diff options
Diffstat (limited to 'arch/arm/mach-sa1100/dma.c')
| -rw-r--r-- | arch/arm/mach-sa1100/dma.c | 348 |
1 files changed, 0 insertions, 348 deletions
diff --git a/arch/arm/mach-sa1100/dma.c b/arch/arm/mach-sa1100/dma.c deleted file mode 100644 index ad660350c29..00000000000 --- a/arch/arm/mach-sa1100/dma.c +++ /dev/null @@ -1,348 +0,0 @@ -/* - * arch/arm/mach-sa1100/dma.c - * - * Support functions for the SA11x0 internal DMA channels. - * - * Copyright (C) 2000, 2001 by Nicolas Pitre - * - * 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 <linux/module.h> -#include <linux/interrupt.h> -#include <linux/init.h> -#include <linux/spinlock.h> -#include <linux/errno.h> - -#include <asm/system.h> -#include <asm/irq.h> -#include <mach/hardware.h> -#include <mach/dma.h> - - -#undef DEBUG -#ifdef DEBUG -#define DPRINTK( s, arg... ) printk( "dma<%p>: " s, regs , ##arg ) -#else -#define DPRINTK( x... ) -#endif - - -typedef struct { - const char *device_id; /* device name */ - u_long device; /* this channel device, 0 if unused*/ - dma_callback_t callback; /* to call when DMA completes */ - void *data; /* ... with private data ptr */ -} sa1100_dma_t; - -static sa1100_dma_t dma_chan[SA1100_DMA_CHANNELS]; - -static DEFINE_SPINLOCK(dma_list_lock); - - -static irqreturn_t dma_irq_handler(int irq, void *dev_id) -{ - dma_regs_t *dma_regs = dev_id; - sa1100_dma_t *dma = dma_chan + (((u_int)dma_regs >> 5) & 7); - int status = dma_regs->RdDCSR; - - if (status & (DCSR_ERROR)) { - printk(KERN_CRIT "DMA on \"%s\" caused an error\n", dma->device_id); - dma_regs->ClrDCSR = DCSR_ERROR; - } - - dma_regs->ClrDCSR = status & (DCSR_DONEA | DCSR_DONEB); - if (dma->callback) { - if (status & DCSR_DONEA) - dma->callback(dma->data); - if (status & DCSR_DONEB) - dma->callback(dma->data); - } - return IRQ_HANDLED; -} - - -/** - * sa1100_request_dma - allocate one of the SA11x0's DMA channels - * @device: The SA11x0 peripheral targeted by this request - * @device_id: An ascii name for the claiming device - * @callback: Function to be called when the DMA completes - * @data: A cookie passed back to the callback function - * @dma_regs: Pointer to the location of the allocated channel's identifier - * - * This function will search for a free DMA channel and returns the - * address of the hardware registers for that channel as the channel - * identifier. This identifier is written to the location pointed by - * @dma_regs. The list of possible values for @device are listed into - * arch/arm/mach-sa1100/include/mach/dma.h as a dma_device_t enum. - * - * Note that reading from a port and writing to the same port are - * actually considered as two different streams requiring separate - * DMA registrations. - * - * The @callback function is called from interrupt context when one - * of the two possible DMA buffers in flight has terminated. That - * function has to be small and efficient while posponing more complex - * processing to a lower priority execution context. - * - * If no channels are available, or if the desired @device is already in - * use by another DMA channel, then an error code is returned. This - * function must be called before any other DMA calls. - **/ - -int sa1100_request_dma (dma_device_t device, const char *device_id, - dma_callback_t callback, void *data, - dma_regs_t **dma_regs) -{ - sa1100_dma_t *dma = NULL; - dma_regs_t *regs; - int i, err; - - *dma_regs = NULL; - - err = 0; - spin_lock(&dma_list_lock); - for (i = 0; i < SA1100_DMA_CHANNELS; i++) { - if (dma_chan[i].device == device) { - err = -EBUSY; - break; - } else if (!dma_chan[i].device && !dma) { - dma = &dma_chan[i]; - } - } - if (!err) { - if (dma) - dma->device = device; - else - err = -ENOSR; - } - spin_unlock(&dma_list_lock); - if (err) - return err; - - i = dma - dma_chan; - regs = (dma_regs_t *)&DDAR(i); - err = request_irq(IRQ_DMA0 + i, dma_irq_handler, IRQF_DISABLED, - device_id, regs); - if (err) { - printk(KERN_ERR - "%s: unable to request IRQ %d for %s\n", - __func__, IRQ_DMA0 + i, device_id); - dma->device = 0; - return err; - } - - *dma_regs = regs; - dma->device_id = device_id; - dma->callback = callback; - dma->data = data; - - regs->ClrDCSR = - (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB | - DCSR_IE | DCSR_ERROR | DCSR_RUN); - regs->DDAR = device; - - return 0; -} - - -/** - * sa1100_free_dma - free a SA11x0 DMA channel - * @regs: identifier for the channel to free - * - * This clears all activities on a given DMA channel and releases it - * for future requests. The @regs identifier is provided by a - * successful call to sa1100_request_dma(). - **/ - -void sa1100_free_dma(dma_regs_t *regs) -{ - int i; - - for (i = 0; i < SA1100_DMA_CHANNELS; i++) - if (regs == (dma_regs_t *)&DDAR(i)) - break; - if (i >= SA1100_DMA_CHANNELS) { - printk(KERN_ERR "%s: bad DMA identifier\n", __func__); - return; - } - - if (!dma_chan[i].device) { - printk(KERN_ERR "%s: Trying to free free DMA\n", __func__); - return; - } - - regs->ClrDCSR = - (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB | - DCSR_IE | DCSR_ERROR | DCSR_RUN); - free_irq(IRQ_DMA0 + i, regs); - dma_chan[i].device = 0; -} - - -/** - * sa1100_start_dma - submit a data buffer for DMA - * @regs: identifier for the channel to use - * @dma_ptr: buffer physical (or bus) start address - * @size: buffer size - * - * This function hands the given data buffer to the hardware for DMA - * access. If another buffer is already in flight then this buffer - * will be queued so the DMA engine will switch to it automatically - * when the previous one is done. The DMA engine is actually toggling - * between two buffers so at most 2 successful calls can be made before - * one of them terminates and the callback function is called. - * - * The @regs identifier is provided by a successful call to - * sa1100_request_dma(). - * - * The @size must not be larger than %MAX_DMA_SIZE. If a given buffer - * is larger than that then it's the caller's responsibility to split - * it into smaller chunks and submit them separately. If this is the - * case then a @size of %CUT_DMA_SIZE is recommended to avoid ending - * up with too small chunks. The callback function can be used to chain - * submissions of buffer chunks. - * - * Error return values: - * %-EOVERFLOW: Given buffer size is too big. - * %-EBUSY: Both DMA buffers are already in use. - * %-EAGAIN: Both buffers were busy but one of them just completed - * but the interrupt handler has to execute first. - * - * This function returs 0 on success. - **/ - -int sa1100_start_dma(dma_regs_t *regs, dma_addr_t dma_ptr, u_int size) -{ - unsigned long flags; - u_long status; - int ret; - - if (dma_ptr & 3) - printk(KERN_WARNING "DMA: unaligned start address (0x%08lx)\n", - (unsigned long)dma_ptr); - - if (size > MAX_DMA_SIZE) - return -EOVERFLOW; - - local_irq_save(flags); - status = regs->RdDCSR; - - /* If both DMA buffers are started, there's nothing else we can do. */ - if ((status & (DCSR_STRTA | DCSR_STRTB)) == (DCSR_STRTA | DCSR_STRTB)) { - DPRINTK("start: st %#x busy\n", status); - ret = -EBUSY; - goto out; - } - - if (((status & DCSR_BIU) && (status & DCSR_STRTB)) || - (!(status & DCSR_BIU) && !(status & DCSR_STRTA))) { - if (status & DCSR_DONEA) { - /* give a chance for the interrupt to be processed */ - ret = -EAGAIN; - goto out; - } - regs->DBSA = dma_ptr; - regs->DBTA = size; - regs->SetDCSR = DCSR_STRTA | DCSR_IE | DCSR_RUN; - DPRINTK("start a=%#x s=%d on A\n", dma_ptr, size); - } else { - if (status & DCSR_DONEB) { - /* give a chance for the interrupt to be processed */ - ret = -EAGAIN; - goto out; - } - regs->DBSB = dma_ptr; - regs->DBTB = size; - regs->SetDCSR = DCSR_STRTB | DCSR_IE | DCSR_RUN; - DPRINTK("start a=%#x s=%d on B\n", dma_ptr, size); - } - ret = 0; - -out: - local_irq_restore(flags); - return ret; -} - - -/** - * sa1100_get_dma_pos - return current DMA position - * @regs: identifier for the channel to use - * - * This function returns the current physical (or bus) address for the - * given DMA channel. If the channel is running i.e. not in a stopped - * state then the caller must disable interrupts prior calling this - * function and process the returned value before re-enabling them to - * prevent races with the completion interrupt handler and the callback - * function. The validation of the returned value is the caller's - * responsibility as well -- the hardware seems to return out of range - * values when the DMA engine completes a buffer. - * - * The @regs identifier is provided by a successful call to - * sa1100_request_dma(). - **/ - -dma_addr_t sa1100_get_dma_pos(dma_regs_t *regs) -{ - int status; - - /* - * We must determine whether buffer A or B is active. - * Two possibilities: either we are in the middle of - * a buffer, or the DMA controller just switched to the - * next toggle but the interrupt hasn't been serviced yet. - * The former case is straight forward. In the later case, - * we'll do like if DMA is just at the end of the previous - * toggle since all registers haven't been reset yet. - * This goes around the edge case and since we're always - * a little behind anyways it shouldn't make a big difference. - * If DMA has been stopped prior calling this then the - * position is exact. - */ - status = regs->RdDCSR; - if ((!(status & DCSR_BIU) && (status & DCSR_STRTA)) || - ( (status & DCSR_BIU) && !(status & DCSR_STRTB))) - return regs->DBSA; - else - return regs->DBSB; -} - - -/** - * sa1100_reset_dma - reset a DMA channel - * @regs: identifier for the channel to use - * - * This function resets and reconfigure the given DMA channel. This is - * particularly useful after a sleep/wakeup event. - * - * The @regs identifier is provided by a successful call to - * sa1100_request_dma(). - **/ - -void sa1100_reset_dma(dma_regs_t *regs) -{ - int i; - - for (i = 0; i < SA1100_DMA_CHANNELS; i++) - if (regs == (dma_regs_t *)&DDAR(i)) - break; - if (i >= SA1100_DMA_CHANNELS) { - printk(KERN_ERR "%s: bad DMA identifier\n", __func__); - return; - } - - regs->ClrDCSR = - (DCSR_DONEA | DCSR_DONEB | DCSR_STRTA | DCSR_STRTB | - DCSR_IE | DCSR_ERROR | DCSR_RUN); - regs->DDAR = dma_chan[i].device; -} - - -EXPORT_SYMBOL(sa1100_request_dma); -EXPORT_SYMBOL(sa1100_free_dma); -EXPORT_SYMBOL(sa1100_start_dma); -EXPORT_SYMBOL(sa1100_get_dma_pos); -EXPORT_SYMBOL(sa1100_reset_dma); - |