[PATCH 3/7] rapidio: update enumerator registration mechanism

From: Alexandre Bounine
Date: Fri Jun 28 2013 - 15:31:18 EST

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Update enumeration/discovery method registration mechanism to allow loading
enumeration/discovery methods before all mports are registered.

Existing statically linked RapidIO subsystem expects that all available RapidIO
mport devices are initialized and registered before the enumeration/discovery
method is registered. Switching to loadable mport device drivers creates
situation when mport device driver can be loaded after enumeration/discovery
method is attached (e.g., loadable mport driver in a system with statically
linked RapidIO core and enumerator). This also will happen in a system with
hot-pluggable RapidIO controllers.

To remove the dependency on the initialization/registration order this patch
introduces enumeration/discovery registration mechanism that supports arbitrary
registration order of mports and enumerator/discovery methods.

The following registration rules are implemented:
- only one enumeration/discovery method can be registered for given mport ID
(including RIO_MPORT_ANY);
- when new enumeration/discovery methods tries to attach to the registered mport
device, method with matching mport ID will replace a default method previously
registered for given mport (if any);
- enumeration/discovery method with target ID=RIO_MPORT_ANY will be attached
only to mports that do not have another enumerator attached to them;
- when new mport device is registered with RapidIO subsystem, registration
routine searches for the enumeration/discovery method with the best matching
mport ID;

Signed-off-by: Alexandre Bounine <alexandre.bounine@xxxxxxx>
Cc: Matt Porter <mporter@xxxxxxxxxxxxxxxxxxx>
Cc: Li Yang <leoli@xxxxxxxxxxxxx>
Cc: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>
Cc: Andre van Herk <andre.van.herk@xxxxxxxxxxx>
Cc: Micha Nelissen <micha.nelissen@xxxxxxxxxxx>
Cc: Stef van Os <stef.van.os@xxxxxxxxxxx>
Cc: Jean Delvare <jdelvare@xxxxxxx>
---
drivers/rapidio/rio-scan.c | 1 +
drivers/rapidio/rio-sysfs.c | 17 +----
drivers/rapidio/rio.c | 176 +++++++++++++++++++++++++++++++++++--------
drivers/rapidio/rio.h | 3 +-
include/linux/rio.h | 15 ++++
5 files changed, 164 insertions(+), 48 deletions(-)

diff --git a/drivers/rapidio/rio-scan.c b/drivers/rapidio/rio-scan.c
index 61c913f..0e86569 100644
--- a/drivers/rapidio/rio-scan.c
+++ b/drivers/rapidio/rio-scan.c
@@ -1162,6 +1162,7 @@ bail:
}

static struct rio_scan rio_scan_ops = {
+ .owner = THIS_MODULE,
.enumerate = rio_enum_mport,
.discover = rio_disc_mport,
};
diff --git a/drivers/rapidio/rio-sysfs.c b/drivers/rapidio/rio-sysfs.c
index 864e52f..0c4473e 100644
--- a/drivers/rapidio/rio-sysfs.c
+++ b/drivers/rapidio/rio-sysfs.c
@@ -286,7 +286,6 @@ static ssize_t bus_scan_store(struct bus_type *bus, const char *buf,
size_t count)
{
long val;
- struct rio_mport *port = NULL;
int rc;

if (kstrtol(buf, 0, &val) < 0)
@@ -300,21 +299,7 @@ static ssize_t bus_scan_store(struct bus_type *bus, const char *buf,
if (val < 0 || val >= RIO_MAX_MPORTS)
return -EINVAL;

- port = rio_find_mport((int)val);
-
- if (!port) {
- pr_debug("RIO: %s: mport_%d not available\n",
- __func__, (int)val);
- return -EINVAL;
- }
-
- if (!port->nscan)
- return -EINVAL;
-
- if (port->host_deviceid >= 0)
- rc = port->nscan->enumerate(port, 0);
- else
- rc = port->nscan->discover(port, RIO_SCAN_ENUM_NO_WAIT);
+ rc = rio_mport_scan((int)val);
exit:
if (!rc)
rc = count;
diff --git a/drivers/rapidio/rio.c b/drivers/rapidio/rio.c
index b17d521..5eb727c 100644
--- a/drivers/rapidio/rio.c
+++ b/drivers/rapidio/rio.c
@@ -34,6 +34,7 @@ static LIST_HEAD(rio_devices);
static DEFINE_SPINLOCK(rio_global_list_lock);

static LIST_HEAD(rio_mports);
+static LIST_HEAD(rio_scans);
static DEFINE_MUTEX(rio_mport_list_lock);
static unsigned char next_portid;
static DEFINE_SPINLOCK(rio_mmap_lock);
@@ -1602,34 +1603,73 @@ found:
* rio_register_scan - enumeration/discovery method registration interface
* @mport_id: mport device ID for which fabric scan routine has to be set
* (RIO_MPORT_ANY = set for all available mports)
- * @scan_ops: enumeration/discovery control structure
+ * @scan_ops: enumeration/discovery operations structure
+ *
+ * Registers enumeration/discovery operations with RapidIO subsystem and
+ * attaches it to the specified mport device (or all available mports
+ * if RIO_MPORT_ANY is specified).
*
- * Assigns enumeration or discovery method to the specified mport device (or all
- * available mports if RIO_MPORT_ANY is specified).
* Returns error if the mport already has an enumerator attached to it.
- * In case of RIO_MPORT_ANY ignores ports with valid scan routines and returns
- * an error if was unable to find at least one available mport.
+ * In case of RIO_MPORT_ANY skips mports with valid scan routines (no error).
*/
int rio_register_scan(int mport_id, struct rio_scan *scan_ops)
{
struct rio_mport *port;
- int rc = -EBUSY;
+ struct rio_scan_node *scan;
+ int rc = 0;

- mutex_lock(&rio_mport_list_lock);
- list_for_each_entry(port, &rio_mports, node) {
- if (port->id == mport_id || mport_id == RIO_MPORT_ANY) {
- if (port->nscan && mport_id == RIO_MPORT_ANY)
- continue;
- else if (port->nscan)
- break;
+ pr_debug("RIO: %s for mport_id=%d\n", __func__, mport_id);

- port->nscan = scan_ops;
- rc = 0;
+ if ((mport_id != RIO_MPORT_ANY && mport_id >= RIO_MAX_MPORTS) ||
+ !scan_ops)
+ return -EINVAL;

- if (mport_id != RIO_MPORT_ANY)
- break;
+ mutex_lock(&rio_mport_list_lock);
+
+ /*
+ * Check if there is another enumerator already registered for
+ * the same mport ID (including RIO_MPORT_ANY). Multiple enumerators
+ * for the same mport ID are not supported.
+ */
+ list_for_each_entry(scan, &rio_scans, node) {
+ if (scan->mport_id == mport_id) {
+ rc = -EBUSY;
+ goto err_out;
}
}
+
+ /*
+ * Allocate and initialize new scan registration node.
+ */
+ scan = kzalloc(sizeof(*scan), GFP_KERNEL);
+ if (!scan) {
+ rc = -ENOMEM;
+ goto err_out;
+ }
+
+ scan->mport_id = mport_id;
+ scan->ops = scan_ops;
+
+ /*
+ * Traverse the list of registered mports to attach this new scan.
+ *
+ * The new scan with matching mport ID overrides any previously attached
+ * scan assuming that old scan (if any) is the default one (based on the
+ * enumerator registration check above).
+ * If the new scan is the global one, it will be attached only to mports
+ * that do not have their own individual operations already attached.
+ */
+ list_for_each_entry(port, &rio_mports, node) {
+ if (port->id == mport_id) {
+ port->nscan = scan_ops;
+ break;
+ } else if (mport_id == RIO_MPORT_ANY && !port->nscan)
+ port->nscan = scan_ops;
+ }
+
+ list_add_tail(&scan->node, &rio_scans);
+
+err_out:
mutex_unlock(&rio_mport_list_lock);

return rc;
@@ -1639,30 +1679,81 @@ EXPORT_SYMBOL_GPL(rio_register_scan);
/**
* rio_unregister_scan - removes enumeration/discovery method from mport
* @mport_id: mport device ID for which fabric scan routine has to be
- * unregistered (RIO_MPORT_ANY = set for all available mports)
+ * unregistered (RIO_MPORT_ANY = apply to all mports that use
+ * the specified scan_ops)
+ * @scan_ops: enumeration/discovery operations structure
*
* Removes enumeration or discovery method assigned to the specified mport
- * device (or all available mports if RIO_MPORT_ANY is specified).
+ * device. If RIO_MPORT_ANY is specified, removes the specified operations from
+ * all mports that have them attached.
*/
-int rio_unregister_scan(int mport_id)
+int rio_unregister_scan(int mport_id, struct rio_scan *scan_ops)
{
struct rio_mport *port;
+ struct rio_scan_node *scan;
+
+ pr_debug("RIO: %s for mport_id=%d\n", __func__, mport_id);
+
+ if (mport_id != RIO_MPORT_ANY && mport_id >= RIO_MAX_MPORTS)
+ return -EINVAL;

mutex_lock(&rio_mport_list_lock);
- list_for_each_entry(port, &rio_mports, node) {
- if (port->id == mport_id || mport_id == RIO_MPORT_ANY) {
- if (port->nscan)
- port->nscan = NULL;
- if (mport_id != RIO_MPORT_ANY)
- break;
+
+ list_for_each_entry(port, &rio_mports, node)
+ if (port->id == mport_id ||
+ (mport_id == RIO_MPORT_ANY && port->nscan == scan_ops))
+ port->nscan = NULL;
+
+ list_for_each_entry(scan, &rio_scans, node)
+ if (scan->mport_id == mport_id) {
+ list_del(&scan->node);
+ kfree(scan);
}
- }
+
mutex_unlock(&rio_mport_list_lock);

return 0;
}
EXPORT_SYMBOL_GPL(rio_unregister_scan);

+/**
+ * rio_mport_scan - execute enumeration/discovery on the specified mport
+ * @mport_id: number (ID) of mport device
+ */
+int rio_mport_scan(int mport_id)
+{
+ struct rio_mport *port = NULL;
+ int rc;
+
+ mutex_lock(&rio_mport_list_lock);
+ list_for_each_entry(port, &rio_mports, node) {
+ if (port->id == mport_id)
+ goto found;
+ }
+ mutex_unlock(&rio_mport_list_lock);
+ return -ENODEV;
+found:
+ if (!port->nscan) {
+ mutex_unlock(&rio_mport_list_lock);
+ return -EINVAL;
+ }
+
+ if (!try_module_get(port->nscan->owner)) {
+ mutex_unlock(&rio_mport_list_lock);
+ return -ENODEV;
+ }
+
+ mutex_unlock(&rio_mport_list_lock);
+
+ if (port->host_deviceid >= 0)
+ rc = port->nscan->enumerate(port, 0);
+ else
+ rc = port->nscan->discover(port, RIO_SCAN_ENUM_NO_WAIT);
+
+ module_put(port->nscan->owner);
+ return rc;
+}
+
static void rio_fixup_device(struct rio_dev *dev)
{
}
@@ -1691,7 +1782,10 @@ static void disc_work_handler(struct work_struct *_work)
work = container_of(_work, struct rio_disc_work, work);
pr_debug("RIO: discovery work for mport %d %s\n",
work->mport->id, work->mport->name);
- work->mport->nscan->discover(work->mport, 0);
+ if (try_module_get(work->mport->nscan->owner)) {
+ work->mport->nscan->discover(work->mport, 0);
+ module_put(work->mport->nscan->owner);
+ }
}

int rio_init_mports(void)
@@ -1710,8 +1804,10 @@ int rio_init_mports(void)
mutex_lock(&rio_mport_list_lock);
list_for_each_entry(port, &rio_mports, node) {
if (port->host_deviceid >= 0) {
- if (port->nscan)
+ if (port->nscan && try_module_get(port->nscan->owner)) {
port->nscan->enumerate(port, 0);
+ module_put(port->nscan->owner);
+ }
} else
n++;
}
@@ -1725,7 +1821,7 @@ int rio_init_mports(void)
* for each of them. If the code below fails to allocate needed
* resources, exit without error to keep results of enumeration
* process (if any).
- * TODO: Implement restart of dicovery process for all or
+ * TODO: Implement restart of discovery process for all or
* individual discovering mports.
*/
rio_wq = alloc_workqueue("riodisc", 0, 0);
@@ -1751,9 +1847,9 @@ int rio_init_mports(void)
n++;
}
}
- mutex_unlock(&rio_mport_list_lock);

flush_workqueue(rio_wq);
+ mutex_unlock(&rio_mport_list_lock);
pr_debug("RIO: destroy discovery workqueue\n");
destroy_workqueue(rio_wq);
kfree(work);
@@ -1784,6 +1880,8 @@ __setup("riohdid=", rio_hdid_setup);

int rio_register_mport(struct rio_mport *port)
{
+ struct rio_scan_node *scan = NULL;
+
if (next_portid >= RIO_MAX_MPORTS) {
pr_err("RIO: reached specified max number of mports\n");
return 1;
@@ -1792,9 +1890,25 @@ int rio_register_mport(struct rio_mport *port)
port->id = next_portid++;
port->host_deviceid = rio_get_hdid(port->id);
port->nscan = NULL;
+
mutex_lock(&rio_mport_list_lock);
list_add_tail(&port->node, &rio_mports);
+
+ /*
+ * Check if there are any registered enumeration/discovery operations
+ * that have to be attached to the added mport.
+ */
+ list_for_each_entry(scan, &rio_scans, node) {
+ if (port->id == scan->mport_id ||
+ scan->mport_id == RIO_MPORT_ANY) {
+ port->nscan = scan->ops;
+ if (port->id == scan->mport_id)
+ break;
+ }
+ }
mutex_unlock(&rio_mport_list_lock);
+
+ pr_debug("RIO: %s %s id=%d\n", __func__, port->name, port->id);
return 0;
}

diff --git a/drivers/rapidio/rio.h b/drivers/rapidio/rio.h
index d595877..085215c 100644
--- a/drivers/rapidio/rio.h
+++ b/drivers/rapidio/rio.h
@@ -42,9 +42,10 @@ extern int rio_add_device(struct rio_dev *rdev);
extern int rio_enable_rx_tx_port(struct rio_mport *port, int local, u16 destid,
u8 hopcount, u8 port_num);
extern int rio_register_scan(int mport_id, struct rio_scan *scan_ops);
-extern int rio_unregister_scan(int mport_id);
+extern int rio_unregister_scan(int mport_id, struct rio_scan *scan_ops);
extern void rio_attach_device(struct rio_dev *rdev);
extern struct rio_mport *rio_find_mport(int mport_id);
+extern int rio_mport_scan(int mport_id);

/* Structures internal to the RIO core code */
extern struct device_attribute rio_dev_attrs[];
diff --git a/include/linux/rio.h b/include/linux/rio.h
index fcd492e..8d3db1b 100644
--- a/include/linux/rio.h
+++ b/include/linux/rio.h
@@ -465,14 +465,29 @@ static inline struct rio_mport *dma_to_mport(struct dma_device *ddev)

/**
* struct rio_scan - RIO enumeration and discovery operations
+ * @owner: The module owner of this structure
* @enumerate: Callback to perform RapidIO fabric enumeration.
* @discover: Callback to perform RapidIO fabric discovery.
*/
struct rio_scan {
+ struct module *owner;
int (*enumerate)(struct rio_mport *mport, u32 flags);
int (*discover)(struct rio_mport *mport, u32 flags);
};

+/**
+ * struct rio_scan_node - list node to register RapidIO enumeration and
+ * discovery methods with RapidIO core.
+ * @mport_id: ID of an mport (net) serviced by this enumerator
+ * @node: node in global list of registered enumerators
+ * @ops: RIO enumeration and discovery operations
+ */
+struct rio_scan_node {
+ int mport_id;
+ struct list_head node;
+ struct rio_scan *ops;
+};
+
/* Architecture and hardware-specific functions */
extern int rio_register_mport(struct rio_mport *);
extern int rio_open_inb_mbox(struct rio_mport *, void *, int, int);
--
1.7.8.4

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