mach-snapdragon: fixup USB nodes

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.

Acked-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

diff --git a/arch/arm/mach-snapdragon/Makefile b/arch/arm/mach-snapdragon/Makefile
index 857171e593da845fb9e30140ae02aa9e703f8a30..7a4495c8108f1fa26383c1dc802cde0458be8b92 100644 (file)
--- a/arch/arm/mach-snapdragon/Makefile
+++ b/arch/arm/mach-snapdragon/Makefile
@@ -3,3 +3,4 @@
 # (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
 
 obj-y += board.o
+obj-$(CONFIG_OF_LIVE) += of_fixup.o

diff --git a/arch/arm/mach-snapdragon/board.c b/arch/arm/mach-snapdragon/board.c
index 6f762fc948bf8e68088fcf516cc265530f8ca20d..65e4c61e866a750806f378f8c382bff6bf71a804 100644 (file)
--- a/arch/arm/mach-snapdragon/board.c
+++ b/arch/arm/mach-snapdragon/board.c
@@ -28,6 +28,8 @@
 #include <usb.h>
 #include <sort.h>
 
+#include "qcom-priv.h"
+
 DECLARE_GLOBAL_DATA_PTR;
 
 static struct mm_region rbx_mem_map[CONFIG_NR_DRAM_BANKS + 2] = { { 0 } };
@@ -160,6 +162,7 @@ void __weak qcom_board_init(void)
 int board_init(void)
 {
        show_psci_version();
+       qcom_of_fixup_nodes();
        qcom_board_init();
        return 0;
 }

diff --git a/arch/arm/mach-snapdragon/of_fixup.c b/arch/arm/mach-snapdragon/of_fixup.c
new file mode 100644 (file)
index 0000000..4fdfed2
--- /dev/null
+++ b/arch/arm/mach-snapdragon/of_fixup.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * OF_LIVE devicetree fixup.
+ *
+ * This file implements runtime fixups for Qualcomm DT to improve
+ * compatibility with U-Boot. This includes adjusting the USB nodes
+ * to only use USB high-speed, as well as remapping volume buttons
+ * to behave as up/down for navigating U-Boot.
+ *
+ * We use OF_LIVE for this rather than early FDT fixup for a couple
+ * of reasons: it has a much nicer API, is most likely more efficient,
+ * and our changes are only applied to U-Boot. This allows us to use a
+ * DT designed for Linux, run U-Boot with a modified version, and then
+ * boot Linux with the original FDT.
+ *
+ * Copyright (c) 2024 Linaro Ltd.
+ *   Author: Caleb Connolly <caleb.connolly@linaro.org>
+ */
+
+#include <dt-bindings/input/linux-event-codes.h>
+#include <dm/of_access.h>
+#include <dm/of.h>
+#include <fdt_support.h>
+#include <linux/errno.h>
+#include <time.h>
+
+/* 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.
+ */
+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", 0, NULL);
+       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;
+       }
+
+       ret = of_write_prop(dwc3, "maximum-speed", strlen("high-speed"), "high-speed");
+       if (ret) {
+               log_err("Failed to set 'maximum-speed' 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);
+       }
+}
+
+#define time_call(func, ...) \
+       do { \
+               u64 start = timer_get_us(); \
+               func(__VA_ARGS__); \
+               debug(#func " took %lluus\n", timer_get_us() - start); \
+       } while (0)
+
+void qcom_of_fixup_nodes(void)
+{
+       time_call(fixup_usb_nodes);
+}

diff --git a/arch/arm/mach-snapdragon/qcom-priv.h b/arch/arm/mach-snapdragon/qcom-priv.h
new file mode 100644 (file)
index 0000000..0a7ed5e
--- /dev/null
+++ b/arch/arm/mach-snapdragon/qcom-priv.h
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef __QCOM_PRIV_H__
+#define __QCOM_PRIV_H__
+
+#if CONFIG_IS_ENABLED(OF_LIVE)
+/**
+ * qcom_of_fixup_nodes() - Fixup Qualcomm DT nodes
+ *
+ * Adjusts nodes in the live tree to improve compatibility with U-Boot.
+ */
+void qcom_of_fixup_nodes(void);
+#else
+static inline void qcom_of_fixup_nodes(void)
+{
+       log_debug("Unable to dynamically fixup USB nodes, please enable CONFIG_OF_LIVE\n");
+}
+#endif /* OF_LIVE */
+
+#endif /* __QCOM_PRIV_H__ */