pci: tegra: implement PCA enable workaround

Tegra210's PCIe controller has a bug that requires the PCA (performance
counter) feature to be enabled. If this isn't done, accesses to device
configuration space will hang the chip for tens of seconds. Implement
the workaround.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

drivers/pci/pci_tegra.c

@@ -166,6 +166,9 @@ DECLARE_GLOBAL_DATA_PTR;
 #define RP_VEND_XP	0x00000F00
 #define  RP_VEND_XP_DL_UP	(1 << 30)
 
+#define RP_VEND_CTL2				0x00000FA8
+#define  RP_VEND_CTL2_PCA_ENABLE		(1 << 7)
+
 #define RP_PRIV_MISC	0x00000FE0
 #define  RP_PRIV_MISC_PRSNT_MAP_EP_PRSNT (0xE << 0)
 #define  RP_PRIV_MISC_PRSNT_MAP_EP_ABSNT (0xF << 0)
@@ -194,6 +197,7 @@ struct tegra_pcie_soc {
 	bool has_pex_bias_ctrl;
 	bool has_cml_clk;
 	bool has_gen2;
+	bool force_pca_enable;
 };
 
 struct tegra_pcie {
@@ -887,6 +891,7 @@ static void tegra_pcie_port_reset(struct tegra_pcie_port *port)
 
 static void tegra_pcie_port_enable(struct tegra_pcie_port *port)
 {
+	const struct tegra_pcie_soc *soc = port->pcie->soc;
 	unsigned long ctrl = tegra_pcie_port_get_pex_ctrl(port);
 	unsigned long value;
 
@@ -902,6 +907,12 @@ static void tegra_pcie_port_enable(struct tegra_pcie_port *port)
 	afi_writel(port->pcie, value, ctrl);
 
 	tegra_pcie_port_reset(port);
+
+	if (soc->force_pca_enable) {
+		value = rp_readl(port, RP_VEND_CTL2);
+		value |= RP_VEND_CTL2_PCA_ENABLE;
+		rp_writel(port, value, RP_VEND_CTL2);
+	}
 }
 
 static bool tegra_pcie_port_check_link(struct tegra_pcie_port *port)
@@ -999,6 +1010,7 @@ static const struct tegra_pcie_soc tegra20_pcie_soc = {
 	.has_pex_bias_ctrl = false,
 	.has_cml_clk = false,
 	.has_gen2 = false,
+	.force_pca_enable = false,
 };
 
 static const struct tegra_pcie_soc tegra30_pcie_soc = {
@@ -1009,6 +1021,7 @@ static const struct tegra_pcie_soc tegra30_pcie_soc = {
 	.has_pex_bias_ctrl = true,
 	.has_cml_clk = true,
 	.has_gen2 = false,
+	.force_pca_enable = false,
 };
 
 static const struct tegra_pcie_soc tegra124_pcie_soc = {
@@ -1019,6 +1032,7 @@ static const struct tegra_pcie_soc tegra124_pcie_soc = {
 	.has_pex_bias_ctrl = true,
 	.has_cml_clk = true,
 	.has_gen2 = true,
+	.force_pca_enable = false,
 };
 
 static int process_nodes(const void *fdt, int nodes[], unsigned int count)