external: control the board using external program

Control the board using external program. It will be called with 3
arguments: <board> <command> <on/off>, where command is one of "power",
"usb", "key-fastboot", "key-power".

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

device.h

@@ -90,6 +90,7 @@ extern const struct control_ops alpaca_ops;
 extern const struct control_ops cdb_assist_ops;
 extern const struct control_ops conmux_ops;
 extern const struct control_ops ftdi_gpio_ops;
+extern const struct control_ops external_ops;
 extern const struct control_ops qcomlt_dbg_ops;
 
 extern const struct console_ops conmux_console_ops;

device_parser.c

@@ -147,6 +147,9 @@ static void parse_board(struct device_parser *dp)
 		} else if (!strcmp(key, "ftdi_gpio")) {
 			dev->control_dev = strdup(value);
 			set_control_ops(dev, &ftdi_gpio_ops);
+		} else if (!strcmp(key, "external")) {
+			dev->control_dev = strdup(value);
+			set_control_ops(dev, &external_ops);
 		} else if (!strcmp(key, "qcomlt_debug_board")) {
 			dev->control_dev = strdup(value);
 			set_control_ops(dev, &qcomlt_dbg_ops);

external.c

@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2021-2023, 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.
+ */
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include <errno.h>
+#include <stdlib.h>
+
+#include "cdba-server.h"
+#include "device.h"
+
+struct external {
+	const char *path;
+	const char *board;
+};
+
+static int external_helper(struct external *ext, const char *command, bool on)
+{
+	pid_t pid, pid_ret;
+	int status;
+
+	pid =  fork();
+	switch (pid) {
+	case 0:
+		/* Do not clobber stdout with program messages or cdba will become confused */
+		dup2(2, 1);
+		return execlp(ext->path, ext->path, ext->board, command, on ? "on": "off", NULL);
+	case -1:
+		return -1;
+	default:
+		break;
+	}
+
+	pid_ret = waitpid(pid, &status, 0);
+	if (pid_ret < 0)
+		return pid_ret;
+
+	if (WIFEXITED(status))
+		return WEXITSTATUS(status);
+	else if (WIFSIGNALED(status))
+		errno = -EINTR;
+	else
+		errno = -EIO;
+
+	return -1;
+}
+
+static void *external_open(struct device *dev)
+{
+	struct external *ext;
+
+	dev->has_power_key = true;
+
+	ext = calloc(1, sizeof(*ext));
+
+	ext->path = dev->control_dev;
+	ext->board = dev->board;
+
+	return ext;
+}
+
+static int external_power(struct device *dev, bool on)
+{
+	struct external *ext = dev->cdb;
+
+	return external_helper(ext, "power", on);
+}
+
+static void external_usb(struct device *dev, bool on)
+{
+	struct external *ext = dev->cdb;
+
+	external_helper(ext, "usb", on);
+}
+
+static void external_key(struct device *dev, int key, bool asserted)
+{
+	struct external *ext = dev->cdb;
+
+	switch (key) {
+	case DEVICE_KEY_FASTBOOT:
+		external_helper(ext, "key-fastboot", asserted);
+		break;
+	case DEVICE_KEY_POWER:
+		external_helper(ext, "key-power", asserted);
+		break;
+	}
+}
+
+const struct control_ops external_ops = {
+	.open = external_open,
+	.power = external_power,
+	.usb = external_usb,
+	.key = external_key,
+};

meson.build

@@ -61,6 +61,7 @@ server_srcs = ['cdba-server.c',
 	       'conmux.c',
 	       'device.c',
 	       'device_parser.c',
+               'external.c',
 	       'fastboot.c',
 	       'alpaca.c',
 	       'ftdi-gpio.c',