[PATCH 09/13] mach-snapdragon: fixup USB nodes

[Caleb Connolly]

We don't support USB super-speed in U-Boot yet, we lack the SS PHY
drivers, however from my testing even with a PHY driver there seem to be
other issues when talking to super-speed peripherals.

In pursuit of maintaining upstream DT compatibility, and simplifying
porting for new devices, let's implement the DT fixups necessary to
configure USB in high-speed only mode at runtime. The pattern is
identical for all Qualcomm boards that use the Synaptics DWC3
controller:

* Add an additional property on the Qualcomm wrapper node
* Remove the super-speed phy phandle and phy-name entries.

Signed-off-by: Caleb Connolly <caleb.connolly at linaro.org>
---
 arch/arm/mach-snapdragon/board.c | 88 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)

diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
index ca300dc843a9..44925e369d8e 100644
--- a/arch/arm/mach-snapdragon/board.c
+++ b/arch/arm/mach-snapdragon/board.c
@@ -146,6 +146,93 @@ int board_usb_init(int index, enum usb_init_type init)
 	return 0;
 }
 
+/* U-Boot only supports USB high-speed mode on Qualcomm platforms with DWC3
+ * USB controllers. Rather than requiring source level DT changes, we fix up
+ * DT here. This improves compatibility with upstream DT and simplifies the
+ * porting process for new devices.
+ */
+#if CONFIG_IS_ENABLED(OF_LIVE)
+static int fixup_qcom_dwc3(struct device_node *glue_np)
+{
+	struct device_node *dwc3;
+	int ret, len, hsphy_idx = 1;
+	const __be32 *phandles;
+	const char *second_phy_name;
+
+	debug("Fixing up %s\n", glue_np->name);
+
+	/* Tell the glue driver to configure the wrapper for high-speed only operation */
+	ret = of_write_prop(glue_np, "qcom,select-utmi-as-pipe-clk", NULL, 0);
+	if (ret) {
+		log_err("Failed to add property 'qcom,select-utmi-as-pipe-clk': %d\n", ret);
+		return ret;
+	}
+
+	/* Find the DWC3 node itself */
+	dwc3 = of_find_compatible_node(glue_np, NULL, "snps,dwc3");
+	if (!dwc3) {
+		log_err("Failed to find dwc3 node\n");
+		return -ENOENT;
+	}
+
+	phandles = of_get_property(dwc3, "phys", &len);
+	len /= sizeof(*phandles);
+	if (len == 1) {
+		log_debug("Only one phy, not a superspeed controller\n");
+		return 0;
+	}
+
+	/* Figure out if the superspeed phy is present and if so then which phy is it? */
+	ret = of_property_read_string_index(dwc3, "phy-names", 1, &second_phy_name);
+	if (ret == -ENODATA) {
+		log_debug("Only one phy, not a super-speed controller\n");
+		return 0;
+	} else if (ret) {
+		log_err("Failed to read second phy name: %d\n", ret);
+		return ret;
+	}
+
+	if (!strncmp("usb3-phy", second_phy_name, strlen("usb3-phy"))) {
+		log_debug("Second phy isn't superspeed (is '%s') assuming first phy is SS\n",
+			  second_phy_name);
+		hsphy_idx = 0;
+	}
+
+	/* Overwrite the "phys" property to only contain the high-speed phy */
+	ret = of_write_prop(dwc3, "phys", sizeof(*phandles), phandles + hsphy_idx);
+	if (ret) {
+		log_err("Failed to overwrite 'phys' property: %d\n", ret);
+		return ret;
+	}
+
+	/* Overwrite "phy-names" to only contain a single entry */
+	ret = of_write_prop(dwc3, "phy-names", strlen("usb2-phy"), "usb2-phy");
+	if (ret) {
+		log_err("Failed to overwrite 'phy-names' property: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void fixup_usb_nodes(void)
+{
+	struct device_node *glue_np = NULL;
+	int ret;
+
+	while ((glue_np = of_find_compatible_node(glue_np, NULL, "qcom,dwc3"))) {
+		ret = fixup_qcom_dwc3(glue_np);
+		if (ret)
+			log_warning("Failed to fixup node %s: %d\n", glue_np->name, ret);
+	}
+}
+#else
+static void fixup_usb_nodes(void)
+{
+	log_debug("Unable to dynamically fixup USB nodes, please enable CONFIG_OF_LIVE\n");
+}
+#endif
+
 /*
  * Some boards still need board specific init code, they can implement that by
  * overriding this function.
@@ -159,6 +246,7 @@ void __weak qcom_board_init(void)
 int board_init(void)
 {
 	show_psci_version();
+	fixup_usb_nodes();
 	qcom_board_init();
 	return 0;
 }

-- 
2.43.0