USB: sam-ba: add driver for Atmel SAM Boot Assistant (SAM-BA)

Add new driver to access the SAM-BA boot application of Atmel AT91SAM
devices.

The SAM-BA firmware cannot handle merged write requests so we cannot use
the generic write implementation (which uses the port write fifo).

Tested with the SAM-BA 2.10 tools and an Atmel at91sam9260-ek.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Tested-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/Kconfig

@@ -527,6 +527,15 @@ config USB_SERIAL_SAFE_PADDED
 	bool "USB Secure Encapsulated Driver - Padded"
 	depends on USB_SERIAL_SAFE
 
+config USB_SERIAL_SAMBA
+	tristate "USB Atmel SAM Boot Assistant (SAM-BA) driver"
+	help
+	  Say Y here if you want to access the SAM-BA boot application of an
+	  Atmel AT91SAM device.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called sam-ba.
+
 config USB_SERIAL_SIEMENS_MPI
 	tristate "USB Siemens MPI driver"
 	help

drivers/usb/serial/Makefile

@@ -48,6 +48,7 @@ obj-$(CONFIG_USB_SERIAL_PL2303)			+= pl2303.o
 obj-$(CONFIG_USB_SERIAL_QCAUX)			+= qcaux.o
 obj-$(CONFIG_USB_SERIAL_QUALCOMM)		+= qcserial.o
 obj-$(CONFIG_USB_SERIAL_SAFE)			+= safe_serial.o
+obj-$(CONFIG_USB_SERIAL_SAMBA)			+= sam-ba.o
 obj-$(CONFIG_USB_SERIAL_SIEMENS_MPI)		+= siemens_mpi.o
 obj-$(CONFIG_USB_SERIAL_SIERRAWIRELESS)		+= sierra.o
 obj-$(CONFIG_USB_SERIAL_SPCP8X5)		+= spcp8x5.o

drivers/usb/serial/sam-ba.c

+/*
+ * Atmel SAM Boot Assistant (SAM-BA) driver
+ *
+ * Copyright (C) 2010 Johan Hovold <jhovold@gmail.com>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License version
+ *	2 as published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+
+
+#define DRIVER_VERSION	"v1.0"
+#define DRIVER_AUTHOR	"Johan Hovold <jhovold@gmail.com>"
+#define DRIVER_DESC	"Atmel SAM Boot Assistant (SAM-BA) driver"
+
+#define SAMBA_VENDOR_ID		0x3eb
+#define SAMBA_PRODUCT_ID	0x6124
+
+
+static int debug;
+
+static const struct usb_device_id id_table[] = {
+	/*
+	 * NOTE: Only match the CDC Data interface.
+	 */
+	{ USB_DEVICE_AND_INTERFACE_INFO(SAMBA_VENDOR_ID, SAMBA_PRODUCT_ID,
+					USB_CLASS_CDC_DATA, 0, 0) },
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+static struct usb_driver samba_driver = {
+	.name		= "sam-ba",
+	.probe		= usb_serial_probe,
+	.disconnect	= usb_serial_disconnect,
+	.id_table	= id_table,
+	.no_dynamic_id	= 1,
+};
+
+
+/*
+ * NOTE: The SAM-BA firmware cannot handle merged write requests so we cannot
+ *       use the generic write implementation (which uses the port write fifo).
+ */
+static int samba_write(struct tty_struct *tty, struct usb_serial_port *port,
+					const unsigned char *buf, int count)
+{
+	struct urb *urb;
+	unsigned long flags;
+	int result;
+	int i;
+
+	if (!count)
+		return 0;
+
+	count = min_t(int, count, port->bulk_out_size);
+
+	spin_lock_irqsave(&port->lock, flags);
+	if (!port->write_urbs_free) {
+		spin_unlock_irqrestore(&port->lock, flags);
+		return 0;
+	}
+	i = find_first_bit(&port->write_urbs_free,
+						ARRAY_SIZE(port->write_urbs));
+	__clear_bit(i, &port->write_urbs_free);
+	port->tx_bytes += count;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	urb = port->write_urbs[i];
+	memcpy(urb->transfer_buffer, buf, count);
+	urb->transfer_buffer_length = count;
+	usb_serial_debug_data(debug, &port->dev, __func__, count,
+						urb->transfer_buffer);
+	result = usb_submit_urb(urb, GFP_ATOMIC);
+	if (result) {
+		dev_err(&port->dev, "%s - error submitting urb: %d\n",
+						__func__, result);
+		spin_lock_irqsave(&port->lock, flags);
+		__set_bit(i, &port->write_urbs_free);
+		port->tx_bytes -= count;
+		spin_unlock_irqrestore(&port->lock, flags);
+
+		return result;
+	}
+
+	return count;
+}
+
+static int samba_write_room(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	unsigned long flags;
+	unsigned long free;
+	int count;
+	int room;
+
+	spin_lock_irqsave(&port->lock, flags);
+	free = port->write_urbs_free;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	count = hweight_long(free);
+	room = count * port->bulk_out_size;
+
+	dbg("%s - returns %d", __func__, room);
+
+	return room;
+}
+
+static int samba_chars_in_buffer(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	unsigned long flags;
+	int chars;
+
+	spin_lock_irqsave(&port->lock, flags);
+	chars = port->tx_bytes;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	dbg("%s - returns %d", __func__, chars);
+
+	return chars;
+}
+
+static void samba_write_bulk_callback(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	unsigned long flags;
+	int i;
+
+	dbg("%s - port %d", __func__, port->number);
+
+	for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
+		if (port->write_urbs[i] == urb)
+			break;
+	}
+	spin_lock_irqsave(&port->lock, flags);
+	__set_bit(i, &port->write_urbs_free);
+	port->tx_bytes -= urb->transfer_buffer_length;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	if (urb->status)
+		dbg("%s - non-zero urb status: %d", __func__, urb->status);
+
+	usb_serial_port_softint(port);
+}
+
+static struct usb_serial_driver samba_device = {
+	.driver = {
+		.owner		= THIS_MODULE,
+		.name		= "sam-ba",
+	},
+	.usb_driver		= &samba_driver,
+	.id_table		= id_table,
+	.num_ports		= 1,
+	.bulk_in_size		= 512,
+	.bulk_out_size		= 2048,
+	.write			= samba_write,
+	.write_room		= samba_write_room,
+	.chars_in_buffer	= samba_chars_in_buffer,
+	.write_bulk_callback	= samba_write_bulk_callback,
+	.throttle		= usb_serial_generic_throttle,
+	.unthrottle		= usb_serial_generic_unthrottle,
+};
+
+static int __init samba_init(void)
+{
+	int retval;
+
+	retval = usb_serial_register(&samba_device);
+	if (retval)
+		return retval;
+
+	retval = usb_register(&samba_driver);
+	if (retval) {
+		usb_serial_deregister(&samba_device);
+		return retval;
+	}
+
+	printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ": "
+							DRIVER_DESC "\n");
+	return 0;
+}
+
+static void __exit samba_exit(void)
+{
+	usb_deregister(&samba_driver);
+	usb_serial_deregister(&samba_device);
+}
+
+module_init(samba_init);
+module_exit(samba_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_VERSION(DRIVER_VERSION);
+MODULE_LICENSE("GPL");
+
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Enable verbose debugging messages");