diff options
author | Ira Snyder <iws@ovro.caltech.edu> | 2010-01-06 13:34:06 +0000 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2010-02-02 14:51:42 -0700 |
commit | 9c3a50b7d7ec45da34e73cac66cde12dd6092dd8 (patch) | |
tree | a16b2dd972ba8ebdd9e6796ad8f0027513316f49 | |
parent | a1c03319018061304be28d131073ac13a5cb86fb (diff) | |
download | linux-3.10-9c3a50b7d7ec45da34e73cac66cde12dd6092dd8.tar.gz linux-3.10-9c3a50b7d7ec45da34e73cac66cde12dd6092dd8.tar.bz2 linux-3.10-9c3a50b7d7ec45da34e73cac66cde12dd6092dd8.zip |
fsldma: major cleanups and fixes
Fix locking. Use two queues in the driver, one for pending transacions, and
one for transactions which are actually running on the hardware. Call
dma_run_dependencies() on descriptor cleanup so that the async_tx API works
correctly.
There are a number of places throughout the code where lists of descriptors
are freed in a loop. Create functions to handle this, and use them instead
of open-coding the loop each time.
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
-rw-r--r-- | drivers/dma/fsldma.c | 386 | ||||
-rw-r--r-- | drivers/dma/fsldma.h | 3 |
2 files changed, 207 insertions, 182 deletions
diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c index 7b5f88cb495..19011c20390 100644 --- a/drivers/dma/fsldma.c +++ b/drivers/dma/fsldma.c @@ -61,7 +61,6 @@ static void dma_init(struct fsldma_chan *chan) | FSL_DMA_MR_PRC_RM, 32); break; } - } static void set_sr(struct fsldma_chan *chan, u32 val) @@ -120,11 +119,6 @@ static dma_addr_t get_cdar(struct fsldma_chan *chan) return DMA_IN(chan, &chan->regs->cdar, 64) & ~FSL_DMA_SNEN; } -static void set_ndar(struct fsldma_chan *chan, dma_addr_t addr) -{ - DMA_OUT(chan, &chan->regs->ndar, addr, 64); -} - static dma_addr_t get_ndar(struct fsldma_chan *chan) { return DMA_IN(chan, &chan->regs->ndar, 64); @@ -178,11 +172,12 @@ static void dma_halt(struct fsldma_chan *chan) for (i = 0; i < 100; i++) { if (dma_is_idle(chan)) - break; + return; + udelay(10); } - if (i >= 100 && !dma_is_idle(chan)) + if (!dma_is_idle(chan)) dev_err(chan->dev, "DMA halt timeout!\n"); } @@ -199,27 +194,6 @@ static void set_ld_eol(struct fsldma_chan *chan, | snoop_bits, 64); } -static void append_ld_queue(struct fsldma_chan *chan, - struct fsl_desc_sw *new_desc) -{ - struct fsl_desc_sw *queue_tail = to_fsl_desc(chan->ld_queue.prev); - - if (list_empty(&chan->ld_queue)) - return; - - /* Link to the new descriptor physical address and - * Enable End-of-segment interrupt for - * the last link descriptor. - * (the previous node's next link descriptor) - * - * For FSL_DMA_IP_83xx, the snoop enable bit need be set. - */ - queue_tail->hw.next_ln_addr = CPU_TO_DMA(chan, - new_desc->async_tx.phys | FSL_DMA_EOSIE | - (((chan->feature & FSL_DMA_IP_MASK) - == FSL_DMA_IP_83XX) ? FSL_DMA_SNEN : 0), 64); -} - /** * fsl_chan_set_src_loop_size - Set source address hold transfer size * @chan : Freescale DMA channel @@ -343,6 +317,31 @@ static void fsl_chan_toggle_ext_start(struct fsldma_chan *chan, int enable) chan->feature &= ~FSL_DMA_CHAN_START_EXT; } +static void append_ld_queue(struct fsldma_chan *chan, + struct fsl_desc_sw *desc) +{ + struct fsl_desc_sw *tail = to_fsl_desc(chan->ld_pending.prev); + + if (list_empty(&chan->ld_pending)) + goto out_splice; + + /* + * Add the hardware descriptor to the chain of hardware descriptors + * that already exists in memory. + * + * This will un-set the EOL bit of the existing transaction, and the + * last link in this transaction will become the EOL descriptor. + */ + set_desc_next(chan, &tail->hw, desc->async_tx.phys); + + /* + * Add the software descriptor and all children to the list + * of pending transactions + */ +out_splice: + list_splice_tail_init(&desc->tx_list, &chan->ld_pending); +} + static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) { struct fsldma_chan *chan = to_fsl_chan(tx->chan); @@ -351,9 +350,12 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) unsigned long flags; dma_cookie_t cookie; - /* cookie increment and adding to ld_queue must be atomic */ spin_lock_irqsave(&chan->desc_lock, flags); + /* + * assign cookies to all of the software descriptors + * that make up this transaction + */ cookie = chan->common.cookie; list_for_each_entry(child, &desc->tx_list, node) { cookie++; @@ -364,8 +366,9 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) } chan->common.cookie = cookie; + + /* put this transaction onto the tail of the pending queue */ append_ld_queue(chan, desc); - list_splice_init(&desc->tx_list, chan->ld_queue.prev); spin_unlock_irqrestore(&chan->desc_lock, flags); @@ -381,20 +384,22 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) static struct fsl_desc_sw *fsl_dma_alloc_descriptor( struct fsldma_chan *chan) { + struct fsl_desc_sw *desc; dma_addr_t pdesc; - struct fsl_desc_sw *desc_sw; - - desc_sw = dma_pool_alloc(chan->desc_pool, GFP_ATOMIC, &pdesc); - if (desc_sw) { - memset(desc_sw, 0, sizeof(struct fsl_desc_sw)); - INIT_LIST_HEAD(&desc_sw->tx_list); - dma_async_tx_descriptor_init(&desc_sw->async_tx, - &chan->common); - desc_sw->async_tx.tx_submit = fsl_dma_tx_submit; - desc_sw->async_tx.phys = pdesc; + + desc = dma_pool_alloc(chan->desc_pool, GFP_ATOMIC, &pdesc); + if (!desc) { + dev_dbg(chan->dev, "out of memory for link desc\n"); + return NULL; } - return desc_sw; + memset(desc, 0, sizeof(*desc)); + INIT_LIST_HEAD(&desc->tx_list); + dma_async_tx_descriptor_init(&desc->async_tx, &chan->common); + desc->async_tx.tx_submit = fsl_dma_tx_submit; + desc->async_tx.phys = pdesc; + + return desc; } @@ -414,45 +419,69 @@ static int fsl_dma_alloc_chan_resources(struct dma_chan *dchan) if (chan->desc_pool) return 1; - /* We need the descriptor to be aligned to 32bytes + /* + * We need the descriptor to be aligned to 32bytes * for meeting FSL DMA specification requirement. */ chan->desc_pool = dma_pool_create("fsl_dma_engine_desc_pool", - chan->dev, sizeof(struct fsl_desc_sw), - 32, 0); + chan->dev, + sizeof(struct fsl_desc_sw), + __alignof__(struct fsl_desc_sw), 0); if (!chan->desc_pool) { - dev_err(chan->dev, "No memory for channel %d " - "descriptor dma pool.\n", chan->id); - return 0; + dev_err(chan->dev, "unable to allocate channel %d " + "descriptor pool\n", chan->id); + return -ENOMEM; } + /* there is at least one descriptor free to be allocated */ return 1; } /** + * fsldma_free_desc_list - Free all descriptors in a queue + * @chan: Freescae DMA channel + * @list: the list to free + * + * LOCKING: must hold chan->desc_lock + */ +static void fsldma_free_desc_list(struct fsldma_chan *chan, + struct list_head *list) +{ + struct fsl_desc_sw *desc, *_desc; + + list_for_each_entry_safe(desc, _desc, list, node) { + list_del(&desc->node); + dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); + } +} + +static void fsldma_free_desc_list_reverse(struct fsldma_chan *chan, + struct list_head *list) +{ + struct fsl_desc_sw *desc, *_desc; + + list_for_each_entry_safe_reverse(desc, _desc, list, node) { + list_del(&desc->node); + dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); + } +} + +/** * fsl_dma_free_chan_resources - Free all resources of the channel. * @chan : Freescale DMA channel */ static void fsl_dma_free_chan_resources(struct dma_chan *dchan) { struct fsldma_chan *chan = to_fsl_chan(dchan); - struct fsl_desc_sw *desc, *_desc; unsigned long flags; dev_dbg(chan->dev, "Free all channel resources.\n"); spin_lock_irqsave(&chan->desc_lock, flags); - list_for_each_entry_safe(desc, _desc, &chan->ld_queue, node) { -#ifdef FSL_DMA_LD_DEBUG - dev_dbg(chan->dev, - "LD %p will be released.\n", desc); -#endif - list_del(&desc->node); - /* free link descriptor */ - dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); - } + fsldma_free_desc_list(chan, &chan->ld_pending); + fsldma_free_desc_list(chan, &chan->ld_running); spin_unlock_irqrestore(&chan->desc_lock, flags); - dma_pool_destroy(chan->desc_pool); + dma_pool_destroy(chan->desc_pool); chan->desc_pool = NULL; } @@ -491,7 +520,6 @@ static struct dma_async_tx_descriptor *fsl_dma_prep_memcpy( { struct fsldma_chan *chan; struct fsl_desc_sw *first = NULL, *prev = NULL, *new; - struct list_head *list; size_t copy; if (!dchan) @@ -550,12 +578,7 @@ fail: if (!first) return NULL; - list = &first->tx_list; - list_for_each_entry_safe_reverse(new, prev, list, node) { - list_del(&new->node); - dma_pool_free(chan->desc_pool, new, new->async_tx.phys); - } - + fsldma_free_desc_list_reverse(chan, &first->tx_list); return NULL; } @@ -578,7 +601,6 @@ static struct dma_async_tx_descriptor *fsl_dma_prep_slave_sg( struct fsldma_chan *chan; struct fsl_desc_sw *first = NULL, *prev = NULL, *new = NULL; struct fsl_dma_slave *slave; - struct list_head *tx_list; size_t copy; int i; @@ -748,19 +770,13 @@ fail: * * We're re-using variables for the loop, oh well */ - tx_list = &first->tx_list; - list_for_each_entry_safe_reverse(new, prev, tx_list, node) { - list_del_init(&new->node); - dma_pool_free(chan->desc_pool, new, new->async_tx.phys); - } - + fsldma_free_desc_list_reverse(chan, &first->tx_list); return NULL; } static void fsl_dma_device_terminate_all(struct dma_chan *dchan) { struct fsldma_chan *chan; - struct fsl_desc_sw *desc, *tmp; unsigned long flags; if (!dchan) @@ -774,10 +790,8 @@ static void fsl_dma_device_terminate_all(struct dma_chan *dchan) spin_lock_irqsave(&chan->desc_lock, flags); /* Remove and free all of the descriptors in the LD queue */ - list_for_each_entry_safe(desc, tmp, &chan->ld_queue, node) { - list_del(&desc->node); - dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); - } + fsldma_free_desc_list(chan, &chan->ld_pending); + fsldma_free_desc_list(chan, &chan->ld_running); spin_unlock_irqrestore(&chan->desc_lock, flags); } @@ -785,31 +799,48 @@ static void fsl_dma_device_terminate_all(struct dma_chan *dchan) /** * fsl_dma_update_completed_cookie - Update the completed cookie. * @chan : Freescale DMA channel + * + * CONTEXT: hardirq */ static void fsl_dma_update_completed_cookie(struct fsldma_chan *chan) { - struct fsl_desc_sw *cur_desc, *desc; - dma_addr_t ld_phy; - - ld_phy = get_cdar(chan) & FSL_DMA_NLDA_MASK; + struct fsl_desc_sw *desc; + unsigned long flags; + dma_cookie_t cookie; - if (ld_phy) { - cur_desc = NULL; - list_for_each_entry(desc, &chan->ld_queue, node) - if (desc->async_tx.phys == ld_phy) { - cur_desc = desc; - break; - } + spin_lock_irqsave(&chan->desc_lock, flags); - if (cur_desc && cur_desc->async_tx.cookie) { - if (dma_is_idle(chan)) - chan->completed_cookie = - cur_desc->async_tx.cookie; - else - chan->completed_cookie = - cur_desc->async_tx.cookie - 1; - } + if (list_empty(&chan->ld_running)) { + dev_dbg(chan->dev, "no running descriptors\n"); + goto out_unlock; } + + /* Get the last descriptor, update the cookie to that */ + desc = to_fsl_desc(chan->ld_running.prev); + if (dma_is_idle(chan)) + cookie = desc->async_tx.cookie; + else + cookie = desc->async_tx.cookie - 1; + + chan->completed_cookie = cookie; + +out_unlock: + spin_unlock_irqrestore(&chan->desc_lock, flags); +} + +/** + * fsldma_desc_status - Check the status of a descriptor + * @chan: Freescale DMA channel + * @desc: DMA SW descriptor + * + * This function will return the status of the given descriptor + */ +static enum dma_status fsldma_desc_status(struct fsldma_chan *chan, + struct fsl_desc_sw *desc) +{ + return dma_async_is_complete(desc->async_tx.cookie, + chan->completed_cookie, + chan->common.cookie); } /** @@ -817,8 +848,6 @@ static void fsl_dma_update_completed_cookie(struct fsldma_chan *chan) * @chan : Freescale DMA channel * * This function clean up the ld_queue of DMA channel. - * If 'in_intr' is set, the function will move the link descriptor to - * the recycle list. Otherwise, free it directly. */ static void fsl_chan_ld_cleanup(struct fsldma_chan *chan) { @@ -827,80 +856,95 @@ static void fsl_chan_ld_cleanup(struct fsldma_chan *chan) spin_lock_irqsave(&chan->desc_lock, flags); - dev_dbg(chan->dev, "chan completed_cookie = %d\n", - chan->completed_cookie); - list_for_each_entry_safe(desc, _desc, &chan->ld_queue, node) { + dev_dbg(chan->dev, "chan completed_cookie = %d\n", chan->completed_cookie); + list_for_each_entry_safe(desc, _desc, &chan->ld_running, node) { dma_async_tx_callback callback; void *callback_param; - if (dma_async_is_complete(desc->async_tx.cookie, - chan->completed_cookie, chan->common.cookie) - == DMA_IN_PROGRESS) + if (fsldma_desc_status(chan, desc) == DMA_IN_PROGRESS) break; - callback = desc->async_tx.callback; - callback_param = desc->async_tx.callback_param; - - /* Remove from ld_queue list */ + /* Remove from the list of running transactions */ list_del(&desc->node); - dev_dbg(chan->dev, "link descriptor %p will be recycle.\n", - desc); - dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); - /* Run the link descriptor callback function */ + callback = desc->async_tx.callback; + callback_param = desc->async_tx.callback_param; if (callback) { spin_unlock_irqrestore(&chan->desc_lock, flags); - dev_dbg(chan->dev, "link descriptor %p callback\n", - desc); + dev_dbg(chan->dev, "LD %p callback\n", desc); callback(callback_param); spin_lock_irqsave(&chan->desc_lock, flags); } + + /* Run any dependencies, then free the descriptor */ + dma_run_dependencies(&desc->async_tx); + dma_pool_free(chan->desc_pool, desc, desc->async_tx.phys); } + spin_unlock_irqrestore(&chan->desc_lock, flags); } /** - * fsl_chan_xfer_ld_queue - Transfer link descriptors in channel ld_queue. + * fsl_chan_xfer_ld_queue - transfer any pending transactions * @chan : Freescale DMA channel + * + * This will make sure that any pending transactions will be run. + * If the DMA controller is idle, it will be started. Otherwise, + * the DMA controller's interrupt handler will start any pending + * transactions when it becomes idle. */ static void fsl_chan_xfer_ld_queue(struct fsldma_chan *chan) { - struct list_head *ld_node; - dma_addr_t next_dst_addr; + struct fsl_desc_sw *desc; unsigned long flags; spin_lock_irqsave(&chan->desc_lock, flags); - if (!dma_is_idle(chan)) + /* + * If the list of pending descriptors is empty, then we + * don't need to do any work at all + */ + if (list_empty(&chan->ld_pending)) { + dev_dbg(chan->dev, "no pending LDs\n"); goto out_unlock; + } + /* + * The DMA controller is not idle, which means the interrupt + * handler will start any queued transactions when it runs + * at the end of the current transaction + */ + if (!dma_is_idle(chan)) { + dev_dbg(chan->dev, "DMA controller still busy\n"); + goto out_unlock; + } + + /* + * TODO: + * make sure the dma_halt() function really un-wedges the + * controller as much as possible + */ dma_halt(chan); - /* If there are some link descriptors - * not transfered in queue. We need to start it. + /* + * If there are some link descriptors which have not been + * transferred, we need to start the controller */ - /* Find the first un-transfer desciptor */ - for (ld_node = chan->ld_queue.next; - (ld_node != &chan->ld_queue) - && (dma_async_is_complete( - to_fsl_desc(ld_node)->async_tx.cookie, - chan->completed_cookie, - chan->common.cookie) == DMA_SUCCESS); - ld_node = ld_node->next); - - if (ld_node != &chan->ld_queue) { - /* Get the ld start address from ld_queue */ - next_dst_addr = to_fsl_desc(ld_node)->async_tx.phys; - dev_dbg(chan->dev, "xfer LDs staring from 0x%llx\n", - (unsigned long long)next_dst_addr); - set_cdar(chan, next_dst_addr); - dma_start(chan); - } else { - set_cdar(chan, 0); - set_ndar(chan, 0); - } + /* + * Move all elements from the queue of pending transactions + * onto the list of running transactions + */ + desc = list_first_entry(&chan->ld_pending, struct fsl_desc_sw, node); + list_splice_tail_init(&chan->ld_pending, &chan->ld_running); + + /* + * Program the descriptor's address into the DMA controller, + * then start the DMA transaction + */ + set_cdar(chan, desc->async_tx.phys); + dma_start(chan); out_unlock: spin_unlock_irqrestore(&chan->desc_lock, flags); @@ -913,30 +957,6 @@ out_unlock: static void fsl_dma_memcpy_issue_pending(struct dma_chan *dchan) { struct fsldma_chan *chan = to_fsl_chan(dchan); - -#ifdef FSL_DMA_LD_DEBUG - struct fsl_desc_sw *ld; - unsigned long flags; - - spin_lock_irqsave(&chan->desc_lock, flags); - if (list_empty(&chan->ld_queue)) { - spin_unlock_irqrestore(&chan->desc_lock, flags); - return; - } - - dev_dbg(chan->dev, "--memcpy issue--\n"); - list_for_each_entry(ld, &chan->ld_queue, node) { - int i; - dev_dbg(chan->dev, "Ch %d, LD %08x\n", - chan->id, ld->async_tx.phys); - for (i = 0; i < 8; i++) - dev_dbg(chan->dev, "LD offset %d: %08x\n", - i, *(((u32 *)&ld->hw) + i)); - } - dev_dbg(chan->dev, "----------------\n"); - spin_unlock_irqrestore(&chan->desc_lock, flags); -#endif - fsl_chan_xfer_ld_queue(chan); } @@ -978,10 +998,10 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data) int xfer_ld_q = 0; u32 stat; + /* save and clear the status register */ stat = get_sr(chan); - dev_dbg(chan->dev, "event: channel %d, stat = 0x%x\n", - chan->id, stat); - set_sr(chan, stat); /* Clear the event register */ + set_sr(chan, stat); + dev_dbg(chan->dev, "irq: channel %d, stat = 0x%x\n", chan->id, stat); stat &= ~(FSL_DMA_SR_CB | FSL_DMA_SR_CH); if (!stat) @@ -990,12 +1010,13 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data) if (stat & FSL_DMA_SR_TE) dev_err(chan->dev, "Transfer Error!\n"); - /* Programming Error + /* + * Programming Error * The DMA_INTERRUPT async_tx is a NULL transfer, which will * triger a PE interrupt. */ if (stat & FSL_DMA_SR_PE) { - dev_dbg(chan->dev, "event: Programming Error INT\n"); + dev_dbg(chan->dev, "irq: Programming Error INT\n"); if (get_bcr(chan) == 0) { /* BCR register is 0, this is a DMA_INTERRUPT async_tx. * Now, update the completed cookie, and continue the @@ -1007,34 +1028,37 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data) stat &= ~FSL_DMA_SR_PE; } - /* If the link descriptor segment transfer finishes, + /* + * If the link descriptor segment transfer finishes, * we will recycle the used descriptor. */ if (stat & FSL_DMA_SR_EOSI) { - dev_dbg(chan->dev, "event: End-of-segments INT\n"); - dev_dbg(chan->dev, "event: clndar 0x%llx, nlndar 0x%llx\n", + dev_dbg(chan->dev, "irq: End-of-segments INT\n"); + dev_dbg(chan->dev, "irq: clndar 0x%llx, nlndar 0x%llx\n", (unsigned long long)get_cdar(chan), (unsigned long long)get_ndar(chan)); stat &= ~FSL_DMA_SR_EOSI; update_cookie = 1; } - /* For MPC8349, EOCDI event need to update cookie + /* + * For MPC8349, EOCDI event need to update cookie * and start the next transfer if it exist. */ if (stat & FSL_DMA_SR_EOCDI) { - dev_dbg(chan->dev, "event: End-of-Chain link INT\n"); + dev_dbg(chan->dev, "irq: End-of-Chain link INT\n"); stat &= ~FSL_DMA_SR_EOCDI; update_cookie = 1; xfer_ld_q = 1; } - /* If it current transfer is the end-of-transfer, + /* + * If it current transfer is the end-of-transfer, * we should clear the Channel Start bit for * prepare next transfer. */ if (stat & FSL_DMA_SR_EOLNI) { - dev_dbg(chan->dev, "event: End-of-link INT\n"); + dev_dbg(chan->dev, "irq: End-of-link INT\n"); stat &= ~FSL_DMA_SR_EOLNI; xfer_ld_q = 1; } @@ -1044,10 +1068,9 @@ static irqreturn_t fsldma_chan_irq(int irq, void *data) if (xfer_ld_q) fsl_chan_xfer_ld_queue(chan); if (stat) - dev_dbg(chan->dev, "event: unhandled sr 0x%02x\n", - stat); + dev_dbg(chan->dev, "irq: unhandled sr 0x%02x\n", stat); - dev_dbg(chan->dev, "event: Exit\n"); + dev_dbg(chan->dev, "irq: Exit\n"); tasklet_schedule(&chan->tasklet); return IRQ_HANDLED; } @@ -1235,7 +1258,8 @@ static int __devinit fsl_dma_chan_probe(struct fsldma_device *fdev, } spin_lock_init(&chan->desc_lock); - INIT_LIST_HEAD(&chan->ld_queue); + INIT_LIST_HEAD(&chan->ld_pending); + INIT_LIST_HEAD(&chan->ld_running); chan->common.device = &fdev->common; diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h index ea3b19c8708..cb4d6ff5159 100644 --- a/drivers/dma/fsldma.h +++ b/drivers/dma/fsldma.h @@ -131,7 +131,8 @@ struct fsldma_chan { struct fsldma_chan_regs __iomem *regs; dma_cookie_t completed_cookie; /* The maximum cookie completed */ spinlock_t desc_lock; /* Descriptor operation lock */ - struct list_head ld_queue; /* Link descriptors queue */ + struct list_head ld_pending; /* Link descriptors queue */ + struct list_head ld_running; /* Link descriptors queue */ struct dma_chan common; /* DMA common channel */ struct dma_pool *desc_pool; /* Descriptors pool */ struct device *dev; /* Channel device */ |