In case that flushing and disabling caches will not work.
(but it is possible that I do above in wrong way).
Would this code below be acceptable as infrastructure?
Is this infrastructure or maybe hack? Are there any HOWTO
write correct infrastructure?
This is draft/proposal.
Can I continue in this way or I shouldn't?
This code (more correct version) will be included in
longhaul.c. There should be include file "cpufreq_longhaul.h"
for drivers knowing about "longhaul problem".
Driver would have all code for longhaul in
"#ifdef CONFIG_X86_LONGHAUL / #else / #endif".
Basic support for longhaul in driver:
1. driver calls longhaul_bmdma_register("driver_name_wq")
at init,
2. driver calls longhaul_bmdma_begin before starting BMDMA
with function that is starting DMA for this driver
(or in case of via-rhine driver with function which queues
packet in hardware queue). You can do it multiple times
before calling longhaul_bmdma_end for the first time,
3. driver calls longhaul_bmdma_end after BMDMA transfer is
completed (via-rhine - after packet was send).
Longhaul would simply lock write longhaul_sem before
CPU frequency change.
Sorry to bother You all again.
Rafał
---
/*
* Longhaul "infrastructure" for bus master DMA
*/
struct longhaul_work {
struct list_head entry;
struct work_struct work;
struct longhaul_data *data;
void (*device_func) (void *data);
void *device_data;
};
struct longhaul_data {
struct workqueue_struct *wq;
spinlock_t lock;
struct list_head work_unused;
struct list_head work_inuse;
struct list_head work_used;
};
/* Access control for PCI bus */
static struct rw_semaphore longhaul_sem;
struct longhaul_data *longhaul_bmdma_register(char *name)
{
struct longhaul_data *longdata;
struct longhaul_work *longwork;
struct workqueue_struct *workqueue;
longdata = kmalloc(sizeof(struct longhaul_data), GFP_KERNEL);
if (longdata == NULL)
return NULL;
spin_lock_init(&longdata->lock);
INIT_LIST_HEAD(&longdata->work_unused);
INIT_LIST_HEAD(&longdata->work_inuse);
INIT_LIST_HEAD(&longdata->work_used);
longwork = kmalloc(sizeof(struct longhaul_work), GFP_KERNEL);
if (longwork == NULL) {
goto free_longdata;
}
INIT_WORK(&longwork->work, &longhaul_bmdma_work, NULL);
list_add(longwork, &longdata->work_unused);
longwork->data = longdata;
workqueue = create_singlethread_workqueue(name);
if (workqueue == NULL) {
printk(KERN_ERR PFX "Can't create workqueue \"%s\".\n", name);
goto free_longwork;
}
longdata->wq = workqueue;
return longdata;
free_longwork:
kfree(longwork);
free_longdata:
kfree(longdata);
return NULL;
}
EXPORT_SYMBOL(longhaul_bmdma_register);
void longhaul_bmdma_unregister(struct longhaul_data *longdata)
{
}
EXPORT_SYMBOL(longhaul_bmdma_unregister);
static void longhaul_bmdma_work(void *data)
{
struct longhaul_work *longwork = data;
struct longhaul_data *longdata = longwork->data;
unsigned long flags;
down_read(&longhaul_sem);
longdata->device_func(longdata->device_data);
spin_lock_irqsave(&longdata->lock, flags);
list_move(longwork, &longdata->work_used);
spin_unlock_irqrestore(&longdata->lock, flags);
}
int longhaul_bmdma_begin(struct longhaul_data *longdata,
void (*device_func) (void *data),
void *device_data);
{
struct longhaul_work *longwork;
unsigned long flags;
spin_lock_irqsave(&longdata->lock, flags);
if ( list_empty(&longdata->work_unused) ) {
longwork = kmalloc(sizeof(struct longhaul_work), GFP_ATOMIC);
if (longwork == NULL) {
spin_unlock_irqrestore(&longdata->lock, flags);
return -ENOMEM;
}
INIT_WORK(&longwork->work, &longhaul_bmdma_work, NULL);
longwork->data = longdata;
list_add(longwork, &longdata->work_inuse);
} else {
longwork = longdata->work_unused->next;
list_move(longwork, &longdata->work_inuse);
}
spin_unlock_irqrestore(&longdata->lock, flags);
longwork->device_func = device_func;
longwork->device_data = device_data;
PREPARE_WORK(longwork, &longhaul_bmdma_work, (void*)longwork);
queue_work(longdata->wq, longwork);
return 0;
}
EXPORT_SYMBOL(longhaul_bmdma_begin);
void longhaul_bmdma_end(struct longhaul_data *longdata)
{
struct list_head pos;
unsigned long flags;
spin_lock_irqsave(&longdata->lock, flags);
if ( !list_empty(&longdata->work_used) ) {
list_for_each(pos, &longdata->work_used) {
list_move(longwork, &longdata->work_unused);
}
}
spin_unlock_irqrestore(&longdata->lock, flags);
up_read(&longhaul_sem);
}
EXPORT_SYMBOL(longhaul_bmdma_end);
----------------------------------------------------------------------
PS. Fajny portal... >>> http://link.interia.pl/f196a
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