drivers/dma/bcm2708-dmaengine.c

   1 /*
   2  * BCM2708 legacy DMA API
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/init.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/list.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_data/dma-bcm2708.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/slab.h>
  22 #include <linux/io.h>
  23 #include <linux/spinlock.h>
  24
  25 #include "virt-dma.h"
  26
  27 #define CACHE_LINE_MASK 31
  28 #define DEFAULT_DMACHAN_BITMAP 0x10  /* channel 4 only */
  29
  30 /* valid only for channels 0 - 14, 15 has its own base address */
  31 #define BCM2708_DMA_CHAN(n)     ((n) << 8) /* base address */
  32 #define BCM2708_DMA_CHANIO(dma_base, n) \
  33         ((void __iomem *)((char *)(dma_base) + BCM2708_DMA_CHAN(n)))
  34
  35 struct vc_dmaman {
  36         void __iomem *dma_base;
  37         u32 chan_available; /* bitmap of available channels */
  38         u32 has_feature[BCM_DMA_FEATURE_COUNT]; /* bitmap of feature presence */
  39         struct mutex lock;
  40 };
  41
  42 static struct device *dmaman_dev;       /* we assume there's only one! */
  43 static struct vc_dmaman *g_dmaman;      /* DMA manager */
  44
  45 /* DMA Auxiliary Functions */
  46
  47 /* A DMA buffer on an arbitrary boundary may separate a cache line into a
  48    section inside the DMA buffer and another section outside it.
  49    Even if we flush DMA buffers from the cache there is always the chance that
  50    during a DMA someone will access the part of a cache line that is outside
  51    the DMA buffer - which will then bring in unwelcome data.
  52    Without being able to dictate our own buffer pools we must insist that
  53    DMA buffers consist of a whole number of cache lines.
  54 */
  55 extern int bcm_sg_suitable_for_dma(struct scatterlist *sg_ptr, int sg_len)
  56 {
  57         int i;
  58
  59         for (i = 0; i < sg_len; i++) {
  60                 if (sg_ptr[i].offset & CACHE_LINE_MASK ||
  61                     sg_ptr[i].length & CACHE_LINE_MASK)
  62                         return 0;
  63         }
  64
  65         return 1;
  66 }
  67 EXPORT_SYMBOL_GPL(bcm_sg_suitable_for_dma);
  68
  69 extern void bcm_dma_start(void __iomem *dma_chan_base,
  70                           dma_addr_t control_block)
  71 {
  72         dsb(sy);        /* ARM data synchronization (push) operation */
  73
  74         writel(control_block, dma_chan_base + BCM2708_DMA_ADDR);
  75         writel(BCM2708_DMA_ACTIVE, dma_chan_base + BCM2708_DMA_CS);
  76 }
  77 EXPORT_SYMBOL_GPL(bcm_dma_start);
  78
  79 extern void bcm_dma_wait_idle(void __iomem *dma_chan_base)
  80 {
  81         dsb(sy);
  82
  83         /* ugly busy wait only option for now */
  84         while (readl(dma_chan_base + BCM2708_DMA_CS) & BCM2708_DMA_ACTIVE)
  85                 cpu_relax();
  86 }
  87 EXPORT_SYMBOL_GPL(bcm_dma_wait_idle);
  88
  89 extern bool bcm_dma_is_busy(void __iomem *dma_chan_base)
  90 {
  91         dsb(sy);
  92
  93         return readl(dma_chan_base + BCM2708_DMA_CS) & BCM2708_DMA_ACTIVE;
  94 }
  95 EXPORT_SYMBOL_GPL(bcm_dma_is_busy);
  96
  97 /* Complete an ongoing DMA (assuming its results are to be ignored)
  98    Does nothing if there is no DMA in progress.
  99    This routine waits for the current AXI transfer to complete before
 100    terminating the current DMA. If the current transfer is hung on a DREQ used
 101    by an uncooperative peripheral the AXI transfer may never complete.  In this
 102    case the routine times out and return a non-zero error code.
 103    Use of this routine doesn't guarantee that the ongoing or aborted DMA
 104    does not produce an interrupt.
 105 */
 106 extern int bcm_dma_abort(void __iomem *dma_chan_base)
 107 {
 108         unsigned long int cs;
 109         int rc = 0;
 110
 111         cs = readl(dma_chan_base + BCM2708_DMA_CS);
 112
 113         if (BCM2708_DMA_ACTIVE & cs) {
 114                 long int timeout = 10000;
 115
 116                 /* write 0 to the active bit - pause the DMA */
 117                 writel(0, dma_chan_base + BCM2708_DMA_CS);
 118
 119                 /* wait for any current AXI transfer to complete */
 120                 while (0 != (cs & BCM2708_DMA_ISPAUSED) && --timeout >= 0)
 121                         cs = readl(dma_chan_base + BCM2708_DMA_CS);
 122
 123                 if (0 != (cs & BCM2708_DMA_ISPAUSED)) {
 124                         /* we'll un-pause when we set of our next DMA */
 125                         rc = -ETIMEDOUT;
 126
 127                 } else if (BCM2708_DMA_ACTIVE & cs) {
 128                         /* terminate the control block chain */
 129                         writel(0, dma_chan_base + BCM2708_DMA_NEXTCB);
 130
 131                         /* abort the whole DMA */
 132                         writel(BCM2708_DMA_ABORT | BCM2708_DMA_ACTIVE,
 133                                dma_chan_base + BCM2708_DMA_CS);
 134                 }
 135         }
 136
 137         return rc;
 138 }
 139 EXPORT_SYMBOL_GPL(bcm_dma_abort);
 140
 141  /* DMA Manager Device Methods */
 142
 143 static void vc_dmaman_init(struct vc_dmaman *dmaman, void __iomem *dma_base,
 144                            u32 chans_available)
 145 {
 146         dmaman->dma_base = dma_base;
 147         dmaman->chan_available = chans_available;
 148         dmaman->has_feature[BCM_DMA_FEATURE_FAST_ORD] = 0x0c;  /* 2 & 3 */
 149         dmaman->has_feature[BCM_DMA_FEATURE_BULK_ORD] = 0x01;  /* 0 */
 150         dmaman->has_feature[BCM_DMA_FEATURE_NORMAL_ORD] = 0xfe;  /* 1 to 7 */
 151         dmaman->has_feature[BCM_DMA_FEATURE_LITE_ORD] = 0x7f00;  /* 8 to 14 */
 152 }
 153
 154 static int vc_dmaman_chan_alloc(struct vc_dmaman *dmaman,
 155                                 unsigned required_feature_set)
 156 {
 157         u32 chans;
 158         int chan = 0;
 159         int feature;
 160
 161         chans = dmaman->chan_available;
 162         for (feature = 0; feature < BCM_DMA_FEATURE_COUNT; feature++)
 163                 /* select the subset of available channels with the desired
 164                    features */
 165                 if (required_feature_set & (1 << feature))
 166                         chans &= dmaman->has_feature[feature];
 167
 168         if (!chans)
 169                 return -ENOENT;
 170
 171         /* return the ordinal of the first channel in the bitmap */
 172         while (chans != 0 && (chans & 1) == 0) {
 173                 chans >>= 1;
 174                 chan++;
 175         }
 176         /* claim the channel */
 177         dmaman->chan_available &= ~(1 << chan);
 178
 179         return chan;
 180 }
 181
 182 static int vc_dmaman_chan_free(struct vc_dmaman *dmaman, int chan)
 183 {
 184         if (chan < 0)
 185                 return -EINVAL;
 186
 187         if ((1 << chan) & dmaman->chan_available)
 188                 return -EIDRM;
 189
 190         dmaman->chan_available |= (1 << chan);
 191
 192         return 0;
 193 }
 194
 195 /* DMA Manager Monitor */
 196
 197 extern int bcm_dma_chan_alloc(unsigned required_feature_set,
 198                               void __iomem **out_dma_base, int *out_dma_irq)
 199 {
 200         struct vc_dmaman *dmaman = g_dmaman;
 201         struct platform_device *pdev = to_platform_device(dmaman_dev);
 202         struct resource *r;
 203         int chan;
 204
 205         if (!dmaman_dev)
 206                 return -ENODEV;
 207
 208         mutex_lock(&dmaman->lock);
 209         chan = vc_dmaman_chan_alloc(dmaman, required_feature_set);
 210         if (chan < 0)
 211                 goto out;
 212
 213         r = platform_get_resource(pdev, IORESOURCE_IRQ, (unsigned int)chan);
 214         if (!r) {
 215                 dev_err(dmaman_dev, "failed to get irq for DMA channel %d\n",
 216                         chan);
 217                 vc_dmaman_chan_free(dmaman, chan);
 218                 chan = -ENOENT;
 219                 goto out;
 220         }
 221
 222         *out_dma_base = BCM2708_DMA_CHANIO(dmaman->dma_base, chan);
 223         *out_dma_irq = r->start;
 224         dev_dbg(dmaman_dev,
 225                 "Legacy API allocated channel=%d, base=%p, irq=%i\n",
 226                 chan, *out_dma_base, *out_dma_irq);
 227
 228 out:
 229         mutex_unlock(&dmaman->lock);
 230
 231         return chan;
 232 }
 233 EXPORT_SYMBOL_GPL(bcm_dma_chan_alloc);
 234
 235 extern int bcm_dma_chan_free(int channel)
 236 {
 237         struct vc_dmaman *dmaman = g_dmaman;
 238         int rc;
 239
 240         if (!dmaman_dev)
 241                 return -ENODEV;
 242
 243         mutex_lock(&dmaman->lock);
 244         rc = vc_dmaman_chan_free(dmaman, channel);
 245         mutex_unlock(&dmaman->lock);
 246
 247         return rc;
 248 }
 249 EXPORT_SYMBOL_GPL(bcm_dma_chan_free);
 250
 251 int bcm_dmaman_probe(struct platform_device *pdev, void __iomem *base,
 252                      u32 chans_available)
 253 {
 254         struct device *dev = &pdev->dev;
 255         struct vc_dmaman *dmaman;
 256
 257         dmaman = devm_kzalloc(dev, sizeof(*dmaman), GFP_KERNEL);
 258         if (!dmaman)
 259                 return -ENOMEM;
 260
 261         mutex_init(&dmaman->lock);
 262         vc_dmaman_init(dmaman, base, chans_available);
 263         g_dmaman = dmaman;
 264         dmaman_dev = dev;
 265
 266         dev_info(dev, "DMA legacy API manager at %p, dmachans=0x%x\n",
 267                  base, chans_available);
 268
 269         return 0;
 270 }
 271 EXPORT_SYMBOL(bcm_dmaman_probe);
 272
 273 int bcm_dmaman_remove(struct platform_device *pdev)
 274 {
 275         dmaman_dev = NULL;
 276
 277         return 0;
 278 }
 279 EXPORT_SYMBOL(bcm_dmaman_remove);
 280
 281 MODULE_LICENSE("GPL");