[PATCH v7 10/13] PCI: Give pci(m)_intx its own devres callback

[Philipp Stanner]

pci_intx() is one of the functions that have "hybrid mode" (i.e.,
sometimes managed, sometimes not). Providing a separate pcim_intx()
function with its own device resource and cleanup callback allows for
removing further large parts of the legacy PCI devres implementation.

As in the region-request-functions, pci_intx() has to call into its
managed counterpart for backwards compatibility.

As pci_intx() is an outdated function, pcim_intx() shall not be made
visible to drivers via a public API.

Implement pcim_intx() with its own device resource.
Make pci_intx() call pcim_intx() in the managed case.

Signed-off-by: Philipp Stanner <pstanner at redhat.com>
---
 drivers/pci/devres.c | 76 ++++++++++++++++++++++++++++++++++++--------
 drivers/pci/pci.c    | 23 ++++++++------
 drivers/pci/pci.h    |  7 ++--
 3 files changed, 80 insertions(+), 26 deletions(-)

diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index 0bafb67e1886..9a997de280df 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -40,6 +40,11 @@ struct pcim_iomap_devres {
 	void __iomem *table[PCI_STD_NUM_BARS];
 };
 
+/* Used to restore the old intx state on driver detach. */
+struct pcim_intx_devres {
+	int orig_intx;
+};
+
 enum pcim_addr_devres_type {
 	/* Default initializer. */
 	PCIM_ADDR_DEVRES_TYPE_INVALID,
@@ -392,32 +397,75 @@ int pcim_set_mwi(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL(pcim_set_mwi);
 
+
 static inline bool mask_contains_bar(int mask, int bar)
 {
 	return mask & BIT(bar);
 }
 
-static void pcim_release(struct device *gendev, void *res)
+static void pcim_intx_restore(struct device *dev, void *data)
 {
-	struct pci_dev *dev = to_pci_dev(gendev);
-	struct pci_devres *this = res;
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct pcim_intx_devres *res = data;
 
-	if (this->restore_intx)
-		pci_intx(dev, this->orig_intx);
+	pci_intx(pdev, res->orig_intx);
+}
 
-	if (!dev->pinned)
-		pci_disable_device(dev);
+static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
+{
+	struct pcim_intx_devres *res;
+
+	res = devres_find(dev, pcim_intx_restore, NULL, NULL);
+	if (res)
+		return res;
+
+	res = devres_alloc(pcim_intx_restore, sizeof(*res), GFP_KERNEL);
+	if (res)
+		devres_add(dev, res);
+
+	return res;
 }
 
-/*
- * TODO: After the last four callers in pci.c are ported, find_pci_dr()
- * needs to be made static again.
+/**
+ * pcim_intx - managed pci_intx()
+ * @pdev: the PCI device to operate on
+ * @enable: boolean: whether to enable or disable PCI INTx
+ *
+ * Returns: 0 on success, -ENOMEM on error.
+ *
+ * Enables/disables PCI INTx for device @pdev.
+ * Restores the original state on driver detach.
  */
-struct pci_devres *find_pci_dr(struct pci_dev *pdev)
+int pcim_intx(struct pci_dev *pdev, int enable)
 {
-	if (pci_is_managed(pdev))
-		return devres_find(&pdev->dev, pcim_release, NULL, NULL);
-	return NULL;
+	u16 pci_command, new;
+	struct pcim_intx_devres *res;
+
+	res = get_or_create_intx_devres(&pdev->dev);
+	if (!res)
+		return -ENOMEM;
+
+	res->orig_intx = !enable;
+
+	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
+
+	if (enable)
+		new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
+	else
+		new = pci_command | PCI_COMMAND_INTX_DISABLE;
+
+	if (new != pci_command)
+		pci_write_config_word(pdev, PCI_COMMAND, new);
+
+	return 0;
+}
+
+static void pcim_release(struct device *gendev, void *res)
+{
+	struct pci_dev *dev = to_pci_dev(gendev);
+
+	if (!dev->pinned)
+		pci_disable_device(dev);
 }
 
 static struct pci_devres *get_pci_dr(struct pci_dev *pdev)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 04accdfab7ce..de58e77f0ee0 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4444,11 +4444,23 @@ void pci_disable_parity(struct pci_dev *dev)
  * This is a "hybrid" function: It's normally unmanaged, but becomes managed
  * when pcim_enable_device() has been called in advance. This hybrid feature is
  * DEPRECATED!
+ *
+ * Use pcim_intx() if you need a managed version.
  */
 void pci_intx(struct pci_dev *pdev, int enable)
 {
 	u16 pci_command, new;
 
+	/*
+	 * This is done for backwards compatibility, because the old PCI devres
+	 * API had a mode in which this function became managed if the dev had
+	 * been enabled with pcim_enable_device() instead of pci_enable_device().
+	 */
+	if (pci_is_managed(pdev)) {
+		WARN_ON_ONCE(pcim_intx(pdev, enable) != 0);
+		return;
+	}
+
 	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
 
 	if (enable)
@@ -4456,17 +4468,8 @@ void pci_intx(struct pci_dev *pdev, int enable)
 	else
 		new = pci_command | PCI_COMMAND_INTX_DISABLE;
 
-	if (new != pci_command) {
-		struct pci_devres *dr;
-
+	if (new != pci_command)
 		pci_write_config_word(pdev, PCI_COMMAND, new);
-
-		dr = find_pci_dr(pdev);
-		if (dr && !dr->restore_intx) {
-			dr->restore_intx = 1;
-			dr->orig_intx = !enable;
-		}
-	}
 }
 EXPORT_SYMBOL_GPL(pci_intx);
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index dbf6772aaaaf..3aa57cd8b3e5 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -823,11 +823,14 @@ static inline pci_power_t mid_pci_get_power_state(struct pci_dev *pdev)
  * then remove them from here.
  */
 struct pci_devres {
-	unsigned int orig_intx:1;
-	unsigned int restore_intx:1;
+	/*
+	 * TODO:
+	 * This struct is now surplus. Remove it by refactoring pci/devres.c
+	 */
 };
 
 struct pci_devres *find_pci_dr(struct pci_dev *pdev);
+int pcim_intx(struct pci_dev *dev, int enable);
 
 int pcim_request_region(struct pci_dev *pdev, int bar, const char *name);
 int pcim_request_region_exclusive(struct pci_dev *pdev, int bar, const char *name);
-- 
2.45.0