arch/cris/arch-v32/mach-fs/arbiter.c - arm/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Memory arbiter functions. Allocates bandwidth through the
  * arbiter and sets up arbiter breakpoints.
  *
  * The algorithm first assigns slots to the clients that has specified
  * bandwidth (e.g. ethernet) and then the remaining slots are divided
  * on all the active clients.
  *
  * Copyright (c) 2004-2007 Axis Communications AB.
  */

 #include <hwregs/reg_map.h>
 #include <hwregs/reg_rdwr.h>
 #include <hwregs/marb_defs.h>
 #include <arbiter.h>
 #include <hwregs/intr_vect.h>
 #include <linux/interrupt.h>
 #include <linux/signal.h>
 #include <linux/errno.h>
 #include <linux/spinlock.h>
 #include <asm/io.h>
 #include <asm/irq_regs.h>

 struct crisv32_watch_entry {
 	unsigned long instance;
 	watch_callback *cb;
 	unsigned long start;
 	unsigned long end;
 	int used;
 };

 #define NUMBER_OF_BP 4
 #define NBR_OF_CLIENTS 14
 #define NBR_OF_SLOTS 64
 #define SDRAM_BANDWIDTH 100000000	/* Some kind of expected value */
 #define INTMEM_BANDWIDTH 400000000
 #define NBR_OF_REGIONS 2

 static struct crisv32_watch_entry watches[NUMBER_OF_BP] = {
 	{regi_marb_bp0},
 	{regi_marb_bp1},
 	{regi_marb_bp2},
 	{regi_marb_bp3}
 };

 static u8 requested_slots[NBR_OF_REGIONS][NBR_OF_CLIENTS];
 static u8 active_clients[NBR_OF_REGIONS][NBR_OF_CLIENTS];
 static int max_bandwidth[NBR_OF_REGIONS] =
     { SDRAM_BANDWIDTH, INTMEM_BANDWIDTH };

 DEFINE_SPINLOCK(arbiter_lock);

 static irqreturn_t crisv32_arbiter_irq(int irq, void *dev_id);

 /*
  * "I'm the arbiter, I know the score.
  *  From square one I'll be watching all 64."
  * (memory arbiter slots, that is)
  *
  *  Or in other words:
  * Program the memory arbiter slots for "region" according to what's
  * in requested_slots[] and active_clients[], while minimizing
  * latency. A caller may pass a non-zero positive amount for
  * "unused_slots", which must then be the unallocated, remaining
  * number of slots, free to hand out to any client.
  */

 static void crisv32_arbiter_config(int region, int unused_slots)
 {
 	int slot;
 	int client;
 	int interval = 0;

 	/*
 	 * This vector corresponds to the hardware arbiter slots (see
 	 * the hardware documentation for semantics). We initialize
 	 * each slot with a suitable sentinel value outside the valid
 	 * range {0 .. NBR_OF_CLIENTS - 1} and replace them with
 	 * client indexes. Then it's fed to the hardware.
 	 */
 	s8 val[NBR_OF_SLOTS];

 	for (slot = 0; slot < NBR_OF_SLOTS; slot++)
 		val[slot] = -1;

 	for (client = 0; client < NBR_OF_CLIENTS; client++) {
 		int pos;
 		/* Allocate the requested non-zero number of slots, but
 		 * also give clients with zero-requests one slot each
 		 * while stocks last. We do the latter here, in client
 		 * order. This makes sure zero-request clients are the
 		 * first to get to any spare slots, else those slots
 		 * could, when bandwidth is allocated close to the limit,
 		 * all be allocated to low-index non-zero-request clients
 		 * in the default-fill loop below. Another positive but
 		 * secondary effect is a somewhat better spread of the
 		 * zero-bandwidth clients in the vector, avoiding some of
 		 * the latency that could otherwise be caused by the
 		 * partitioning of non-zero-bandwidth clients at low
 		 * indexes and zero-bandwidth clients at high
 		 * indexes. (Note that this spreading can only affect the
 		 * unallocated bandwidth.)  All the above only matters for
 		 * memory-intensive situations, of course.
 		 */
 		if (!requested_slots[region][client]) {
 			/*
 			 * Skip inactive clients. Also skip zero-slot
 			 * allocations in this pass when there are no known
 			 * free slots.
 			 */
 			if (!active_clients[region][client]
 			    || unused_slots <= 0)
 				continue;

 			unused_slots--;

 			/* Only allocate one slot for this client. */
 			interval = NBR_OF_SLOTS;
 		} else
 			interval =
 			    NBR_OF_SLOTS / requested_slots[region][client];

 		pos = 0;
 		while (pos < NBR_OF_SLOTS) {
 			if (val[pos] >= 0)
 				pos++;
 			else {
 				val[pos] = client;
 				pos += interval;
 			}
 		}
 	}

 	client = 0;
 	for (slot = 0; slot < NBR_OF_SLOTS; slot++) {
 		/*
 		 * Allocate remaining slots in round-robin
 		 * client-number order for active clients. For this
 		 * pass, we ignore requested bandwidth and previous
 		 * allocations.
 		 */
 		if (val[slot] < 0) {
 			int first = client;
 			while (!active_clients[region][client]) {
 				client = (client + 1) % NBR_OF_CLIENTS;
 				if (client == first)
 					break;
 			}
 			val[slot] = client;
 			client = (client + 1) % NBR_OF_CLIENTS;
 		}
 		if (region == EXT_REGION)
 			REG_WR_INT_VECT(marb, regi_marb, rw_ext_slots, slot,
 					val[slot]);
 		else if (region == INT_REGION)
 			REG_WR_INT_VECT(marb, regi_marb, rw_int_slots, slot,
 					val[slot]);
 	}
 }

 extern char _stext[], _etext[];

 static void crisv32_arbiter_init(void)
 {
 	static int initialized;

 	if (initialized)
 		return;

 	initialized = 1;

 	/*
 	 * CPU caches are always set to active, but with zero
 	 * bandwidth allocated. It should be ok to allocate zero
 	 * bandwidth for the caches, because DMA for other channels
 	 * will supposedly finish, once their programmed amount is
 	 * done, and then the caches will get access according to the
 	 * "fixed scheme" for unclaimed slots. Though, if for some
 	 * use-case somewhere, there's a maximum CPU latency for
 	 * e.g. some interrupt, we have to start allocating specific
 	 * bandwidth for the CPU caches too.
 	 */
 	active_clients[EXT_REGION][10] = active_clients[EXT_REGION][11] = 1;
 	crisv32_arbiter_config(EXT_REGION, 0);
 	crisv32_arbiter_config(INT_REGION, 0);

 	if (request_irq(MEMARB_INTR_VECT, crisv32_arbiter_irq, 0,
 			"arbiter", NULL))
 		printk(KERN_ERR "Couldn't allocate arbiter IRQ\n");

 #ifndef CONFIG_ETRAX_KGDB
 	/* Global watch for writes to kernel text segment. */
 	crisv32_arbiter_watch(virt_to_phys(_stext), _etext - _stext,
 			      arbiter_all_clients, arbiter_all_write, NULL);
 #endif
 }

 /* Main entry for bandwidth allocation. */

 int crisv32_arbiter_allocate_bandwidth(int client, int region,
 				       unsigned long bandwidth)
 {
 	int i;
 	int total_assigned = 0;
 	int total_clients = 0;
 	int req;

 	crisv32_arbiter_init();

 	for (i = 0; i < NBR_OF_CLIENTS; i++) {
 		total_assigned += requested_slots[region][i];
 		total_clients += active_clients[region][i];
 	}

 	/* Avoid division by 0 for 0-bandwidth requests. */
 	req = bandwidth == 0
 	    ? 0 : NBR_OF_SLOTS / (max_bandwidth[region] / bandwidth);

 	/*
 	 * We make sure that there are enough slots only for non-zero
 	 * requests. Requesting 0 bandwidth *may* allocate slots,
 	 * though if all bandwidth is allocated, such a client won't
 	 * get any and will have to rely on getting memory access
 	 * according to the fixed scheme that's the default when one
 	 * of the slot-allocated clients doesn't claim their slot.
 	 */
 	if (total_assigned + req > NBR_OF_SLOTS)
 		return -ENOMEM;

 	active_clients[region][client] = 1;
 	requested_slots[region][client] = req;
 	crisv32_arbiter_config(region, NBR_OF_SLOTS - total_assigned);

 	return 0;
 }

 /*
  * Main entry for bandwidth deallocation.
  *
  * Strictly speaking, for a somewhat constant set of clients where
  * each client gets a constant bandwidth and is just enabled or
  * disabled (somewhat dynamically), no action is necessary here to
  * avoid starvation for non-zero-allocation clients, as the allocated
  * slots will just be unused. However, handing out those unused slots
  * to active clients avoids needless latency if the "fixed scheme"
  * would give unclaimed slots to an eager low-index client.
  */

 void crisv32_arbiter_deallocate_bandwidth(int client, int region)
 {
 	int i;
 	int total_assigned = 0;

 	requested_slots[region][client] = 0;
 	active_clients[region][client] = 0;

 	for (i = 0; i < NBR_OF_CLIENTS; i++)
 		total_assigned += requested_slots[region][i];

 	crisv32_arbiter_config(region, NBR_OF_SLOTS - total_assigned);
 }

 int crisv32_arbiter_watch(unsigned long start, unsigned long size,
 			  unsigned long clients, unsigned long accesses,
 			  watch_callback *cb)
 {
 	int i;

 	crisv32_arbiter_init();

 	if (start > 0x80000000) {
 		printk(KERN_ERR "Arbiter: %lX doesn't look like a "
 			"physical address", start);
 		return -EFAULT;
 	}

 	spin_lock(&arbiter_lock);

 	for (i = 0; i < NUMBER_OF_BP; i++) {
 		if (!watches[i].used) {
 			reg_marb_rw_intr_mask intr_mask =
 			    REG_RD(marb, regi_marb, rw_intr_mask);

 			watches[i].used = 1;
 			watches[i].start = start;
 			watches[i].end = start + size;
 			watches[i].cb = cb;

 			REG_WR_INT(marb_bp, watches[i].instance, rw_first_addr,
 				   watches[i].start);
 			REG_WR_INT(marb_bp, watches[i].instance, rw_last_addr,
 				   watches[i].end);
 			REG_WR_INT(marb_bp, watches[i].instance, rw_op,
 				   accesses);
 			REG_WR_INT(marb_bp, watches[i].instance, rw_clients,
 				   clients);

 			if (i == 0)
 				intr_mask.bp0 = regk_marb_yes;
 			else if (i == 1)
 				intr_mask.bp1 = regk_marb_yes;
 			else if (i == 2)
 				intr_mask.bp2 = regk_marb_yes;
 			else if (i == 3)
 				intr_mask.bp3 = regk_marb_yes;

 			REG_WR(marb, regi_marb, rw_intr_mask, intr_mask);
 			spin_unlock(&arbiter_lock);

 			return i;
 		}
 	}
 	spin_unlock(&arbiter_lock);
 	return -ENOMEM;
 }

 int crisv32_arbiter_unwatch(int id)
 {
 	reg_marb_rw_intr_mask intr_mask = REG_RD(marb, regi_marb, rw_intr_mask);

 	crisv32_arbiter_init();

 	spin_lock(&arbiter_lock);

 	if ((id < 0) || (id >= NUMBER_OF_BP) || (!watches[id].used)) {
 		spin_unlock(&arbiter_lock);
 		return -EINVAL;
 	}

 	memset(&watches[id], 0, sizeof(struct crisv32_watch_entry));

 	if (id == 0)
 		intr_mask.bp0 = regk_marb_no;
 	else if (id == 1)
 		intr_mask.bp1 = regk_marb_no;
 	else if (id == 2)
 		intr_mask.bp2 = regk_marb_no;
 	else if (id == 3)
 		intr_mask.bp3 = regk_marb_no;

 	REG_WR(marb, regi_marb, rw_intr_mask, intr_mask);

 	spin_unlock(&arbiter_lock);
 	return 0;
 }

 extern void show_registers(struct pt_regs *regs);

 static irqreturn_t crisv32_arbiter_irq(int irq, void *dev_id)
 {
 	reg_marb_r_masked_intr masked_intr =
 	    REG_RD(marb, regi_marb, r_masked_intr);
 	reg_marb_bp_r_brk_clients r_clients;
 	reg_marb_bp_r_brk_addr r_addr;
 	reg_marb_bp_r_brk_op r_op;
 	reg_marb_bp_r_brk_first_client r_first;
 	reg_marb_bp_r_brk_size r_size;
 	reg_marb_bp_rw_ack ack = { 0 };
 	reg_marb_rw_ack_intr ack_intr = {
 		.bp0 = 1, .bp1 = 1, .bp2 = 1, .bp3 = 1
 	};
 	struct crisv32_watch_entry *watch;

 	if (masked_intr.bp0) {
 		watch = &watches[0];
 		ack_intr.bp0 = regk_marb_yes;
 	} else if (masked_intr.bp1) {
 		watch = &watches[1];
 		ack_intr.bp1 = regk_marb_yes;
 	} else if (masked_intr.bp2) {
 		watch = &watches[2];
 		ack_intr.bp2 = regk_marb_yes;
 	} else if (masked_intr.bp3) {
 		watch = &watches[3];
 		ack_intr.bp3 = regk_marb_yes;
 	} else {
 		return IRQ_NONE;
 	}

 	/* Retrieve all useful information and print it. */
 	r_clients = REG_RD(marb_bp, watch->instance, r_brk_clients);
 	r_addr = REG_RD(marb_bp, watch->instance, r_brk_addr);
 	r_op = REG_RD(marb_bp, watch->instance, r_brk_op);
 	r_first = REG_RD(marb_bp, watch->instance, r_brk_first_client);
 	r_size = REG_RD(marb_bp, watch->instance, r_brk_size);

 	printk(KERN_INFO "Arbiter IRQ\n");
 	printk(KERN_INFO "Clients %X addr %X op %X first %X size %X\n",
 	       REG_TYPE_CONV(int, reg_marb_bp_r_brk_clients, r_clients),
 	       REG_TYPE_CONV(int, reg_marb_bp_r_brk_addr, r_addr),
 	       REG_TYPE_CONV(int, reg_marb_bp_r_brk_op, r_op),
 	       REG_TYPE_CONV(int, reg_marb_bp_r_brk_first_client, r_first),
 	       REG_TYPE_CONV(int, reg_marb_bp_r_brk_size, r_size));

 	REG_WR(marb_bp, watch->instance, rw_ack, ack);
 	REG_WR(marb, regi_marb, rw_ack_intr, ack_intr);

 	printk(KERN_INFO "IRQ occurred at %lX\n", get_irq_regs()->erp);

 	if (watch->cb)
 		watch->cb();

 	return IRQ_HANDLED;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Memory arbiter functions. Allocates bandwidth through the
	* arbiter and sets up arbiter breakpoints.
	*
	* The algorithm first assigns slots to the clients that has specified
	* bandwidth (e.g. ethernet) and then the remaining slots are divided
	* on all the active clients.
	*
	* Copyright (c) 2004-2007 Axis Communications AB.
	*/

	#include <hwregs/reg_map.h>
	#include <hwregs/reg_rdwr.h>
	#include <hwregs/marb_defs.h>
	#include <arbiter.h>
	#include <hwregs/intr_vect.h>
	#include <linux/interrupt.h>
	#include <linux/signal.h>
	#include <linux/errno.h>
	#include <linux/spinlock.h>
	#include <asm/io.h>
	#include <asm/irq_regs.h>

	struct crisv32_watch_entry {
	unsigned long instance;
	watch_callback *cb;
	unsigned long start;
	unsigned long end;
	int used;
	};

	#define NUMBER_OF_BP 4
	#define NBR_OF_CLIENTS 14
	#define NBR_OF_SLOTS 64
	#define SDRAM_BANDWIDTH 100000000 /* Some kind of expected value */
	#define INTMEM_BANDWIDTH 400000000
	#define NBR_OF_REGIONS 2

	static struct crisv32_watch_entry watches[NUMBER_OF_BP] = {
	{regi_marb_bp0},
	{regi_marb_bp1},
	{regi_marb_bp2},
	{regi_marb_bp3}
	};

	static u8 requested_slots[NBR_OF_REGIONS][NBR_OF_CLIENTS];
	static u8 active_clients[NBR_OF_REGIONS][NBR_OF_CLIENTS];
	static int max_bandwidth[NBR_OF_REGIONS] =
	{ SDRAM_BANDWIDTH, INTMEM_BANDWIDTH };

	DEFINE_SPINLOCK(arbiter_lock);

	static irqreturn_t crisv32_arbiter_irq(int irq, void *dev_id);

	/*
	* "I'm the arbiter, I know the score.
	* From square one I'll be watching all 64."
	* (memory arbiter slots, that is)
	*
	* Or in other words:
	* Program the memory arbiter slots for "region" according to what's
	* in requested_slots[] and active_clients[], while minimizing
	* latency. A caller may pass a non-zero positive amount for
	* "unused_slots", which must then be the unallocated, remaining
	* number of slots, free to hand out to any client.
	*/

	static void crisv32_arbiter_config(int region, int unused_slots)
	{
	int slot;
	int client;
	int interval = 0;

	/*
	* This vector corresponds to the hardware arbiter slots (see
	* the hardware documentation for semantics). We initialize
	* each slot with a suitable sentinel value outside the valid
	* range {0 .. NBR_OF_CLIENTS - 1} and replace them with
	* client indexes. Then it's fed to the hardware.
	*/
	s8 val[NBR_OF_SLOTS];

	for (slot = 0; slot < NBR_OF_SLOTS; slot++)
	val[slot] = -1;

	for (client = 0; client < NBR_OF_CLIENTS; client++) {
	int pos;
	/* Allocate the requested non-zero number of slots, but
	* also give clients with zero-requests one slot each
	* while stocks last. We do the latter here, in client
	* order. This makes sure zero-request clients are the
	* first to get to any spare slots, else those slots
	* could, when bandwidth is allocated close to the limit,
	* all be allocated to low-index non-zero-request clients
	* in the default-fill loop below. Another positive but
	* secondary effect is a somewhat better spread of the
	* zero-bandwidth clients in the vector, avoiding some of
	* the latency that could otherwise be caused by the
	* partitioning of non-zero-bandwidth clients at low
	* indexes and zero-bandwidth clients at high
	* indexes. (Note that this spreading can only affect the
	* unallocated bandwidth.) All the above only matters for
	* memory-intensive situations, of course.
	*/
	if (!requested_slots[region][client]) {
	/*
	* Skip inactive clients. Also skip zero-slot
	* allocations in this pass when there are no known
	* free slots.
	*/
	if (!active_clients[region][client]
	\|\| unused_slots <= 0)
	continue;

	unused_slots--;

	/* Only allocate one slot for this client. */
	interval = NBR_OF_SLOTS;
	} else
	interval =
	NBR_OF_SLOTS / requested_slots[region][client];

	pos = 0;
	while (pos < NBR_OF_SLOTS) {
	if (val[pos] >= 0)
	pos++;
	else {
	val[pos] = client;
	pos += interval;
	}
	}
	}

	client = 0;
	for (slot = 0; slot < NBR_OF_SLOTS; slot++) {
	/*
	* Allocate remaining slots in round-robin
	* client-number order for active clients. For this
	* pass, we ignore requested bandwidth and previous
	* allocations.
	*/
	if (val[slot] < 0) {
	int first = client;
	while (!active_clients[region][client]) {
	client = (client + 1) % NBR_OF_CLIENTS;
	if (client == first)
	break;
	}
	val[slot] = client;
	client = (client + 1) % NBR_OF_CLIENTS;
	}
	if (region == EXT_REGION)
	REG_WR_INT_VECT(marb, regi_marb, rw_ext_slots, slot,
	val[slot]);
	else if (region == INT_REGION)
	REG_WR_INT_VECT(marb, regi_marb, rw_int_slots, slot,
	val[slot]);
	}
	}

	extern char _stext[], _etext[];

	static void crisv32_arbiter_init(void)
	{
	static int initialized;

	if (initialized)
	return;

	initialized = 1;

	/*
	* CPU caches are always set to active, but with zero
	* bandwidth allocated. It should be ok to allocate zero
	* bandwidth for the caches, because DMA for other channels
	* will supposedly finish, once their programmed amount is
	* done, and then the caches will get access according to the
	* "fixed scheme" for unclaimed slots. Though, if for some
	* use-case somewhere, there's a maximum CPU latency for
	* e.g. some interrupt, we have to start allocating specific
	* bandwidth for the CPU caches too.
	*/
	active_clients[EXT_REGION][10] = active_clients[EXT_REGION][11] = 1;
	crisv32_arbiter_config(EXT_REGION, 0);
	crisv32_arbiter_config(INT_REGION, 0);

	if (request_irq(MEMARB_INTR_VECT, crisv32_arbiter_irq, 0,
	"arbiter", NULL))
	printk(KERN_ERR "Couldn't allocate arbiter IRQ\n");

	#ifndef CONFIG_ETRAX_KGDB
	/* Global watch for writes to kernel text segment. */
	crisv32_arbiter_watch(virt_to_phys(_stext), _etext - _stext,
	arbiter_all_clients, arbiter_all_write, NULL);
	#endif
	}

	/* Main entry for bandwidth allocation. */

	int crisv32_arbiter_allocate_bandwidth(int client, int region,
	unsigned long bandwidth)
	{
	int i;
	int total_assigned = 0;
	int total_clients = 0;
	int req;

	crisv32_arbiter_init();

	for (i = 0; i < NBR_OF_CLIENTS; i++) {
	total_assigned += requested_slots[region][i];
	total_clients += active_clients[region][i];
	}

	/* Avoid division by 0 for 0-bandwidth requests. */
	req = bandwidth == 0
	? 0 : NBR_OF_SLOTS / (max_bandwidth[region] / bandwidth);

	/*
	* We make sure that there are enough slots only for non-zero
	* requests. Requesting 0 bandwidth may allocate slots,
	* though if all bandwidth is allocated, such a client won't
	* get any and will have to rely on getting memory access
	* according to the fixed scheme that's the default when one
	* of the slot-allocated clients doesn't claim their slot.
	*/
	if (total_assigned + req > NBR_OF_SLOTS)
	return -ENOMEM;

	active_clients[region][client] = 1;
	requested_slots[region][client] = req;
	crisv32_arbiter_config(region, NBR_OF_SLOTS - total_assigned);

	return 0;
	}

	/*
	* Main entry for bandwidth deallocation.
	*
	* Strictly speaking, for a somewhat constant set of clients where
	* each client gets a constant bandwidth and is just enabled or
	* disabled (somewhat dynamically), no action is necessary here to
	* avoid starvation for non-zero-allocation clients, as the allocated
	* slots will just be unused. However, handing out those unused slots
	* to active clients avoids needless latency if the "fixed scheme"
	* would give unclaimed slots to an eager low-index client.
	*/

	void crisv32_arbiter_deallocate_bandwidth(int client, int region)
	{
	int i;
	int total_assigned = 0;

	requested_slots[region][client] = 0;
	active_clients[region][client] = 0;

	for (i = 0; i < NBR_OF_CLIENTS; i++)
	total_assigned += requested_slots[region][i];

	crisv32_arbiter_config(region, NBR_OF_SLOTS - total_assigned);
	}

	int crisv32_arbiter_watch(unsigned long start, unsigned long size,
	unsigned long clients, unsigned long accesses,
	watch_callback *cb)
	{
	int i;

	crisv32_arbiter_init();

	if (start > 0x80000000) {
	printk(KERN_ERR "Arbiter: %lX doesn't look like a "
	"physical address", start);
	return -EFAULT;
	}

	spin_lock(&arbiter_lock);

	for (i = 0; i < NUMBER_OF_BP; i++) {
	if (!watches[i].used) {
	reg_marb_rw_intr_mask intr_mask =
	REG_RD(marb, regi_marb, rw_intr_mask);

	watches[i].used = 1;
	watches[i].start = start;
	watches[i].end = start + size;
	watches[i].cb = cb;

	REG_WR_INT(marb_bp, watches[i].instance, rw_first_addr,
	watches[i].start);
	REG_WR_INT(marb_bp, watches[i].instance, rw_last_addr,
	watches[i].end);
	REG_WR_INT(marb_bp, watches[i].instance, rw_op,
	accesses);
	REG_WR_INT(marb_bp, watches[i].instance, rw_clients,
	clients);

	if (i == 0)
	intr_mask.bp0 = regk_marb_yes;
	else if (i == 1)
	intr_mask.bp1 = regk_marb_yes;
	else if (i == 2)
	intr_mask.bp2 = regk_marb_yes;
	else if (i == 3)
	intr_mask.bp3 = regk_marb_yes;

	REG_WR(marb, regi_marb, rw_intr_mask, intr_mask);
	spin_unlock(&arbiter_lock);

	return i;
	}
	}
	spin_unlock(&arbiter_lock);
	return -ENOMEM;
	}

	int crisv32_arbiter_unwatch(int id)
	{
	reg_marb_rw_intr_mask intr_mask = REG_RD(marb, regi_marb, rw_intr_mask);

	crisv32_arbiter_init();

	spin_lock(&arbiter_lock);

	if ((id < 0) \|\| (id >= NUMBER_OF_BP) \|\| (!watches[id].used)) {
	spin_unlock(&arbiter_lock);
	return -EINVAL;
	}

	memset(&watches[id], 0, sizeof(struct crisv32_watch_entry));

	if (id == 0)
	intr_mask.bp0 = regk_marb_no;
	else if (id == 1)
	intr_mask.bp1 = regk_marb_no;
	else if (id == 2)
	intr_mask.bp2 = regk_marb_no;
	else if (id == 3)
	intr_mask.bp3 = regk_marb_no;

	REG_WR(marb, regi_marb, rw_intr_mask, intr_mask);

	spin_unlock(&arbiter_lock);
	return 0;
	}

	extern void show_registers(struct pt_regs *regs);

	static irqreturn_t crisv32_arbiter_irq(int irq, void *dev_id)
	{
	reg_marb_r_masked_intr masked_intr =
	REG_RD(marb, regi_marb, r_masked_intr);
	reg_marb_bp_r_brk_clients r_clients;
	reg_marb_bp_r_brk_addr r_addr;
	reg_marb_bp_r_brk_op r_op;
	reg_marb_bp_r_brk_first_client r_first;
	reg_marb_bp_r_brk_size r_size;
	reg_marb_bp_rw_ack ack = { 0 };
	reg_marb_rw_ack_intr ack_intr = {
	.bp0 = 1, .bp1 = 1, .bp2 = 1, .bp3 = 1
	};
	struct crisv32_watch_entry *watch;

	if (masked_intr.bp0) {
	watch = &watches[0];
	ack_intr.bp0 = regk_marb_yes;
	} else if (masked_intr.bp1) {
	watch = &watches[1];
	ack_intr.bp1 = regk_marb_yes;
	} else if (masked_intr.bp2) {
	watch = &watches[2];
	ack_intr.bp2 = regk_marb_yes;
	} else if (masked_intr.bp3) {
	watch = &watches[3];
	ack_intr.bp3 = regk_marb_yes;
	} else {
	return IRQ_NONE;
	}

	/* Retrieve all useful information and print it. */
	r_clients = REG_RD(marb_bp, watch->instance, r_brk_clients);
	r_addr = REG_RD(marb_bp, watch->instance, r_brk_addr);
	r_op = REG_RD(marb_bp, watch->instance, r_brk_op);
	r_first = REG_RD(marb_bp, watch->instance, r_brk_first_client);
	r_size = REG_RD(marb_bp, watch->instance, r_brk_size);

	printk(KERN_INFO "Arbiter IRQ\n");
	printk(KERN_INFO "Clients %X addr %X op %X first %X size %X\n",
	REG_TYPE_CONV(int, reg_marb_bp_r_brk_clients, r_clients),
	REG_TYPE_CONV(int, reg_marb_bp_r_brk_addr, r_addr),
	REG_TYPE_CONV(int, reg_marb_bp_r_brk_op, r_op),
	REG_TYPE_CONV(int, reg_marb_bp_r_brk_first_client, r_first),
	REG_TYPE_CONV(int, reg_marb_bp_r_brk_size, r_size));

	REG_WR(marb_bp, watch->instance, rw_ack, ack);
	REG_WR(marb, regi_marb, rw_ack_intr, ack_intr);

	printk(KERN_INFO "IRQ occurred at %lX\n", get_irq_regs()->erp);

	if (watch->cb)
	watch->cb();

	return IRQ_HANDLED;
	}