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path: root/drivers/platform/x86/p2sb.c
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Diffstat (limited to 'drivers/platform/x86/p2sb.c')
-rw-r--r--drivers/platform/x86/p2sb.c172
1 files changed, 41 insertions, 131 deletions
diff --git a/drivers/platform/x86/p2sb.c b/drivers/platform/x86/p2sb.c
index fcf1ce8bbdc5..1cf2471d54dd 100644
--- a/drivers/platform/x86/p2sb.c
+++ b/drivers/platform/x86/p2sb.c
@@ -26,21 +26,6 @@ static const struct x86_cpu_id p2sb_cpu_ids[] = {
{}
};
-/*
- * Cache BAR0 of P2SB device functions 0 to 7.
- * TODO: The constant 8 is the number of functions that PCI specification
- * defines. Same definitions exist tree-wide. Unify this definition and
- * the other definitions then move to include/uapi/linux/pci.h.
- */
-#define NR_P2SB_RES_CACHE 8
-
-struct p2sb_res_cache {
- u32 bus_dev_id;
- struct resource res;
-};
-
-static struct p2sb_res_cache p2sb_resources[NR_P2SB_RES_CACHE];
-
static int p2sb_get_devfn(unsigned int *devfn)
{
unsigned int fn = P2SB_DEVFN_DEFAULT;
@@ -54,16 +39,8 @@ static int p2sb_get_devfn(unsigned int *devfn)
return 0;
}
-static bool p2sb_valid_resource(struct resource *res)
-{
- if (res->flags)
- return true;
-
- return false;
-}
-
/* Copy resource from the first BAR of the device in question */
-static void p2sb_read_bar0(struct pci_dev *pdev, struct resource *mem)
+static int p2sb_read_bar0(struct pci_dev *pdev, struct resource *mem)
{
struct resource *bar0 = &pdev->resource[0];
@@ -79,64 +56,47 @@ static void p2sb_read_bar0(struct pci_dev *pdev, struct resource *mem)
mem->end = bar0->end;
mem->flags = bar0->flags;
mem->desc = bar0->desc;
+
+ return 0;
}
-static void p2sb_scan_and_cache_devfn(struct pci_bus *bus, unsigned int devfn)
+static int p2sb_scan_and_read(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
{
- struct p2sb_res_cache *cache = &p2sb_resources[PCI_FUNC(devfn)];
struct pci_dev *pdev;
+ int ret;
pdev = pci_scan_single_device(bus, devfn);
if (!pdev)
- return;
+ return -ENODEV;
- p2sb_read_bar0(pdev, &cache->res);
- cache->bus_dev_id = bus->dev.id;
+ ret = p2sb_read_bar0(pdev, mem);
pci_stop_and_remove_bus_device(pdev);
- return;
-}
-
-static int p2sb_scan_and_cache(struct pci_bus *bus, unsigned int devfn)
-{
- unsigned int slot, fn;
-
- if (PCI_FUNC(devfn) == 0) {
- /*
- * When function number of the P2SB device is zero, scan it and
- * other function numbers, and if devices are available, cache
- * their BAR0s.
- */
- slot = PCI_SLOT(devfn);
- for (fn = 0; fn < NR_P2SB_RES_CACHE; fn++)
- p2sb_scan_and_cache_devfn(bus, PCI_DEVFN(slot, fn));
- } else {
- /* Scan the P2SB device and cache its BAR0 */
- p2sb_scan_and_cache_devfn(bus, devfn);
- }
-
- if (!p2sb_valid_resource(&p2sb_resources[PCI_FUNC(devfn)].res))
- return -ENOENT;
-
- return 0;
-}
-
-static struct pci_bus *p2sb_get_bus(struct pci_bus *bus)
-{
- static struct pci_bus *p2sb_bus;
-
- bus = bus ?: p2sb_bus;
- if (bus)
- return bus;
-
- /* Assume P2SB is on the bus 0 in domain 0 */
- p2sb_bus = pci_find_bus(0, 0);
- return p2sb_bus;
+ return ret;
}
-static int p2sb_cache_resources(void)
+/**
+ * p2sb_bar - Get Primary to Sideband (P2SB) bridge device BAR
+ * @bus: PCI bus to communicate with
+ * @devfn: PCI slot and function to communicate with
+ * @mem: memory resource to be filled in
+ *
+ * The BIOS prevents the P2SB device from being enumerated by the PCI
+ * subsystem, so we need to unhide and hide it back to lookup the BAR.
+ *
+ * if @bus is NULL, the bus 0 in domain 0 will be used.
+ * If @devfn is 0, it will be replaced by devfn of the P2SB device.
+ *
+ * Caller must provide a valid pointer to @mem.
+ *
+ * Locking is handled by pci_rescan_remove_lock mutex.
+ *
+ * Return:
+ * 0 on success or appropriate errno value on error.
+ */
+int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
{
- struct pci_bus *bus;
+ struct pci_dev *pdev_p2sb;
unsigned int devfn_p2sb;
u32 value = P2SBC_HIDE;
int ret;
@@ -146,9 +106,8 @@ static int p2sb_cache_resources(void)
if (ret)
return ret;
- bus = p2sb_get_bus(NULL);
- if (!bus)
- return -ENODEV;
+ /* if @bus is NULL, use bus 0 in domain 0 */
+ bus = bus ?: pci_find_bus(0, 0);
/*
* Prevent concurrent PCI bus scan from seeing the P2SB device and
@@ -156,16 +115,17 @@ static int p2sb_cache_resources(void)
*/
pci_lock_rescan_remove();
- /*
- * The BIOS prevents the P2SB device from being enumerated by the PCI
- * subsystem, so we need to unhide and hide it back to lookup the BAR.
- * Unhide the P2SB device here, if needed.
- */
+ /* Unhide the P2SB device, if needed */
pci_bus_read_config_dword(bus, devfn_p2sb, P2SBC, &value);
if (value & P2SBC_HIDE)
pci_bus_write_config_dword(bus, devfn_p2sb, P2SBC, 0);
- ret = p2sb_scan_and_cache(bus, devfn_p2sb);
+ pdev_p2sb = pci_scan_single_device(bus, devfn_p2sb);
+ if (devfn)
+ ret = p2sb_scan_and_read(bus, devfn, mem);
+ else
+ ret = p2sb_read_bar0(pdev_p2sb, mem);
+ pci_stop_and_remove_bus_device(pdev_p2sb);
/* Hide the P2SB device, if it was hidden */
if (value & P2SBC_HIDE)
@@ -173,62 +133,12 @@ static int p2sb_cache_resources(void)
pci_unlock_rescan_remove();
- return ret;
-}
-
-/**
- * p2sb_bar - Get Primary to Sideband (P2SB) bridge device BAR
- * @bus: PCI bus to communicate with
- * @devfn: PCI slot and function to communicate with
- * @mem: memory resource to be filled in
- *
- * If @bus is NULL, the bus 0 in domain 0 will be used.
- * If @devfn is 0, it will be replaced by devfn of the P2SB device.
- *
- * Caller must provide a valid pointer to @mem.
- *
- * Return:
- * 0 on success or appropriate errno value on error.
- */
-int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
-{
- struct p2sb_res_cache *cache;
- int ret;
-
- bus = p2sb_get_bus(bus);
- if (!bus)
- return -ENODEV;
-
- if (!devfn) {
- ret = p2sb_get_devfn(&devfn);
- if (ret)
- return ret;
- }
+ if (ret)
+ return ret;
- cache = &p2sb_resources[PCI_FUNC(devfn)];
- if (cache->bus_dev_id != bus->dev.id)
+ if (mem->flags == 0)
return -ENODEV;
- if (!p2sb_valid_resource(&cache->res))
- return -ENOENT;
-
- memcpy(mem, &cache->res, sizeof(*mem));
return 0;
}
EXPORT_SYMBOL_GPL(p2sb_bar);
-
-static int __init p2sb_fs_init(void)
-{
- p2sb_cache_resources();
- return 0;
-}
-
-/*
- * pci_rescan_remove_lock to avoid access to unhidden P2SB devices can
- * not be locked in sysfs pci bus rescan path because of deadlock. To
- * avoid the deadlock, access to P2SB devices with the lock at an early
- * step in kernel initialization and cache required resources. This
- * should happen after subsys_initcall which initializes PCI subsystem
- * and before device_initcall which requires P2SB resources.
- */
-fs_initcall(p2sb_fs_init);