[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>

arch/arm/include/asm/mach/dma.h

@@ -48,10 +48,12 @@ struct dma_struct {
 	struct dma_ops	*d_ops;
 };
 
-/* Prototype: void arch_dma_init(dma)
- * Purpose  : Initialise architecture specific DMA
- * Params   : dma - pointer to array of DMA structures
+/*
+ * isa_dma_add - add an ISA-style DMA channel
  */
-extern void arch_dma_init(dma_t *dma);
+extern int isa_dma_add(unsigned int, dma_t *dma);
 
-extern void isa_init_dma(dma_t *dma);
+/*
+ * Add the ISA DMA controller.  Always takes channels 0-7.
+ */
+extern void isa_init_dma(void);

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);
+		}
 	}
 }

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);

arch/arm/mach-footbridge/dma.c

@@ -41,7 +41,7 @@ static struct dma_ops fb_dma_ops = {
 };
 #endif
 
-void __init arch_dma_init(dma_t *dma)
+static int __init fb_dma_init(void)
 {
 #if 0
 	dma[_DC21285_DMA(0)].d_ops = &fb_dma_ops;
@@ -49,6 +49,8 @@ void __init arch_dma_init(dma_t *dma)
 #endif
 #ifdef CONFIG_ISA_DMA
 	if (footbridge_cfn_mode())
-		isa_init_dma(dma + _ISA_DMA(0));
+		isa_init_dma();
 #endif
+	return 0;
 }
+core_initcall(fb_dma_init);

arch/arm/mach-rpc/dma.c

@@ -302,8 +302,22 @@ static struct dma_ops sound_dma_ops = {
 	.disable	= sound_enable_disable_dma,
 };
 
-void __init arch_dma_init(dma_t *dma)
+static dma_t iomd_dma[6];
+
+static dma_t floppy_dma = {
+	.dma_irq	= FIQ_FLOPPYDATA,
+	.d_ops		= &floppy_dma_ops,
+};
+
+static dma_t sound_dma = {
+	.d_ops		= &sound_dma_ops,
+};
+
+static int __init rpc_dma_init(void)
 {
+	unsigned int i;
+	int ret;
+
 	iomd_writeb(0, IOMD_IO0CR);
 	iomd_writeb(0, IOMD_IO1CR);
 	iomd_writeb(0, IOMD_IO2CR);
@@ -311,31 +325,39 @@ void __init arch_dma_init(dma_t *dma)
 
 	iomd_writeb(0xa0, IOMD_DMATCR);
 
-	dma[DMA_0].dma_base		= IOMD_IO0CURA;
-	dma[DMA_0].dma_irq		= IRQ_DMA0;
-	dma[DMA_0].d_ops		= &iomd_dma_ops;
-	dma[DMA_1].dma_base		= IOMD_IO1CURA;
-	dma[DMA_1].dma_irq		= IRQ_DMA1;
-	dma[DMA_1].d_ops		= &iomd_dma_ops;
-	dma[DMA_2].dma_base		= IOMD_IO2CURA;
-	dma[DMA_2].dma_irq		= IRQ_DMA2;
-	dma[DMA_2].d_ops		= &iomd_dma_ops;
-	dma[DMA_3].dma_base		= IOMD_IO3CURA;
-	dma[DMA_3].dma_irq		= IRQ_DMA3;
-	dma[DMA_3].d_ops		= &iomd_dma_ops;
-	dma[DMA_S0].dma_base		= IOMD_SD0CURA;
-	dma[DMA_S0].dma_irq		= IRQ_DMAS0;
-	dma[DMA_S0].d_ops		= &iomd_dma_ops;
-	dma[DMA_S1].dma_base		= IOMD_SD1CURA;
-	dma[DMA_S1].dma_irq		= IRQ_DMAS1;
-	dma[DMA_S1].d_ops		= &iomd_dma_ops;
-	dma[DMA_VIRTUAL_FLOPPY].dma_irq	= FIQ_FLOPPYDATA;
-	dma[DMA_VIRTUAL_FLOPPY].d_ops	= &floppy_dma_ops;
-	dma[DMA_VIRTUAL_SOUND].d_ops	= &sound_dma_ops;
-
 	/*
 	 * Setup DMA channels 2,3 to be for podules
 	 * and channels 0,1 for internal devices
 	 */
 	iomd_writeb(DMA_EXT_IO3|DMA_EXT_IO2, IOMD_DMAEXT);
+
+	iomd_dma[DMA_0].dma_base	= IOMD_IO0CURA;
+	iomd_dma[DMA_0].dma_irq		= IRQ_DMA0;
+	iomd_dma[DMA_1].dma_base	= IOMD_IO1CURA;
+	iomd_dma[DMA_1].dma_irq		= IRQ_DMA1;
+	iomd_dma[DMA_2].dma_base	= IOMD_IO2CURA;
+	iomd_dma[DMA_2].dma_irq		= IRQ_DMA2;
+	iomd_dma[DMA_3].dma_base	= IOMD_IO3CURA;
+	iomd_dma[DMA_3].dma_irq		= IRQ_DMA3;
+	iomd_dma[DMA_S0].dma_base	= IOMD_SD0CURA;
+	iomd_dma[DMA_S0].dma_irq	= IRQ_DMAS0;
+	iomd_dma[DMA_S1].dma_base	= IOMD_SD1CURA;
+	iomd_dma[DMA_S1].dma_irq	= IRQ_DMAS1;
+
+	for (i = DMA_0; i <= DMA_S1; i++) {
+		iomd_dma[i].d_ops = &iomd_dma_ops;
+
+		ret = isa_dma_add(i, &iomd_dma[i]);
+		if (ret)
+			printk("IOMDDMA%u: unable to register: %d\n", i, ret);
+	}
+
+	ret = isa_dma_add(DMA_VIRTUAL_FLOPPY, &floppy_dma);
+	if (ret)
+		printk("IOMDFLOPPY: unable to register: %d\n", ret);
+	ret = isa_dma_add(DMA_VIRTUAL_SOUND, &sound_dma);
+	if (ret)
+		printk("IOMDSOUND: unable to register: %d\n", ret);
+	return 0;
 }
+core_initcall(rpc_dma_init);

arch/arm/mach-shark/dma.c

@@ -13,9 +13,11 @@
 #include <asm/dma.h>
 #include <asm/mach/dma.h>
 
-void __init arch_dma_init(dma_t *dma)
+static int __init shark_dma_init(void)
 {
 #ifdef CONFIG_ISA_DMA
-	isa_init_dma(dma);
+	isa_init_dma();
 #endif
+	return 0;
 }
+core_initcall(shark_dma_init);