[ARM] dma: rejig DMA initialization

Rather than having the central DMA multiplexer call the architecture
specific DMA initialization function, have each architecture DMA
initialization function use core_initcall(), and register each DMA
channel separately with the multiplexer.

This removes the array of dma structures in the central multiplexer,
replacing it with an array of pointers instead; this is more flexible
since it allows the drivers to wrap the DMA structure (eventually
allowing us to transition non-ISA DMA drivers away.)

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 28 insertions, 15 deletions

diff --git a/arch/arm/kernel/dma-isa.c b/arch/arm/kernel/dma-isa.c
index 29eca48925d8..da02a7ff3419 100644
--- a/arch/arm/kernel/dma-isa.c
+++ b/arch/arm/kernel/dma-isa.c
@@ -160,7 +160,12 @@ static struct resource dma_resources[] = { {
         .end    = 0x048f
 } };
 
-void __init isa_init_dma(dma_t *dma)
+static dma_t isa_dma[8];
+
+/*
+ * ISA DMA always starts at channel 0
+ */
+void __init isa_init_dma(void)
 {
         /*
          * Try to autodetect presence of an ISA DMA controller.
@@ -178,10 +183,10 @@ void __init isa_init_dma(dma_t *dma)
         outb(0xaa, 0x00);
 
         if (inb(0) == 0x55 && inb(0) == 0xaa) {
-                int chan, i;
+                unsigned int chan, i;
 
                 for (chan = 0; chan < 8; chan++) {
-                        dma[chan].d_ops = &isa_dma_ops;
+                        isa_dma[chan].d_ops = &isa_dma_ops;
                         isa_disable_dma(chan, NULL);
                 }
 
@@ -217,5 +222,12 @@ void __init isa_init_dma(dma_t *dma)
 
                 for (i = 0; i < ARRAY_SIZE(dma_resources); i++)
                         request_resource(&ioport_resource, dma_resources + i);
+
+                for (chan = 0; chan < 8; chan++) {
+                        int ret = isa_dma_add(chan, &isa_dma[chan]);
+                        if (ret)
+                                printk(KERN_ERR "ISADMA%u: unable to register: %d\n",
+                                        chan, ret);
+                }
         }
 }
diff --git a/arch/arm/kernel/dma.c b/arch/arm/kernel/dma.c
index 0ffea3fc22db..aab24f03ea14 100644
--- a/arch/arm/kernel/dma.c
+++ b/arch/arm/kernel/dma.c
@@ -23,16 +23,24 @@
 DEFINE_SPINLOCK(dma_spin_lock);
 EXPORT_SYMBOL(dma_spin_lock);
 
-static dma_t dma_chan[MAX_DMA_CHANNELS];
+static dma_t *dma_chan[MAX_DMA_CHANNELS];
 
 static inline dma_t *dma_channel(unsigned int chan)
 {
-        dma_t *dma = dma_chan + chan;
-
-        if (chan >= MAX_DMA_CHANNELS || !dma->d_ops)
+        if (chan >= MAX_DMA_CHANNELS)
                 return NULL;
 
-        return dma;
+        return dma_chan[chan];
+}
+
+int __init isa_dma_add(unsigned int chan, dma_t *dma)
+{
+        if (!dma->d_ops)
+                return -EINVAL;
+        if (dma_chan[chan])
+                return -EBUSY;
+        dma_chan[chan] = dma;
+        return 0;
 }
 
 /*
@@ -252,10 +260,3 @@ int get_dma_residue(unsigned int chan)
         return ret;
 }
 EXPORT_SYMBOL(get_dma_residue);
-
-static int __init init_dma(void)
-{
-        arch_dma_init(dma_chan);
-        return 0;
-}
-core_initcall(init_dma);