scpi: add a generic scan API and implement it in usbtmc and serial transport

note that sr_usb_find_serial() is copied from the hameg-hmo driver

hardware/common/scpi.c

@@ -87,6 +87,78 @@ static const struct sr_scpi_dev_inst *scpi_devs[] = {
 #endif
 };
 
+static GSList *sr_scpi_scan_resource(struct drv_context *drvc,
+		const char *resource, const char *serialcomm,
+		struct sr_dev_inst *(*probe_device)(struct sr_scpi_dev_inst *scpi))
+{
+	struct sr_scpi_dev_inst *scpi;
+	struct sr_dev_inst *sdi;
+
+	if (!(scpi = scpi_dev_inst_new(drvc, resource, serialcomm)))
+		return NULL;
+
+	if (sr_scpi_open(scpi) != SR_OK) {
+		sr_info("Couldn't open SCPI device.");
+		sr_scpi_free(scpi);
+		return NULL;
+	};
+
+	if ((sdi = probe_device(scpi)))
+		return g_slist_append(NULL, sdi);
+
+	sr_scpi_close(scpi);
+	sr_scpi_free(scpi);
+	return NULL;
+}
+
+SR_PRIV GSList *sr_scpi_scan(struct drv_context *drvc, GSList *options,
+		struct sr_dev_inst *(*probe_device)(struct sr_scpi_dev_inst *scpi))
+{
+	GSList *resources, *l, *d, *devices = NULL;
+	const char *resource = NULL;
+	const char *serialcomm = NULL;
+	gchar **res;
+	unsigned i;
+
+	for (l = options; l; l = l->next) {
+		struct sr_config *src = l->data;
+		switch (src->key) {
+		case SR_CONF_CONN:
+			resource = g_variant_get_string(src->data, NULL);
+			break;
+		case SR_CONF_SERIALCOMM:
+			serialcomm = g_variant_get_string(src->data, NULL);
+			break;
+		}
+	}
+
+	for (i = 0; i < ARRAY_SIZE(scpi_devs); i++) {
+		if ((resource && strcmp(resource, scpi_devs[i]->prefix))
+		    || !scpi_devs[i]->scan)
+			continue;
+		resources = scpi_devs[i]->scan(drvc);
+		for (l = resources; l; l = l->next) {
+			res = g_strsplit(l->data, ":", 2);
+			if (res[0] && (d = sr_scpi_scan_resource(drvc, res[0],
+			               serialcomm ? serialcomm : res[1], probe_device)))
+				devices = g_slist_concat(devices, d);
+			g_strfreev(res);
+		}
+		g_slist_free_full(resources, g_free);
+	}
+
+	if (!devices && resource)
+		devices = sr_scpi_scan_resource(drvc, resource, serialcomm,
+		                                probe_device);
+
+	/* Tack a copy of the newly found devices onto the driver list. */
+	if (devices)
+		drvc->instances = g_slist_concat(drvc->instances,
+		                                 g_slist_copy(devices));
+
+	return devices;
+}
+
 SR_PRIV struct sr_scpi_dev_inst *scpi_dev_inst_new(struct drv_context *drvc,
 		const char *resource, const char *serialcomm)
 {

hardware/common/scpi_serial.c

@@ -22,6 +22,7 @@
 #include "libsigrok-internal.h"
 
 #include <glib.h>
+#include <stdlib.h>
 #include <string.h>
 
 #define LOG_PREFIX "scpi_serial"
@@ -35,6 +36,41 @@ struct scpi_serial {
 	size_t read;
 };
 
+static struct {
+	uint16_t vendor_id;
+	uint16_t product_id;
+	const char *serialcomm;
+} scpi_serial_usb_ids[] = {
+	{ 0x0403, 0xed72, "115200/8n1/flow=1" }, /* Hameg HO720 */
+	{ 0x0403, 0xed73, "115200/8n1/flow=1" }, /* Hameg HO730 */
+};
+
+static GSList *scpi_serial_scan(struct drv_context *drvc)
+{
+	GSList *l, *r, *resources = NULL;
+	gchar *res;
+	unsigned i;
+
+	(void)drvc;
+
+	for (i = 0; i < ARRAY_SIZE(scpi_serial_usb_ids); i++) {
+		if ((l = sr_serial_find_usb(scpi_serial_usb_ids[i].vendor_id,
+		                            scpi_serial_usb_ids[i].product_id)) == NULL)
+			continue;
+		for (r = l; r; r = r->next) {
+			if (scpi_serial_usb_ids[i].serialcomm)
+				res = g_strdup_printf("%s:%s", (char *) r->data,
+				                      scpi_serial_usb_ids[i].serialcomm);
+			else
+				res = g_strdup(r->data);
+			resources = g_slist_append(resources, res);
+		}
+		g_slist_free_full(l, g_free);
+	}
+
+	return resources;
+}
+
 static int scpi_serial_dev_inst_new(void *priv, struct drv_context *drvc,
 		const char *resource, char **params, const char *serialcomm)
 {
@@ -190,6 +226,7 @@ SR_PRIV const struct sr_scpi_dev_inst scpi_serial_dev = {
 	.name          = "serial",
 	.prefix        = "",
 	.priv_size     = sizeof(struct scpi_serial),
+	.scan          = scpi_serial_scan,
 	.dev_inst_new  = scpi_serial_dev_inst_new,
 	.open          = scpi_serial_open,
 	.source_add    = scpi_serial_source_add,

hardware/common/scpi_usbtmc.c

@@ -37,6 +37,29 @@ struct usbtmc_scpi {
 	int response_bytes_read;
 };
 
+static GSList *scpi_usbtmc_scan(struct drv_context *drvc)
+{
+	GSList *resources = NULL;
+	GDir *dir;
+	const char *dev_name;
+	char *resource;
+
+	(void)drvc;
+
+	if (!(dir = g_dir_open("/sys/class/usbmisc/", 0, NULL)))
+		if (!(dir = g_dir_open("/sys/class/usb/", 0, NULL)))
+			return NULL;
+	while ((dev_name = g_dir_read_name(dir))) {
+		if (strncmp(dev_name, "usbtmc", 6))
+			continue;
+		resource = g_strconcat("/dev/", dev_name, NULL);
+		resources = g_slist_append(resources, resource);
+	}
+	g_dir_close(dir);
+
+	return resources;
+}
+
 static int scpi_usbtmc_dev_inst_new(void *priv, struct drv_context *drvc,
 		const char *resource, char **params, const char *serialcomm)
 {
@@ -190,6 +213,7 @@ SR_PRIV const struct sr_scpi_dev_inst scpi_usbtmc_dev = {
 	.name          = "USBTMC",
 	.prefix        = "/dev/usbtmc",
 	.priv_size     = sizeof(struct usbtmc_scpi),
+	.scan          = scpi_usbtmc_scan,
 	.dev_inst_new  = scpi_usbtmc_dev_inst_new,
 	.open          = scpi_usbtmc_open,
 	.source_add    = scpi_usbtmc_source_add,

hardware/common/serial.c

@@ -22,6 +22,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <glib.h>
+#include <glib/gstdio.h>
 #include <libserialport.h>
 #include "libsigrok.h"
 #include "libsigrok-internal.h"
@@ -742,3 +743,142 @@ SR_PRIV int serial_source_remove(struct sr_serial_dev_inst *serial)
 
 	return SR_OK;
 }
+
+/**
+ * Find USB serial devices via the USB vendor ID and product ID.
+ *
+ * @param vendor_id Vendor ID of the USB device.
+ * @param product_id Product ID of the USB device.
+ *
+ * @return A GSList of strings containing the path of the serial device or
+ *         NULL if no serial device is found. The returned list must be freed
+ *         by the caller.
+ */
+SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id)
+{
+#ifdef __linux__
+	const gchar *usb_dev;
+	const char device_tree[] = "/sys/bus/usb/devices/";
+	GDir *devices_dir, *device_dir;
+	GSList *l = NULL;
+	GSList *tty_devs;
+	GSList *matched_paths;
+	FILE *fd;
+	char tmp[5];
+	gchar *vendor_path, *product_path, *path_copy;
+	gchar *prefix, *subdir_path, *device_path, *tty_path;
+	unsigned long read_vendor_id, read_product_id;
+	const char *file;
+
+	l = NULL;
+	tty_devs = NULL;
+	matched_paths = NULL;
+
+	if (!(devices_dir = g_dir_open(device_tree, 0, NULL)))
+		return NULL;
+
+	/*
+	 * Find potential candidates using the vendor ID and product ID
+	 * and store them in matched_paths.
+	 */
+	while ((usb_dev = g_dir_read_name(devices_dir))) {
+		vendor_path = g_strconcat(device_tree,
+					  usb_dev, "/idVendor", NULL);
+		product_path = g_strconcat(device_tree,
+					   usb_dev, "/idProduct", NULL);
+
+		if (!g_file_test(vendor_path, G_FILE_TEST_EXISTS) ||
+		    !g_file_test(product_path, G_FILE_TEST_EXISTS))
+			goto skip_device;
+
+		if ((fd = g_fopen(vendor_path, "r")) == NULL)
+			goto skip_device;
+
+		if (fgets(tmp, sizeof(tmp), fd) == NULL) {
+			fclose(fd);
+			goto skip_device;
+		}
+		read_vendor_id = strtoul(tmp, NULL, 16);
+
+		fclose(fd);
+
+		if ((fd = g_fopen(product_path, "r")) == NULL)
+			goto skip_device;
+
+		if (fgets(tmp, sizeof(tmp), fd) == NULL) {
+			fclose(fd);
+			goto skip_device;
+		}
+		read_product_id = strtoul(tmp, NULL, 16);
+
+		fclose(fd);
+
+		if (vendor_id == read_vendor_id &&
+		    product_id == read_product_id) {
+			path_copy = g_strdup(usb_dev);
+			matched_paths = g_slist_prepend(matched_paths,
+							path_copy);
+		}
+
+skip_device:
+		g_free(vendor_path);
+		g_free(product_path);
+	}
+	g_dir_close(devices_dir);
+
+	/* For every matched device try to find a ttyUSBX subfolder. */
+	for (l = matched_paths; l; l = l->next) {
+		subdir_path = NULL;
+
+		device_path = g_strconcat(device_tree, l->data, NULL);
+
+		if (!(device_dir = g_dir_open(device_path, 0, NULL))) {
+			g_free(device_path);
+			continue;
+		}
+
+		prefix = g_strconcat(l->data, ":", NULL);
+
+		while ((file = g_dir_read_name(device_dir))) {
+			if (g_str_has_prefix(file, prefix)) {
+				subdir_path = g_strconcat(device_path,
+						"/", file, NULL);
+				break;
+			}
+		}
+		g_dir_close(device_dir);
+
+		g_free(prefix);
+		g_free(device_path);
+
+		if (subdir_path) {
+			if (!(device_dir = g_dir_open(subdir_path, 0, NULL))) {
+				g_free(subdir_path);
+				continue;
+			}
+			g_free(subdir_path);
+
+			while ((file = g_dir_read_name(device_dir))) {
+				if (g_str_has_prefix(file, "ttyUSB")) {
+					tty_path = g_strconcat("/dev/",
+							       file, NULL);
+					sr_dbg("Found USB device %04x:%04x attached to %s.",
+					       vendor_id, product_id, tty_path);
+					tty_devs = g_slist_prepend(tty_devs,
+							tty_path);
+					break;
+				}
+			}
+			g_dir_close(device_dir);
+		}
+	}
+	g_slist_free_full(matched_paths, g_free);
+
+	return tty_devs;
+#else
+	(void)vendor_id;
+	(void)product_id;
+
+	return NULL;
+#endif
+}

libsigrok-internal.h

@@ -374,6 +374,7 @@ SR_PRIV int sr_serial_extract_options(GSList *options, const char **serial_devic
 SR_PRIV int serial_source_add(struct sr_serial_dev_inst *serial, int events,
 		int timeout, sr_receive_data_callback_t cb, void *cb_data);
 SR_PRIV int serial_source_remove(struct sr_serial_dev_inst *serial);
+SR_PRIV GSList *sr_serial_find_usb(uint16_t vendor_id, uint16_t product_id);
 #endif
 
 /*--- hardware/common/ezusb.c -----------------------------------------------*/
@@ -438,6 +439,7 @@ struct sr_scpi_dev_inst {
 	const char *name;
 	const char *prefix;
 	int priv_size;
+	GSList *(*scan)(struct drv_context *drvc);
 	int (*dev_inst_new)(void *priv, struct drv_context *drvc,
 		const char *resource, char **params, const char *serialcomm);
 	int (*open)(void *priv);
@@ -453,6 +455,8 @@ struct sr_scpi_dev_inst {
 	void *priv;
 };
 
+SR_PRIV GSList *sr_scpi_scan(struct drv_context *drvc, GSList *options,
+		struct sr_dev_inst *(*probe_device)(struct sr_scpi_dev_inst *scpi));
 SR_PRIV struct sr_scpi_dev_inst *scpi_dev_inst_new(struct drv_context *drvc,
 		const char *resource, const char *serialcomm);
 SR_PRIV int sr_scpi_open(struct sr_scpi_dev_inst *scpi);