/*
   * A driver for the Griffin Technology, Inc. "PowerMate" USB controller dial.
   *
   * v1.1, (c)2002 William R Sowerbutts <will@sowerbutts.com>
   *
   * This device is a anodised aluminium knob which connects over USB. It can measure
   * clockwise and anticlockwise rotation. The dial also acts as a pushbutton with
   * a spring for automatic release. The base contains a pair of LEDs which illuminate
   * the translucent base. It rotates without limit and reports its relative rotation
   * back to the host when polled by the USB controller.
   *
   * Testing with the knob I have has shown that it measures approximately 94 "clicks"
   * for one full rotation. Testing with my High Speed Rotation Actuator (ok, it was
   * a variable speed cordless electric drill) has shown that the device can measure
   * speeds of up to 7 clicks either clockwise or anticlockwise between pollings from
   * the host. If it counts more than 7 clicks before it is polled, it will wrap back
   * to zero and start counting again. This was at quite high speed, however, almost
   * certainly faster than the human hand could turn it. Griffin say that it loses a
   * pulse or two on a direction change; the granularity is so fine that I never
   * noticed this in practice.
   *
   * The device's microcontroller can be programmed to set the LED to either a constant
   * intensity, or to a rhythmic pulsing. Several patterns and speeds are available.
   *
   * Griffin were very happy to provide documentation and free hardware for development.
   *
   * Some userspace tools are available on the web: http://sowerbutts.com/powermate/
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/spinlock.h>
  #include <linux/usb/input.h>
  
  #define POWERMATE_VENDOR	0x077d	/* Griffin Technology, Inc. */
  #define POWERMATE_PRODUCT_NEW	0x0410	/* Griffin PowerMate */
  #define POWERMATE_PRODUCT_OLD	0x04AA	/* Griffin soundKnob */
  
  #define CONTOUR_VENDOR		0x05f3	/* Contour Design, Inc. */
  #define CONTOUR_JOG		0x0240	/* Jog and Shuttle */
  
  /* these are the command codes we send to the device */
  #define SET_STATIC_BRIGHTNESS  0x01
  #define SET_PULSE_ASLEEP       0x02
  #define SET_PULSE_AWAKE        0x03
  #define SET_PULSE_MODE         0x04
  
  /* these refer to bits in the powermate_device's requires_update field. */
  #define UPDATE_STATIC_BRIGHTNESS (1<<0)
  #define UPDATE_PULSE_ASLEEP      (1<<1)
  #define UPDATE_PULSE_AWAKE       (1<<2)
  #define UPDATE_PULSE_MODE        (1<<3)
  
  /* at least two versions of the hardware exist, with differing payload
     sizes. the first three bytes always contain the "interesting" data in
     the relevant format. */
  #define POWERMATE_PAYLOAD_SIZE_MAX 6
  #define POWERMATE_PAYLOAD_SIZE_MIN 3
  struct powermate_device {
  	signed char *data;
  	dma_addr_t data_dma;
  	struct urb *irq, *config;
  	struct usb_ctrlrequest *configcr;
  	struct usb_device *udev;
  	struct usb_interface *intf;
  	struct input_dev *input;
  	spinlock_t lock;
  	int static_brightness;
  	int pulse_speed;
  	int pulse_table;
  	int pulse_asleep;
  	int pulse_awake;
  	int requires_update; // physical settings which are out of sync
  	char phys[64];
  };
  
  static char pm_name_powermate[] = "Griffin PowerMate";
  static char pm_name_soundknob[] = "Griffin SoundKnob";
  
  static void powermate_config_complete(struct urb *urb);
  
  /* Callback for data arriving from the PowerMate over the USB interrupt pipe */
  static void powermate_irq(struct urb *urb)
  {
  	struct powermate_device *pm = urb->context;
  	struct device *dev = &pm->intf->dev;
  	int retval;
  
  	switch (urb->status) {
  	case 0:
  		/* success */
  		break;
  	case -ECONNRESET:
  	case -ENOENT:
  	case -ESHUTDOWN:
  		/* this urb is terminated, clean up */
  		dev_dbg(dev, "%s - urb shutting down with status: %d
  ",
  			__func__, urb->status);
  		return;
  	default:
  		dev_dbg(dev, "%s - nonzero urb status received: %d
  ",
  			__func__, urb->status);
  		goto exit;
  	}
  
  	/* handle updates to device state */
  	input_report_key(pm->input, BTN_0, pm->data[0] & 0x01);
  	input_report_rel(pm->input, REL_DIAL, pm->data[1]);
  	input_sync(pm->input);
  
  exit:
  	retval = usb_submit_urb (urb, GFP_ATOMIC);
  	if (retval)
  		dev_err(dev, "%s - usb_submit_urb failed with result: %d
  ",
  			__func__, retval);
  }
  
  /* Decide if we need to issue a control message and do so. Must be called with pm->lock taken */
  static void powermate_sync_state(struct powermate_device *pm)
  {
  	if (pm->requires_update == 0)
  		return; /* no updates are required */
  	if (pm->config->status == -EINPROGRESS)
  		return; /* an update is already in progress; it'll issue this update when it completes */
  
  	if (pm->requires_update & UPDATE_PULSE_ASLEEP){
  		pm->configcr->wValue = cpu_to_le16( SET_PULSE_ASLEEP );
  		pm->configcr->wIndex = cpu_to_le16( pm->pulse_asleep ? 1 : 0 );
  		pm->requires_update &= ~UPDATE_PULSE_ASLEEP;
  	}else if (pm->requires_update & UPDATE_PULSE_AWAKE){
  		pm->configcr->wValue = cpu_to_le16( SET_PULSE_AWAKE );
  		pm->configcr->wIndex = cpu_to_le16( pm->pulse_awake ? 1 : 0 );
  		pm->requires_update &= ~UPDATE_PULSE_AWAKE;
  	}else if (pm->requires_update & UPDATE_PULSE_MODE){
  		int op, arg;
  		/* the powermate takes an operation and an argument for its pulse algorithm.
  		   the operation can be:
  		   0: divide the speed
  		   1: pulse at normal speed
  		   2: multiply the speed
  		   the argument only has an effect for operations 0 and 2, and ranges between
  		   1 (least effect) to 255 (maximum effect).
  
  		   thus, several states are equivalent and are coalesced into one state.
  
  		   we map this onto a range from 0 to 510, with:
  		   0 -- 254    -- use divide (0 = slowest)
  		   255         -- use normal speed
  		   256 -- 510  -- use multiple (510 = fastest).
  
  		   Only values of 'arg' quite close to 255 are particularly useful/spectacular.
  		*/
  		if (pm->pulse_speed < 255) {
  			op = 0;                   // divide
  			arg = 255 - pm->pulse_speed;
  		} else if (pm->pulse_speed > 255) {
  			op = 2;                   // multiply
  			arg = pm->pulse_speed - 255;
  		} else {
  			op = 1;                   // normal speed
  			arg = 0;                  // can be any value
  		}
  		pm->configcr->wValue = cpu_to_le16( (pm->pulse_table << 8) | SET_PULSE_MODE );
  		pm->configcr->wIndex = cpu_to_le16( (arg << 8) | op );
  		pm->requires_update &= ~UPDATE_PULSE_MODE;
  	} else if (pm->requires_update & UPDATE_STATIC_BRIGHTNESS) {
  		pm->configcr->wValue = cpu_to_le16( SET_STATIC_BRIGHTNESS );
  		pm->configcr->wIndex = cpu_to_le16( pm->static_brightness );
  		pm->requires_update &= ~UPDATE_STATIC_BRIGHTNESS;
  	} else {
  		printk(KERN_ERR "powermate: unknown update required");
  		pm->requires_update = 0; /* fudge the bug */
  		return;
  	}
  
  /*	printk("powermate: %04x %04x
  ", pm->configcr->wValue, pm->configcr->wIndex); */
  
  	pm->configcr->bRequestType = 0x41; /* vendor request */
  	pm->configcr->bRequest = 0x01;
  	pm->configcr->wLength = 0;
  
  	usb_fill_control_urb(pm->config, pm->udev, usb_sndctrlpipe(pm->udev, 0),
  			     (void *) pm->configcr, NULL, 0,
  			     powermate_config_complete, pm);
  
  	if (usb_submit_urb(pm->config, GFP_ATOMIC))
  		printk(KERN_ERR "powermate: usb_submit_urb(config) failed");
  }
  
  /* Called when our asynchronous control message completes. We may need to issue another immediately */
  static void powermate_config_complete(struct urb *urb)
  {
  	struct powermate_device *pm = urb->context;
  	unsigned long flags;
  
  	if (urb->status)
  		printk(KERN_ERR "powermate: config urb returned %d
  ", urb->status);
  
  	spin_lock_irqsave(&pm->lock, flags);
  	powermate_sync_state(pm);
  	spin_unlock_irqrestore(&pm->lock, flags);
  }
  
  /* Set the LED up as described and begin the sync with the hardware if required */
  static void powermate_pulse_led(struct powermate_device *pm, int static_brightness, int pulse_speed,
  				int pulse_table, int pulse_asleep, int pulse_awake)
  {
  	unsigned long flags;
  
  	if (pulse_speed < 0)
  		pulse_speed = 0;
  	if (pulse_table < 0)
  		pulse_table = 0;
  	if (pulse_speed > 510)
  		pulse_speed = 510;
  	if (pulse_table > 2)
  		pulse_table = 2;
  
  	pulse_asleep = !!pulse_asleep;
  	pulse_awake = !!pulse_awake;
  
  
  	spin_lock_irqsave(&pm->lock, flags);
  
  	/* mark state updates which are required */
  	if (static_brightness != pm->static_brightness) {
  		pm->static_brightness = static_brightness;
  		pm->requires_update |= UPDATE_STATIC_BRIGHTNESS;
  	}
  	if (pulse_asleep != pm->pulse_asleep) {
  		pm->pulse_asleep = pulse_asleep;
  		pm->requires_update |= (UPDATE_PULSE_ASLEEP | UPDATE_STATIC_BRIGHTNESS);
  	}
  	if (pulse_awake != pm->pulse_awake) {
  		pm->pulse_awake = pulse_awake;
  		pm->requires_update |= (UPDATE_PULSE_AWAKE | UPDATE_STATIC_BRIGHTNESS);
  	}
  	if (pulse_speed != pm->pulse_speed || pulse_table != pm->pulse_table) {
  		pm->pulse_speed = pulse_speed;
  		pm->pulse_table = pulse_table;
  		pm->requires_update |= UPDATE_PULSE_MODE;
  	}
  
  	powermate_sync_state(pm);
  
  	spin_unlock_irqrestore(&pm->lock, flags);
  }
  
  /* Callback from the Input layer when an event arrives from userspace to configure the LED */
  static int powermate_input_event(struct input_dev *dev, unsigned int type, unsigned int code, int _value)
  {
  	unsigned int command = (unsigned int)_value;
  	struct powermate_device *pm = input_get_drvdata(dev);
  
  	if (type == EV_MSC && code == MSC_PULSELED){
  		/*
  		    bits  0- 7: 8 bits: LED brightness
  		    bits  8-16: 9 bits: pulsing speed modifier (0 ... 510); 0-254 = slower, 255 = standard, 256-510 = faster.
  		    bits 17-18: 2 bits: pulse table (0, 1, 2 valid)
  		    bit     19: 1 bit : pulse whilst asleep?
  		    bit     20: 1 bit : pulse constantly?
  		*/
  		int static_brightness = command & 0xFF;   // bits 0-7
  		int pulse_speed = (command >> 8) & 0x1FF; // bits 8-16
  		int pulse_table = (command >> 17) & 0x3;  // bits 17-18
  		int pulse_asleep = (command >> 19) & 0x1; // bit 19
  		int pulse_awake  = (command >> 20) & 0x1; // bit 20
  
  		powermate_pulse_led(pm, static_brightness, pulse_speed, pulse_table, pulse_asleep, pulse_awake);
  	}
  
  	return 0;
  }
  
  static int powermate_alloc_buffers(struct usb_device *udev, struct powermate_device *pm)
  {
  	pm->data = usb_alloc_coherent(udev, POWERMATE_PAYLOAD_SIZE_MAX,
  				      GFP_ATOMIC, &pm->data_dma);
  	if (!pm->data)
  		return -1;
  
  	pm->configcr = kmalloc(sizeof(*(pm->configcr)), GFP_KERNEL);
  	if (!pm->configcr)
  		return -ENOMEM;
  
  	return 0;
  }
  
  static void powermate_free_buffers(struct usb_device *udev, struct powermate_device *pm)
  {
  	usb_free_coherent(udev, POWERMATE_PAYLOAD_SIZE_MAX,
  			  pm->data, pm->data_dma);
  	kfree(pm->configcr);
  }
  
  /* Called whenever a USB device matching one in our supported devices table is connected */
  static int powermate_probe(struct usb_interface *intf, const struct usb_device_id *id)
  {
  	struct usb_device *udev = interface_to_usbdev (intf);
  	struct usb_host_interface *interface;
  	struct usb_endpoint_descriptor *endpoint;
  	struct powermate_device *pm;
  	struct input_dev *input_dev;
  	int pipe, maxp;
  	int error = -ENOMEM;
  
  	interface = intf->cur_altsetting;
  	endpoint = &interface->endpoint[0].desc;
  	if (!usb_endpoint_is_int_in(endpoint))
  		return -EIO;
  
  	usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
  		0x0a, USB_TYPE_CLASS | USB_RECIP_INTERFACE,
  		0, interface->desc.bInterfaceNumber, NULL, 0,
  		USB_CTRL_SET_TIMEOUT);
  
  	pm = kzalloc(sizeof(struct powermate_device), GFP_KERNEL);
  	input_dev = input_allocate_device();
  	if (!pm || !input_dev)
  		goto fail1;
  
  	if (powermate_alloc_buffers(udev, pm))
  		goto fail2;
  
  	pm->irq = usb_alloc_urb(0, GFP_KERNEL);
  	if (!pm->irq)
  		goto fail2;
  
  	pm->config = usb_alloc_urb(0, GFP_KERNEL);
  	if (!pm->config)
  		goto fail3;
  
  	pm->udev = udev;
  	pm->intf = intf;
  	pm->input = input_dev;
  
  	usb_make_path(udev, pm->phys, sizeof(pm->phys));
  	strlcat(pm->phys, "/input0", sizeof(pm->phys));
  
  	spin_lock_init(&pm->lock);
  
  	switch (le16_to_cpu(udev->descriptor.idProduct)) {
  	case POWERMATE_PRODUCT_NEW:
  		input_dev->name = pm_name_powermate;
  		break;
  	case POWERMATE_PRODUCT_OLD:
  		input_dev->name = pm_name_soundknob;
  		break;
  	default:
  		input_dev->name = pm_name_soundknob;
  		printk(KERN_WARNING "powermate: unknown product id %04x
  ",
  		       le16_to_cpu(udev->descriptor.idProduct));
  	}
  
  	input_dev->phys = pm->phys;
  	usb_to_input_id(udev, &input_dev->id);
  	input_dev->dev.parent = &intf->dev;
  
  	input_set_drvdata(input_dev, pm);
  
  	input_dev->event = powermate_input_event;
  
  	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL) |
  		BIT_MASK(EV_MSC);
  	input_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);
  	input_dev->relbit[BIT_WORD(REL_DIAL)] = BIT_MASK(REL_DIAL);
  	input_dev->mscbit[BIT_WORD(MSC_PULSELED)] = BIT_MASK(MSC_PULSELED);
  
  	/* get a handle to the interrupt data pipe */
  	pipe = usb_rcvintpipe(udev, endpoint->bEndpointAddress);
  	maxp = usb_maxpacket(udev, pipe, usb_pipeout(pipe));
  
  	if (maxp < POWERMATE_PAYLOAD_SIZE_MIN || maxp > POWERMATE_PAYLOAD_SIZE_MAX) {
  		printk(KERN_WARNING "powermate: Expected payload of %d--%d bytes, found %d bytes!
  ",
  			POWERMATE_PAYLOAD_SIZE_MIN, POWERMATE_PAYLOAD_SIZE_MAX, maxp);
  		maxp = POWERMATE_PAYLOAD_SIZE_MAX;
  	}
  
  	usb_fill_int_urb(pm->irq, udev, pipe, pm->data,
  			 maxp, powermate_irq,
  			 pm, endpoint->bInterval);
  	pm->irq->transfer_dma = pm->data_dma;
  	pm->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
  
  	/* register our interrupt URB with the USB system */
  	if (usb_submit_urb(pm->irq, GFP_KERNEL)) {
  		error = -EIO;
  		goto fail4;
  	}
  
  	error = input_register_device(pm->input);
  	if (error)
  		goto fail5;
  
  
  	/* force an update of everything */
  	pm->requires_update = UPDATE_PULSE_ASLEEP | UPDATE_PULSE_AWAKE | UPDATE_PULSE_MODE | UPDATE_STATIC_BRIGHTNESS;
  	powermate_pulse_led(pm, 0x80, 255, 0, 1, 0); // set default pulse parameters
  
  	usb_set_intfdata(intf, pm);
  	return 0;
  
   fail5:	usb_kill_urb(pm->irq);
   fail4:	usb_free_urb(pm->config);
   fail3:	usb_free_urb(pm->irq);
   fail2:	powermate_free_buffers(udev, pm);
   fail1:	input_free_device(input_dev);
  	kfree(pm);
  	return error;
  }
  
  /* Called when a USB device we've accepted ownership of is removed */
  static void powermate_disconnect(struct usb_interface *intf)
  {
  	struct powermate_device *pm = usb_get_intfdata (intf);
  
  	usb_set_intfdata(intf, NULL);
  	if (pm) {
  		pm->requires_update = 0;
  		usb_kill_urb(pm->irq);
  		input_unregister_device(pm->input);
  		usb_free_urb(pm->irq);
  		usb_free_urb(pm->config);
  		powermate_free_buffers(interface_to_usbdev(intf), pm);
  
  		kfree(pm);
  	}
  }
  
  static struct usb_device_id powermate_devices [] = {
  	{ USB_DEVICE(POWERMATE_VENDOR, POWERMATE_PRODUCT_NEW) },
  	{ USB_DEVICE(POWERMATE_VENDOR, POWERMATE_PRODUCT_OLD) },
  	{ USB_DEVICE(CONTOUR_VENDOR, CONTOUR_JOG) },
  	{ } /* Terminating entry */
  };
  
  MODULE_DEVICE_TABLE (usb, powermate_devices);
  
  static struct usb_driver powermate_driver = {
          .name =         "powermate",
          .probe =        powermate_probe,
          .disconnect =   powermate_disconnect,
          .id_table =     powermate_devices,
  };
  
  module_usb_driver(powermate_driver);
  
  MODULE_AUTHOR( "William R Sowerbutts" );
  MODULE_DESCRIPTION( "Griffin Technology, Inc PowerMate driver" );
  MODULE_LICENSE("GPL");