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SubjectRe: [PATCH] 3/3 maple: update bus driver to support Dreamcast VMU
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Date
Changes to allow support of the VMU as well as clean up some of the
horrors that got imported in with the rewrite of the 2.4 driver.

- Adds a mutex to allow packets (eg block reads and writes) to be
injected into the waiting queue with any risk of data corruption.

- Removes unneeded locking of queue of processed packets while properly
locking access to the queue of waiting packets

- Allows proper probing and removal of device drivers rather than
force majure approach based on function supported

- Separate out "rescan" function to make the code easier to read
and maintain.

- properly initialise and clean up waiting and sent queues

Signed-off-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>


---
diff -ruN a/include/linux/maple.h b/include/linux/maple.h
--- a/include/linux/maple.h 2008-03-22 17:26:48.000000000 +0000
+++ b/include/linux/maple.h 2008-03-22 17:21:03.000000000 +0000
@@ -33,6 +33,7 @@
void *sendbuf, *recvbuf, *recvbufdcsp;
unsigned char length;
enum maple_code command;
+ struct mutex mutex;
};

struct maple_devinfo {
diff -ruN a/drivers/sh/maple/maple.c b/drivers/sh/maple/maple.c
--- a/drivers/sh/maple/maple.c 2008-03-22 17:26:31.000000000 +0000
+++ b/drivers/sh/maple/maple.c 2008-03-22 17:53:50.000000000 +0000
@@ -46,14 +46,15 @@
static LIST_HEAD(maple_waitq);
static LIST_HEAD(maple_sentq);

-static DEFINE_MUTEX(maple_list_lock);
+/* mutex to protect queue of waiting packets */
+static DEFINE_MUTEX(maple_wlist_lock);

static struct maple_driver maple_dummy_driver;
static struct device maple_bus;
static int subdevice_map[MAPLE_PORTS];
static unsigned long *maple_sendbuf, *maple_sendptr, *maple_lastptr;
static unsigned long maple_pnp_time;
-static int started, scanning, liststatus, fullscan;
+static int started, scanning, fullscan;
static struct kmem_cache *maple_queue_cache;

struct maple_device_specify {
@@ -135,9 +136,9 @@
*/
void maple_add_packet(struct mapleq *mq)
{
- mutex_lock(&maple_list_lock);
+ mutex_lock(&maple_wlist_lock);
list_add(&mq->list, &maple_waitq);
- mutex_unlock(&maple_list_lock);
+ mutex_unlock(&maple_wlist_lock);
}
EXPORT_SYMBOL_GPL(maple_add_packet);

@@ -147,17 +148,26 @@

mq = kmalloc(sizeof(*mq), GFP_KERNEL);
if (!mq)
- return NULL;
+ goto failed_nomem;

mq->dev = mdev;
mq->recvbufdcsp = kmem_cache_zalloc(maple_queue_cache, GFP_KERNEL);
mq->recvbuf = (void *) P2SEGADDR(mq->recvbufdcsp);
- if (!mq->recvbuf) {
- kfree(mq);
- return NULL;
- }
+ if (!mq->recvbuf)
+ goto failed_p2;
+ /***
+ * most devices do not need the mutex - but
+ * anything that injects block reads or writes
+ * will rely on it
+ */
+ mutex_init(&mq->mutex);

return mq;
+
+failed_p2:
+ kfree(mq);
+failed_nomem:
+ return NULL;
}

static struct maple_device *maple_alloc_dev(int port, int unit)
@@ -178,7 +188,6 @@
}
mdev->dev.bus = &maple_bus_type;
mdev->dev.parent = &maple_bus;
- mdev->function = 0;
return mdev;
}

@@ -216,7 +225,6 @@
*maple_sendptr++ = PHYSADDR(mq->recvbuf);
*maple_sendptr++ =
mq->command | (to << 8) | (from << 16) | (len << 24);
-
while (len-- > 0)
*maple_sendptr++ = *lsendbuf++;
}
@@ -230,16 +238,22 @@

if (!list_empty(&maple_sentq))
return;
- if (list_empty(&maple_waitq) || !maple_dma_done())
+ mutex_lock(&maple_wlist_lock);
+ if (list_empty(&maple_waitq) || !maple_dma_done()) {
+ mutex_unlock(&maple_wlist_lock);
return;
+ }
+ mutex_unlock(&maple_wlist_lock);
maple_packets = 0;
maple_sendptr = maple_lastptr = maple_sendbuf;
+ mutex_lock(&maple_wlist_lock);
list_for_each_entry_safe(mq, nmq, &maple_waitq, list) {
maple_build_block(mq);
list_move(&mq->list, &maple_sentq);
if (maple_packets++ > MAPLE_MAXPACKETS)
break;
}
+ mutex_unlock(&maple_wlist_lock);
if (maple_packets > 0) {
for (i = 0; i < (1 << MAPLE_DMA_PAGES); i++)
dma_cache_sync(0, maple_sendbuf + i * PAGE_SIZE,
@@ -247,7 +261,8 @@
}
}

-static int attach_matching_maple_driver(struct device_driver *driver,
+/* check if there is a driver registered likely to match this device */
+static int check_matching_maple_driver(struct device_driver *driver,
void *devptr)
{
struct maple_driver *maple_drv;
@@ -255,12 +270,8 @@

mdev = devptr;
maple_drv = to_maple_driver(driver);
- if (mdev->devinfo.function & be32_to_cpu(maple_drv->function)) {
- if (maple_drv->connect(mdev) == 0) {
- mdev->driver = maple_drv;
- return 1;
- }
- }
+ if (mdev->devinfo.function & cpu_to_be32(maple_drv->function))
+ return 1;
return 0;
}

@@ -268,11 +279,6 @@
{
if (!mdev)
return;
- if (mdev->driver) {
- if (mdev->driver->disconnect)
- mdev->driver->disconnect(mdev);
- }
- mdev->driver = NULL;
device_unregister(&mdev->dev);
mdev = NULL;
}
@@ -328,8 +334,8 @@
mdev->port, mdev->unit, function);

matched =
- bus_for_each_drv(&maple_bus_type, NULL, mdev,
- attach_matching_maple_driver);
+ bus_for_each_drv(&maple_bus_type, NULL, mdev,
+ check_matching_maple_driver);

if (matched == 0) {
/* Driver does not exist yet */
@@ -377,53 +383,62 @@

if ((maple_dev->interval > 0)
&& time_after(jiffies, maple_dev->when)) {
+ /***
+ * Can only queue one command per device at a time
+ * so if cannot aquire the mutex, just return
+ */
+ if (!mutex_trylock(&maple_dev->mq->mutex))
+ goto setup_finished;
maple_dev->when = jiffies + maple_dev->interval;
maple_dev->mq->command = MAPLE_COMMAND_GETCOND;
maple_dev->mq->sendbuf = &maple_dev->function;
maple_dev->mq->length = 1;
maple_add_packet(maple_dev->mq);
- liststatus++;
} else {
if (time_after(jiffies, maple_pnp_time)) {
+ if (!mutex_trylock(&maple_dev->mq->mutex))
+ goto setup_finished;
maple_dev->mq->command = MAPLE_COMMAND_DEVINFO;
maple_dev->mq->length = 0;
maple_add_packet(maple_dev->mq);
- liststatus++;
}
}
-
+setup_finished:
return 0;
}

/* VBLANK bottom half - implemented via workqueue */
static void maple_vblank_handler(struct work_struct *work)
{
- if (!maple_dma_done())
- return;
if (!list_empty(&maple_sentq))
return;
+ if (!maple_dma_done())
+ return;
ctrl_outl(0, MAPLE_ENABLE);
- liststatus = 0;
bus_for_each_dev(&maple_bus_type, NULL, NULL,
setup_maple_commands);
if (time_after(jiffies, maple_pnp_time))
maple_pnp_time = jiffies + MAPLE_PNP_INTERVAL;
- if (liststatus && list_empty(&maple_sentq)) {
- INIT_LIST_HEAD(&maple_sentq);
+ mutex_lock(&maple_wlist_lock);
+ if (!list_empty(&maple_waitq) && list_empty(&maple_sentq)) {
+ mutex_unlock(&maple_wlist_lock);
maple_send();
+ } else {
+ mutex_unlock(&maple_wlist_lock);
}
+
maplebus_dma_reset();
}

/* handle devices added via hotplugs - placing them on queue for DEVINFO*/
static void maple_map_subunits(struct maple_device *mdev, int submask)
{
- int retval, k, devcheck;
+ int retval, k, devcheck, locking;
struct maple_device *mdev_add;
struct maple_device_specify ds;

+ ds.port = mdev->port;
for (k = 0; k < 5; k++) {
- ds.port = mdev->port;
ds.unit = k + 1;
retval =
bus_for_each_dev(&maple_bus_type, NULL, &ds,
@@ -437,9 +452,15 @@
mdev_add = maple_alloc_dev(mdev->port, k + 1);
if (!mdev_add)
return;
+ /* Use trylock again to avoid corrupting
+ * any already queued commands */
+ locking = mutex_trylock(&mdev_add->mq->mutex);
+ if (locking == 0)
+ return;
mdev_add->mq->command = MAPLE_COMMAND_DEVINFO;
mdev_add->mq->length = 0;
maple_add_packet(mdev_add->mq);
+ /* mark that we are checking sub devices */
scanning = 1;
}
submask = submask >> 1;
@@ -505,6 +526,35 @@
}
}

+static void maple_port_rescan(void)
+{
+ int i, locking;
+ struct maple_device *mdev;
+
+ fullscan = 1;
+ for (i = 0; i < MAPLE_PORTS; i++) {
+ if (checked[i] == false) {
+ fullscan = 0;
+ mdev = baseunits[i];
+ /**
+ * Use trylock in case scan has failed
+ * but device is still locked
+ */
+ locking = mutex_trylock(&mdev->mq->mutex);
+ if (locking == 0) {
+ mutex_unlock(&mdev->mq->mutex);
+ locking = mutex_lock_interruptible
+ (&mdev->mq->mutex);
+ if (locking)
+ continue;
+ }
+ mdev->mq->command = MAPLE_COMMAND_DEVINFO;
+ mdev->mq->length = 0;
+ maple_add_packet(mdev->mq);
+ }
+ }
+}
+
/* maple dma end bottom half - implemented via workqueue */
static void maple_dma_handler(struct work_struct *work)
{
@@ -512,7 +562,6 @@
struct maple_device *dev;
char *recvbuf;
enum maple_code code;
- int i;

if (!maple_dma_done())
return;
@@ -521,7 +570,10 @@
list_for_each_entry_safe(mq, nmq, &maple_sentq, list) {
recvbuf = mq->recvbuf;
code = recvbuf[0];
+ if (mutex_is_locked(&mq->mutex))
+ mutex_unlock(&mq->mutex);
dev = mq->dev;
+ list_del_init(&mq->list);
switch (code) {
case MAPLE_RESPONSE_NONE:
maple_response_none(dev, mq);
@@ -558,26 +610,16 @@
break;
}
}
- INIT_LIST_HEAD(&maple_sentq);
+ /* if scanning is 1 then we have subdevices to check */
if (scanning == 1) {
maple_send();
scanning = 2;
} else
scanning = 0;
-
- if (!fullscan) {
- fullscan = 1;
- for (i = 0; i < MAPLE_PORTS; i++) {
- if (checked[i] == false) {
- fullscan = 0;
- dev = baseunits[i];
- dev->mq->command =
- MAPLE_COMMAND_DEVINFO;
- dev->mq->length = 0;
- maple_add_packet(dev->mq);
- }
- }
- }
+ /*check if we have actually tested all ports yet */
+ if (!fullscan)
+ maple_port_rescan();
+ /* mark that we have been through the first scan */
if (started == 0)
started = 1;
}
@@ -631,7 +673,7 @@
if (maple_dev->devinfo.function == 0xFFFFFFFF)
return 0;
else if (maple_dev->devinfo.function &
- be32_to_cpu(maple_drv->function))
+ cpu_to_be32(maple_drv->function))
return 1;
return 0;
}
@@ -713,14 +755,19 @@
if (!maple_queue_cache)
goto cleanup_bothirqs;

+ INIT_LIST_HEAD(&maple_waitq);
+ INIT_LIST_HEAD(&maple_sentq);
+
/* setup maple ports */
for (i = 0; i < MAPLE_PORTS; i++) {
checked[i] = false;
mdev[i] = maple_alloc_dev(i, 0);
baseunits[i] = mdev[i];
- if (!mdev[i]) {
- while (i-- > 0)
+ if (!mdev[i] || mutex_lock_interruptible(&mdev[i]->mq->mutex)) {
+ while (i-- > 0) {
+ mutex_unlock(&mdev[i]->mq->mutex);
maple_free_dev(mdev[i]);
+ }
goto cleanup_cache;
}
mdev[i]->mq->command = MAPLE_COMMAND_DEVINFO;



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