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Message-Id: <1206209786.6324.41.camel@localhost.localdomain>
Date: Sat, 22 Mar 2008 18:16:26 +0000
From: Adrian McMenamin <adrian@...golddream.dyndns.info>
To: Greg KH <greg@...ah.com>
Cc: dwmw2 <dwmw2@...radead.org>, LKML <linux-kernel@...r.kernel.org>,
MTD <linux-mtd@...ts.infradead.org>,
linux-sh <linux-sh@...r.kernel.org>,
Paul Mundt <lethal@...rs.sourceforge.net>,
Andrew Morton <akpm@...l.org>
Subject: Re: [PATCH] 3/3 maple: update bus driver to support Dreamcast VMU
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@...en.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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