sh: dma-api channel capability extensions.

This extends the SH DMA API for allowing handling of DMA
channels based off of their respective capabilities.

A couple of functions are added to the existing API,
the core bits are register_chan_caps() for registering
channel capabilities, and request_dma_bycap() for fetching
a channel dynamically based off of a capability set.

Signed-off-by: Mark Glaisher <mark.glaisher@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Mark Glaisher 2006-11-24 15:13:52 +09:00 committed by Paul Mundt
parent e803aaf63a
commit db9b99d461
2 changed files with 225 additions and 103 deletions

View File

@ -11,61 +11,27 @@
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/proc_fs.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/mm.h>
#include <asm/dma.h>
DEFINE_SPINLOCK(dma_spin_lock);
static LIST_HEAD(registered_dmac_list);
/*
* A brief note about the reasons for this API as it stands.
*
* For starters, the old ISA DMA API didn't work for us for a number of
* reasons, for one, the vast majority of channels on the SH DMAC are
* dual-address mode only, and both the new and the old DMA APIs are after the
* concept of managing a DMA buffer, which doesn't overly fit this model very
* well. In addition to which, the new API is largely geared at IOMMUs and
* GARTs, and doesn't even support the channel notion very well.
*
* The other thing that's a marginal issue, is the sheer number of random DMA
* engines that are present (ie, in boards like the Dreamcast), some of which
* cascade off of the SH DMAC, and others do not. As such, there was a real
* need for a scalable subsystem that could deal with both single and
* dual-address mode usage, in addition to interoperating with cascaded DMACs.
*
* There really isn't any reason why this needs to be SH specific, though I'm
* not aware of too many other processors (with the exception of some MIPS)
* that have the same concept of a dual address mode, or any real desire to
* actually make use of the DMAC even if such a subsystem were exposed
* elsewhere.
*
* The idea for this was derived from the ARM port, which acted as an excellent
* reference when trying to address these issues.
*
* It should also be noted that the decision to add Yet Another DMA API(tm) to
* the kernel wasn't made easily, and was only decided upon after conferring
* with jejb with regards to the state of the old and new APIs as they applied
* to these circumstances. Philip Blundell was also a great help in figuring
* out some single-address mode DMA semantics that were otherwise rather
* confusing.
*/
struct dma_info *get_dma_info(unsigned int chan)
{
struct dma_info *info;
unsigned int total = 0;
/*
* Look for each DMAC's range to determine who the owner of
* the channel is.
*/
list_for_each_entry(info, &registered_dmac_list, list) {
total += info->nr_channels;
if (chan > total)
if ((chan < info->first_channel_nr) ||
(chan >= info->first_channel_nr + info->nr_channels))
continue;
return info;
@ -73,6 +39,22 @@ struct dma_info *get_dma_info(unsigned int chan)
return NULL;
}
EXPORT_SYMBOL(get_dma_info);
struct dma_info *get_dma_info_by_name(const char *dmac_name)
{
struct dma_info *info;
list_for_each_entry(info, &registered_dmac_list, list) {
if (dmac_name && (strcmp(dmac_name, info->name) != 0))
continue;
else
return info;
}
return NULL;
}
EXPORT_SYMBOL(get_dma_info_by_name);
static unsigned int get_nr_channels(void)
{
@ -91,63 +73,161 @@ static unsigned int get_nr_channels(void)
struct dma_channel *get_dma_channel(unsigned int chan)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel;
int i;
if (!info)
if (unlikely(!info))
return ERR_PTR(-EINVAL);
return info->channels + chan;
for (i = 0; i < info->nr_channels; i++) {
channel = &info->channels[i];
if (channel->chan == chan)
return channel;
}
return NULL;
}
EXPORT_SYMBOL(get_dma_channel);
int get_dma_residue(unsigned int chan)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = &info->channels[chan];
struct dma_channel *channel = get_dma_channel(chan);
if (info->ops->get_residue)
return info->ops->get_residue(channel);
return 0;
}
EXPORT_SYMBOL(get_dma_residue);
int request_dma(unsigned int chan, const char *dev_id)
static int search_cap(const char **haystack, const char *needle)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = &info->channels[chan];
const char **p;
down(&channel->sem);
if (!info->ops || chan >= MAX_DMA_CHANNELS) {
up(&channel->sem);
return -EINVAL;
}
atomic_set(&channel->busy, 1);
strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
up(&channel->sem);
if (info->ops->request)
return info->ops->request(channel);
for (p = haystack; *p; p++)
if (strcmp(*p, needle) == 0)
return 1;
return 0;
}
/**
* request_dma_bycap - Allocate a DMA channel based on its capabilities
* @dmac: List of DMA controllers to search
* @caps: List of capabilites
*
* Search all channels of all DMA controllers to find a channel which
* matches the requested capabilities. The result is the channel
* number if a match is found, or %-ENODEV if no match is found.
*
* Note that not all DMA controllers export capabilities, in which
* case they can never be allocated using this API, and so
* request_dma() must be used specifying the channel number.
*/
int request_dma_bycap(const char **dmac, const char **caps, const char *dev_id)
{
unsigned int found = 0;
struct dma_info *info;
const char **p;
int i;
BUG_ON(!dmac || !caps);
list_for_each_entry(info, &registered_dmac_list, list)
if (strcmp(*dmac, info->name) == 0) {
found = 1;
break;
}
if (!found)
return -ENODEV;
for (i = 0; i < info->nr_channels; i++) {
struct dma_channel *channel = &info->channels[i];
if (unlikely(!channel->caps))
continue;
for (p = caps; *p; p++) {
if (!search_cap(channel->caps, *p))
break;
if (request_dma(channel->chan, dev_id) == 0)
return channel->chan;
}
}
return -EINVAL;
}
EXPORT_SYMBOL(request_dma_bycap);
int dmac_search_free_channel(const char *dev_id)
{
struct dma_channel *channel = { 0 };
struct dma_info *info = get_dma_info(0);
int i;
for (i = 0; i < info->nr_channels; i++) {
channel = &info->channels[i];
if (unlikely(!channel))
return -ENODEV;
if (atomic_read(&channel->busy) == 0)
break;
}
if (info->ops->request) {
int result = info->ops->request(channel);
if (result)
return result;
atomic_set(&channel->busy, 1);
return channel->chan;
}
return -ENOSYS;
}
int request_dma(unsigned int chan, const char *dev_id)
{
struct dma_channel *channel = { 0 };
struct dma_info *info = get_dma_info(chan);
int result;
channel = get_dma_channel(chan);
if (atomic_xchg(&channel->busy, 1))
return -EBUSY;
strlcpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
if (info->ops->request) {
result = info->ops->request(channel);
if (result)
atomic_set(&channel->busy, 0);
return result;
}
return 0;
}
EXPORT_SYMBOL(request_dma);
void free_dma(unsigned int chan)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = &info->channels[chan];
struct dma_channel *channel = get_dma_channel(chan);
if (info->ops->free)
info->ops->free(channel);
atomic_set(&channel->busy, 0);
}
EXPORT_SYMBOL(free_dma);
void dma_wait_for_completion(unsigned int chan)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = &info->channels[chan];
struct dma_channel *channel = get_dma_channel(chan);
if (channel->flags & DMA_TEI_CAPABLE) {
wait_event(channel->wait_queue,
@ -158,21 +238,52 @@ void dma_wait_for_completion(unsigned int chan)
while (info->ops->get_residue(channel))
cpu_relax();
}
EXPORT_SYMBOL(dma_wait_for_completion);
int register_chan_caps(const char *dmac, struct dma_chan_caps *caps)
{
struct dma_info *info;
unsigned int found = 0;
int i;
list_for_each_entry(info, &registered_dmac_list, list)
if (strcmp(dmac, info->name) == 0) {
found = 1;
break;
}
if (unlikely(!found))
return -ENODEV;
for (i = 0; i < info->nr_channels; i++, caps++) {
struct dma_channel *channel;
if ((info->first_channel_nr + i) != caps->ch_num)
return -EINVAL;
channel = &info->channels[i];
channel->caps = caps->caplist;
}
return 0;
}
EXPORT_SYMBOL(register_chan_caps);
void dma_configure_channel(unsigned int chan, unsigned long flags)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = &info->channels[chan];
struct dma_channel *channel = get_dma_channel(chan);
if (info->ops->configure)
info->ops->configure(channel, flags);
}
EXPORT_SYMBOL(dma_configure_channel);
int dma_xfer(unsigned int chan, unsigned long from,
unsigned long to, size_t size, unsigned int mode)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = &info->channels[chan];
struct dma_channel *channel = get_dma_channel(chan);
channel->sar = from;
channel->dar = to;
@ -181,8 +292,20 @@ int dma_xfer(unsigned int chan, unsigned long from,
return info->ops->xfer(channel);
}
EXPORT_SYMBOL(dma_xfer);
int dma_extend(unsigned int chan, unsigned long op, void *param)
{
struct dma_info *info = get_dma_info(chan);
struct dma_channel *channel = get_dma_channel(chan);
if (info->ops->extend)
return info->ops->extend(channel, op, param);
return -ENOSYS;
}
EXPORT_SYMBOL(dma_extend);
#ifdef CONFIG_PROC_FS
static int dma_read_proc(char *buf, char **start, off_t off,
int len, int *eof, void *data)
{
@ -214,8 +337,6 @@ static int dma_read_proc(char *buf, char **start, off_t off,
return p - buf;
}
#endif
int register_dmac(struct dma_info *info)
{
@ -224,8 +345,7 @@ int register_dmac(struct dma_info *info)
INIT_LIST_HEAD(&info->list);
printk(KERN_INFO "DMA: Registering %s handler (%d channel%s).\n",
info->name, info->nr_channels,
info->nr_channels > 1 ? "s" : "");
info->name, info->nr_channels, info->nr_channels > 1 ? "s" : "");
BUG_ON((info->flags & DMAC_CHANNELS_CONFIGURED) && !info->channels);
@ -242,28 +362,26 @@ int register_dmac(struct dma_info *info)
size = sizeof(struct dma_channel) * info->nr_channels;
info->channels = kmalloc(size, GFP_KERNEL);
info->channels = kzalloc(size, GFP_KERNEL);
if (!info->channels)
return -ENOMEM;
memset(info->channels, 0, size);
}
total_channels = get_nr_channels();
for (i = 0; i < info->nr_channels; i++) {
struct dma_channel *chan = info->channels + i;
struct dma_channel *chan = &info->channels[i];
chan->chan = i;
chan->vchan = i + total_channels;
atomic_set(&chan->busy, 0);
chan->chan = info->first_channel_nr + i;
chan->vchan = info->first_channel_nr + i + total_channels;
memcpy(chan->dev_id, "Unused", 7);
if (info->flags & DMAC_CHANNELS_TEI_CAPABLE)
chan->flags |= DMA_TEI_CAPABLE;
init_MUTEX(&chan->sem);
init_waitqueue_head(&chan->wait_queue);
dma_create_sysfs_files(chan, info);
}
@ -271,6 +389,7 @@ int register_dmac(struct dma_info *info)
return 0;
}
EXPORT_SYMBOL(register_dmac);
void unregister_dmac(struct dma_info *info)
{
@ -285,31 +404,16 @@ void unregister_dmac(struct dma_info *info)
list_del(&info->list);
platform_device_unregister(info->pdev);
}
EXPORT_SYMBOL(unregister_dmac);
static int __init dma_api_init(void)
{
printk("DMA: Registering DMA API.\n");
#ifdef CONFIG_PROC_FS
printk(KERN_NOTICE "DMA: Registering DMA API.\n");
create_proc_read_entry("dma", 0, 0, dma_read_proc, 0);
#endif
return 0;
}
subsys_initcall(dma_api_init);
MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("DMA API for SuperH");
MODULE_LICENSE("GPL");
EXPORT_SYMBOL(request_dma);
EXPORT_SYMBOL(free_dma);
EXPORT_SYMBOL(register_dmac);
EXPORT_SYMBOL(get_dma_residue);
EXPORT_SYMBOL(get_dma_info);
EXPORT_SYMBOL(get_dma_channel);
EXPORT_SYMBOL(dma_xfer);
EXPORT_SYMBOL(dma_wait_for_completion);
EXPORT_SYMBOL(dma_configure_channel);

View File

@ -14,9 +14,7 @@
#include <linux/spinlock.h>
#include <linux/wait.h>
#include <linux/sysdev.h>
#include <linux/device.h>
#include <asm/cpu/dma.h>
#include <asm/semaphore.h>
/* The maximum address that we can perform a DMA transfer to on this platform */
/* Don't define MAX_DMA_ADDRESS; it's useless on the SuperH and any
@ -46,16 +44,21 @@
* DMAC (dma_info) flags
*/
enum {
DMAC_CHANNELS_CONFIGURED = 0x00,
DMAC_CHANNELS_TEI_CAPABLE = 0x01,
DMAC_CHANNELS_CONFIGURED = 0x01,
DMAC_CHANNELS_TEI_CAPABLE = 0x02, /* Transfer end interrupt */
};
/*
* DMA channel capabilities / flags
*/
enum {
DMA_TEI_CAPABLE = 0x01,
DMA_CONFIGURED = 0x02,
DMA_CONFIGURED = 0x01,
/*
* Transfer end interrupt, inherited from DMAC.
* wait_queue used in dma_wait_for_completion.
*/
DMA_TEI_CAPABLE = 0x02,
};
extern spinlock_t dma_spin_lock;
@ -68,28 +71,31 @@ struct dma_ops {
int (*get_residue)(struct dma_channel *chan);
int (*xfer)(struct dma_channel *chan);
void (*configure)(struct dma_channel *chan, unsigned long flags);
int (*configure)(struct dma_channel *chan, unsigned long flags);
int (*extend)(struct dma_channel *chan, unsigned long op, void *param);
};
struct dma_channel {
char dev_id[16];
char dev_id[16]; /* unique name per DMAC of channel */
unsigned int chan; /* Physical channel number */
unsigned int chan; /* DMAC channel number */
unsigned int vchan; /* Virtual channel number */
unsigned int mode;
unsigned int count;
unsigned long sar;
unsigned long dar;
const char **caps;
unsigned long flags;
atomic_t busy;
struct semaphore sem;
wait_queue_head_t wait_queue;
struct sys_device dev;
char *name;
void *priv_data;
};
struct dma_info {
@ -103,6 +109,12 @@ struct dma_info {
struct dma_channel *channels;
struct list_head list;
int first_channel_nr;
};
struct dma_chan_caps {
int ch_num;
const char **caplist;
};
#define to_dma_channel(channel) container_of(channel, struct dma_channel, dev)
@ -121,6 +133,8 @@ extern int dma_xfer(unsigned int chan, unsigned long from,
#define dma_read_page(chan, from, to) \
dma_read(chan, from, to, PAGE_SIZE)
extern int request_dma_bycap(const char **dmac, const char **caps,
const char *dev_id);
extern int request_dma(unsigned int chan, const char *dev_id);
extern void free_dma(unsigned int chan);
extern int get_dma_residue(unsigned int chan);
@ -131,6 +145,10 @@ extern void dma_configure_channel(unsigned int chan, unsigned long flags);
extern int register_dmac(struct dma_info *info);
extern void unregister_dmac(struct dma_info *info);
extern struct dma_info *get_dma_info_by_name(const char *dmac_name);
extern int dma_extend(unsigned int chan, unsigned long op, void *param);
extern int register_chan_caps(const char *dmac, struct dma_chan_caps *capslist);
#ifdef CONFIG_SYSFS
/* arch/sh/drivers/dma/dma-sysfs.c */