[RFT PATCH] PCI: provide helper to reset all domain for host drivers

[Shawn Lin]

Otherwise the domain_nr will be increased if doing ubind and
bind host drives. I don't find any useful routine to reset it
from current code, so add this helper. This patch is based on patchset[1]
from Brian.

[1]: https://patchwork.kernel.org/patch/9614517/
Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>

---
Hi Brian,

I wasn't able to run my platfrom with linux-next but I test this for
my local kernel-v4.4, and I just send this for test!

 drivers/pci/host/pcie-rockchip.c | 1 +
 drivers/pci/pci.c                | 6 ++++++
 include/linux/pci.h              | 3 +++
 3 files changed, 10 insertions(+)

diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
index bd6df72..61787e7 100644
--- a/drivers/pci/host/pcie-rockchip.c
+++ b/drivers/pci/host/pcie-rockchip.c
@@ -1435,6 +1435,7 @@ static int rockchip_pcie_remove(struct platform_device *pdev)
 	pci_remove_root_bus(rockchip->root_bus);
 	pci_unmap_iospace(rockchip->io);
 	irq_domain_remove(rockchip->irq_domain);
+	pci_reset_all_domain();
 
 	phy_power_off(rockchip->phy);
 	phy_exit(rockchip->phy);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3ec24877..7c7c63b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5181,6 +5181,12 @@ int pci_get_new_domain_nr(void)
 	return atomic_inc_return(&__domain_nr);
 }
 
+void pci_reset_all_domain(void)
+{
+	atomic_set(&__domain_nr, -1);
+}
+EXPORT_SYMBOL(pci_reset_all_domain);
+
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
 static int of_pci_bus_find_domain_nr(struct device *parent)
 {
diff --git a/include/linux/pci.h b/include/linux/pci.h
index eb3da1a..c9bd939 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1456,11 +1456,13 @@ static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
 #ifdef CONFIG_PCI_DOMAINS
 extern int pci_domains_supported;
 int pci_get_new_domain_nr(void);
+void pci_reset_all_domain(void);
 #else
 enum { pci_domains_supported = 0 };
 static inline int pci_domain_nr(struct pci_bus *bus) { return 0; }
 static inline int pci_proc_domain(struct pci_bus *bus) { return 0; }
 static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
+static inline void pci_reset_all_domain(void) {}
 #endif /* CONFIG_PCI_DOMAINS */
 
 /*
@@ -1617,6 +1619,7 @@ static inline struct pci_dev *pci_get_bus_and_slot(unsigned int bus,
 static inline int pci_domain_nr(struct pci_bus *bus) { return 0; }
 static inline struct pci_dev *pci_dev_get(struct pci_dev *dev) { return NULL; }
 static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
+static inline void pci_reset_all_domain(void) {};
 
 #define dev_is_pci(d) (false)
 #define dev_is_pf(d) (false)
-- 
1.9.1