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Subject[PATCH 04/30] staging/vme: allow non-dynamic allocation of bus numbers
Date
From: Emilio G. Cota <cota@braap.org>

In a configuration with several bridges, each bridge is
assigned a certain bus number depending on the order in which
vme_register_bridge is called. This can complicate multi-bridge
installations because the eventual bus numbers will depend
on the order the bridges were loaded.

The appended allows bridges to register with a bus number of
their choice, while keeping the previous 'first come, first
served' behaviour as the default.

Signed-off-by: Emilio G. Cota <cota@braap.org>
---
drivers/staging/vme/bridges/vme_ca91cx42.c | 1 +
drivers/staging/vme/bridges/vme_tsi148.c | 1 +
drivers/staging/vme/vme.c | 46 +++++++++++++++++++++-------
drivers/staging/vme/vme.h | 1 +
4 files changed, 38 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/vme/bridges/vme_ca91cx42.c b/drivers/staging/vme/bridges/vme_ca91cx42.c
index 1f2089f..14e10a6 100644
--- a/drivers/staging/vme/bridges/vme_ca91cx42.c
+++ b/drivers/staging/vme/bridges/vme_ca91cx42.c
@@ -1600,6 +1600,7 @@ static int ca91cx42_probe(struct pci_dev *pdev, const struct pci_device_id *id)
}

ca91cx42_bridge->driver_priv = ca91cx42_device;
+ ca91cx42_bridge->num = -1;

/* Enable the device */
retval = pci_enable_device(pdev);
diff --git a/drivers/staging/vme/bridges/vme_tsi148.c b/drivers/staging/vme/bridges/vme_tsi148.c
index 1cba1fa..e341122 100644
--- a/drivers/staging/vme/bridges/vme_tsi148.c
+++ b/drivers/staging/vme/bridges/vme_tsi148.c
@@ -2247,6 +2247,7 @@ static int tsi148_probe(struct pci_dev *pdev, const struct pci_device_id *id)
}

tsi148_bridge->driver_priv = tsi148_device;
+ tsi148_bridge->num = -1;

/* Enable the device */
retval = pci_enable_device(pdev);
diff --git a/drivers/staging/vme/vme.c b/drivers/staging/vme/vme.c
index 47e9d5c..9fa0609 100644
--- a/drivers/staging/vme/vme.c
+++ b/drivers/staging/vme/vme.c
@@ -1307,20 +1307,42 @@ EXPORT_SYMBOL(vme_slot_get);

/* - Bridge Registration --------------------------------------------------- */

-static int vme_alloc_bus_num(void)
+/* call with vme_bus_num_mtx held */
+static int __vme_alloc_bus_num(int *bus)
{
- int i;
-
- mutex_lock(&vme_bus_num_mtx);
- for (i = 0; i < sizeof(vme_bus_numbers) * 8; i++) {
- if (((vme_bus_numbers >> i) & 0x1) == 0) {
- vme_bus_numbers |= (0x1 << i);
- break;
+ int index;
+
+ if (*bus == -1) {
+ /* try to find a free bus number */
+ for (index = 0; index < VME_MAX_BRIDGES; index++) {
+ if (~vme_bus_numbers & 1 << index) {
+ *bus = index;
+ break;
+ }
+ }
+ if (index == VME_MAX_BRIDGES) {
+ pr_warn("vme: No bus numbers left\n");
+ return -ENODEV;
+ }
+ } else {
+ /* check if the given bus number is already in use */
+ if (vme_bus_numbers & (1 << *bus)) {
+ pr_warn("vme: bus number %d already in use\n", *bus);
+ return -EBUSY;
}
}
- mutex_unlock(&vme_bus_num_mtx);
+ vme_bus_numbers |= 1 << *bus;
+ return 0;
+}
+
+static int vme_alloc_bus_num(int *bus)
+{
+ int ret;

- return i;
+ mutex_lock(&vme_bus_num_mtx);
+ ret = __vme_alloc_bus_num(bus);
+ mutex_unlock(&vme_bus_num_mtx);
+ return ret;
}

static void vme_free_bus_num(int bus)
@@ -1336,7 +1358,9 @@ int vme_register_bridge(struct vme_bridge *bridge)
int retval;
int i;

- bridge->num = vme_alloc_bus_num();
+ retval = vme_alloc_bus_num(&bridge->num);
+ if (retval)
+ return retval;

/* 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
diff --git a/drivers/staging/vme/vme.h b/drivers/staging/vme/vme.h
index 48768ca..5cdfa52 100644
--- a/drivers/staging/vme/vme.h
+++ b/drivers/staging/vme/vme.h
@@ -88,6 +88,7 @@ struct vme_resource {

extern struct bus_type vme_bus_type;

+#define VME_MAX_BRIDGES 32
#define VME_SLOT_CURRENT -1
#define VME_SLOT_ALL -2

--
1.7.1


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