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>

3 files changed, 216 insertions, 0 deletions

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index 916b2b6d765..95058109f9f 100644
--- a/drivers/usb/serial/Kconfig
+++ b/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
diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index 40ebe17b6ea..cf41b6209c7 100644
--- a/drivers/usb/serial/Makefile
+++ b/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
diff --git a/drivers/usb/serial/sam-ba.c b/drivers/usb/serial/sam-ba.c
new file mode 100644
index 00000000000..e3bba64afc5
--- /dev/null
+++ b/drivers/usb/serial/sam-ba.c
@@ -0,0 +1,206 @@
+/*
+ * 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");