Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Uwe Zeisberger | f30c226 | 2006-10-03 23:01:26 +0200 | [diff] [blame] | 2 | * arch/arm/mach-sa1100/dma.c |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * Support functions for the SA11x0 internal DMA channels. |
| 5 | * |
| 6 | * Copyright (C) 2000, 2001 by Nicolas Pitre |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License version 2 as |
| 10 | * published by the Free Software Foundation. |
| 11 | */ |
| 12 | |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/interrupt.h> |
| 15 | #include <linux/init.h> |
| 16 | #include <linux/spinlock.h> |
| 17 | #include <linux/errno.h> |
| 18 | |
| 19 | #include <asm/system.h> |
| 20 | #include <asm/irq.h> |
| 21 | #include <asm/hardware.h> |
| 22 | #include <asm/dma.h> |
| 23 | |
| 24 | |
| 25 | #undef DEBUG |
| 26 | #ifdef DEBUG |
| 27 | #define DPRINTK( s, arg... ) printk( "dma<%p>: " s, regs , ##arg ) |
| 28 | #else |
| 29 | #define DPRINTK( x... ) |
| 30 | #endif |
| 31 | |
| 32 | |
| 33 | typedef struct { |
| 34 | const char *device_id; /* device name */ |
| 35 | u_long device; /* this channel device, 0 if unused*/ |
| 36 | dma_callback_t callback; /* to call when DMA completes */ |
| 37 | void *data; /* ... with private data ptr */ |
| 38 | } sa1100_dma_t; |
| 39 | |
| 40 | static sa1100_dma_t dma_chan[SA1100_DMA_CHANNELS]; |
| 41 | |
| 42 | static spinlock_t dma_list_lock; |
| 43 | |
| 44 | |
Linus Torvalds | 0cd61b6 | 2006-10-06 10:53:39 -0700 | [diff] [blame] | 45 | static irqreturn_t dma_irq_handler(int irq, void *dev_id) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | { |
| 47 | dma_regs_t *dma_regs = dev_id; |
| 48 | sa1100_dma_t *dma = dma_chan + (((u_int)dma_regs >> 5) & 7); |
| 49 | int status = dma_regs->RdDCSR; |
| 50 | |
| 51 | if (status & (DCSR_ERROR)) { |
| 52 | printk(KERN_CRIT "DMA on \"%s\" caused an error\n", dma->device_id); |
| 53 | dma_regs->ClrDCSR = DCSR_ERROR; |
| 54 | } |
| 55 | |
| 56 | dma_regs->ClrDCSR = status & (DCSR_DONEA | DCSR_DONEB); |
| 57 | if (dma->callback) { |
| 58 | if (status & DCSR_DONEA) |
| 59 | dma->callback(dma->data); |
| 60 | if (status & DCSR_DONEB) |
| 61 | dma->callback(dma->data); |
| 62 | } |
| 63 | return IRQ_HANDLED; |
| 64 | } |
| 65 | |
| 66 | |
| 67 | /** |
| 68 | * sa1100_request_dma - allocate one of the SA11x0's DMA chanels |
| 69 | * @device: The SA11x0 peripheral targeted by this request |
| 70 | * @device_id: An ascii name for the claiming device |
| 71 | * @callback: Function to be called when the DMA completes |
| 72 | * @data: A cookie passed back to the callback function |
| 73 | * @dma_regs: Pointer to the location of the allocated channel's identifier |
| 74 | * |
| 75 | * This function will search for a free DMA channel and returns the |
| 76 | * address of the hardware registers for that channel as the channel |
| 77 | * identifier. This identifier is written to the location pointed by |
| 78 | * @dma_regs. The list of possible values for @device are listed into |
| 79 | * linux/include/asm-arm/arch-sa1100/dma.h as a dma_device_t enum. |
| 80 | * |
| 81 | * Note that reading from a port and writing to the same port are |
| 82 | * actually considered as two different streams requiring separate |
| 83 | * DMA registrations. |
| 84 | * |
| 85 | * The @callback function is called from interrupt context when one |
| 86 | * of the two possible DMA buffers in flight has terminated. That |
| 87 | * function has to be small and efficient while posponing more complex |
| 88 | * processing to a lower priority execution context. |
| 89 | * |
| 90 | * If no channels are available, or if the desired @device is already in |
| 91 | * use by another DMA channel, then an error code is returned. This |
| 92 | * function must be called before any other DMA calls. |
| 93 | **/ |
| 94 | |
| 95 | int sa1100_request_dma (dma_device_t device, const char *device_id, |
| 96 | dma_callback_t callback, void *data, |
| 97 | dma_regs_t **dma_regs) |
| 98 | { |
| 99 | sa1100_dma_t *dma = NULL; |
| 100 | dma_regs_t *regs; |
| 101 | int i, err; |
| 102 | |
| 103 | *dma_regs = NULL; |
| 104 | |
| 105 | err = 0; |
| 106 | spin_lock(&dma_list_lock); |
| 107 | for (i = 0; i < SA1100_DMA_CHANNELS; i++) { |
| 108 | if (dma_chan[i].device == device) { |
| 109 | err = -EBUSY; |
| 110 | break; |
| 111 | } else if (!dma_chan[i].device && !dma) { |
| 112 | dma = &dma_chan[i]; |
| 113 | } |
| 114 | } |
| 115 | if (!err) { |
| 116 | if (dma) |
| 117 | dma->device = device; |
| 118 | else |
| 119 | err = -ENOSR; |
| 120 | } |
| 121 | spin_unlock(&dma_list_lock); |
| 122 | if (err) |
| 123 | return err; |
| 124 | |
| 125 | i = dma - dma_chan; |
| 126 | regs = (dma_regs_t *)&DDAR(i); |
Thomas Gleixner | 52e405e | 2006-07-03 02:20:05 +0200 | [diff] [blame] | 127 | err = request_irq(IRQ_DMA0 + i, dma_irq_handler, IRQF_DISABLED, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 128 | device_id, regs); |
| 129 | if (err) { |
| 130 | printk(KERN_ERR |
| 131 | "%s: unable to request IRQ %d for %s\n", |
| 132 | __FUNCTION__, IRQ_DMA0 + i, device_id); |
| 133 | dma->device = 0; |
| 134 | return err; |
| 135 | } |
| 136 | |
| 137 | *dma_regs = regs; |
| 138 | dma->device_id = device_id; |
| 139 | dma->callback = callback; |
| 140 | dma->data = data; |
| 141 | |
| 142 | regs->ClrDCSR = |
| 143 | (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB | |
| 144 | DCSR_IE | DCSR_ERROR | DCSR_RUN); |
| 145 | regs->DDAR = device; |
| 146 | |
| 147 | return 0; |
| 148 | } |
| 149 | |
| 150 | |
| 151 | /** |
| 152 | * sa1100_free_dma - free a SA11x0 DMA channel |
| 153 | * @regs: identifier for the channel to free |
| 154 | * |
| 155 | * This clears all activities on a given DMA channel and releases it |
| 156 | * for future requests. The @regs identifier is provided by a |
| 157 | * successful call to sa1100_request_dma(). |
| 158 | **/ |
| 159 | |
| 160 | void sa1100_free_dma(dma_regs_t *regs) |
| 161 | { |
| 162 | int i; |
| 163 | |
| 164 | for (i = 0; i < SA1100_DMA_CHANNELS; i++) |
| 165 | if (regs == (dma_regs_t *)&DDAR(i)) |
| 166 | break; |
| 167 | if (i >= SA1100_DMA_CHANNELS) { |
| 168 | printk(KERN_ERR "%s: bad DMA identifier\n", __FUNCTION__); |
| 169 | return; |
| 170 | } |
| 171 | |
| 172 | if (!dma_chan[i].device) { |
| 173 | printk(KERN_ERR "%s: Trying to free free DMA\n", __FUNCTION__); |
| 174 | return; |
| 175 | } |
| 176 | |
| 177 | regs->ClrDCSR = |
| 178 | (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB | |
| 179 | DCSR_IE | DCSR_ERROR | DCSR_RUN); |
| 180 | free_irq(IRQ_DMA0 + i, regs); |
| 181 | dma_chan[i].device = 0; |
| 182 | } |
| 183 | |
| 184 | |
| 185 | /** |
| 186 | * sa1100_start_dma - submit a data buffer for DMA |
| 187 | * @regs: identifier for the channel to use |
| 188 | * @dma_ptr: buffer physical (or bus) start address |
| 189 | * @size: buffer size |
| 190 | * |
| 191 | * This function hands the given data buffer to the hardware for DMA |
| 192 | * access. If another buffer is already in flight then this buffer |
| 193 | * will be queued so the DMA engine will switch to it automatically |
| 194 | * when the previous one is done. The DMA engine is actually toggling |
| 195 | * between two buffers so at most 2 successful calls can be made before |
| 196 | * one of them terminates and the callback function is called. |
| 197 | * |
| 198 | * The @regs identifier is provided by a successful call to |
| 199 | * sa1100_request_dma(). |
| 200 | * |
| 201 | * The @size must not be larger than %MAX_DMA_SIZE. If a given buffer |
| 202 | * is larger than that then it's the caller's responsibility to split |
| 203 | * it into smaller chunks and submit them separately. If this is the |
| 204 | * case then a @size of %CUT_DMA_SIZE is recommended to avoid ending |
| 205 | * up with too small chunks. The callback function can be used to chain |
| 206 | * submissions of buffer chunks. |
| 207 | * |
| 208 | * Error return values: |
| 209 | * %-EOVERFLOW: Given buffer size is too big. |
| 210 | * %-EBUSY: Both DMA buffers are already in use. |
| 211 | * %-EAGAIN: Both buffers were busy but one of them just completed |
| 212 | * but the interrupt handler has to execute first. |
| 213 | * |
| 214 | * This function returs 0 on success. |
| 215 | **/ |
| 216 | |
| 217 | int sa1100_start_dma(dma_regs_t *regs, dma_addr_t dma_ptr, u_int size) |
| 218 | { |
| 219 | unsigned long flags; |
| 220 | u_long status; |
| 221 | int ret; |
| 222 | |
| 223 | if (dma_ptr & 3) |
| 224 | printk(KERN_WARNING "DMA: unaligned start address (0x%08lx)\n", |
| 225 | (unsigned long)dma_ptr); |
| 226 | |
| 227 | if (size > MAX_DMA_SIZE) |
| 228 | return -EOVERFLOW; |
| 229 | |
| 230 | local_irq_save(flags); |
| 231 | status = regs->RdDCSR; |
| 232 | |
| 233 | /* If both DMA buffers are started, there's nothing else we can do. */ |
| 234 | if ((status & (DCSR_STRTA | DCSR_STRTB)) == (DCSR_STRTA | DCSR_STRTB)) { |
| 235 | DPRINTK("start: st %#x busy\n", status); |
| 236 | ret = -EBUSY; |
| 237 | goto out; |
| 238 | } |
| 239 | |
| 240 | if (((status & DCSR_BIU) && (status & DCSR_STRTB)) || |
| 241 | (!(status & DCSR_BIU) && !(status & DCSR_STRTA))) { |
| 242 | if (status & DCSR_DONEA) { |
| 243 | /* give a chance for the interrupt to be processed */ |
| 244 | ret = -EAGAIN; |
| 245 | goto out; |
| 246 | } |
| 247 | regs->DBSA = dma_ptr; |
| 248 | regs->DBTA = size; |
| 249 | regs->SetDCSR = DCSR_STRTA | DCSR_IE | DCSR_RUN; |
| 250 | DPRINTK("start a=%#x s=%d on A\n", dma_ptr, size); |
| 251 | } else { |
| 252 | if (status & DCSR_DONEB) { |
| 253 | /* give a chance for the interrupt to be processed */ |
| 254 | ret = -EAGAIN; |
| 255 | goto out; |
| 256 | } |
| 257 | regs->DBSB = dma_ptr; |
| 258 | regs->DBTB = size; |
| 259 | regs->SetDCSR = DCSR_STRTB | DCSR_IE | DCSR_RUN; |
| 260 | DPRINTK("start a=%#x s=%d on B\n", dma_ptr, size); |
| 261 | } |
| 262 | ret = 0; |
| 263 | |
| 264 | out: |
| 265 | local_irq_restore(flags); |
| 266 | return ret; |
| 267 | } |
| 268 | |
| 269 | |
| 270 | /** |
| 271 | * sa1100_get_dma_pos - return current DMA position |
| 272 | * @regs: identifier for the channel to use |
| 273 | * |
| 274 | * This function returns the current physical (or bus) address for the |
| 275 | * given DMA channel. If the channel is running i.e. not in a stopped |
| 276 | * state then the caller must disable interrupts prior calling this |
| 277 | * function and process the returned value before re-enabling them to |
| 278 | * prevent races with the completion interrupt handler and the callback |
| 279 | * function. The validation of the returned value is the caller's |
| 280 | * responsibility as well -- the hardware seems to return out of range |
| 281 | * values when the DMA engine completes a buffer. |
| 282 | * |
| 283 | * The @regs identifier is provided by a successful call to |
| 284 | * sa1100_request_dma(). |
| 285 | **/ |
| 286 | |
| 287 | dma_addr_t sa1100_get_dma_pos(dma_regs_t *regs) |
| 288 | { |
| 289 | int status; |
| 290 | |
| 291 | /* |
| 292 | * We must determine whether buffer A or B is active. |
| 293 | * Two possibilities: either we are in the middle of |
| 294 | * a buffer, or the DMA controller just switched to the |
| 295 | * next toggle but the interrupt hasn't been serviced yet. |
| 296 | * The former case is straight forward. In the later case, |
| 297 | * we'll do like if DMA is just at the end of the previous |
| 298 | * toggle since all registers haven't been reset yet. |
| 299 | * This goes around the edge case and since we're always |
| 300 | * a little behind anyways it shouldn't make a big difference. |
| 301 | * If DMA has been stopped prior calling this then the |
| 302 | * position is exact. |
| 303 | */ |
| 304 | status = regs->RdDCSR; |
| 305 | if ((!(status & DCSR_BIU) && (status & DCSR_STRTA)) || |
| 306 | ( (status & DCSR_BIU) && !(status & DCSR_STRTB))) |
| 307 | return regs->DBSA; |
| 308 | else |
| 309 | return regs->DBSB; |
| 310 | } |
| 311 | |
| 312 | |
| 313 | /** |
| 314 | * sa1100_reset_dma - reset a DMA channel |
| 315 | * @regs: identifier for the channel to use |
| 316 | * |
| 317 | * This function resets and reconfigure the given DMA channel. This is |
| 318 | * particularly useful after a sleep/wakeup event. |
| 319 | * |
| 320 | * The @regs identifier is provided by a successful call to |
| 321 | * sa1100_request_dma(). |
| 322 | **/ |
| 323 | |
| 324 | void sa1100_reset_dma(dma_regs_t *regs) |
| 325 | { |
| 326 | int i; |
| 327 | |
| 328 | for (i = 0; i < SA1100_DMA_CHANNELS; i++) |
| 329 | if (regs == (dma_regs_t *)&DDAR(i)) |
| 330 | break; |
| 331 | if (i >= SA1100_DMA_CHANNELS) { |
| 332 | printk(KERN_ERR "%s: bad DMA identifier\n", __FUNCTION__); |
| 333 | return; |
| 334 | } |
| 335 | |
| 336 | regs->ClrDCSR = |
| 337 | (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB | |
| 338 | DCSR_IE | DCSR_ERROR | DCSR_RUN); |
| 339 | regs->DDAR = dma_chan[i].device; |
| 340 | } |
| 341 | |
| 342 | |
| 343 | EXPORT_SYMBOL(sa1100_request_dma); |
| 344 | EXPORT_SYMBOL(sa1100_free_dma); |
| 345 | EXPORT_SYMBOL(sa1100_start_dma); |
| 346 | EXPORT_SYMBOL(sa1100_get_dma_pos); |
| 347 | EXPORT_SYMBOL(sa1100_reset_dma); |
| 348 | |