Merge branch 'sa1100-for-next'; commit 'riscpc^{/ARM: riscpc: enable chained scatterlist support}' into for-arm-soc

11 files changed, 160 insertions, 172 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 70aebb6d2905..fe31c97c74ea 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -528,7 +528,7 @@ config ARCH_RPC
 	select ARCH_ACORN
 	select ARCH_MAY_HAVE_PC_FDC
 	select ARCH_SPARSEMEM_ENABLE
-	select ARCH_USES_GETTIMEOFFSET
+	select ARM_HAS_SG_CHAIN
 	select CPU_SA110
 	select FIQ
 	select HAVE_IDE
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile
index 0bff0176db2c..b25c54585048 100644
--- a/arch/arm/lib/Makefile
+++ b/arch/arm/lib/Makefile
@@ -31,7 +31,6 @@ else
 endif
 
 ifeq ($(CONFIG_ARCH_RPC),y)
-  lib-y				+= ecard.o io-acorn.o floppydma.o
   AFLAGS_delay-loop.o		+= -march=armv4
 endif
 
diff --git a/arch/arm/mach-rpc/Makefile b/arch/arm/mach-rpc/Makefile
index 056ef5460290..90a645a18444 100644
--- a/arch/arm/mach-rpc/Makefile
+++ b/arch/arm/mach-rpc/Makefile
@@ -5,4 +5,5 @@
 
 # Object file lists.
 
-obj-y			:= dma.o ecard.o fiq.o irq.o riscpc.o time.o
+obj-y	:=dma.o ecard.o ecard-loader.o fiq.o floppydma.o io-acorn.o irq.o \
+	  riscpc.o time.o
diff --git a/arch/arm/mach-rpc/dma.c b/arch/arm/mach-rpc/dma.c
index f2703ca17954..e221f6bb935f 100644
--- a/arch/arm/mach-rpc/dma.c
+++ b/arch/arm/mach-rpc/dma.c
@@ -27,10 +27,11 @@
 
 struct iomd_dma {
 	struct dma_struct	dma;
-	unsigned int		state;
-	unsigned long		base;		/* Controller base address */
+	void __iomem		*base;		/* Controller base address */
 	int			irq;		/* Controller IRQ */
-	struct scatterlist	cur_sg;		/* Current controller buffer */
+	unsigned int		state;
+	dma_addr_t		cur_addr;
+	unsigned int		cur_len;
 	dma_addr_t		dma_addr;
 	unsigned int		dma_len;
 };
@@ -53,13 +54,13 @@ typedef enum {
 #define CR	(IOMD_IO0CR - IOMD_IO0CURA)
 #define ST	(IOMD_IO0ST - IOMD_IO0CURA)
 
-static void iomd_get_next_sg(struct scatterlist *sg, struct iomd_dma *idma)
+static void iomd_get_next_sg(struct iomd_dma *idma)
 {
 	unsigned long end, offset, flags = 0;
 
 	if (idma->dma.sg) {
-		sg->dma_address = idma->dma_addr;
-		offset = sg->dma_address & ~PAGE_MASK;
+		idma->cur_addr = idma->dma_addr;
+		offset = idma->cur_addr & ~PAGE_MASK;
 
 		end = offset + idma->dma_len;
 
@@ -69,7 +70,7 @@ static void iomd_get_next_sg(struct scatterlist *sg, struct iomd_dma *idma)
 		if (offset + TRANSFER_SIZE >= end)
 			flags |= DMA_END_L;
 
-		sg->length = end - TRANSFER_SIZE;
+		idma->cur_len = end - TRANSFER_SIZE;
 
 		idma->dma_len -= end - offset;
 		idma->dma_addr += end - offset;
@@ -87,52 +88,49 @@ static void iomd_get_next_sg(struct scatterlist *sg, struct iomd_dma *idma)
 		}
 	} else {
 		flags = DMA_END_S | DMA_END_L;
-		sg->dma_address = 0;
-		sg->length = 0;
+		idma->cur_addr = 0;
+		idma->cur_len = 0;
 	}
 
-	sg->length |= flags;
+	idma->cur_len |= flags;
 }
 
 static irqreturn_t iomd_dma_handle(int irq, void *dev_id)
 {
 	struct iomd_dma *idma = dev_id;
-	unsigned long base = idma->base;
+	void __iomem *base = idma->base;
+	unsigned int state = idma->state;
+	unsigned int status, cur, end;
 
 	do {
-		unsigned int status;
-
-		status = iomd_readb(base + ST);
+		status = readb(base + ST);
 		if (!(status & DMA_ST_INT))
-			return IRQ_HANDLED;
-
-		if ((idma->state ^ status) & DMA_ST_AB)
-			iomd_get_next_sg(&idma->cur_sg, idma);
-
-		switch (status & (DMA_ST_OFL | DMA_ST_AB)) {
-		case DMA_ST_OFL:			/* OIA */
-		case DMA_ST_AB:				/* .IB */
-			iomd_writel(idma->cur_sg.dma_address, base + CURA);
-			iomd_writel(idma->cur_sg.length, base + ENDA);
-			idma->state = DMA_ST_AB;
-			break;
-
-		case DMA_ST_OFL | DMA_ST_AB:		/* OIB */
-		case 0:					/* .IA */
-			iomd_writel(idma->cur_sg.dma_address, base + CURB);
-			iomd_writel(idma->cur_sg.length, base + ENDB);
-			idma->state = 0;
-			break;
+			goto out;
+
+		if ((state ^ status) & DMA_ST_AB)
+			iomd_get_next_sg(idma);
+
+		// This efficiently implements state = OFL != AB ? AB : 0
+		state = ((status >> 2) ^ status) & DMA_ST_AB;
+		if (state) {
+			cur = CURA;
+			end = ENDA;
+		} else {
+			cur = CURB;
+			end = ENDB;
 		}
+		writel(idma->cur_addr, base + cur);
+		writel(idma->cur_len, base + end);
 
 		if (status & DMA_ST_OFL &&
-		    idma->cur_sg.length == (DMA_END_S|DMA_END_L))
+		    idma->cur_len == (DMA_END_S|DMA_END_L))
 			break;
 	} while (1);
 
-	idma->state = ~DMA_ST_AB;
-	disable_irq(irq);
-
+	state = ~DMA_ST_AB;
+	disable_irq_nosync(irq);
+out:
+	idma->state = state;
 	return IRQ_HANDLED;
 }
 
@@ -160,7 +158,7 @@ static struct device isa_dma_dev = {
 static void iomd_enable_dma(unsigned int chan, dma_t *dma)
 {
 	struct iomd_dma *idma = container_of(dma, struct iomd_dma, dma);
-	unsigned long dma_base = idma->base;
+	void __iomem *base = idma->base;
 	unsigned int ctrl = TRANSFER_SIZE | DMA_CR_E;
 
 	if (idma->dma.invalid) {
@@ -180,27 +178,30 @@ static void iomd_enable_dma(unsigned int chan, dma_t *dma)
 				DMA_FROM_DEVICE : DMA_TO_DEVICE);
 		}
 
-		iomd_writeb(DMA_CR_C, dma_base + CR);
+		idma->dma_addr = idma->dma.sg->dma_address;
+		idma->dma_len = idma->dma.sg->length;
+
+		writeb(DMA_CR_C, base + CR);
 		idma->state = DMA_ST_AB;
 	}
 
 	if (idma->dma.dma_mode == DMA_MODE_READ)
 		ctrl |= DMA_CR_D;
 
-	iomd_writeb(ctrl, dma_base + CR);
+	writeb(ctrl, base + CR);
 	enable_irq(idma->irq);
 }
 
 static void iomd_disable_dma(unsigned int chan, dma_t *dma)
 {
 	struct iomd_dma *idma = container_of(dma, struct iomd_dma, dma);
-	unsigned long dma_base = idma->base;
+	void __iomem *base = idma->base;
 	unsigned long flags;
 
 	local_irq_save(flags);
 	if (idma->state != ~DMA_ST_AB)
 		disable_irq(idma->irq);
-	iomd_writeb(0, dma_base + CR);
+	writeb(0, base + CR);
 	local_irq_restore(flags);
 }
 
@@ -363,17 +364,17 @@ static int __init rpc_dma_init(void)
 	 */
 	iomd_writeb(DMA_EXT_IO3|DMA_EXT_IO2, IOMD_DMAEXT);
 
-	iomd_dma[DMA_0].base	= IOMD_IO0CURA;
+	iomd_dma[DMA_0].base	= IOMD_BASE + IOMD_IO0CURA;
 	iomd_dma[DMA_0].irq	= IRQ_DMA0;
-	iomd_dma[DMA_1].base	= IOMD_IO1CURA;
+	iomd_dma[DMA_1].base	= IOMD_BASE + IOMD_IO1CURA;
 	iomd_dma[DMA_1].irq	= IRQ_DMA1;
-	iomd_dma[DMA_2].base	= IOMD_IO2CURA;
+	iomd_dma[DMA_2].base	= IOMD_BASE + IOMD_IO2CURA;
 	iomd_dma[DMA_2].irq	= IRQ_DMA2;
-	iomd_dma[DMA_3].base	= IOMD_IO3CURA;
+	iomd_dma[DMA_3].base	= IOMD_BASE + IOMD_IO3CURA;
 	iomd_dma[DMA_3].irq	= IRQ_DMA3;
-	iomd_dma[DMA_S0].base	= IOMD_SD0CURA;
+	iomd_dma[DMA_S0].base	= IOMD_BASE + IOMD_SD0CURA;
 	iomd_dma[DMA_S0].irq	= IRQ_DMAS0;
-	iomd_dma[DMA_S1].base	= IOMD_SD1CURA;
+	iomd_dma[DMA_S1].base	= IOMD_BASE + IOMD_SD1CURA;
 	iomd_dma[DMA_S1].irq	= IRQ_DMAS1;
 
 	for (i = DMA_0; i <= DMA_S1; i++) {
diff --git a/arch/arm/lib/ecard.S b/arch/arm/mach-rpc/ecard-loader.S
index e6057fa851bb..e6057fa851bb 100644
--- a/arch/arm/lib/ecard.S
+++ b/arch/arm/mach-rpc/ecard-loader.S
diff --git a/arch/arm/mach-rpc/ecard.c b/arch/arm/mach-rpc/ecard.c
index 04b2f22c2739..eec5ecd6e948 100644
--- a/arch/arm/mach-rpc/ecard.c
+++ b/arch/arm/mach-rpc/ecard.c
@@ -70,17 +70,21 @@ struct expcard_blacklist {
 	unsigned short	 manufacturer;
 	unsigned short	 product;
 	const char	*type;
+	void (*init)(ecard_t *ec);
 };
 
 static ecard_t *cards;
 static ecard_t *slot_to_expcard[MAX_ECARDS];
 static unsigned int ectcr;
 
+static void atomwide_3p_quirk(ecard_t *ec);
+
 /* List of descriptions of cards which don't have an extended
  * identification, or chunk directories containing a description.
  */
 static struct expcard_blacklist __initdata blacklist[] = {
-	{ MANU_ACORN, PROD_ACORN_ETHER1, "Acorn Ether1" }
+	{ MANU_ACORN, PROD_ACORN_ETHER1, "Acorn Ether1" },
+	{ MANU_ATOMWIDE, PROD_ATOMWIDE_3PSERIAL, NULL, atomwide_3p_quirk },
 };
 
 asmlinkage extern int
@@ -496,18 +500,21 @@ static void ecard_dump_irq_state(void)
 	printk("Expansion card IRQ state:\n");
 
 	for (ec = cards; ec; ec = ec->next) {
+		const char *claimed;
+
 		if (ec->slot_no == 8)
 			continue;
 
-		printk("  %d: %sclaimed, ",
-		       ec->slot_no, ec->claimed ? "" : "not ");
+		claimed = ec->claimed ? "" : "not ";
 
 		if (ec->ops && ec->ops->irqpending &&
 		    ec->ops != &ecard_default_ops)
-			printk("irq %spending\n",
+			printk("  %d: %sclaimed irq %spending\n",
+			       ec->slot_no, claimed,
 			       ec->ops->irqpending(ec) ? "" : "not ");
 		else
-			printk("irqaddr %p, mask = %02X, status = %02X\n",
+			printk("  %d: %sclaimed irqaddr %p, mask = %02X, status = %02X\n",
+			       ec->slot_no, claimed,
 			       ec->irqaddr, ec->irqmask, readb(ec->irqaddr));
 	}
 }
@@ -868,6 +875,16 @@ void __iomem *ecardm_iomap(struct expansion_card *ec, unsigned int res,
 }
 EXPORT_SYMBOL(ecardm_iomap);
 
+static void atomwide_3p_quirk(ecard_t *ec)
+{
+	void __iomem *addr = __ecard_address(ec, ECARD_IOC, ECARD_SYNC);
+	unsigned int i;
+
+	/* Disable interrupts on each port */
+	for (i = 0x2000; i <= 0x2800; i += 0x0400)
+		writeb(0, addr + i + 4);	
+}
+
 /*
  * Probe for an expansion card.
  *
@@ -924,7 +941,10 @@ static int __init ecard_probe(int slot, unsigned irq, card_type_t type)
 	for (i = 0; i < ARRAY_SIZE(blacklist); i++)
 		if (blacklist[i].manufacturer == ec->cid.manufacturer &&
 		    blacklist[i].product == ec->cid.product) {
-			ec->card_desc = blacklist[i].type;
+		    	if (blacklist[i].type)
+				ec->card_desc = blacklist[i].type;
+			if (blacklist[i].init)
+				blacklist[i].init(ec);
 			break;
 		}
 
diff --git a/arch/arm/lib/floppydma.S b/arch/arm/mach-rpc/floppydma.S
index de68d3b343e3..de68d3b343e3 100644
--- a/arch/arm/lib/floppydma.S
+++ b/arch/arm/mach-rpc/floppydma.S
diff --git a/arch/arm/mach-rpc/include/mach/uncompress.h b/arch/arm/mach-rpc/include/mach/uncompress.h
index 654a6f3f2547..edc1961e8d1e 100644
--- a/arch/arm/mach-rpc/include/mach/uncompress.h
+++ b/arch/arm/mach-rpc/include/mach/uncompress.h
@@ -118,29 +118,22 @@ static void arch_decomp_setup(void)
 	struct tag *t = (struct tag *)params;
 	unsigned int nr_pages = 0, page_size = PAGE_SIZE;
 
-	if (t->hdr.tag == ATAG_CORE)
-	{
-		for (; t->hdr.size; t = tag_next(t))
-		{
-			if (t->hdr.tag == ATAG_VIDEOTEXT)
-			{
+	if (t->hdr.tag == ATAG_CORE) {
+		for (; t->hdr.size; t = tag_next(t)) {
+			if (t->hdr.tag == ATAG_VIDEOTEXT) {
 				video_num_rows = t->u.videotext.video_lines;
 				video_num_cols = t->u.videotext.video_cols;
-				bytes_per_char_h = t->u.videotext.video_points;
-				bytes_per_char_v = t->u.videotext.video_points;
 				video_x = t->u.videotext.x;
 				video_y = t->u.videotext.y;
-			}
-
-			if (t->hdr.tag == ATAG_MEM)
-			{
+			} else if (t->hdr.tag == ATAG_VIDEOLFB) {
+				bytes_per_char_h = t->u.videolfb.lfb_depth;
+				bytes_per_char_v = 8;
+			} else if (t->hdr.tag == ATAG_MEM) {
 				page_size = PAGE_SIZE;
 				nr_pages += (t->u.mem.size / PAGE_SIZE);
 			}
 		}
-	}
-	else
-	{
+	} else {
 		nr_pages = params->nr_pages;
 		page_size = params->page_size;
 		video_num_rows = params->video_num_rows;
diff --git a/arch/arm/lib/io-acorn.S b/arch/arm/mach-rpc/io-acorn.S
index 69719bad674d..69719bad674d 100644
--- a/arch/arm/lib/io-acorn.S
+++ b/arch/arm/mach-rpc/io-acorn.S
diff --git a/arch/arm/mach-rpc/irq.c b/arch/arm/mach-rpc/irq.c
index b8a61cb11207..803aeb126f0e 100644
--- a/arch/arm/mach-rpc/irq.c
+++ b/arch/arm/mach-rpc/irq.c
@@ -8,117 +8,71 @@
 #include <asm/irq.h>
 #include <asm/fiq.h>
 
-static void iomd_ack_irq_a(struct irq_data *d)
-{
-	unsigned int val, mask;
-
-	mask = 1 << d->irq;
-	val = iomd_readb(IOMD_IRQMASKA);
-	iomd_writeb(val & ~mask, IOMD_IRQMASKA);
-	iomd_writeb(mask, IOMD_IRQCLRA);
-}
-
-static void iomd_mask_irq_a(struct irq_data *d)
-{
-	unsigned int val, mask;
+// These are offsets from the stat register for each IRQ bank
+#define STAT	0x00
+#define REQ	0x04
+#define CLR	0x04
+#define MASK	0x08
 
-	mask = 1 << d->irq;
-	val = iomd_readb(IOMD_IRQMASKA);
-	iomd_writeb(val & ~mask, IOMD_IRQMASKA);
-}
-
-static void iomd_unmask_irq_a(struct irq_data *d)
+static void __iomem *iomd_get_base(struct irq_data *d)
 {
-	unsigned int val, mask;
+	void *cd = irq_data_get_irq_chip_data(d);
 
-	mask = 1 << d->irq;
-	val = iomd_readb(IOMD_IRQMASKA);
-	iomd_writeb(val | mask, IOMD_IRQMASKA);
+	return (void __iomem *)(unsigned long)cd;
 }
 
-static struct irq_chip iomd_a_chip = {
-	.irq_ack	= iomd_ack_irq_a,
-	.irq_mask	= iomd_mask_irq_a,
-	.irq_unmask	= iomd_unmask_irq_a,
-};
-
-static void iomd_mask_irq_b(struct irq_data *d)
+static void iomd_set_base_mask(unsigned int irq, void __iomem *base, u32 mask)
 {
-	unsigned int val, mask;
+	struct irq_data *d = irq_get_irq_data(irq);
 
-	mask = 1 << (d->irq & 7);
-	val = iomd_readb(IOMD_IRQMASKB);
-	iomd_writeb(val & ~mask, IOMD_IRQMASKB);
+	d->mask = mask;
+	irq_set_chip_data(irq, (void *)(unsigned long)base);
 }
 
-static void iomd_unmask_irq_b(struct irq_data *d)
+static void iomd_irq_mask_ack(struct irq_data *d)
 {
-	unsigned int val, mask;
+	void __iomem *base = iomd_get_base(d);
+	unsigned int val, mask = d->mask;
 
-	mask = 1 << (d->irq & 7);
-	val = iomd_readb(IOMD_IRQMASKB);
-	iomd_writeb(val | mask, IOMD_IRQMASKB);
+	val = readb(base + MASK);
+	writeb(val & ~mask, base + MASK);
+	writeb(mask, base + CLR);
 }
 
-static struct irq_chip iomd_b_chip = {
-	.irq_ack	= iomd_mask_irq_b,
-	.irq_mask	= iomd_mask_irq_b,
-	.irq_unmask	= iomd_unmask_irq_b,
-};
-
-static void iomd_mask_irq_dma(struct irq_data *d)
+static void iomd_irq_mask(struct irq_data *d)
 {
-	unsigned int val, mask;
+	void __iomem *base = iomd_get_base(d);
+	unsigned int val, mask = d->mask;
 
-	mask = 1 << (d->irq & 7);
-	val = iomd_readb(IOMD_DMAMASK);
-	iomd_writeb(val & ~mask, IOMD_DMAMASK);
+	val = readb(base + MASK);
+	writeb(val & ~mask, base + MASK);
 }
 
-static void iomd_unmask_irq_dma(struct irq_data *d)
+static void iomd_irq_unmask(struct irq_data *d)
 {
-	unsigned int val, mask;
+	void __iomem *base = iomd_get_base(d);
+	unsigned int val, mask = d->mask;
 
-	mask = 1 << (d->irq & 7);
-	val = iomd_readb(IOMD_DMAMASK);
-	iomd_writeb(val | mask, IOMD_DMAMASK);
+	val = readb(base + MASK);
+	writeb(val | mask, base + MASK);
 }
 
-static struct irq_chip iomd_dma_chip = {
-	.irq_ack	= iomd_mask_irq_dma,
-	.irq_mask	= iomd_mask_irq_dma,
-	.irq_unmask	= iomd_unmask_irq_dma,
+static struct irq_chip iomd_chip_clr = {
+	.irq_mask_ack	= iomd_irq_mask_ack,
+	.irq_mask	= iomd_irq_mask,
+	.irq_unmask	= iomd_irq_unmask,
 };
 
-static void iomd_mask_irq_fiq(struct irq_data *d)
-{
-	unsigned int val, mask;
-
-	mask = 1 << (d->irq & 7);
-	val = iomd_readb(IOMD_FIQMASK);
-	iomd_writeb(val & ~mask, IOMD_FIQMASK);
-}
-
-static void iomd_unmask_irq_fiq(struct irq_data *d)
-{
-	unsigned int val, mask;
-
-	mask = 1 << (d->irq & 7);
-	val = iomd_readb(IOMD_FIQMASK);
-	iomd_writeb(val | mask, IOMD_FIQMASK);
-}
-
-static struct irq_chip iomd_fiq_chip = {
-	.irq_ack	= iomd_mask_irq_fiq,
-	.irq_mask	= iomd_mask_irq_fiq,
-	.irq_unmask	= iomd_unmask_irq_fiq,
+static struct irq_chip iomd_chip_noclr = {
+	.irq_mask	= iomd_irq_mask,
+	.irq_unmask	= iomd_irq_unmask,
 };
 
 extern unsigned char rpc_default_fiq_start, rpc_default_fiq_end;
 
 void __init rpc_init_irq(void)
 {
-	unsigned int irq, clr, set = 0;
+	unsigned int irq, clr, set;
 
 	iomd_writeb(0, IOMD_IRQMASKA);
 	iomd_writeb(0, IOMD_IRQMASKB);
@@ -130,6 +84,7 @@ void __init rpc_init_irq(void)
 
 	for (irq = 0; irq < NR_IRQS; irq++) {
 		clr = IRQ_NOREQUEST;
+		set = 0;
 
 		if (irq <= 6 || (irq >= 9 && irq <= 15))
 			clr |= IRQ_NOPROBE;
@@ -140,30 +95,37 @@ void __init rpc_init_irq(void)
 
 		switch (irq) {
 		case 0 ... 7:
-			irq_set_chip_and_handler(irq, &iomd_a_chip,
+			irq_set_chip_and_handler(irq, &iomd_chip_clr,
 						 handle_level_irq);
 			irq_modify_status(irq, clr, set);
+			iomd_set_base_mask(irq, IOMD_BASE + IOMD_IRQSTATA,
+					   BIT(irq));
 			break;
 
 		case 8 ... 15:
-			irq_set_chip_and_handler(irq, &iomd_b_chip,
+			irq_set_chip_and_handler(irq, &iomd_chip_noclr,
 						 handle_level_irq);
 			irq_modify_status(irq, clr, set);
+			iomd_set_base_mask(irq, IOMD_BASE + IOMD_IRQSTATB,
+					   BIT(irq - 8));
 			break;
 
 		case 16 ... 21:
-			irq_set_chip_and_handler(irq, &iomd_dma_chip,
+			irq_set_chip_and_handler(irq, &iomd_chip_noclr,
 						 handle_level_irq);
 			irq_modify_status(irq, clr, set);
+			iomd_set_base_mask(irq, IOMD_BASE + IOMD_DMASTAT,
+					   BIT(irq - 16));
 			break;
 
 		case 64 ... 71:
-			irq_set_chip(irq, &iomd_fiq_chip);
+			irq_set_chip(irq, &iomd_chip_noclr);
 			irq_modify_status(irq, clr, set);
+			iomd_set_base_mask(irq, IOMD_BASE + IOMD_FIQSTAT,
+					   BIT(irq - 64));
 			break;
 		}
 	}
 
 	init_FIQ(FIQ_START);
 }
-
diff --git a/arch/arm/mach-rpc/time.c b/arch/arm/mach-rpc/time.c
index 2689771c1d38..1c84efc9db1f 100644
--- a/arch/arm/mach-rpc/time.c
+++ b/arch/arm/mach-rpc/time.c
@@ -13,7 +13,7 @@
  *   04-Dec-1997	RMK	Updated for new arch/arm/time.c
  *   13=Jun-2004	DS	Moved to arch/arm/common b/c shared w/CLPS7500
  */
-#include <linux/timex.h>
+#include <linux/clocksource.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
@@ -27,11 +27,15 @@
 #define RPC_CLOCK_FREQ 2000000
 #define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
 
-static u32 ioc_timer_gettimeoffset(void)
+static u32 ioc_time;
+
+static u64 ioc_timer_read(struct clocksource *cs)
 {
 	unsigned int count1, count2, status;
-	long offset;
+	unsigned long flags;
+	u32 ticks;
 
+	local_irq_save(flags);
 	ioc_writeb (0, IOC_T0LATCH);
 	barrier ();
 	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
@@ -41,27 +45,34 @@ static u32 ioc_timer_gettimeoffset(void)
 	ioc_writeb (0, IOC_T0LATCH);
 	barrier ();
 	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
+	ticks = ioc_time + RPC_LATCH - count2;
+	local_irq_restore(flags);
 
-	offset = count2;
 	if (count2 < count1) {
 		/*
-		 * We have not had an interrupt between reading count1
-		 * and count2.
+		 * The timer has not reloaded between reading count1 and
+		 * count2, check whether an interrupt was actually pending.
 		 */
 		if (status & (1 << 5))
-			offset -= RPC_LATCH;
+			ticks += RPC_LATCH;
 	} else if (count2 > count1) {
 		/*
-		 * We have just had another interrupt between reading
-		 * count1 and count2.
+		 * The timer has reloaded, so count2 indicates the new
+		 * count since the wrap.  The interrupt would not have
+		 * been processed, so add the missed ticks.
 		 */
-		offset -= RPC_LATCH;
+		ticks += RPC_LATCH;
 	}
 
-	offset = (RPC_LATCH - offset) * (tick_nsec / 1000);
-	return DIV_ROUND_CLOSEST(offset, RPC_LATCH) * 1000;
+	return ticks;
 }
 
+static struct clocksource ioctime_clocksource = {
+	.read = ioc_timer_read,
+	.mask = CLOCKSOURCE_MASK(32),
+	.rating = 100,
+};
+
 void __init ioctime_init(void)
 {
 	ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
@@ -72,6 +83,7 @@ void __init ioctime_init(void)
 static irqreturn_t
 ioc_timer_interrupt(int irq, void *dev_id)
 {
+	ioc_time += RPC_LATCH;
 	timer_tick();
 	return IRQ_HANDLED;
 }
@@ -86,7 +98,7 @@ static struct irqaction ioc_timer_irq = {
  */
 void __init ioc_timer_init(void)
 {
-	arch_gettimeoffset = ioc_timer_gettimeoffset;
+	WARN_ON(clocksource_register_hz(&ioctime_clocksource, RPC_CLOCK_FREQ));
 	ioctime_init();
 	setup_irq(IRQ_TIMER0, &ioc_timer_irq);
 }