[PATCH 3/3] staging: vme: make match() driver specific to improve non-VME64x support

From: Manohar Vanga
Date: Mon Aug 29 2011 - 05:06:49 EST

For jumper based boards (non VME64x), there is no mechanism
for detecting the card that is plugged into a specific slot. This
leads to issues in non-autodiscovery crates/cards when a card is
plugged into a slot that is "claimed" by a different driver. In
reality, there is no problem, but the driver rejects such a
configuration due to its dependence on the concept of slots.

This patch makes the concept of slots less critical and pushes the
driver match() to individual drivers (similar to what happens in the
ISA bus in driver/base/isa.c). This allows drivers to register the
number of devices that they expect without any restrictions. Devices
in this new model are now formatted as $driver_name-$bus_id.$device_id
(as compared to the earlier vme-$bus_id.$slot_number).

This model also makes the device model more logical as devices
are only registered when they actually exist whereas earlier,
a set of devices were being created automatically regardless of
them actually being there.

Another change introduced in this patch is that devices are now created
within the VME driver structure rather than in the VME bridge structure.
This way, things don't go haywire if the bridge driver is removed while
a driver is using it (this is also additionally prevented by having
reference counting of used bridge modules).

Signed-off-by: Manohar Vanga <manohar.vanga@xxxxxxx>
---
drivers/staging/vme/devices/vme_user.c | 53 +++-----
drivers/staging/vme/devices/vme_user.h | 2 +-
drivers/staging/vme/vme.c | 214 ++++++++++++++++---------------
drivers/staging/vme/vme.h | 22 +++-
drivers/staging/vme/vme_api.txt | 60 +++++-----
drivers/staging/vme/vme_bridge.h | 4 -
6 files changed, 177 insertions(+), 178 deletions(-)

diff --git a/drivers/staging/vme/devices/vme_user.c b/drivers/staging/vme/devices/vme_user.c
index bb33dc2..f85be2c 100644
--- a/drivers/staging/vme/devices/vme_user.c
+++ b/drivers/staging/vme/devices/vme_user.c
@@ -43,7 +43,7 @@
static DEFINE_MUTEX(vme_user_mutex);
static const char driver_name[] = "vme_user";

-static int bus[USER_BUS_MAX];
+static int bus[VME_USER_BUS_MAX];
static unsigned int bus_num;

/* Currently Documentation/devices.txt defines the following for VME:
@@ -135,6 +135,7 @@ static ssize_t vme_user_write(struct file *, const char __user *, size_t,
static loff_t vme_user_llseek(struct file *, loff_t, int);
static long vme_user_unlocked_ioctl(struct file *, unsigned int, unsigned long);

+static int vme_user_match(struct vme_dev *);
static int __devinit vme_user_probe(struct vme_dev *);
static int __devexit vme_user_remove(struct vme_dev *);

@@ -620,6 +621,7 @@ static void buf_unalloc(int num)

static struct vme_driver vme_user_driver = {
.name = driver_name,
+ .match = vme_user_match,
.probe = vme_user_probe,
.remove = __devexit_p(vme_user_remove),
};
@@ -628,8 +630,6 @@ static struct vme_driver vme_user_driver = {
static int __init vme_user_init(void)
{
int retval = 0;
- int i;
- struct vme_device_id *ids;

printk(KERN_INFO "VME User Space Access Driver\n");

@@ -643,47 +643,36 @@ static int __init vme_user_init(void)
/* Let's start by supporting one bus, we can support more than one
* in future revisions if that ever becomes necessary.
*/
- if (bus_num > USER_BUS_MAX) {
+ if (bus_num > VME_USER_BUS_MAX) {
printk(KERN_ERR "%s: Driver only able to handle %d buses\n",
- driver_name, USER_BUS_MAX);
- bus_num = USER_BUS_MAX;
- }
-
-
- /* Dynamically create the bind table based on module parameters */
- ids = kzalloc(sizeof(struct vme_device_id) * (bus_num + 1), GFP_KERNEL);
- if (ids == NULL) {
- printk(KERN_ERR "%s: Unable to allocate ID table\n",
- driver_name);
- retval = -ENOMEM;
- goto err_id;
- }
-
- for (i = 0; i < bus_num; i++) {
- ids[i].bus = bus[i];
- /*
- * We register the driver against the slot occupied by *this*
- * card, since it's really a low level way of controlling
- * the VME bridge
- */
- ids[i].slot = VME_SLOT_CURRENT;
+ driver_name, VME_USER_BUS_MAX);
+ bus_num = VME_USER_BUS_MAX;
}

- vme_user_driver.bind_table = ids;
-
- retval = vme_register_driver(&vme_user_driver);
+ /*
+ * Here we just register the maximum number of devices we can and
+ * leave vme_user_match() to allow only 1 to go through to probe().
+ * This way, if we later want to allow multiple user access devices,
+ * we just change the code in vme_user_match().
+ */
+ retval = vme_register_driver(&vme_user_driver, VME_MAX_SLOTS);
if (retval != 0)
goto err_reg;

return retval;

err_reg:
- kfree(ids);
-err_id:
err_nocard:
return retval;
}

+static int vme_user_match(struct vme_dev *vdev)
+{
+ if (vdev->id.num >= VME_USER_BUS_MAX)
+ return 0;
+ return 1;
+}
+
/*
* In this simple access driver, the old behaviour is being preserved as much
* as practical. We will therefore reserve the buffers and request the images
@@ -896,8 +885,6 @@ static int __devexit vme_user_remove(struct vme_dev *dev)
static void __exit vme_user_exit(void)
{
vme_unregister_driver(&vme_user_driver);
-
- kfree(vme_user_driver.bind_table);
}


diff --git a/drivers/staging/vme/devices/vme_user.h b/drivers/staging/vme/devices/vme_user.h
index 24bf4e5..d85a1e9 100644
--- a/drivers/staging/vme/devices/vme_user.h
+++ b/drivers/staging/vme/devices/vme_user.h
@@ -1,7 +1,7 @@
#ifndef _VME_USER_H_
#define _VME_USER_H_

-#define USER_BUS_MAX 1
+#define VME_USER_BUS_MAX 1

/*
* VMEbus Master Window Configuration Structure
diff --git a/drivers/staging/vme/vme.c b/drivers/staging/vme/vme.c
index 19a4ad2..2fc00df 100644
--- a/drivers/staging/vme/vme.c
+++ b/drivers/staging/vme/vme.c
@@ -42,10 +42,7 @@ static DEFINE_MUTEX(vme_buses_lock);
static void __exit vme_exit(void);
static int __init vme_init(void);

-static struct vme_dev *dev_to_vme_dev(struct device *dev)
-{
- return container_of(dev, struct vme_dev, dev);
-}
+#define dev_to_vme_dev(dev) container_of(dev, struct vme_dev, dev)

/*
* Increments the reference count of a VME bridge.
@@ -1363,147 +1360,158 @@ static void vme_remove_bus(struct vme_bridge *bridge)

int vme_register_bridge(struct vme_bridge *bridge)
{
- struct vme_dev *vdev;
- int retval;
- int i;
+ return vme_add_bus(bridge);
+}
+EXPORT_SYMBOL(vme_register_bridge);

- retval = vme_add_bus(bridge);
- if (retval)
- return retval;
+void vme_unregister_bridge(struct vme_bridge *bridge)
+{
+ vme_remove_bus(bridge);
+}
+EXPORT_SYMBOL(vme_unregister_bridge);

- /* This creates 32 vme "slot" devices. This equates to a slot for each
- * ID available in a system conforming to the ANSI/VITA 1-1994
- * specification.
- */
- for (i = 0; i < VME_SLOTS_MAX; i++) {
- vdev = &bridge->dev[i];
- memset(vdev, 0, sizeof(struct vme_dev));

+/* - Driver Registration --------------------------------------------------- */
+
+static void vme_dev_release(struct device *dev)
+{
+ kfree(dev_to_vme_dev(dev));
+}
+
+static int __vme_register_driver_bus(struct vme_driver *drv,
+ struct vme_bridge *bridge, unsigned int ndevs)
+{
+ int err;
+ unsigned int i;
+ struct vme_dev *vdev;
+ struct vme_dev *tmp;
+
+ for (i = 0; i < ndevs; i++) {
+ vdev = kzalloc(sizeof(struct vme_dev), GFP_KERNEL);
+ if (!vdev) {
+ err = -ENOMEM;
+ goto err_alloc;
+ }
+ vdev->id.num = i;
vdev->id.bus = bridge->num;
vdev->id.slot = i + 1;
vdev->bridge = bridge;
+ vdev->dev.platform_data = drv;
+ vdev->dev.release = vme_dev_release;
vdev->dev.parent = bridge->parent;
vdev->dev.bus = &vme_bus_type;
- /*
- * We save a pointer to the bridge in platform_data so that we
- * can get to it later. We keep driver_data for use by the
- * driver that binds against the slot
- */
- vdev->dev.platform_data = bridge;
- dev_set_name(&vdev->dev, "vme-%x.%x", bridge->num, i + 1);
-
- retval = device_register(&vdev->dev);
- if (retval)
- goto err_reg;
+ dev_set_name(&vdev->dev, "%s.%u-%u", drv->name, vdev->id.bus,
+ vdev->id.num);
+
+ err = device_register(&vdev->dev);
+ if (err)
+ goto err_dev_reg;
+
+ if (vdev->dev.platform_data) {
+ list_add_tail(&vdev->list, &drv->devices);
+ drv->ndev++;
+ } else {
+ device_unregister(&vdev->dev);
+ kfree(vdev);
+ }
}
+ return 0;

- return retval;
-
-err_reg:
- while (--i >= 0) {
- vdev = &bridge->dev[i];
+err_dev_reg:
+ kfree(vdev);
+err_alloc:
+ list_for_each_entry_safe(vdev, tmp, &drv->devices, list) {
+ list_del(&vdev->list);
device_unregister(&vdev->dev);
}
- vme_remove_bus(bridge);
- return retval;
+ return err;
}
-EXPORT_SYMBOL(vme_register_bridge);

-void vme_unregister_bridge(struct vme_bridge *bridge)
+static int __vme_register_driver(struct vme_driver *drv, unsigned int ndevs)
{
- int i;
- struct vme_dev *vdev;
-
+ struct vme_bridge *bridge;
+ int err = 0;

- for (i = 0; i < VME_SLOTS_MAX; i++) {
- vdev = &bridge->dev[i];
- device_unregister(&vdev->dev);
+ mutex_lock(&vme_buses_lock);
+ list_for_each_entry(bridge, &vme_bus_list, bus_list) {
+ /*
+ * This cannot cause trouble as we already have vme_buses_lock
+ * and if the bridge is removed, it will have to go through
+ * vme_unregister_bridge() to do it (which calls remove() on
+ * the bridge which in turn tries to acquire vme_buses_lock and
+ * will have to wait). The probe() called after device
+ * registration in __vme_register_driver below will also fail
+ * as the bridge is being removed (since the probe() calls
+ * vme_bridge_get()).
+ */
+ err = __vme_register_driver_bus(drv, bridge, ndevs);
+ if (err)
+ break;
}
- vme_remove_bus(bridge);
+ mutex_unlock(&vme_buses_lock);
+ return err;
}
-EXPORT_SYMBOL(vme_unregister_bridge);
-

-/* - Driver Registration --------------------------------------------------- */
-
-int vme_register_driver(struct vme_driver *drv)
+int vme_register_driver(struct vme_driver *drv, unsigned int ndevs)
{
+ int err;
+
drv->driver.name = drv->name;
drv->driver.bus = &vme_bus_type;
-
- return driver_register(&drv->driver);
+ INIT_LIST_HEAD(&drv->devices);
+
+ err = driver_register(&drv->driver);
+ if (err)
+ return err;
+
+ err = __vme_register_driver(drv, ndevs);
+ if (!err & (drv->ndev == 0))
+ err = -ENODEV;
+ if (err)
+ vme_unregister_driver(drv);
+ return err;
}
EXPORT_SYMBOL(vme_register_driver);

void vme_unregister_driver(struct vme_driver *drv)
{
+ struct vme_dev *dev, *dev_tmp;
+
+ list_for_each_entry_safe(dev, dev_tmp, &drv->devices, list) {
+ device_unregister(&dev->dev);
+ list_del(&dev->list);
+ }
driver_unregister(&drv->driver);
}
EXPORT_SYMBOL(vme_unregister_driver);

/* - Bus Registration ------------------------------------------------------ */

-static struct vme_driver *dev_to_vme_driver(struct device *dev)
-{
- if (dev->driver == NULL)
- printk(KERN_ERR "Bugger dev->driver is NULL\n");
-
- return container_of(dev->driver, struct vme_driver, driver);
-}
-
static int vme_bus_match(struct device *dev, struct device_driver *drv)
{
- struct vme_dev *vdev;
- struct vme_bridge *bridge;
- struct vme_driver *driver;
- int i, num;
-
- vdev = dev_to_vme_dev(dev);
- bridge = vdev->bridge;
- driver = container_of(drv, struct vme_driver, driver);
+ struct vme_driver *vme_drv;

- num = vdev->id.slot;
- if (num <= 0 || num >= VME_SLOTS_MAX)
- goto err_dev;
+ vme_drv = container_of(drv, struct vme_driver, driver);

- if (driver->bind_table == NULL) {
- dev_err(dev, "Bind table NULL\n");
- goto err_table;
- }
-
- i = 0;
- while ((driver->bind_table[i].bus != 0) ||
- (driver->bind_table[i].slot != 0)) {
-
- if (bridge->num == driver->bind_table[i].bus) {
- if (num == driver->bind_table[i].slot)
- return 1;
+ if (dev->platform_data == vme_drv) {
+ struct vme_dev *vdev = dev_to_vme_dev(dev);

- if (driver->bind_table[i].slot == VME_SLOT_ALL)
- return 1;
+ if (vme_drv->match && vme_drv->match(vdev))
+ return 1;

- if ((driver->bind_table[i].slot == VME_SLOT_CURRENT) &&
- (num == vme_slot_get(vdev)))
- return 1;
- }
- i++;
+ dev->platform_data = NULL;
}
-
-err_dev:
-err_table:
return 0;
}

static int vme_bus_probe(struct device *dev)
{
- struct vme_bridge *bridge;
- struct vme_driver *driver;
- struct vme_dev *vdev;
int retval = 0;
+ struct vme_driver *driver;
+ struct vme_dev *vdev = dev_to_vme_dev(dev);
+ struct vme_bridge *bridge = vdev->bridge;

- driver = dev_to_vme_driver(dev);
- vdev = dev_to_vme_dev(dev);
- bridge = vdev->bridge;
+ driver = dev->platform_data;

if (driver->probe) {
if (vme_bridge_get(bridge))
@@ -1519,14 +1527,12 @@ static int vme_bus_probe(struct device *dev)

static int vme_bus_remove(struct device *dev)
{
- struct vme_bridge *bridge;
- struct vme_driver *driver;
- struct vme_dev *vdev;
int retval = 0;
+ struct vme_driver *driver;
+ struct vme_dev *vdev = dev_to_vme_dev(dev);
+ struct vme_bridge *bridge = vdev->bridge;

- driver = dev_to_vme_driver(dev);
- vdev = dev_to_vme_dev(dev);
- bridge = vdev->bridge;
+ driver = dev->platform_data;

if (driver->remove)
retval = driver->remove(vdev);
diff --git a/drivers/staging/vme/vme.h b/drivers/staging/vme/vme.h
index d442cce..1033344 100644
--- a/drivers/staging/vme/vme.h
+++ b/drivers/staging/vme/vme.h
@@ -88,15 +88,21 @@ struct vme_resource {

extern struct bus_type vme_bus_type;

+/* VME_MAX_BRIDGES comes from the type of vme_bus_numbers */
+#define VME_MAX_BRIDGES (sizeof(unsigned int)*8)
+#define VME_MAX_SLOTS 32
+
#define VME_SLOT_CURRENT -1
#define VME_SLOT_ALL -2

/**
* VME device identifier structure
+ * @num: The device ID (ranges from 0 to N-1 for N devices)
* @bus: The bus ID of the bus the device is on
* @slot: The slot this device is plugged into
*/
struct vme_device_id {
+ int num;
int bus;
int slot;
};
@@ -106,21 +112,25 @@ struct vme_device_id {
* @id: The ID of the device (currently the bus and slot number)
* @bridge: Pointer to the bridge device this device is on
* @dev: Internal device structure
+ * @list: List of devices (per driver)
*/
struct vme_dev {
struct vme_device_id id;
struct vme_bridge *bridge;
struct device dev;
+ struct list_head list;
};

struct vme_driver {
struct list_head node;
const char *name;
- const struct vme_device_id *bind_table;
- int (*probe) (struct vme_dev *);
- int (*remove) (struct vme_dev *);
- void (*shutdown) (void);
- struct device_driver driver;
+ int (*match)(struct vme_dev *);
+ int (*probe)(struct vme_dev *);
+ int (*remove)(struct vme_dev *);
+ void (*shutdown)(void);
+ struct device_driver driver;
+ struct list_head devices;
+ unsigned int ndev;
};

void *vme_alloc_consistent(struct vme_resource *, size_t, dma_addr_t *);
@@ -179,7 +189,7 @@ void vme_lm_free(struct vme_resource *);

int vme_slot_get(struct vme_dev *);

-int vme_register_driver(struct vme_driver *);
+int vme_register_driver(struct vme_driver *, unsigned int);
void vme_unregister_driver(struct vme_driver *);


diff --git a/drivers/staging/vme/vme_api.txt b/drivers/staging/vme/vme_api.txt
index 03f4813..ffe28c3 100644
--- a/drivers/staging/vme/vme_api.txt
+++ b/drivers/staging/vme/vme_api.txt
@@ -18,24 +18,37 @@ registration function. The structure is as follows:

struct vme_driver {
struct list_head node;
- char *name;
- const struct vme_device_id *bind_table;
- int (*probe) (struct vme_dev *);
- int (*remove) (struct vme_dev *);
- void (*shutdown) (void);
- struct device_driver driver;
+ const char *name;
+ int (*match)(struct vme_dev *);
+ int (*probe)(struct vme_dev *);
+ int (*remove)(struct vme_dev *);
+ void (*shutdown)(void);
+ struct device_driver driver;
+ struct list_head devices;
+ unsigned int ndev;
};

-At the minimum, the '.name', '.probe' and '.bind_table' elements of this
-structure should be correctly set. The '.name' element is a pointer to a string
-holding the device driver's name. The '.probe' element should contain a pointer
-to the probe routine.
+At the minimum, the '.name', '.match' and '.probe' elements of this structure
+should be correctly set. The '.name' element is a pointer to a string holding
+the device driver's name.

-The arguments of the probe routine are as follows:
+The '.match' function allows controlling the number of devices that need to
+be registered. The match function should return 1 if a device should be
+probed and 0 otherwise. This example match function (from vme_user.c) limits
+the number of devices probed to one:

- probe(struct vme_dev *dev);
+ #define VME_USER_BUS_MAX 1
+ ...
+ static int vme_user_match(struct vme_dev *vdev)
+ {
+ if (vdev->id.num >= VME_USER_BUS_MAX)
+ return 0;
+ return 1;
+ }

-The device structure looks like the following:
+The '.probe' element should contain a pointer to the probe routine. The
+probe routine is passed a 'struct vme_dev' pointer as an argument. The
+'struct vme_dev' structure looks like the following:

struct vme_dev {
struct vme_device_id id;
@@ -49,25 +62,12 @@ contains information useful for the probe function:
struct vme_device_id {
int bus;
int slot;
+ int num;
};

-'bus' is the number of the bus the device being probed is on. 'slot' refers
-to the specific slot on the VME bus.
-
-The '.bind_table' is a pointer to an array of type 'vme_device_id':
-
- struct vme_device_id {
- int bus;
- int slot;
- };
-
-Each structure in this array should provide a bus and slot number where the core
-should probe, using the driver's probe routine, for a device on the specified
-VME bus.
-
-The VME subsystem supports a single VME driver per 'slot'. There are considered
-to be 32 slots per bus, one for each slot-ID as defined in the ANSI/VITA 1-1994
-specification and are analogious to the physical slots on the VME backplane.
+Here, 'bus' is the number of the bus the device being probed is on. 'slot'
+refers to the specific slot on the VME bus. The 'num' field refers to the
+sequential device ID for this specific driver.

A function is also provided to unregister the driver from the VME core and is
usually called from the device driver's exit routine:
diff --git a/drivers/staging/vme/vme_bridge.h b/drivers/staging/vme/vme_bridge.h
index 74d0103..24cb4b8 100644
--- a/drivers/staging/vme/vme_bridge.h
+++ b/drivers/staging/vme/vme_bridge.h
@@ -2,7 +2,6 @@
#define _VME_BRIDGE_H_

#define VME_CRCSR_BUF_SIZE (508*1024)
-#define VME_SLOTS_MAX 32
/*
* Resource structures
*/
@@ -115,9 +114,6 @@ struct vme_bridge {
struct list_head bus_list; /* list of VME buses */
struct module *owner; /* module that owns the bridge */

- struct vme_dev dev[VME_SLOTS_MAX]; /* Device registered
- * on VME bus */
-
/* Interrupt callbacks */
struct vme_irq irq[7];
/* Locking for VME irq callback configuration */
--
1.7.4.1

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