rtlwifi: add MSI interrupts mode support

Add MSI interrupts mode support, enable it when submodules' msi_support
flag is true, also could fallback to pin-based interrupts mode if MSI
interrupts mode fails.

RealTek's policy(on modules which work well with MSI interrupts mode) is:

> If the platform supports both MSI and pin-based, use MSI.
> If the platform supports MSI only, use MSI.
> If the platform supports pin-based only, use pin-based.

Also as RealTek's testing results, RTL8188EE and RTL8723BE work well
with both MSI mode and pin-based mode fallback.

Signed-off-by: Adam Lee <adam.lee@canonical.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 63 insertions, 2 deletions

diff --git a/drivers/net/wireless/rtlwifi/pci.c b/drivers/net/wireless/rtlwifi/pci.c
index 7d711708d2f3..dae55257f0e8 100644
--- a/drivers/net/wireless/rtlwifi/pci.c
+++ b/drivers/net/wireless/rtlwifi/pci.c
@@ -1853,6 +1853,65 @@ static bool _rtl_pci_find_adapter(struct pci_dev *pdev,
         return true;
 }
 
+static int rtl_pci_intr_mode_msi(struct ieee80211_hw *hw)
+{
+        struct rtl_priv *rtlpriv = rtl_priv(hw);
+        struct rtl_pci_priv *pcipriv = rtl_pcipriv(hw);
+        struct rtl_pci *rtlpci = rtl_pcidev(pcipriv);
+        int ret;
+
+        ret = pci_enable_msi(rtlpci->pdev);
+        if (ret < 0)
+                return ret;
+
+        ret = request_irq(rtlpci->pdev->irq, &_rtl_pci_interrupt,
+                          IRQF_SHARED, KBUILD_MODNAME, hw);
+        if (ret < 0) {
+                pci_disable_msi(rtlpci->pdev);
+                return ret;
+        }
+
+        rtlpci->using_msi = true;
+
+        RT_TRACE(rtlpriv, COMP_INIT|COMP_INTR, DBG_DMESG,
+                 "MSI Interrupt Mode!\n");
+        return 0;
+}
+
+static int rtl_pci_intr_mode_legacy(struct ieee80211_hw *hw)
+{
+        struct rtl_priv *rtlpriv = rtl_priv(hw);
+        struct rtl_pci_priv *pcipriv = rtl_pcipriv(hw);
+        struct rtl_pci *rtlpci = rtl_pcidev(pcipriv);
+        int ret;
+
+        ret = request_irq(rtlpci->pdev->irq, &_rtl_pci_interrupt,
+                          IRQF_SHARED, KBUILD_MODNAME, hw);
+        if (ret < 0)
+                return ret;
+
+        rtlpci->using_msi = false;
+        RT_TRACE(rtlpriv, COMP_INIT|COMP_INTR, DBG_DMESG,
+                 "Pin-based Interrupt Mode!\n");
+        return 0;
+}
+
+static int rtl_pci_intr_mode_decide(struct ieee80211_hw *hw)
+{
+        struct rtl_pci_priv *pcipriv = rtl_pcipriv(hw);
+        struct rtl_pci *rtlpci = rtl_pcidev(pcipriv);
+        int ret;
+
+        if (rtlpci->msi_support) {
+                ret = rtl_pci_intr_mode_msi(hw);
+                if (ret < 0)
+                        ret = rtl_pci_intr_mode_legacy(hw);
+        } else {
+                ret = rtl_pci_intr_mode_legacy(hw);
+        }
+        return ret;
+}
+
 int rtl_pci_probe(struct pci_dev *pdev,
                             const struct pci_device_id *id)
 {
@@ -1995,8 +2054,7 @@ int rtl_pci_probe(struct pci_dev *pdev,
         }
 
         rtlpci = rtl_pcidev(pcipriv);
-        err = request_irq(rtlpci->pdev->irq, &_rtl_pci_interrupt,
-                          IRQF_SHARED, KBUILD_MODNAME, hw);
+        err = rtl_pci_intr_mode_decide(hw);
         if (err) {
                 RT_TRACE(rtlpriv, COMP_INIT, DBG_DMESG,
                          "%s: failed to register IRQ handler\n",
@@ -2064,6 +2122,9 @@ void rtl_pci_disconnect(struct pci_dev *pdev)
                 rtlpci->irq_alloc = 0;
         }
 
+        if (rtlpci->using_msi)
+                pci_disable_msi(rtlpci->pdev);
+
         list_del(&rtlpriv->list);
         if (rtlpriv->io.pci_mem_start != 0) {
                 pci_iounmap(pdev, (void __iomem *)rtlpriv->io.pci_mem_start);