Add helper routines for PCI device drivers to read, write, and modify

PCI-Express capability registers (that is, PCI config registers in the
standard PCI config space belonging to the PCI-Express capability
register set).

Note that all of the current PCI-e registers are either 16 or 32-bits,
so only widths of 2 or 4 bytes are supported.

Reviewed by:	imp
MFC after:	1 week
Sponsored by:	Chelsio
Differential Revision:	https://reviews.freebsd.org/D4088

2 files changed, 61 insertions, 0 deletions

diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c
index 39d311f65095..5116a4fa579a 100644
--- a/sys/dev/pci/pci.c
+++ b/sys/dev/pci/pci.c
@@ -1917,6 +1917,63 @@ pci_set_max_read_req(device_t dev, int size)
 	return (size);
 }
 
+uint32_t
+pcie_read_config(device_t dev, int reg, int width)
+{
+	struct pci_devinfo *dinfo = device_get_ivars(dev);
+	int cap;
+
+	cap = dinfo->cfg.pcie.pcie_location;
+	if (cap == 0) {
+		if (width == 2)
+			return (0xffff);
+		return (0xffffffff);
+	}
+
+	return (pci_read_config(dev, cap + reg, width));
+}
+
+void
+pcie_write_config(device_t dev, int reg, uint32_t value, int width)
+{
+	struct pci_devinfo *dinfo = device_get_ivars(dev);
+	int cap;
+
+	cap = dinfo->cfg.pcie.pcie_location;
+	if (cap == 0)
+		return;
+	pci_write_config(dev, cap + reg, value, width);
+}
+
+/*
+ * Adjusts a PCI-e capability register by clearing the bits in mask
+ * and setting the bits in (value & mask).  Bits not set in mask are
+ * not adjusted.
+ *
+ * Returns the old value on success or all ones on failure.
+ */
+uint32_t
+pcie_adjust_config(device_t dev, int reg, uint32_t mask, uint32_t value,
+    int width)
+{
+	struct pci_devinfo *dinfo = device_get_ivars(dev);
+	uint32_t old, new;
+	int cap;
+
+	cap = dinfo->cfg.pcie.pcie_location;
+	if (cap == 0) {
+		if (width == 2)
+			return (0xffff);
+		return (0xffffffff);
+	}
+
+	old = pci_read_config(dev, cap + reg, width);
+	new = old & ~mask;
+	new |= (value & mask);
+	pci_write_config(dev, cap + reg, new, width);
+	return (old);
+}
+
 /*
  * Support for MSI message signalled interrupts.
  */
diff --git a/sys/dev/pci/pcivar.h b/sys/dev/pci/pcivar.h
index 7f2e95836a30..242201b13390 100644
--- a/sys/dev/pci/pcivar.h
+++ b/sys/dev/pci/pcivar.h
@@ -551,6 +551,10 @@ int	pci_get_max_read_req(device_t dev);
 void	pci_restore_state(device_t dev);
 void	pci_save_state(device_t dev);
 int	pci_set_max_read_req(device_t dev, int size);
+uint32_t pcie_read_config(device_t dev, int reg, int width);
+void	pcie_write_config(device_t dev, int reg, uint32_t value, int width);
+uint32_t pcie_adjust_config(device_t dev, int reg, uint32_t mask,
+	    uint32_t value, int width);
 
 
 #ifdef BUS_SPACE_MAXADDR