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281 lines
7.4 KiB
281 lines
7.4 KiB
/* |
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* BCM2708 legacy DMA API |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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*/ |
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#include <linux/init.h> |
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#include <linux/interrupt.h> |
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#include <linux/list.h> |
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#include <linux/module.h> |
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#include <linux/platform_data/dma-bcm2708.h> |
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#include <linux/platform_device.h> |
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#include <linux/slab.h> |
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#include <linux/io.h> |
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#include <linux/spinlock.h> |
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#include "virt-dma.h" |
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#define CACHE_LINE_MASK 31 |
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#define DEFAULT_DMACHAN_BITMAP 0x10 /* channel 4 only */ |
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/* valid only for channels 0 - 14, 15 has its own base address */ |
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#define BCM2708_DMA_CHAN(n) ((n) << 8) /* base address */ |
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#define BCM2708_DMA_CHANIO(dma_base, n) \ |
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((void __iomem *)((char *)(dma_base) + BCM2708_DMA_CHAN(n))) |
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struct vc_dmaman { |
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void __iomem *dma_base; |
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u32 chan_available; /* bitmap of available channels */ |
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u32 has_feature[BCM_DMA_FEATURE_COUNT]; /* bitmap of feature presence */ |
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struct mutex lock; |
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}; |
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static struct device *dmaman_dev; /* we assume there's only one! */ |
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static struct vc_dmaman *g_dmaman; /* DMA manager */ |
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/* DMA Auxiliary Functions */ |
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/* A DMA buffer on an arbitrary boundary may separate a cache line into a |
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section inside the DMA buffer and another section outside it. |
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Even if we flush DMA buffers from the cache there is always the chance that |
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during a DMA someone will access the part of a cache line that is outside |
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the DMA buffer - which will then bring in unwelcome data. |
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Without being able to dictate our own buffer pools we must insist that |
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DMA buffers consist of a whole number of cache lines. |
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*/ |
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extern int bcm_sg_suitable_for_dma(struct scatterlist *sg_ptr, int sg_len) |
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{ |
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int i; |
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for (i = 0; i < sg_len; i++) { |
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if (sg_ptr[i].offset & CACHE_LINE_MASK || |
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sg_ptr[i].length & CACHE_LINE_MASK) |
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return 0; |
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} |
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return 1; |
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} |
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EXPORT_SYMBOL_GPL(bcm_sg_suitable_for_dma); |
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extern void bcm_dma_start(void __iomem *dma_chan_base, |
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dma_addr_t control_block) |
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{ |
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dsb(sy); /* ARM data synchronization (push) operation */ |
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writel(control_block, dma_chan_base + BCM2708_DMA_ADDR); |
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writel(BCM2708_DMA_ACTIVE, dma_chan_base + BCM2708_DMA_CS); |
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} |
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EXPORT_SYMBOL_GPL(bcm_dma_start); |
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extern void bcm_dma_wait_idle(void __iomem *dma_chan_base) |
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{ |
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dsb(sy); |
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/* ugly busy wait only option for now */ |
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while (readl(dma_chan_base + BCM2708_DMA_CS) & BCM2708_DMA_ACTIVE) |
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cpu_relax(); |
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} |
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EXPORT_SYMBOL_GPL(bcm_dma_wait_idle); |
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extern bool bcm_dma_is_busy(void __iomem *dma_chan_base) |
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{ |
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dsb(sy); |
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return readl(dma_chan_base + BCM2708_DMA_CS) & BCM2708_DMA_ACTIVE; |
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} |
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EXPORT_SYMBOL_GPL(bcm_dma_is_busy); |
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/* Complete an ongoing DMA (assuming its results are to be ignored) |
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Does nothing if there is no DMA in progress. |
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This routine waits for the current AXI transfer to complete before |
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terminating the current DMA. If the current transfer is hung on a DREQ used |
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by an uncooperative peripheral the AXI transfer may never complete. In this |
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case the routine times out and return a non-zero error code. |
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Use of this routine doesn't guarantee that the ongoing or aborted DMA |
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does not produce an interrupt. |
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*/ |
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extern int bcm_dma_abort(void __iomem *dma_chan_base) |
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{ |
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unsigned long int cs; |
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int rc = 0; |
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cs = readl(dma_chan_base + BCM2708_DMA_CS); |
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if (BCM2708_DMA_ACTIVE & cs) { |
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long int timeout = 10000; |
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/* write 0 to the active bit - pause the DMA */ |
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writel(0, dma_chan_base + BCM2708_DMA_CS); |
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/* wait for any current AXI transfer to complete */ |
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while (0 != (cs & BCM2708_DMA_ISPAUSED) && --timeout >= 0) |
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cs = readl(dma_chan_base + BCM2708_DMA_CS); |
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if (0 != (cs & BCM2708_DMA_ISPAUSED)) { |
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/* we'll un-pause when we set of our next DMA */ |
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rc = -ETIMEDOUT; |
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} else if (BCM2708_DMA_ACTIVE & cs) { |
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/* terminate the control block chain */ |
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writel(0, dma_chan_base + BCM2708_DMA_NEXTCB); |
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/* abort the whole DMA */ |
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writel(BCM2708_DMA_ABORT | BCM2708_DMA_ACTIVE, |
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dma_chan_base + BCM2708_DMA_CS); |
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} |
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} |
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return rc; |
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} |
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EXPORT_SYMBOL_GPL(bcm_dma_abort); |
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/* DMA Manager Device Methods */ |
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static void vc_dmaman_init(struct vc_dmaman *dmaman, void __iomem *dma_base, |
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u32 chans_available) |
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{ |
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dmaman->dma_base = dma_base; |
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dmaman->chan_available = chans_available; |
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dmaman->has_feature[BCM_DMA_FEATURE_FAST_ORD] = 0x0c; /* 2 & 3 */ |
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dmaman->has_feature[BCM_DMA_FEATURE_BULK_ORD] = 0x01; /* 0 */ |
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dmaman->has_feature[BCM_DMA_FEATURE_NORMAL_ORD] = 0xfe; /* 1 to 7 */ |
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dmaman->has_feature[BCM_DMA_FEATURE_LITE_ORD] = 0x7f00; /* 8 to 14 */ |
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} |
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static int vc_dmaman_chan_alloc(struct vc_dmaman *dmaman, |
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unsigned required_feature_set) |
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{ |
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u32 chans; |
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int chan = 0; |
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int feature; |
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chans = dmaman->chan_available; |
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for (feature = 0; feature < BCM_DMA_FEATURE_COUNT; feature++) |
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/* select the subset of available channels with the desired |
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features */ |
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if (required_feature_set & (1 << feature)) |
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chans &= dmaman->has_feature[feature]; |
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if (!chans) |
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return -ENOENT; |
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/* return the ordinal of the first channel in the bitmap */ |
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while (chans != 0 && (chans & 1) == 0) { |
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chans >>= 1; |
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chan++; |
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} |
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/* claim the channel */ |
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dmaman->chan_available &= ~(1 << chan); |
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return chan; |
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} |
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static int vc_dmaman_chan_free(struct vc_dmaman *dmaman, int chan) |
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{ |
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if (chan < 0) |
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return -EINVAL; |
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if ((1 << chan) & dmaman->chan_available) |
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return -EIDRM; |
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dmaman->chan_available |= (1 << chan); |
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return 0; |
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} |
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/* DMA Manager Monitor */ |
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extern int bcm_dma_chan_alloc(unsigned required_feature_set, |
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void __iomem **out_dma_base, int *out_dma_irq) |
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{ |
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struct vc_dmaman *dmaman = g_dmaman; |
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struct platform_device *pdev = to_platform_device(dmaman_dev); |
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struct resource *r; |
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int chan; |
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if (!dmaman_dev) |
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return -ENODEV; |
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mutex_lock(&dmaman->lock); |
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chan = vc_dmaman_chan_alloc(dmaman, required_feature_set); |
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if (chan < 0) |
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goto out; |
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r = platform_get_resource(pdev, IORESOURCE_IRQ, (unsigned int)chan); |
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if (!r) { |
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dev_err(dmaman_dev, "failed to get irq for DMA channel %d\n", |
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chan); |
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vc_dmaman_chan_free(dmaman, chan); |
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chan = -ENOENT; |
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goto out; |
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} |
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*out_dma_base = BCM2708_DMA_CHANIO(dmaman->dma_base, chan); |
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*out_dma_irq = r->start; |
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dev_dbg(dmaman_dev, |
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"Legacy API allocated channel=%d, base=%p, irq=%i\n", |
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chan, *out_dma_base, *out_dma_irq); |
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out: |
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mutex_unlock(&dmaman->lock); |
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return chan; |
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} |
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EXPORT_SYMBOL_GPL(bcm_dma_chan_alloc); |
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extern int bcm_dma_chan_free(int channel) |
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{ |
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struct vc_dmaman *dmaman = g_dmaman; |
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int rc; |
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if (!dmaman_dev) |
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return -ENODEV; |
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mutex_lock(&dmaman->lock); |
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rc = vc_dmaman_chan_free(dmaman, channel); |
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mutex_unlock(&dmaman->lock); |
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return rc; |
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} |
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EXPORT_SYMBOL_GPL(bcm_dma_chan_free); |
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int bcm_dmaman_probe(struct platform_device *pdev, void __iomem *base, |
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u32 chans_available) |
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{ |
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struct device *dev = &pdev->dev; |
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struct vc_dmaman *dmaman; |
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dmaman = devm_kzalloc(dev, sizeof(*dmaman), GFP_KERNEL); |
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if (!dmaman) |
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return -ENOMEM; |
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mutex_init(&dmaman->lock); |
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vc_dmaman_init(dmaman, base, chans_available); |
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g_dmaman = dmaman; |
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dmaman_dev = dev; |
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dev_info(dev, "DMA legacy API manager, dmachans=0x%x\n", |
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chans_available); |
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return 0; |
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} |
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EXPORT_SYMBOL(bcm_dmaman_probe); |
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int bcm_dmaman_remove(struct platform_device *pdev) |
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{ |
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dmaman_dev = NULL; |
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return 0; |
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} |
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EXPORT_SYMBOL(bcm_dmaman_remove); |
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MODULE_LICENSE("GPL");
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