usb: gadget: allocate & giveback serial ports instead hard code them

This patch removes gserial_setup() and gserial_cleanup() and adds
gserial_alloc_line() and gserial_free_line() to replace them.

The initial setup of u_serial happens now on module load time. A
maximum of four TTY ports can be requested which is the current limit.
In theory we could extend this limit, the hard limit is the number of
available endpoints.
alloc_tty_driver() is now called at module init time with the max
available ports. The per-line footprint here is on 32bit is 3 * size of
pointer + 60 bytes (for cdevs).
The remaining memory (struct gs_port) is allocated once a port is
requested.

With this change it is possible to load g_multi and g_serial at the same
time. GS0 receives the module that is loaded first, GS1 is received by
the next module and so on. With the configfs interface the port number
can be exported and the device node is more predictable. Nothing changes
for g_serial and friends as long as one module is used.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/acm_ms.c

@@ -111,6 +111,7 @@ FSG_MODULE_PARAMETERS(/* no prefix */, fsg_mod_data);
 static struct fsg_common fsg_common;
 
 /*-------------------------------------------------------------------------*/
+static unsigned char tty_line;
 
 /*
  * We _always_ have both ACM and mass storage functions.
@@ -125,7 +126,7 @@ static int __init acm_ms_do_config(struct usb_configuration *c)
 	}
 
 
-	status = acm_bind_config(c, 0);
+	status = acm_bind_config(c, tty_line);
 	if (status < 0)
 		return status;
 
@@ -152,7 +153,7 @@ static int __init acm_ms_bind(struct usb_composite_dev *cdev)
 	void			*retp;
 
 	/* set up serial link layer */
-	status = gserial_setup(cdev->gadget, 1);
+	status = gserial_alloc_line(&tty_line);
 	if (status < 0)
 		return status;
 
@@ -188,14 +189,13 @@ static int __init acm_ms_bind(struct usb_composite_dev *cdev)
 fail1:
 	fsg_common_put(&fsg_common);
 fail0:
-	gserial_cleanup();
+	gserial_free_line(tty_line);
 	return status;
 }
 
 static int __exit acm_ms_unbind(struct usb_composite_dev *cdev)
 {
-	gserial_cleanup();
-
+	gserial_free_line(tty_line);
 	return 0;
 }
 

drivers/usb/gadget/cdc2.c

@@ -108,6 +108,7 @@ static u8 hostaddr[ETH_ALEN];
 
 /*-------------------------------------------------------------------------*/
 
+static unsigned char tty_line;
 /*
  * We _always_ have both CDC ECM and CDC ACM functions.
  */
@@ -124,7 +125,7 @@ static int __init cdc_do_config(struct usb_configuration *c)
 	if (status < 0)
 		return status;
 
-	status = acm_bind_config(c, 0);
+	status = acm_bind_config(c, tty_line);
 	if (status < 0)
 		return status;
 
@@ -157,7 +158,7 @@ static int __init cdc_bind(struct usb_composite_dev *cdev)
 		return status;
 
 	/* set up serial link layer */
-	status = gserial_setup(cdev->gadget, 1);
+	status = gserial_alloc_line(&tty_line);
 	if (status < 0)
 		goto fail0;
 
@@ -183,7 +184,7 @@ static int __init cdc_bind(struct usb_composite_dev *cdev)
 	return 0;
 
 fail1:
-	gserial_cleanup();
+	gserial_free_line(tty_line);
 fail0:
 	gether_cleanup();
 	return status;
@@ -191,7 +192,7 @@ static int __init cdc_bind(struct usb_composite_dev *cdev)
 
 static int __exit cdc_unbind(struct usb_composite_dev *cdev)
 {
-	gserial_cleanup();
+	gserial_free_line(tty_line);
 	gether_cleanup();
 	return 0;
 }

drivers/usb/gadget/dbgp.c

@@ -231,6 +231,10 @@ static void dbgp_unbind(struct usb_gadget *gadget)
 	gadget->ep0->driver_data = NULL;
 }
 
+#ifdef CONFIG_USB_G_DBGP_SERIAL
+static unsigned char tty_line;
+#endif
+
 static int __init dbgp_configure_endpoints(struct usb_gadget *gadget)
 {
 	int stp;
@@ -268,7 +272,7 @@ static int __init dbgp_configure_endpoints(struct usb_gadget *gadget)
 	dbgp.serial->in->desc = &i_desc;
 	dbgp.serial->out->desc = &o_desc;
 
-	if (gserial_setup(gadget, 1) < 0) {
+	if (gserial_alloc_line(&tty_line)) {
 		stp = 3;
 		goto fail_3;
 	}
@@ -377,7 +381,7 @@ static int dbgp_setup(struct usb_gadget *gadget,
 #ifdef CONFIG_USB_G_DBGP_PRINTK
 		err = dbgp_enable_ep();
 #else
-		err = gserial_connect(dbgp.serial, 0);
+		err = gserial_connect(dbgp.serial, tty_line);
 #endif
 		if (err < 0)
 			goto fail;
@@ -420,7 +424,7 @@ static void __exit dbgp_exit(void)
 {
 	usb_gadget_unregister_driver(&dbgp_driver);
 #ifdef CONFIG_USB_G_DBGP_SERIAL
-	gserial_cleanup();
+	gserial_free_line(tty_line);
 #endif
 }
 

drivers/usb/gadget/f_acm.c

@@ -719,9 +719,6 @@ acm_unbind(struct usb_configuration *c, struct usb_function *f)
  *
  * Returns zero on success, else negative errno.
  *
- * Caller must have called @gserial_setup() with enough ports to
- * handle all the ones it binds.  Caller is also responsible
- * for calling @gserial_cleanup() before module unload.
  */
 int acm_bind_config(struct usb_configuration *c, u8 port_num)
 {

drivers/usb/gadget/f_obex.c

@@ -406,10 +406,6 @@ static inline bool can_support_obex(struct usb_configuration *c)
  * Context: single threaded during gadget setup
  *
  * Returns zero on success, else negative errno.
- *
- * Caller must have called @gserial_setup() with enough ports to
- * handle all the ones it binds.  Caller is also responsible
- * for calling @gserial_cleanup() before module unload.
  */
 int __init obex_bind_config(struct usb_configuration *c, u8 port_num)
 {

drivers/usb/gadget/f_serial.c

@@ -260,10 +260,6 @@ gser_unbind(struct usb_configuration *c, struct usb_function *f)
  * Context: single threaded during gadget setup
  *
  * Returns zero on success, else negative errno.
- *
- * Caller must have called @gserial_setup() with enough ports to
- * handle all the ones it binds.  Caller is also responsible
- * for calling @gserial_cleanup() before module unload.
  */
 int __init gser_bind_config(struct usb_configuration *c, u8 port_num)
 {

drivers/usb/gadget/multi.c

@@ -136,6 +136,7 @@ static struct fsg_common fsg_common;
 
 static u8 hostaddr[ETH_ALEN];
 
+static unsigned char tty_line;
 
 /********** RNDIS **********/
 
@@ -154,7 +155,7 @@ static __init int rndis_do_config(struct usb_configuration *c)
 	if (ret < 0)
 		return ret;
 
-	ret = acm_bind_config(c, 0);
+	ret = acm_bind_config(c, tty_line);
 	if (ret < 0)
 		return ret;
 
@@ -205,7 +206,7 @@ static __init int cdc_do_config(struct usb_configuration *c)
 	if (ret < 0)
 		return ret;
 
-	ret = acm_bind_config(c, 0);
+	ret = acm_bind_config(c, tty_line);
 	if (ret < 0)
 		return ret;
 
@@ -242,7 +243,6 @@ static int cdc_config_register(struct usb_composite_dev *cdev)
 
 /****************************** Gadget Bind ******************************/
 
-
 static int __ref multi_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget *gadget = cdev->gadget;
@@ -260,7 +260,7 @@ static int __ref multi_bind(struct usb_composite_dev *cdev)
 		return status;
 
 	/* set up serial link layer */
-	status = gserial_setup(cdev->gadget, 1);
+	status = gserial_alloc_line(&tty_line);
 	if (status < 0)
 		goto fail0;
 
@@ -300,7 +300,7 @@ static int __ref multi_bind(struct usb_composite_dev *cdev)
 fail2:
 	fsg_common_put(&fsg_common);
 fail1:
-	gserial_cleanup();
+	gserial_free_line(tty_line);
 fail0:
 	gether_cleanup();
 	return status;
@@ -308,7 +308,7 @@ static int __ref multi_bind(struct usb_composite_dev *cdev)
 
 static int __exit multi_unbind(struct usb_composite_dev *cdev)
 {
-	gserial_cleanup();
+	gserial_free_line(tty_line);
 	gether_cleanup();
 	return 0;
 }

drivers/usb/gadget/nokia.c

@@ -100,6 +100,15 @@ MODULE_LICENSE("GPL");
 
 static u8 hostaddr[ETH_ALEN];
 
+enum {
+	TTY_PORT_OBEX0,
+	TTY_PORT_OBEX1,
+	TTY_PORT_ACM,
+	TTY_PORTS_MAX,
+};
+
+static unsigned char tty_lines[TTY_PORTS_MAX];
+
 static int __init nokia_bind_config(struct usb_configuration *c)
 {
 	int status = 0;
@@ -108,15 +117,15 @@ static int __init nokia_bind_config(struct usb_configuration *c)
 	if (status)
 		printk(KERN_DEBUG "could not bind phonet config\n");
 
-	status = obex_bind_config(c, 0);
+	status = obex_bind_config(c, tty_lines[TTY_PORT_OBEX0]);
 	if (status)
 		printk(KERN_DEBUG "could not bind obex config %d\n", 0);
 
-	status = obex_bind_config(c, 1);
+	status = obex_bind_config(c, tty_lines[TTY_PORT_OBEX1]);
 	if (status)
 		printk(KERN_DEBUG "could not bind obex config %d\n", 0);
 
-	status = acm_bind_config(c, 2);
+	status = acm_bind_config(c, tty_lines[TTY_PORT_ACM]);
 	if (status)
 		printk(KERN_DEBUG "could not bind acm config\n");
 
@@ -147,14 +156,17 @@ static int __init nokia_bind(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget	*gadget = cdev->gadget;
 	int			status;
+	int			cur_line;
 
 	status = gphonet_setup(cdev->gadget);
 	if (status < 0)
 		goto err_phonet;
 
-	status = gserial_setup(cdev->gadget, 3);
-	if (status < 0)
-		goto err_serial;
+	for (cur_line = 0; cur_line < TTY_PORTS_MAX; cur_line++) {
+		status = gserial_alloc_line(&tty_lines[cur_line]);
+		if (status)
+			goto err_ether;
+	}
 
 	status = gether_setup(cdev->gadget, hostaddr);
 	if (status < 0)
@@ -191,8 +203,10 @@ static int __init nokia_bind(struct usb_composite_dev *cdev)
 err_usb:
 	gether_cleanup();
 err_ether:
-	gserial_cleanup();
-err_serial:
+	cur_line--;
+	while (cur_line >= 0)
+		gserial_free_line(tty_lines[cur_line--]);
+
 	gphonet_cleanup();
 err_phonet:
 	return status;
@@ -200,8 +214,13 @@ static int __init nokia_bind(struct usb_composite_dev *cdev)
 
 static int __exit nokia_unbind(struct usb_composite_dev *cdev)
 {
+	int i;
+
 	gphonet_cleanup();
-	gserial_cleanup();
+
+	for (i = 0; i < TTY_PORTS_MAX; i++)
+		gserial_free_line(tty_lines[i]);
+
 	gether_cleanup();
 
 	return 0;

drivers/usb/gadget/serial.c

@@ -127,6 +127,7 @@ module_param(n_ports, uint, 0);
 MODULE_PARM_DESC(n_ports, "number of ports to create, default=1");
 
 /*-------------------------------------------------------------------------*/
+static unsigned char tty_lines[MAX_U_SERIAL_PORTS];
 
 static int __init serial_bind_acm_config(struct usb_configuration *c)
 {
@@ -134,7 +135,7 @@ static int __init serial_bind_acm_config(struct usb_configuration *c)
 	int status = 0;
 
 	for (i = 0; i < n_ports && status == 0; i++)
-		status = acm_bind_config(c, i);
+		status = acm_bind_config(c, tty_lines[i]);
 	return status;
 }
 
@@ -144,7 +145,7 @@ static int __init serial_bind_obex_config(struct usb_configuration *c)
 	int status = 0;
 
 	for (i = 0; i < n_ports && status == 0; i++)
-		status = obex_bind_config(c, i);
+		status = obex_bind_config(c, tty_lines[i]);
 	return status;
 }
 
@@ -154,7 +155,7 @@ static int __init serial_bind_gser_config(struct usb_configuration *c)
 	int status = 0;
 
 	for (i = 0; i < n_ports && status == 0; i++)
-		status = gser_bind_config(c, i);
+		status = gser_bind_config(c, tty_lines[i]);
 	return status;
 }
 
@@ -165,13 +166,25 @@ static struct usb_configuration serial_config_driver = {
 	.bmAttributes	= USB_CONFIG_ATT_SELFPOWER,
 };
 
+static int gs_unbind(struct usb_composite_dev *cdev)
+{
+	int i;
+
+	for (i = 0; i < n_ports; i++)
+		gserial_free_line(tty_lines[i]);
+	return 0;
+}
+
 static int __init gs_bind(struct usb_composite_dev *cdev)
 {
 	int			status;
+	int			cur_line;
 
-	status = gserial_setup(cdev->gadget, n_ports);
-	if (status < 0)
-		return status;
+	for (cur_line = 0; cur_line < n_ports; cur_line++) {
+		status = gserial_alloc_line(&tty_lines[cur_line]);
+		if (status)
+			goto fail;
+	}
 
 	/* Allocate string descriptor numbers ... note that string
 	 * contents can be overridden by the composite_dev glue.
@@ -209,7 +222,9 @@ static int __init gs_bind(struct usb_composite_dev *cdev)
 	return 0;
 
 fail:
-	gserial_cleanup();
+	cur_line--;
+	while (cur_line >= 0)
+		gserial_free_line(tty_lines[cur_line--]);
 	return status;
 }
 
@@ -219,6 +234,7 @@ static __refdata struct usb_composite_driver gserial_driver = {
 	.strings	= dev_strings,
 	.max_speed	= USB_SPEED_SUPER,
 	.bind		= gs_bind,
+	.unbind		= gs_unbind,
 };
 
 static int __init init(void)
@@ -254,6 +270,5 @@ module_init(init);
 static void __exit cleanup(void)
 {
 	usb_composite_unregister(&gserial_driver);
-	gserial_cleanup();
 }
 module_exit(cleanup);

drivers/usb/gadget/u_serial.h

@@ -15,6 +15,8 @@
 #include <linux/usb/composite.h>
 #include <linux/usb/cdc.h>
 
+#define MAX_U_SERIAL_PORTS	4
+
 /*
  * One non-multiplexed "serial" I/O port ... there can be several of these
  * on any given USB peripheral device, if it provides enough endpoints.
@@ -49,9 +51,9 @@ struct gserial {
 struct usb_request *gs_alloc_req(struct usb_ep *ep, unsigned len, gfp_t flags);
 void gs_free_req(struct usb_ep *, struct usb_request *req);
 
-/* port setup/teardown is handled by gadget driver */
-int gserial_setup(struct usb_gadget *g, unsigned n_ports);
-void gserial_cleanup(void);
+/* management of individual TTY ports */
+int gserial_alloc_line(unsigned char *port_line);
+void gserial_free_line(unsigned char port_line);
 
 /* connect/disconnect is handled by individual functions */
 int gserial_connect(struct gserial *, u8 port_num);