1 files changed, 348 insertions, 0 deletions

diff --git a/arch/arm/mach-sa1100/dma.c b/arch/arm/mach-sa1100/dma.c
new file mode 100644
index 000000000000..be0e4427bec7
--- /dev/null
+++ b/arch/arm/mach-sa1100/dma.c
@@ -0,0 +1,348 @@
+/*
+ * arch/arm/kernel/dma-sa1100.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 <asm/hardware.h>
+#include <asm/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 spinlock_t dma_list_lock;
+
+
+static irqreturn_t dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
+{
+        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 chanels
+ *      @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
+ *      linux/include/asm-arm/arch-sa1100/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, SA_INTERRUPT,
+                          device_id, regs);
+        if (err) {
+                printk(KERN_ERR
+                       "%s: unable to request IRQ %d for %s\n",
+                       __FUNCTION__, 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", __FUNCTION__);
+                return;
+        }
+
+        if (!dma_chan[i].device) {
+                printk(KERN_ERR "%s: Trying to free free DMA\n", __FUNCTION__);
+                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", __FUNCTION__);
+                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);
+