len(sg);
> +
> + if ((len & 3) || (mem & 3) ||
> + (len > tdc->tdma->chip_data.max_dma_count)) {
> + dev_err(tdc2dev(tdc),
> + "Dma length/memory address is not correct\n");
> + goto fail;
> + }
> +
> + sg_req = tegra_dma_sg_req_get(tdc);
> + if (!sg_req) {
> + dev_err(tdc2dev(tdc), "Dma sg-req not available\n");
> + goto fail;
> + }
> +
> + ahb_seq |= get_burst_size(tdc, len);
> + dma_desc->bytes_requested += len;
> +
> + sg_req->ch_regs.apb_ptr = apb_ptr;
> + sg_req->ch_regs.ahb_ptr = mem;
> + sg_req->ch_regs.csr = csr | ((len - 4) & 0xFFFC);
> + sg_req->ch_regs.apb_seq = apb_seq;
> + sg_req->ch_regs.ahb_seq = ahb_seq;
> + sg_req->configured = false;
> + sg_req->last_sg = false;
> + sg_req->dma_desc = dma_desc;
> + sg_req->req_len = len;
> +
> + list_add_tail(&sg_req->node, &dma_desc->tx_list);
> + }
> + sg_req->last_sg = true;
> + dma_desc->ack_reqd = (flags & DMA_CTRL_ACK) ? false : true;
> + if (dma_desc->ack_reqd)
> + dma_desc->txd.flags = DMA_CTRL_ACK;
> +
> + /*
> + * Make sure that mode should not be conflicting with currently
> + * configured mode.
> + */
> + if (!init_dma_mode(tdc, DMA_MODE_ONCE)) {
> + dev_err(tdc2dev(tdc), "Conflict in dma modes\n");
> + goto fail;
> + }
> +
> + return &dma_desc->txd;
> +
> +fail:
> + tegra_dma_desc_put(tdc, dma_desc);
> + return NULL;
> +}
> +
> +struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
> + struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_len,
> + size_t period_len, enum dma_transfer_direction direction,
> + void *context)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + struct tegra_dma_desc *dma_desc = NULL;
> + struct tegra_dma_sg_req *sg_req = NULL;
> + unsigned long csr, ahb_seq, apb_ptr, apb_seq;
> + int len;
> + bool half_buffer_notify;
> + enum dma_transfer_mode new_mode;
> + size_t remain_len;
> + dma_addr_t mem = buf_addr;
> +
> + if (!buf_len) {
> + dev_err(tdc2dev(tdc),
> + "Buffer length is invalid len %d\n", buf_len);
> + }
> +
> + if (!tdc->config_init) {
> + dev_err(tdc2dev(tdc),
> + "DMA is not configured for slave\n");
> + return NULL;
> + }
> +
> + if (tdc->busy) {
> + dev_err(tdc2dev(tdc),
> + "DMA is already started, can not accept any more requests\n");
> + return NULL;
> + }
> +
> + /*
> + * We only support cyclic transfer when buf_len is multiple of
> + * period_len.
> + * With period of buf_len, it will set dma mode DMA_MODE_CYCLE
> + * with one request.
> + * With period of buf_len/2, it will set dma mode
> + * DMA_MODE_CYCLE_HALF_NOTIFY with one requsts.
> + * Othercase, the transfer is broken in smaller requests of size
> + * of period_len and the transfer continues forever in cyclic way
> + * dma mode of DMA_MODE_CYCLE.
> + * If period_len is zero then assume dma mode DMA_MODE_CYCLE.
> + * We also allow to take more number of requests till dma is
> + * not started. The driver will loop over all requests.
> + * Once dma is started then new requests can be queued only after
> + * terminating the dma.
> + */
> + if (!period_len)
> + period_len = buf_len;
i am not sure about this assignment here. Why should period length be
ZERO?

> +
> + if (buf_len % period_len) {
> + dev_err(tdc2dev(tdc),
> + "buf_len %d should be multiple of period_len %d\n",
> + buf_len, period_len);
> + return NULL;
> + }
I am assuming you are also putting this as a constraint in sound driver.

> +
> + half_buffer_notify = (buf_len == (2 * period_len)) ? true : false;
> + len = (half_buffer_notify) ? buf_len / 2 : period_len;
> + if ((len & 3) || (buf_addr & 3) ||
> + (len > tdc->tdma->chip_data.max_dma_count)) {
> + dev_err(tdc2dev(tdc),
> + "Dma length/memory address is not correct\n");
not supported would be apt
> + return NULL;
> + }
> +
> + ahb_seq = AHB_SEQ_INTR_ENB;
> + ahb_seq |= AHB_SEQ_WRAP_NONE << AHB_SEQ_WRAP_SHIFT;
> + ahb_seq |= AHB_SEQ_BUS_WIDTH_32;
> + if (half_buffer_notify)
> + ahb_seq |= AHB_SEQ_DBL_BUF;
> +
> + csr = CSR_FLOW | CSR_IE_EOC;
> + csr |= tdc->dma_slave.dma_req_id << CSR_REQ_SEL_SHIFT;
> +
> + apb_seq = APB_SEQ_WRAP_WORD_1;
> +
> + switch (direction) {
> + case DMA_MEM_TO_DEV:
> + apb_ptr = tdc->dma_sconfig.dst_addr;
> + apb_seq |= get_bus_width(tdc->dma_sconfig.dst_addr_width);
> + csr |= CSR_DIR;
> + break;
> +
> + case DMA_DEV_TO_MEM:
> + apb_ptr = tdc->dma_sconfig.src_addr;
> + apb_seq |= get_bus_width(tdc->dma_sconfig.src_addr_width);
> + break;
> + default:
> + dev_err(tdc2dev(tdc), "Dma direction is not supported\n");
> + return NULL;
> + }
> +
> + dma_desc = tegra_dma_desc_get(tdc);
> + if (!dma_desc) {
> + dev_err(tdc2dev(tdc), "not enough descriptors available\n");
> + goto fail;
> + }
> + INIT_LIST_HEAD(&dma_desc->tx_list);
> +
> + dma_desc->bytes_transferred = 0;
> + dma_desc->bytes_requested = buf_len;
> + remain_len = (half_buffer_notify) ? len : buf_len;
> + ahb_seq |= get_burst_size(tdc, len);
> +
> + while (remain_len) {
> + sg_req = tegra_dma_sg_req_get(tdc);
> + if (!sg_req) {
> + dev_err(tdc2dev(tdc), "Dma sg-req not available\n");
> + goto fail;
> + }
> +
> + ahb_seq |= get_burst_size(tdc, len);
> + sg_req->ch_regs.apb_ptr = apb_ptr;
> + sg_req->ch_regs.ahb_ptr = mem;
> + sg_req->ch_regs.csr = csr | ((len - 4) & 0xFFFC);
> + sg_req->ch_regs.apb_seq = apb_seq;
> + sg_req->ch_regs.ahb_seq = ahb_seq;
> + sg_req->configured = false;
> + sg_req->half_done = false;
> + sg_req->last_sg = false;
> + sg_req->dma_desc = dma_desc;
> + sg_req->req_len = len;
> +
> + list_add_tail(&sg_req->node, &dma_desc->tx_list);
> + remain_len -= len;
> + mem += len;
> + }
> + sg_req->last_sg = true;
> + dma_desc->ack_reqd = true;
> + dma_desc->txd.flags = DMA_CTRL_ACK;
> +
> + /*
> + * We can not change the dma mode once it is initialized
> + * until all desc are terminated.
> + */
> + new_mode = (half_buffer_notify) ?
> + DMA_MODE_CYCLE_HALF_NOTIFY : DMA_MODE_CYCLE;
> + if (!init_dma_mode(tdc, new_mode)) {
> + dev_err(tdc2dev(tdc), "Conflict in dma modes\n");
> + goto fail;
> + }
> +
> + return &dma_desc->txd;
> +
> +fail:
> + tegra_dma_desc_put(tdc, dma_desc);
> + return NULL;
> +}
> +
> +static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + int total_desc;
> +
> + total_desc = allocate_tegra_desc(tdc, DMA_NR_DESCS_PER_CHANNEL,
> + DMA_NR_DESCS_PER_CHANNEL * DMA_NR_REQ_PER_DESC);
> + dma_cookie_init(&tdc->dma_chan);
> + dev_dbg(tdc2dev(tdc),
> + "%s(): allocated %d descriptors\n", __func__, total_desc);
> + tdc->config_init = false;
> + return total_desc;
> +}
> +
> +static void tegra_dma_free_chan_resources(struct dma_chan *dc)
> +{
> + struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
> + struct tegra_dma_chan_mem_alloc *mptr;
> +
> + dev_dbg(tdc2dev(tdc),
> + "%s(): channel %d and desc freeing %d\n",
> + __func__, tdc->id, tdc->descs_allocated);
> + if (tdc->busy)
> + tegra_dma_terminate_all(dc);
> +
> + INIT_LIST_HEAD(&tdc->pending_sg_req);
> + INIT_LIST_HEAD(&tdc->free_sg_req);
> + INIT_LIST_HEAD(&tdc->alloc_ptr_list);
> + INIT_LIST_HEAD(&tdc->free_dma_desc);
> + INIT_LIST_HEAD(&tdc->wait_ack_dma_desc);
> + INIT_LIST_HEAD(&tdc->cb_desc);
> + tdc->descs_allocated = 0;
> + tdc->config_init = false;
> + while (!list_empty(&tdc->alloc_ptr_list)) {
> + mptr = list_first_entry(&tdc->alloc_ptr_list,
> + typeof(*mptr), node);
> + list_del(&mptr->node);
> + kfree(mptr);
> + }
> +}
> +
> +/* Tegra20 specific dma controller information */
> +static struct tegra_dma_chip_data tegra20_chip_data = {
> + .nr_channels = 16,
> + .max_dma_count = 1024UL * 64,
> +};
> +
> +/* Tegra30 specific dma controller information */
> +static struct tegra_dma_chip_data tegra30_chip_data = {
> + .nr_channels = 32,
> + .max_dma_count = 1024UL * 64,
> +};
> +
> +#if defined(CONFIG_OF)
> +/* Match table for of_platform binding */
> +static const struct of_device_id tegra_dma_of_match[] __devinitconst = {
> + { .compatible = "nvidia,tegra30-apbdma", .data = &tegra30_chip_data, },
> + { .compatible = "nvidia,tegra20-apbdma", .data = &tegra20_chip_data, },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, tegra_dma_of_match);
> +#else
> +#define tegra_dma_of_match NULL
> +#endif
> +
> +static struct platform_device_id dma_id_table[] = {
> + {.name = "tegra30-apbdma", .driver_data = (ulong)&tegra30_chip_data, },
> + {.name = "tegra20-apbdma", .driver_data = (ulong)&tegra20_chip_data, },
> + {},
> +};
> +
> +static bool tdma_volatile_reg(struct device *dev, unsigned int reg)
> +{
> + unsigned int chan_reg;
> +
> + if (reg < DMA_CHANNEL_BASE_ADDRESS_OFFSET)
> + return false;
> +
> + chan_reg = (reg - DMA_CHANNEL_BASE_ADDRESS_OFFSET) %
> + DMA_CHANNEL_REGISTER_SIZE;
> + switch (chan_reg) {
> + case APB_DMA_CHAN_STA:
> + case APB_DMA_CHAN_CSR:
> + return true;
> + }
> + return false;
> +}
> +
> +static bool tdma_wr_rd_reg(struct device *dev, unsigned int reg)
> +{
> + unsigned int chan_reg;
> +
> + /* Dma base registers */
> + if (reg < DMA_CHANNEL_BASE_ADDRESS_OFFSET) {
> + switch (reg) {
> + case APB_DMA_GEN:
> + case APB_DMA_CNTRL:
> + case APB_DMA_IRQ_MASK:
> + case APB_DMA_IRQ_MASK_SET:
> + return true;
> + default:
> + return false;
> + }
> + }
> +
> + /* Channel registers */
> + chan_reg = (reg - DMA_CHANNEL_BASE_ADDRESS_OFFSET) %
> + DMA_CHANNEL_REGISTER_SIZE;
> + switch (chan_reg) {
> + case APB_DMA_CHAN_CSR:
> + case APB_DMA_CHAN_STA:
> + case APB_DMA_CHAN_APB_SEQ:
> + case APB_DMA_CHAN_APB_PTR:
> + case APB_DMA_CHAN_AHB_SEQ:
> + case APB_DMA_CHAN_AHB_PTR:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static struct regmap_config tdma_regmap_config = {
> + .name = "tegra-apbdma",
> + .reg_bits = 32,
> + .val_bits = 32,
> + .reg_stride = 4,
> + .volatile_reg = tdma_volatile_reg,
> + .writeable_reg = tdma_wr_rd_reg,
> + .readable_reg = tdma_wr_rd_reg,
> + .cache_type = REGCACHE_RBTREE,
> +};
> +
> +static int __devinit tegra_dma_probe(struct platform_device *pdev)
> +{
> + struct resource *res;
> + struct tegra_dma *tdma;
> + size_t size;
> + int ret;
> + int i;
> + struct tegra_dma_chip_data *chip_data = NULL;
> +
> +#if defined(CONFIG_OF)
> + {
> + const struct of_device_id *match;
> + match = of_match_device(of_match_ptr(tegra_dma_of_match),
> + &pdev->dev);
> + if (match)
> + chip_data = match->data;
> + }
> +#else
> + chip_data = (struct tegra_dma_chip_data *)pdev->id_entry->driver_data;
> +#endif
> + if (!chip_data) {
> + dev_err(&pdev->dev, "Error: Chip data is not valid\n");
> + return -EINVAL;
> + }
> +
> + size = sizeof(struct tegra_dma);
> + size += chip_data->nr_channels * sizeof(struct tegra_dma_channel);
> + tdma = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
> + if (!tdma) {
> + dev_err(&pdev->dev, "Error: memory allocation failed\n");
> + return -ENOMEM;
> + }
> +
> + tdma->dev = &pdev->dev;
> + memcpy(&tdma->chip_data, chip_data, sizeof(*chip_data));
> + platform_set_drvdata(pdev, tdma);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res) {
> + dev_err(&pdev->dev, "no mem resource for DMA\n");
> + return -EINVAL;
> + }
> +
> + tdma->base_addr = devm_request_and_ioremap(&pdev->dev, res);
> + if (!tdma->base_addr) {
> + dev_err(&pdev->dev,
> + "Cannot request memregion/iomap dma address\n");
> + return -EADDRNOTAVAIL;
> + }
> +
> + /* Dma base register */
> + tdma_regmap_config.max_register = resource_size(res);
> + tdma->regmap_dma = devm_regmap_init_mmio(&pdev->dev, tdma->base_addr,
> + (const struct regmap_config *)&tdma_regmap_config);
> + if (IS_ERR(tdma->regmap_dma)) {
> + dev_err(&pdev->dev, "regmap init failed\n");
> + return PTR_ERR(tdma->regmap_dma);
> + }
> +
> + /* Clock */
> + tdma->dma_clk = clk_get(&pdev->dev, "clk");
> + if (IS_ERR(tdma->dma_clk)) {
> + dev_err(&pdev->dev, "Error: Missing controller clock");
> + return PTR_ERR(tdma->dma_clk);
> + }
> +
> + spin_lock_init(&tdma->global_lock);
> +
> + INIT_LIST_HEAD(&tdma->dma_dev.channels);
> + for (i = 0; i < chip_data->nr_channels; i++) {
> + struct tegra_dma_channel *tdc = &tdma->channels[i];
> + char irq_name[30];
> +
> + tdc->chan_base_offset = DMA_CHANNEL_BASE_ADDRESS_OFFSET +
> + i * DMA_CHANNEL_REGISTER_SIZE;
> +
> + res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
> + if (!res) {
> + ret = -EINVAL;
> + dev_err(&pdev->dev,
> + "Irq resource not found for channel %d\n", i);
> + goto err_irq;
> + }
> + tdc->irq = res->start;
> + snprintf(irq_name, sizeof(irq_name), "tegra_dma_chan.%d", i);
> + ret = devm_request_irq(&pdev->dev, tdc->irq,
> + tegra_dma_isr, 0, irq_name, tdc);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "request_irq failed for channel %d error %d\n",
> + i, ret);
> + goto err_irq;
> + }
> +
> + tdc->dma_chan.device = &tdma->dma_dev;
> + dma_cookie_init(&tdc->dma_chan);
> + list_add_tail(&tdc->dma_chan.device_node,
> + &tdma->dma_dev.channels);
> + tdc->tdma = tdma;
> + tdc->id = i;
> +
> + tasklet_init(&tdc->tasklet,
> + tegra_dma_tasklet, (unsigned long)tdc);
> + spin_lock_init(&tdc->lock);
> +
> + INIT_LIST_HEAD(&tdc->pending_sg_req);
> + INIT_LIST_HEAD(&tdc->free_sg_req);
> + INIT_LIST_HEAD(&tdc->alloc_ptr_list);
> + INIT_LIST_HEAD(&tdc->free_dma_desc);
> + INIT_LIST_HEAD(&tdc->wait_ack_dma_desc);
> + INIT_LIST_HEAD(&tdc->cb_desc);
> + }
> +
> + dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
> + dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
> + tdma->dma_dev.dev = &pdev->dev;
> + tdma->dma_dev.device_alloc_chan_resources =
> + tegra_dma_alloc_chan_resources;
> + tdma->dma_dev.device_free_chan_resources =
> + tegra_dma_free_chan_resources;
> + tdma->dma_dev.device_prep_slave_sg = tegra_dma_prep_slave_sg;
> + tdma->dma_dev.device_prep_dma_cyclic = tegra_dma_prep_dma_cyclic;
> + tdma->dma_dev.device_control = tegra_dma_device_control;
> + tdma->dma_dev.device_tx_status = tegra_dma_tx_status;
> + tdma->dma_dev.device_issue_pending = tegra_dma_issue_pending;
> +
> + ret = dma_async_device_register(&tdma->dma_dev);
> + if (ret < 0) {
> + dev_err(&pdev->dev,
> + "Error in registering Tegra APB DMA driver %d\n", ret);
> + goto err_irq;
> + }
> + dev_info(&pdev->dev, "Tegra APB DMA Controller, %d channels\n",
> + chip_data->nr_channels);
> + pm_runtime_enable(&pdev->dev);
> + pm_runtime_get_sync(&pdev->dev);
> +
> + /* Reset dma controller */
> + tegra_periph_reset_assert(tdma->dma_clk);
> + tegra_periph_reset_deassert(tdma->dma_clk);
> +
> + /* Enable global dma registers */
> + tdma_write(tdma, APB_DMA_GEN, GEN_ENABLE);
> + tdma_write(tdma, APB_DMA_CNTRL, 0);
> + tdma_write(tdma, APB_DMA_IRQ_MASK_SET, 0xFFFFFFFFul);
> + return 0;
> +
> +err_irq:
> + while (--i >= 0) {
> + struct tegra_dma_channel *tdc = &tdma->channels[i];
> + tasklet_kill(&tdc->tasklet);
> + }
> +
> + pm_runtime_disable(&pdev->dev);
> + clk_put(tdma->dma_clk);
> + return ret;
> +}
> +
> +static int __exit tegra_dma_remove(struct platform_device *pdev)
> +{
> + struct tegra_dma *tdma = platform_get_drvdata(pdev);
> + int i;
> + struct tegra_dma_channel *tdc;
> +
> + dma_async_device_unregister(&tdma->dma_dev);
> +
> + for (i = 0; i < tdma->chip_data.nr_channels; ++i) {
> + tdc = &tdma->channels[i];
> + tasklet_kill(&tdc->tasklet);
> + }
> +
> + pm_runtime_disable(&pdev->dev);
> + clk_put(tdma->dma_clk);
> +
> + return 0;
> +}
> +
> +static int tegra_dma_runtime_idle(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct tegra_dma *tdma = platform_get_drvdata(pdev);
> +
> + regcache_cache_only(tdma->regmap_dma, true);
> + clk_disable(tdma->dma_clk);
> + return 0;
> +}
> +
> +static int tegra_dma_runtime_resume(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct tegra_dma *tdma = platform_get_drvdata(pdev);
> + clk_enable(tdma->dma_clk);
> + regcache_cache_only(tdma->regmap_dma, false);
> + return 0;
> +}
> +
> +static int tegra_dma_suspend_noirq(struct device *dev)
> +{
> + tegra_dma_runtime_idle(dev);
> + return 0;
> +}
> +
> +static int tegra_dma_resume_noirq(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct tegra_dma *tdma = platform_get_drvdata(pdev);
> +
> + tegra_dma_runtime_resume(dev);
> +
> + /*
> + * After resume, dma register will not be sync with the cached value.
> + * Making sure they are in sync.
> + */
> + regcache_mark_dirty(tdma->regmap_dma);
> + regcache_sync(tdma->regmap_dma);
> + return 0;
> +}
> +
> +static const struct dev_pm_ops tegra_dma_dev_pm_ops = {
> + .suspend_noirq = tegra_dma_suspend_noirq,
> + .resume_noirq = tegra_dma_resume_noirq,
> + .runtime_idle = tegra_dma_runtime_idle,
> + .runtime_resume = tegra_dma_runtime_resume,
> +};
> +
> +static struct platform_driver tegra_dmac_driver = {
> + .driver = {
> + .name = "tegra-apbdma",
> + .owner = THIS_MODULE,
> + .pm = &tegra_dma_dev_pm_ops,
> + .of_match_table = tegra_dma_of_match,
> + },
> + .probe = tegra_dma_probe,
> + .remove = __exit_p(tegra_dma_remove),
> + .id_table = dma_id_table,
> +};
> +
> +static int __init tegra_dmac_init(void)
> +{
> + return platform_driver_register(&tegra_dmac_driver);
> +}
> +arch_initcall_sync(tegra_dmac_init);
> +
> +static void __exit tegra_dmac_exit(void)
> +{
> + platform_driver_unregister(&tegra_dmac_driver);
> +}
> +module_exit(tegra_dmac_exit);
> +
> +MODULE_DESCRIPTION("NVIDIA Tegra DMA Controller driver");
> +MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:tegra-apbdma");
> diff --git a/include/linux/tegra_dma.h b/include/linux/tegra_dma.h
> new file mode 100644
> index 0000000..e94aac3
> --- /dev/null
> +++ b/include/linux/tegra_dma.h
> @@ -0,0 +1,95 @@
> +/*
> + * Dma driver for Nvidia's Tegra dma controller.
> + *
> + * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef LINUX_TEGRA_DMA_H
> +#define LINUX_TEGRA_DMA_H
> +
> +/*
> + * tegra_dma_burst_size: Burst size of dma.
> + * @TEGRA_DMA_AUTO: Based on transfer size, select the burst size.
> + * If it is multple of 32 bytes then burst size will be 32 bytes else
> + * If it is multiple of 16 bytes then burst size will be 16 bytes else
> + * If it is multiple of 4 bytes then burst size will be 4 bytes.
> + * @TEGRA_DMA_BURST_1: Burst size is 1 word/4 bytes.
> + * @TEGRA_DMA_BURST_4: Burst size is 4 word/16 bytes.
> + * @TEGRA_DMA_BURST_8: Burst size is 8 words/32 bytes.
> + */
> +enum tegra_dma_burst_size {
> + TEGRA_DMA_AUTO,
> + TEGRA_DMA_BURST_1,
> + TEGRA_DMA_BURST_4,
> + TEGRA_DMA_BURST_8,
> +};
why should this be global, clinet should pass them as defined in
dmaengine.h
> +
> +/* Dma slave requestor */
> +enum tegra_dma_requestor {
> + TEGRA_DMA_REQ_SEL_CNTR,
> + TEGRA_DMA_REQ_SEL_I2S_2,
> + TEGRA_DMA_REQ_SEL_APBIF_CH0 = TEGRA_DMA_REQ_SEL_I2S_2,
> + TEGRA_DMA_REQ_SEL_I2S_1,
> + TEGRA_DMA_REQ_SEL_APBIF_CH1 = TEGRA_DMA_REQ_SEL_I2S_1,
> + TEGRA_DMA_REQ_SEL_SPD_I,
> + TEGRA_DMA_REQ_SEL_APBIF_CH2 = TEGRA_DMA_REQ_SEL_SPD_I,
> + TEGRA_DMA_REQ_SEL_UI_I,
> + TEGRA_DMA_REQ_SEL_APBIF_CH3 = TEGRA_DMA_REQ_SEL_UI_I,
> + TEGRA_DMA_REQ_SEL_MIPI,
> + TEGRA_DMA_REQ_SEL_I2S2_2,
> + TEGRA_DMA_REQ_SEL_I2S2_1,
> + TEGRA_DMA_REQ_SEL_UARTA,
> + TEGRA_DMA_REQ_SEL_UARTB,
> + TEGRA_DMA_REQ_SEL_UARTC,
> + TEGRA_DMA_REQ_SEL_SPI,
> + TEGRA_DMA_REQ_SEL_DTV = TEGRA_DMA_REQ_SEL_SPI,
> + TEGRA_DMA_REQ_SEL_AC97,
> + TEGRA_DMA_REQ_SEL_ACMODEM,
> + TEGRA_DMA_REQ_SEL_SL4B,
> + TEGRA_DMA_REQ_SEL_SL2B1,
> + TEGRA_DMA_REQ_SEL_SL2B2,
> + TEGRA_DMA_REQ_SEL_SL2B3,
> + TEGRA_DMA_REQ_SEL_SL2B4,
> + TEGRA_DMA_REQ_SEL_UARTD,
> + TEGRA_DMA_REQ_SEL_UARTE,
> + TEGRA_DMA_REQ_SEL_I2C,
> + TEGRA_DMA_REQ_SEL_I2C2,
> + TEGRA_DMA_REQ_SEL_I2C3,
> + TEGRA_DMA_REQ_SEL_DVC_I2C,
> + TEGRA_DMA_REQ_SEL_OWR,
> + TEGRA_DMA_REQ_SEL_I2C4,
> + TEGRA_DMA_REQ_SEL_SL2B5,
> + TEGRA_DMA_REQ_SEL_SL2B6,
> + TEGRA_DMA_REQ_SEL_INVALID,
> +};
> +
> +/**
> + * struct tegra_dma_slave - Controller-specific information about a slave
> + * After requesting a dma channel by client through interface
> + * dma_request_channel(), the chan->private should be initialized with
> + * this structure.
> + * Once the chan->private is got initialized with proper client data,
> + * client need to call dmaengine_slave_config() to configure dma channel.
> + *
> + * @dma_dev: required DMA master client device.
> + * @dm_req_id: Peripheral dma requestor ID.
> + */
> +struct tegra_dma_slave {
> + struct device *client_dev;
> + enum tegra_dma_requestor dma_req_id;
> + enum tegra_dma_burst_size burst_size;
pls remove
> +};
> +
> +#endif /* LINUX_TEGRA_DMA_H */

Please also update the driver to use the cookie helpers in
drivers/dma/dmaengine.h

--
~Vinod



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