support ppps usb control

Since Linux kernel 6.0, PPPS capable USB hubs expose a simple sysfs
attribute for power control. Allow overwriting the usb control callback
to use PPPS hub control instead.

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

Makefile

@@ -34,7 +34,7 @@ LDFLAGS := $(shell pkg-config --libs yaml-0.1 $(LIBFTDI) libudev)
 CLIENT_SRCS := cdba.c circ_buf.c
 CLIENT_OBJS := $(CLIENT_SRCS:.c=.o)
 
-SERVER_SRCS := cdba-server.c cdb_assist.c circ_buf.c conmux.c device.c device_parser.c fastboot.c alpaca.c ftdi-gpio.c console.c qcomlt_dbg.c
+SERVER_SRCS := cdba-server.c cdb_assist.c circ_buf.c conmux.c device.c device_parser.c fastboot.c alpaca.c ftdi-gpio.c console.c qcomlt_dbg.c ppps.c
 SERVER_OBJS := $(SERVER_SRCS:.c=.o)
 
 $(CLIENT): $(CLIENT_OBJS)

device.c

@@ -44,6 +44,7 @@
 #include "fastboot.h"
 #include "console.h"
 #include "list.h"
+#include "ppps.h"
 
 #define ARRAY_SIZE(x) ((sizeof(x)/sizeof((x)[0])))
 
@@ -252,8 +253,12 @@ void device_print_status(struct device *device)
 
 void device_usb(struct device *device, bool on)
 {
-	if (device->usb)
-		device->usb(device, on);
+	if (device->usb) {
+		if (device->ppps_path)
+			ppps_power(device, on);
+		else
+			device->usb(device, on);
+	}
 }
 
 int device_write(struct device *device, const void *buf, size_t len)

device.h

@@ -15,6 +15,7 @@ struct device {
 	char *name;
 	char *serial;
 	char *description;
+	char *ppps_path;
 	struct list_head *users;
 	unsigned voltage;
 	bool tickle_mmc;

device_parser.c

@@ -39,6 +39,7 @@
 #include "conmux.h"
 #include "console.h"
 #include "qcomlt_dbg.h"
+#include "ppps.h"
 
 #define TOKEN_LENGTH	16384
 
@@ -179,6 +180,8 @@ static void parse_board(struct device_parser *dp)
 			dev->fastboot_key_timeout = strtoul(value, NULL, 10);
 		} else if (!strcmp(key, "usb_always_on")) {
 			dev->usb_always_on = !strcmp(value, "true");
+		} else if (!strcmp(key, "ppps_path")) {
+			dev->ppps_path = strdup(value);
 		} else {
 			fprintf(stderr, "device parser: unknown key \"%s\"\n", key);
 			exit(1);

ppps.c

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2023, Linaro Ltd.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define _GNU_SOURCE /* for asprintf */
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <arpa/inet.h>
+#include <ctype.h>
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdbool.h>
+
+#include "device.h"
+
+#define PPPS_BASE_PATH "/sys/bus/usb/devices"
+#define PPPS_BASE_PATH_LEN strlen(PPPS_BASE_PATH)
+
+void ppps_power(struct device *dev, bool on)
+{
+	static char *path = NULL;
+	int rc, fd;
+
+	/* Only need to figure out the whole string once */
+	if (!path) {
+		/* ppps_path should be like "2-2:1.0/2-2-port2" */
+		asprintf(&path, "%s/%s/disable", PPPS_BASE_PATH, dev->ppps_path);
+	}
+
+	// fprintf(stderr, "ppps_power: %-3s %s\n", on ? "on" : "off", path);
+
+	fd = open(path, O_WRONLY);
+	if (fd < 0) {
+		fprintf(stderr, "failed to open %s: %s\n", path, strerror(errno));
+		if (errno != ENOENT)
+			fprintf(stderr, "Maybe missing permissions (see https://git.io/JIB2Z)\n");
+		return;
+	}
+
+	rc = write(fd, on ? "0" : "1", 1);
+	if (rc < 0)
+		fprintf(stderr, "failed to write to %s: %s\n", path, strerror(errno));
+
+	close(fd);
+}

ppps.h

@@ -0,0 +1,6 @@
+#ifndef __PPPS_H__
+#define __PPPS_H__
+
+void ppps_power(struct device *dev, bool on);
+
+#endif