/*
* 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;
}
