/* * Driver for the Synopsys DesignWare DMA Controller (aka DMACA on * AVR32 systems.) * * Copyright (C) 2007-2008 Atmel Corporation * Copyright (C) 2010-2011 ST Microelectronics * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include "dw_dmac_regs.h" #include "dmaengine.h" /* * This supports the Synopsys "DesignWare AHB Central DMA Controller", * (DW_ahb_dmac) which is used with various AMBA 2.0 systems (not all * of which use ARM any more). See the "Databook" from Synopsys for * information beyond what licensees probably provide. * * The driver has currently been tested only with the Atmel AT32AP7000, * which does not support descriptor writeback. */ #define DWC_DEFAULT_CTLLO(_chan) ({ \ struct dw_dma_slave *__slave = (_chan->private); \ struct dw_dma_chan *_dwc = to_dw_dma_chan(_chan); \ struct dma_slave_config *_sconfig = &_dwc->dma_sconfig; \ int _dms = __slave ? __slave->dst_master : 0; \ int _sms = __slave ? __slave->src_master : 1; \ u8 _smsize = __slave ? _sconfig->src_maxburst : \ DW_DMA_MSIZE_16; \ u8 _dmsize = __slave ? _sconfig->dst_maxburst : \ DW_DMA_MSIZE_16; \ \ (DWC_CTLL_DST_MSIZE(_dmsize) \ | DWC_CTLL_SRC_MSIZE(_smsize) \ | DWC_CTLL_LLP_D_EN \ | DWC_CTLL_LLP_S_EN \ | DWC_CTLL_DMS(_dms) \ | DWC_CTLL_SMS(_sms)); \ }) /* * This is configuration-dependent and usually a funny size like 4095. * * Note that this is a transfer count, i.e. if we transfer 32-bit * words, we can do 16380 bytes per descriptor. * * This parameter is also system-specific. */ #define DWC_MAX_COUNT 4095U /* * Number of descriptors to allocate for each channel. This should be * made configurable somehow; preferably, the clients (at least the * ones using slave transfers) should be able to give us a hint. */ #define NR_DESCS_PER_CHANNEL 64 /*----------------------------------------------------------------------*/ /* * Because we're not relying on writeback from the controller (it may not * even be configured into the core!) we don't need to use dma_pool. These * descriptors -- and associated data -- are cacheable. We do need to make * sure their dcache entries are written back before handing them off to * the controller, though. */ static struct device *chan2dev(struct dma_chan *chan) { return &chan->dev->device; } static struct device *chan2parent(struct dma_chan *chan) { return chan->dev->device.parent; } static struct dw_desc *dwc_first_active(struct dw_dma_chan *dwc) { return list_entry(dwc->active_list.next, struct dw_desc, desc_node); } static struct dw_desc *dwc_desc_get(struct dw_dma_chan *dwc) { struct dw_desc *desc, *_desc; struct dw_desc *ret = NULL; unsigned int i = 0; unsigned long flags; spin_lock_irqsave(&dwc->lock, flags); list_for_each_entry_safe(desc, _desc, &dwc->free_list, desc_node) { if (async_tx_test_ack(&desc->txd)) { list_del(&desc->desc_node); ret = desc; break; } dev_dbg(chan2dev(&dwc->chan), "desc %p not ACKed\n", desc); i++; } spin_unlock_irqrestore(&dwc->lock, flags); dev_vdbg(chan2dev(&dwc->chan), "scanned %u descriptors on freelist\n", i); return ret; } static void dwc_sync_desc_for_cpu(struct dw_dma_chan *dwc, struct dw_desc *desc) { struct dw_desc *child; list_for_each_entry(child, &desc->tx_list, desc_node) dma_sync_single_for_cpu(chan2parent(&dwc->chan), child->txd.phys, sizeof(child->lli), DMA_TO_DEVICE); dma_sync_single_for_cpu(chan2parent(&dwc->chan), desc->txd.phys, sizeof(desc->lli), DMA_TO_DEVICE); } /* * Move a descriptor, including any children, to the free list. * `desc' must not be on any lists. */ static void dwc_desc_put(struct dw_dma_chan *dwc, struct dw_desc *desc) { unsigned long flags; if (desc) { struct dw_desc *child; dwc_sync_desc_for_cpu(dwc, desc); spin_lock_irqsave(&dwc->lock, flags); list_for_each_entry(child, &desc->tx_list, desc_node) dev_vdbg(chan2dev(&dwc->chan), "moving child desc %p to freelist\n", child); list_splice_init(&desc->tx_list, &dwc->free_list); dev_vdbg(chan2dev(&dwc->chan), "moving desc %p to freelist\n", desc); list_add(&desc->desc_node, &dwc->free_list); spin_unlock_irqrestore(&dwc->lock, flags); } } static void dwc_initialize(struct dw_dma_chan *dwc) { struct dw_dma *dw = to_dw_dma(dwc->chan.device); struct dw_dma_slave *dws = dwc->chan.private; u32 cfghi = DWC_CFGH_FIFO_MODE; u32 cfglo = DWC_CFGL_CH_PRIOR(dwc->priority); if (dwc->initialized == true) return; if (dws) { /* * We need controller-specific data to set up slave * transfers. */ BUG_ON(!dws->dma_dev || dws->dma_dev != dw->dma.dev); cfghi = dws->cfg_hi; cfglo |= dws->cfg_lo & ~DWC_CFGL_CH_PRIOR_MASK; } channel_writel(dwc, CFG_LO, cfglo); channel_writel(dwc, CFG_HI, cfghi); /* Enable interrupts */ channel_set_bit(dw, MASK.XFER, dwc->mask); channel_set_bit(dw, MASK.ERROR, dwc->mask); dwc->initialized = true; } /*----------------------------------------------------------------------*/ static void dwc_dump_chan_regs(struct dw_dma_chan *dwc) { 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)); } /*----------------------------------------------------------------------*/ /* Called with dwc->lock held and bh disabled */ static void dwc_dostart(struct dw_dma_chan *dwc, struct dw_desc *first) { struct dw_dma *dw = to_dw_dma(dwc->chan.device); /* 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"); dwc_dump_chan_regs(dwc); /* The tasklet will hopefully advance the queue... */ return; } dwc_initialize(dwc); channel_writel(dwc, LLP, first->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); } /*----------------------------------------------------------------------*/ static void dwc_descriptor_complete(struct dw_dma_chan *dwc, struct dw_desc *desc, bool callback_required) { dma_async_tx_callback callback = NULL; void *param = NULL; struct dma_async_tx_descriptor *txd = &desc->txd; struct dw_desc *child; unsigned long flags; dev_vdbg(chan2dev(&dwc->chan), "descriptor %u complete\n", txd->cookie); spin_lock_irqsave(&dwc->lock, flags); dma_cookie_complete(txd); if (callback_required) { callback = txd->callback; param = txd->callback_param; } dwc_sync_desc_for_cpu(dwc, desc); /* async_tx_ack */ list_for_each_entry(child, &desc->tx_list, desc_node) async_tx_ack(&child->txd); async_tx_ack(&desc->txd); list_splice_init(&desc->tx_list, &dwc->free_list); list_move(&desc->desc_node, &dwc->free_list); if (!dwc->chan.private) { struct device *parent = chan2parent(&dwc->chan); if (!(txd->flags & DMA_COMPL_SKIP_DEST_UNMAP)) { if (txd->flags & DMA_COMPL_DEST_UNMAP_SINGLE) dma_unmap_single(parent, desc->lli.dar, desc->len, DMA_FROM_DEVICE); else dma_unmap_page(parent, desc->lli.dar, desc->len, DMA_FROM_DEVICE); } if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP)) { if (txd->flags & DMA_COMPL_SRC_UNMAP_SINGLE) dma_unmap_single(parent, desc->lli.sar, desc->len, DMA_TO_DEVICE); else dma_unmap_page(parent, desc->lli.sar, desc->len, DMA_TO_DEVICE); } } spin_unlock_irqrestore(&dwc->lock, flags); if (callback_required && callback) callback(param); } static void dwc_complete_all(struct dw_dma *dw, struct dw_dma_chan *dwc) { struct dw_desc *desc, *_desc; LIST_HEAD(list); unsigned long flags; spin_lock_irqsave(&dwc->lock, flags); if (dma_readl(dw, CH_EN) & dwc->mask) { dev_err(chan2dev(&dwc->chan), "BUG: XFER bit set, but channel not idle!\n"); /* Try to continue after resetting the channel... */ channel_clear_bit(dw, CH_EN, dwc->mask); while (dma_readl(dw, CH_EN) & dwc->mask) cpu_relax(); } /* * Submit queued descriptors ASAP, i.e. before we go through * the completed ones. */ list_splice_init(&dwc->active_list, &list); if (!list_empty(&dwc->queue)) { list_move(dwc->queue.next, &dwc->active_list); dwc_dostart(dwc, dwc_first_active(dwc)); } spin_unlock_irqrestore(&dwc->lock, flags); list_for_each_entry_safe(desc, _desc, &list, desc_node) dwc_descriptor_complete(dwc, desc, true); } static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc) { dma_addr_t llp; struct dw_desc *desc, *_desc; struct dw_desc *child; u32 status_xfer; unsigned long flags; spin_lock_irqsave(&dwc->lock, flags); llp = channel_readl(dwc, LLP); status_xfer = dma_readl(dw, RAW.XFER); if (status_xfer & dwc->mask) { /* Everything we've submitted is done */ dma_writel(dw, CLEAR.XFER, dwc->mask); spin_unlock_irqrestore(&dwc->lock, flags); dwc_complete_all(dw, dwc); return; } if (list_empty(&dwc->active_list)) { spin_unlock_irqrestore(&dwc->lock, flags); return; } dev_vdbg(chan2dev(&dwc->chan), "scan_descriptors: llp=0x%llx\n", (unsigned long long)llp); list_for_each_entry_safe(desc, _desc, &dwc->active_list, desc_node) { /* check first descriptors addr */ if (desc->txd.phys == llp) { spin_unlock_irqrestore(&dwc->lock, flags); return; } /* check first descriptors llp */ if (desc->lli.llp == llp) { /* This one is currently in progress */ spin_unlock_irqrestore(&dwc->lock, flags); return; } list_for_each_entry(child, &desc->tx_list, desc_node) if (child->lli.llp == llp) { /* Currently in progress */ spin_unlock_irqrestore(&dwc->lock, flags); return; } /* * No descriptors so far seem to be in progress, i.e. * this one must be done. */ spin_unlock_irqrestore(&dwc->lock, flags); dwc_descriptor_complete(dwc, desc, true); spin_lock_irqsave(&dwc->lock, flags); } dev_err(chan2dev(&dwc->chan), "BUG: All descriptors done, but channel not idle!\n"); /* Try to continue after resetting the channel... */ channel_clear_bit(dw, CH_EN, dwc->mask); while (dma_readl(dw, CH_EN) & dwc->mask) cpu_relax(); if (!list_empty(&dwc->queue)) { list_move(dwc->queue.next, &dwc->active_list); dwc_dostart(dwc, dwc_first_active(dwc)); } spin_unlock_irqrestore(&dwc->lock, flags); } static void dwc_dump_lli(struct dw_dma_chan *dwc, struct dw_lli *lli) { dev_printk(KERN_CRIT, chan2dev(&dwc->chan), " desc: s0x%llx d0x%llx l0x%llx c0x%x:%x\n", (unsigned long long)lli->sar, (unsigned long long)lli->dar, (unsigned long long)lli->llp, lli->ctlhi, lli->ctllo); } static void dwc_handle_error(struct dw_dma *dw, struct dw_dma_chan *dwc) { struct dw_desc *bad_desc; struct dw_desc *child; unsigned long flags; dwc_scan_descriptors(dw, dwc); spin_lock_irqsave(&dwc->lock, flags); /* * The descriptor currently at the head of the active list is * borked. Since we don't have any way to report errors, we'll * just have to scream loudly and try to carry on. */ bad_desc = dwc_first_active(dwc); list_del_init(&bad_desc->desc_node); list_move(dwc->queue.next, dwc->active_list.prev); /* Clear the error flag and try to restart the controller */ dma_writel(dw, CLEAR.ERROR, dwc->mask); if (!list_empty(&dwc->active_list)) dwc_dostart(dwc, dwc_first_active(dwc)); /* * KERN_CRITICAL may seem harsh, but since this only happens * when someone submits a bad physical address in a * descriptor, we should consider ourselves lucky that the * controller flagged an error instead of scribbling over * random memory locations. */ dev_printk(KERN_CRIT, chan2dev(&dwc->chan), "Bad descriptor submitted for DMA!\n"); dev_printk(KERN_CRIT, chan2dev(&dwc->chan), " cookie: %d\n", bad_desc->txd.cookie); dwc_dump_lli(dwc, &bad_desc->lli); list_for_each_entry(child, &bad_desc->tx_list, desc_node) dwc_dump_lli(dwc, &child->lli); spin_unlock_irqrestore(&dwc->lock, flags); /* Pretend the descriptor completed successfully */ dwc_descriptor_complete(dwc, bad_desc, true); } /* --------------------- 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_err, u32 status_xfer) { unsigned long flags; if (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)); callback = dwc->cdesc->period_callback; callback_param = dwc->cdesc->period_callback_param; if (callback) callback(callback_param); } /* * 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"); spin_lock_irqsave(&dwc->lock, flags); dwc_dump_chan_regs(dwc); 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.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); spin_unlock_irqrestore(&dwc->lock, flags); } } /* ------------------------------------------------------------------------- */ static void dw_dma_tasklet(unsigned long data) { struct dw_dma *dw = (struct dw_dma *)data; struct dw_dma_chan *dwc; u32 status_xfer; u32 status_err; int i; status_xfer = dma_readl(dw, RAW.XFER); status_err = dma_readl(dw, RAW.ERROR); dev_vdbg(dw->dma.dev, "tasklet: status_err=%x\n", status_err); for (i = 0; i < dw->dma.chancnt; i++) { dwc = &dw->chan[i]; if (test_bit(DW_DMA_IS_CYCLIC, &dwc->flags)) dwc_handle_cyclic(dw, dwc, status_err, status_xfer); else if (status_err & (1 << i)) dwc_handle_error(dw, dwc); else if (status_xfer & (1 << i)) dwc_scan_descriptors(dw, dwc); } /* * Re-enable interrupts. */ channel_set_bit(dw, MASK.XFER, dw->all_chan_mask); channel_set_bit(dw, MASK.ERROR, dw->all_chan_mask); } static irqreturn_t dw_dma_interrupt(int irq, void *dev_id) { struct dw_dma *dw = dev_id; u32 status; dev_vdbg(dw->dma.dev, "interrupt: status=0x%x\n", dma_readl(dw, STATUS_INT)); /* * Just disable the interrupts. We'll turn them back on in the * softirq handler. */ channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask); channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask); status = dma_readl(dw, STATUS_INT); if (status) { dev_err(dw->dma.dev, "BUG: Unexpected interrupts pending: 0x%x\n", status); /* Try to recover */ channel_clear_bit(dw, MASK.XFER, (1 << 8) - 1); channel_clear_bit(dw, MASK.SRC_TRAN, (1 << 8) - 1); channel_clear_bit(dw, MASK.DST_TRAN, (1 << 8) - 1); channel_clear_bit(dw, MASK.ERROR, (1 << 8) - 1); } tasklet_schedule(&dw->tasklet); return IRQ_HANDLED; } /*----------------------------------------------------------------------*/ static dma_cookie_t dwc_tx_submit(struct dma_async_tx_descriptor *tx) { struct dw_desc *desc = txd_to_dw_desc(tx); struct dw_dma_chan *dwc = to_dw_dma_chan(tx->chan); dma_cookie_t cookie; unsigned long flags; spin_lock_irqsave(&dwc->lock, flags); cookie = dma_cookie_assign(tx); /* * REVISIT: We should attempt to chain as many descriptors as * possible, perhaps even appending to those already submitted * for DMA. But this is hard to do in a race-free manner. */ if (list_empty(&dwc->active_list)) { dev_vdbg(chan2dev(tx->chan), "tx_submit: started %u\n", desc->txd.cookie); list_add_tail(&desc->desc_node, &dwc->active_list); dwc_dostart(dwc, dwc_first_active(dwc)); } else { dev_vdbg(chan2dev(tx->chan), "tx_submit: queued %u\n", desc->txd.cookie); list_add_tail(&desc->desc_node, &dwc->queue); } spin_unlock_irqrestore(&dwc->lock, flags); return cookie; } static struct dma_async_tx_descriptor * dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, size_t len, unsigned long flags) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); struct dw_desc *desc; struct dw_desc *first; struct dw_desc *prev; size_t xfer_count; size_t offset; unsigned int src_width; unsigned int dst_width; u32 ctllo; dev_vdbg(chan2dev(chan), "prep_dma_memcpy d0x%llx s0x%llx l0x%zx f0x%lx\n", (unsigned long long)dest, (unsigned long long)src, len, flags); if (unlikely(!len)) { dev_dbg(chan2dev(chan), "prep_dma_memcpy: length is zero!\n"); return NULL; } /* * We can be a lot more clever here, but this should take care * of the most common optimization. */ if (!((src | dest | len) & 7)) src_width = dst_width = 3; else if (!((src | dest | len) & 3)) src_width = dst_width = 2; else if (!((src | dest | len) & 1)) src_width = dst_width = 1; else src_width = dst_width = 0; ctllo = DWC_DEFAULT_CTLLO(chan) | DWC_CTLL_DST_WIDTH(dst_width) | DWC_CTLL_SRC_WIDTH(src_width) | DWC_CTLL_DST_INC | DWC_CTLL_SRC_INC | DWC_CTLL_FC_M2M; prev = first = NULL; for (offset = 0; offset < len; offset += xfer_count << src_width) { xfer_count = min_t(size_t, (len - offset) >> src_width, DWC_MAX_COUNT); desc = dwc_desc_get(dwc); if (!desc) goto err_desc_get; desc->lli.sar = src + offset; desc->lli.dar = dest + offset; desc->lli.ctllo = ctllo; desc->lli.ctlhi = xfer_count; if (!first) { first = desc; } else { prev->lli.llp = desc->txd.phys; dma_sync_single_for_device(chan2parent(chan), prev->txd.phys, sizeof(prev->lli), DMA_TO_DEVICE); list_add_tail(&desc->desc_node, &first->tx_list); } prev = desc; } if (flags & DMA_PREP_INTERRUPT) /* Trigger interrupt after last block */ prev->lli.ctllo |= DWC_CTLL_INT_EN; prev->lli.llp = 0; dma_sync_single_for_device(chan2parent(chan), prev->txd.phys, sizeof(prev->lli), DMA_TO_DEVICE); first->txd.flags = flags; first->len = len; return &first->txd; err_desc_get: dwc_desc_put(dwc, first); return NULL; } static struct dma_async_tx_descriptor * dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len, enum dma_transfer_direction direction, unsigned long flags, void *context) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); struct dw_dma_slave *dws = chan->private; struct dma_slave_config *sconfig = &dwc->dma_sconfig; struct dw_desc *prev; struct dw_desc *first; u32 ctllo; dma_addr_t reg; unsigned int reg_width; unsigned int mem_width; unsigned int i; struct scatterlist *sg; size_t total_len = 0; dev_vdbg(chan2dev(chan), "prep_dma_slave\n"); if (unlikely(!dws || !sg_len)) return NULL; prev = first = NULL; switch (direction) { case DMA_MEM_TO_DEV: reg_width = __fls(sconfig->dst_addr_width); reg = sconfig->dst_addr; ctllo = (DWC_DEFAULT_CTLLO(chan) | DWC_CTLL_DST_WIDTH(reg_width) | DWC_CTLL_DST_FIX | DWC_CTLL_SRC_INC); ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_M2P) : DWC_CTLL_FC(DW_DMA_FC_D_M2P); for_each_sg(sgl, sg, sg_len, i) { struct dw_desc *desc; u32 len, dlen, mem; mem = sg_dma_address(sg); len = sg_dma_len(sg); if (!((mem | len) & 7)) mem_width = 3; else if (!((mem | len) & 3)) mem_width = 2; else if (!((mem | len) & 1)) mem_width = 1; else mem_width = 0; slave_sg_todev_fill_desc: desc = dwc_desc_get(dwc); if (!desc) { dev_err(chan2dev(chan), "not enough descriptors available\n"); goto err_desc_get; } desc->lli.sar = mem; desc->lli.dar = reg; desc->lli.ctllo = ctllo | DWC_CTLL_SRC_WIDTH(mem_width); if ((len >> mem_width) > DWC_MAX_COUNT) { dlen = DWC_MAX_COUNT << mem_width; mem += dlen; len -= dlen; } else { dlen = len; len = 0; } desc->lli.ctlhi = dlen >> mem_width; if (!first) { first = desc; } else { prev->lli.llp = desc->txd.phys; dma_sync_single_for_device(chan2parent(chan), prev->txd.phys, sizeof(prev->lli), DMA_TO_DEVICE); list_add_tail(&desc->desc_node, &first->tx_list); } prev = desc; total_len += dlen; if (len) goto slave_sg_todev_fill_desc; } break; case DMA_DEV_TO_MEM: reg_width = __fls(sconfig->src_addr_width); reg = sconfig->src_addr; ctllo = (DWC_DEFAULT_CTLLO(chan) | DWC_CTLL_SRC_WIDTH(reg_width) | DWC_CTLL_DST_INC | DWC_CTLL_SRC_FIX); ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_P2M) : DWC_CTLL_FC(DW_DMA_FC_D_P2M); for_each_sg(sgl, sg, sg_len, i) { struct dw_desc *desc; u32 len, dlen, mem; mem = sg_dma_address(sg); len = sg_dma_len(sg); if (!((mem | len) & 7)) mem_width = 3; else if (!((mem | len) & 3)) mem_width = 2; else if (!((mem | len) & 1)) mem_width = 1; else mem_width = 0; slave_sg_fromdev_fill_desc: desc = dwc_desc_get(dwc); if (!desc) { dev_err(chan2dev(chan), "not enough descriptors available\n"); goto err_desc_get; } desc->lli.sar = reg; desc->lli.dar = mem; desc->lli.ctllo = ctllo | DWC_CTLL_DST_WIDTH(mem_width); if ((len >> reg_width) > DWC_MAX_COUNT) { dlen = DWC_MAX_COUNT << reg_width; mem += dlen; len -= dlen; } else { dlen = len; len = 0; } desc->lli.ctlhi = dlen >> reg_width; if (!first) { first = desc; } else { prev->lli.llp = desc->txd.phys; dma_sync_single_for_device(chan2parent(chan), prev->txd.phys, sizeof(prev->lli), DMA_TO_DEVICE); list_add_tail(&desc->desc_node, &first->tx_list); } prev = desc; total_len += dlen; if (len) goto slave_sg_fromdev_fill_desc; } break; default: return NULL; } if (flags & DMA_PREP_INTERRUPT) /* Trigger interrupt after last block */ prev->lli.ctllo |= DWC_CTLL_INT_EN; prev->lli.llp = 0; dma_sync_single_for_device(chan2parent(chan), prev->txd.phys, sizeof(prev->lli), DMA_TO_DEVICE); first->len = total_len; return &first->txd; err_desc_get: dwc_desc_put(dwc, first); return NULL; } /* * Fix sconfig's burst size according to dw_dmac. We need to convert them as: * 1 -> 0, 4 -> 1, 8 -> 2, 16 -> 3. * * NOTE: burst size 2 is not supported by controller. * * This can be done by finding least significant bit set: n & (n - 1) */ static inline void convert_burst(u32 *maxburst) { if (*maxburst > 1) *maxburst = fls(*maxburst) - 2; else *maxburst = 0; } static int set_runtime_config(struct dma_chan *chan, struct dma_slave_config *sconfig) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); /* Check if it is chan is configured for slave transfers */ if (!chan->private) return -EINVAL; memcpy(&dwc->dma_sconfig, sconfig, sizeof(*sconfig)); convert_burst(&dwc->dma_sconfig.src_maxburst); convert_burst(&dwc->dma_sconfig.dst_maxburst); return 0; } static int dwc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, unsigned long arg) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); struct dw_dma *dw = to_dw_dma(chan->device); struct dw_desc *desc, *_desc; unsigned long flags; u32 cfglo; LIST_HEAD(list); if (cmd == DMA_PAUSE) { spin_lock_irqsave(&dwc->lock, flags); cfglo = channel_readl(dwc, CFG_LO); channel_writel(dwc, CFG_LO, cfglo | DWC_CFGL_CH_SUSP); while (!(channel_readl(dwc, CFG_LO) & DWC_CFGL_FIFO_EMPTY)) cpu_relax(); dwc->paused = true; spin_unlock_irqrestore(&dwc->lock, flags); } else if (cmd == DMA_RESUME) { if (!dwc->paused) return 0; spin_lock_irqsave(&dwc->lock, flags); cfglo = channel_readl(dwc, CFG_LO); channel_writel(dwc, CFG_LO, cfglo & ~DWC_CFGL_CH_SUSP); dwc->paused = false; spin_unlock_irqrestore(&dwc->lock, flags); } else if (cmd == DMA_TERMINATE_ALL) { spin_lock_irqsave(&dwc->lock, flags); channel_clear_bit(dw, CH_EN, dwc->mask); while (dma_readl(dw, CH_EN) & dwc->mask) cpu_relax(); dwc->paused = false; /* active_list entries will end up before queued entries */ list_splice_init(&dwc->queue, &list); list_splice_init(&dwc->active_list, &list); spin_unlock_irqrestore(&dwc->lock, flags); /* Flush all pending and queued descriptors */ list_for_each_entry_safe(desc, _desc, &list, desc_node) dwc_descriptor_complete(dwc, desc, false); } else if (cmd == DMA_SLAVE_CONFIG) { return set_runtime_config(chan, (struct dma_slave_config *)arg); } else { return -ENXIO; } return 0; } static enum dma_status dwc_tx_status(struct dma_chan *chan, dma_cookie_t cookie, struct dma_tx_state *txstate) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); enum dma_status ret; ret = dma_cookie_status(chan, cookie, txstate); if (ret != DMA_SUCCESS) { dwc_scan_descriptors(to_dw_dma(chan->device), dwc); ret = dma_cookie_status(chan, cookie, txstate); } if (ret != DMA_SUCCESS) dma_set_residue(txstate, dwc_first_active(dwc)->len); if (dwc->paused) return DMA_PAUSED; return ret; } static void dwc_issue_pending(struct dma_chan *chan) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); if (!list_empty(&dwc->queue)) dwc_scan_descriptors(to_dw_dma(chan->device), dwc); } static int dwc_alloc_chan_resources(struct dma_chan *chan) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); struct dw_dma *dw = to_dw_dma(chan->device); struct dw_desc *desc; int i; unsigned long flags; dev_vdbg(chan2dev(chan), "alloc_chan_resources\n"); /* ASSERT: channel is idle */ if (dma_readl(dw, CH_EN) & dwc->mask) { dev_dbg(chan2dev(chan), "DMA channel not idle?\n"); return -EIO; } dma_cookie_init(chan); /* * NOTE: some controllers may have additional features that we * need to initialize here, like "scatter-gather" (which * doesn't mean what you think it means), and status writeback. */ spin_lock_irqsave(&dwc->lock, flags); i = dwc->descs_allocated; while (dwc->descs_allocated < NR_DESCS_PER_CHANNEL) { spin_unlock_irqrestore(&dwc->lock, flags); desc = kzalloc(sizeof(struct dw_desc), GFP_KERNEL); if (!desc) { dev_info(chan2dev(chan), "only allocated %d descriptors\n", i); spin_lock_irqsave(&dwc->lock, flags); break; } INIT_LIST_HEAD(&desc->tx_list); dma_async_tx_descriptor_init(&desc->txd, chan); desc->txd.tx_submit = dwc_tx_submit; desc->txd.flags = DMA_CTRL_ACK; desc->txd.phys = dma_map_single(chan2parent(chan), &desc->lli, sizeof(desc->lli), DMA_TO_DEVICE); dwc_desc_put(dwc, desc); spin_lock_irqsave(&dwc->lock, flags); i = ++dwc->descs_allocated; } spin_unlock_irqrestore(&dwc->lock, flags); dev_dbg(chan2dev(chan), "alloc_chan_resources allocated %d descriptors\n", i); return i; } static void dwc_free_chan_resources(struct dma_chan *chan) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); struct dw_dma *dw = to_dw_dma(chan->device); struct dw_desc *desc, *_desc; unsigned long flags; LIST_HEAD(list); dev_dbg(chan2dev(chan), "free_chan_resources (descs allocated=%u)\n", dwc->descs_allocated); /* ASSERT: channel is idle */ BUG_ON(!list_empty(&dwc->active_list)); BUG_ON(!list_empty(&dwc->queue)); BUG_ON(dma_readl(to_dw_dma(chan->device), CH_EN) & dwc->mask); spin_lock_irqsave(&dwc->lock, flags); list_splice_init(&dwc->free_list, &list); dwc->descs_allocated = 0; dwc->initialized = false; /* Disable interrupts */ channel_clear_bit(dw, MASK.XFER, dwc->mask); channel_clear_bit(dw, MASK.ERROR, dwc->mask); spin_unlock_irqrestore(&dwc->lock, flags); list_for_each_entry_safe(desc, _desc, &list, desc_node) { dev_vdbg(chan2dev(chan), " freeing descriptor %p\n", desc); dma_unmap_single(chan2parent(chan), desc->txd.phys, sizeof(desc->lli), DMA_TO_DEVICE); kfree(desc); } 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); unsigned long flags; if (!test_bit(DW_DMA_IS_CYCLIC, &dwc->flags)) { dev_err(chan2dev(&dwc->chan), "missing prep for cyclic DMA\n"); return -ENODEV; } spin_lock_irqsave(&dwc->lock, flags); /* 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"); dwc_dump_chan_regs(dwc); spin_unlock_irqrestore(&dwc->lock, flags); return -EBUSY; } 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_irqrestore(&dwc->lock, flags); 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); unsigned long flags; spin_lock_irqsave(&dwc->lock, flags); channel_clear_bit(dw, CH_EN, dwc->mask); while (dma_readl(dw, CH_EN) & dwc->mask) cpu_relax(); spin_unlock_irqrestore(&dwc->lock, flags); } 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_transfer_direction direction) { struct dw_dma_chan *dwc = to_dw_dma_chan(chan); struct dma_slave_config *sconfig = &dwc->dma_sconfig; struct dw_cyclic_desc *cdesc; struct dw_cyclic_desc *retval = NULL; struct dw_desc *desc; struct dw_desc *last = NULL; unsigned long was_cyclic; unsigned int reg_width; unsigned int periods; unsigned int i; unsigned long flags; spin_lock_irqsave(&dwc->lock, flags); if (!list_empty(&dwc->queue) || !list_empty(&dwc->active_list)) { spin_unlock_irqrestore(&dwc->lock, flags); 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_irqrestore(&dwc->lock, flags); if (was_cyclic) { dev_dbg(chan2dev(&dwc->chan), "channel already prepared for cyclic DMA\n"); return ERR_PTR(-EBUSY); } retval = ERR_PTR(-EINVAL); if (direction == DMA_MEM_TO_DEV) reg_width = __ffs(sconfig->dst_addr_width); else reg_width = __ffs(sconfig->src_addr_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_MEM_TO_DEV | DMA_DEV_TO_MEM)))) 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_MEM_TO_DEV: desc->lli.dar = sconfig->dst_addr; desc->lli.sar = buf_addr + (period_len * i); desc->lli.ctllo = (DWC_DEFAULT_CTLLO(chan) | DWC_CTLL_DST_WIDTH(reg_width) | DWC_CTLL_SRC_WIDTH(reg_width) | DWC_CTLL_DST_FIX | DWC_CTLL_SRC_INC | DWC_CTLL_INT_EN); desc->lli.ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_M2P) : DWC_CTLL_FC(DW_DMA_FC_D_M2P); break; case DMA_DEV_TO_MEM: desc->lli.dar = buf_addr + (period_len * i); desc->lli.sar = sconfig->src_addr; desc->lli.ctllo = (DWC_DEFAULT_CTLLO(chan) | DWC_CTLL_SRC_WIDTH(reg_width) | DWC_CTLL_DST_WIDTH(reg_width) | DWC_CTLL_DST_INC | DWC_CTLL_SRC_FIX | DWC_CTLL_INT_EN); desc->lli.ctllo |= sconfig->device_fc ? DWC_CTLL_FC(DW_DMA_FC_P_P2M) : DWC_CTLL_FC(DW_DMA_FC_D_P2M); 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%llx len %zu " "period %zu periods %d\n", (unsigned long long)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; unsigned long flags; dev_dbg(chan2dev(&dwc->chan), "cyclic free\n"); if (!cdesc) return; spin_lock_irqsave(&dwc->lock, flags); channel_clear_bit(dw, CH_EN, dwc->mask); while (dma_readl(dw, CH_EN) & dwc->mask) cpu_relax(); dma_writel(dw, CLEAR.ERROR, dwc->mask); dma_writel(dw, CLEAR.XFER, dwc->mask); spin_unlock_irqrestore(&dwc->lock, flags); 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) { int i; dma_writel(dw, CFG, 0); channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask); channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask); channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask); channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask); while (dma_readl(dw, CFG) & DW_CFG_DMA_EN) cpu_relax(); for (i = 0; i < dw->dma.chancnt; i++) dw->chan[i].initialized = false; } static int __init dw_probe(struct platform_device *pdev) { struct dw_dma_platform_data *pdata; struct resource *io; struct dw_dma *dw; size_t size; int irq; int err; int i; pdata = dev_get_platdata(&pdev->dev); if (!pdata || pdata->nr_channels > DW_DMA_MAX_NR_CHANNELS) return -EINVAL; io = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!io) return -EINVAL; irq = platform_get_irq(pdev, 0); if (irq < 0) return irq; size = sizeof(struct dw_dma); size += pdata->nr_channels * sizeof(struct dw_dma_chan); dw = kzalloc(size, GFP_KERNEL); if (!dw) return -ENOMEM; if (!request_mem_region(io->start, DW_REGLEN, pdev->dev.driver->name)) { err = -EBUSY; goto err_kfree; } dw->regs = ioremap(io->start, DW_REGLEN); if (!dw->regs) { err = -ENOMEM; goto err_release_r; } dw->clk = clk_get(&pdev->dev, "hclk"); if (IS_ERR(dw->clk)) { err = PTR_ERR(dw->clk); goto err_clk; } clk_prepare_enable(dw->clk); /* force dma off, just in case */ dw_dma_off(dw); err = request_irq(irq, dw_dma_interrupt, 0, "dw_dmac", dw); if (err) goto err_irq; platform_set_drvdata(pdev, dw); tasklet_init(&dw->tasklet, dw_dma_tasklet, (unsigned long)dw); dw->all_chan_mask = (1 << pdata->nr_channels) - 1; INIT_LIST_HEAD(&dw->dma.channels); for (i = 0; i < pdata->nr_channels; i++) { struct dw_dma_chan *dwc = &dw->chan[i]; dwc->chan.device = &dw->dma; dma_cookie_init(&dwc->chan); if (pdata->chan_allocation_order == CHAN_ALLOCATION_ASCENDING) list_add_tail(&dwc->chan.device_node, &dw->dma.channels); else list_add(&dwc->chan.device_node, &dw->dma.channels); /* 7 is highest priority & 0 is lowest. */ if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING) dwc->priority = pdata->nr_channels - i - 1; else dwc->priority = i; dwc->ch_regs = &__dw_regs(dw)->CHAN[i]; spin_lock_init(&dwc->lock); dwc->mask = 1 << i; INIT_LIST_HEAD(&dwc->active_list); INIT_LIST_HEAD(&dwc->queue); INIT_LIST_HEAD(&dwc->free_list); channel_clear_bit(dw, CH_EN, dwc->mask); } /* Clear/disable all interrupts on all channels. */ dma_writel(dw, CLEAR.XFER, dw->all_chan_mask); dma_writel(dw, CLEAR.SRC_TRAN, dw->all_chan_mask); dma_writel(dw, CLEAR.DST_TRAN, dw->all_chan_mask); dma_writel(dw, CLEAR.ERROR, dw->all_chan_mask); channel_clear_bit(dw, MASK.XFER, dw->all_chan_mask); channel_clear_bit(dw, MASK.SRC_TRAN, dw->all_chan_mask); channel_clear_bit(dw, MASK.DST_TRAN, dw->all_chan_mask); channel_clear_bit(dw, MASK.ERROR, dw->all_chan_mask); dma_cap_set(DMA_MEMCPY, dw->dma.cap_mask); dma_cap_set(DMA_SLAVE, dw->dma.cap_mask); if (pdata->is_private) dma_cap_set(DMA_PRIVATE, dw->dma.cap_mask); dw->dma.dev = &pdev->dev; dw->dma.device_alloc_chan_resources = dwc_alloc_chan_resources; dw->dma.device_free_chan_resources = dwc_free_chan_resources; dw->dma.device_prep_dma_memcpy = dwc_prep_dma_memcpy; dw->dma.device_prep_slave_sg = dwc_prep_slave_sg; dw->dma.device_control = dwc_control; dw->dma.device_tx_status = dwc_tx_status; dw->dma.device_issue_pending = dwc_issue_pending; dma_writel(dw, CFG, DW_CFG_DMA_EN); printk(KERN_INFO "%s: DesignWare DMA Controller, %d channels\n", dev_name(&pdev->dev), pdata->nr_channels); dma_async_device_register(&dw->dma); return 0; err_irq: clk_disable_unprepare(dw->clk); clk_put(dw->clk); err_clk: iounmap(dw->regs); dw->regs = NULL; err_release_r: release_resource(io); err_kfree: kfree(dw); return err; } static int __exit dw_remove(struct platform_device *pdev) { struct dw_dma *dw = platform_get_drvdata(pdev); struct dw_dma_chan *dwc, *_dwc; struct resource *io; dw_dma_off(dw); dma_async_device_unregister(&dw->dma); free_irq(platform_get_irq(pdev, 0), dw); tasklet_kill(&dw->tasklet); list_for_each_entry_safe(dwc, _dwc, &dw->dma.channels, chan.device_node) { list_del(&dwc->chan.device_node); channel_clear_bit(dw, CH_EN, dwc->mask); } clk_disable_unprepare(dw->clk); clk_put(dw->clk); iounmap(dw->regs); dw->regs = NULL; io = platform_get_resource(pdev, IORESOURCE_MEM, 0); release_mem_region(io->start, DW_REGLEN); kfree(dw); return 0; } static void dw_shutdown(struct platform_device *pdev) { struct dw_dma *dw = platform_get_drvdata(pdev); dw_dma_off(platform_get_drvdata(pdev)); clk_disable_unprepare(dw->clk); } static int dw_suspend_noirq(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct dw_dma *dw = platform_get_drvdata(pdev); dw_dma_off(platform_get_drvdata(pdev)); clk_disable_unprepare(dw->clk); return 0; } static int dw_resume_noirq(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct dw_dma *dw = platform_get_drvdata(pdev); clk_prepare_enable(dw->clk); dma_writel(dw, CFG, DW_CFG_DMA_EN); return 0; } static const struct dev_pm_ops dw_dev_pm_ops = { .suspend_noirq = dw_suspend_noirq, .resume_noirq = dw_resume_noirq, .freeze_noirq = dw_suspend_noirq, .thaw_noirq = dw_resume_noirq, .restore_noirq = dw_resume_noirq, .poweroff_noirq = dw_suspend_noirq, }; #ifdef CONFIG_OF static const struct of_device_id dw_dma_id_table[] = { { .compatible = "snps,dma-spear1340" }, {} }; MODULE_DEVICE_TABLE(of, dw_dma_id_table); #endif static struct platform_driver dw_driver = { .remove = __exit_p(dw_remove), .shutdown = dw_shutdown, .driver = { .name = "dw_dmac", .pm = &dw_dev_pm_ops, .of_match_table = of_match_ptr(dw_dma_id_table), }, }; static int __init dw_init(void) { return platform_driver_probe(&dw_driver, dw_probe); } subsys_initcall(dw_init); static void __exit dw_exit(void) { platform_driver_unregister(&dw_driver); } module_exit(dw_exit); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("Synopsys DesignWare DMA Controller driver"); MODULE_AUTHOR("Haavard Skinnemoen (Atmel)"); MODULE_AUTHOR("Viresh Kumar ");