[PATCH 3/3] PCI: j721e: Add support for enabling ACSPCIE PAD IO Buffer output

Siddharth Vadapalli
2024-07-15T12:11:38Z

The ACSPCIE module is capable of driving the reference clock required by
the PCIe Endpoint device. It is an alternative to on-board and external
reference clock generators. Enabling the output from the ACSPCIE module's
PAD IO Buffers requires clearing the "PAD IO disable" bits of the
ACSPCIE_PROXY_CTRL register in the CTRL_MMR register space.

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---
drivers/pci/controller/cadence/pci-j721e.c | 33 ++++++++++++++++++++++
1 file changed, 33 insertions(+)

diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index 85718246016b..2fa0eff68a8a 100644
--- a/drivers/pci/controller/cadence/pci-j721e.c
+++ b/drivers/pci/controller/cadence/pci-j721e.c
@@ -44,6 +44,7 @@ enum link_status {
#define J721E_MODE_RC BIT(7)
#define LANE_COUNT(n) ((n) << 8)

+#define ACSPCIE_PAD_ENABLE_MASK GENMASK(1, 0)
#define GENERATION_SEL_MASK GENMASK(1, 0)

struct j721e_pcie {
@@ -220,6 +221,30 @@ static int j721e_pcie_set_lane_count(struct j721e_pcie *pcie,
return ret;
}

+static int j721e_acspcie_pad_enable(struct j721e_pcie *pcie, struct regmap *syscon)
+{
+ struct device *dev = pcie->cdns_pcie->dev;
+ struct device_node *node = dev->of_node;
+ u32 mask = ACSPCIE_PAD_ENABLE_MASK;
+ struct of_phandle_args args;
+ u32 val;
+ int ret;
+
+ ret = of_parse_phandle_with_fixed_args(node, "ti,syscon-acspcie-proxy-ctrl",
+ 1, 0, &args);
+ if (!ret) {
+ /* PAD Enable Bits have to be cleared to in order to enable output */
+ val = ~(args.args[0]);
+ ret = regmap_update_bits(syscon, 0, mask, val);
+ if (ret)
+ dev_err(dev, "Enabling ACSPCIE PAD output failed: %d\n", ret);
+ } else {
+ dev_err(dev, "ti,syscon-acspcie-proxy-ctrl has invalid parameters\n");
+ }
+
+ return ret;
+}
+
static int j721e_pcie_ctrl_init(struct j721e_pcie *pcie)
{
struct device *dev = pcie->cdns_pcie->dev;
@@ -259,6 +284,14 @@ static int j721e_pcie_ctrl_init(struct j721e_pcie *pcie)
return ret;
}

+ /* Enable ACSPCIe PAD IO Buffers if the optional property exists */
+ syscon = syscon_regmap_lookup_by_phandle_optional(node, "ti,syscon-acspcie-proxy-ctrl");
+ if (syscon) {
+ ret = j721e_acspcie_pad_enable(pcie, syscon);
+ if (ret)
+ return ret;
+ }
+
return 0;
}

--
2.40.1