lw35-upgrade/ioc/kernel-driver/lw35ioc.c

#include <linux/device.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/serdev.h>
#include <linux/types.h>
#include <linux/input.h>
#include <linux/gpio/consumer.h>
#include <linux/uaccess.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/circ_buf.h>

// #define ENABLE_DEBUG ENABLE_DEBUG

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Markus Koch");
MODULE_DESCRIPTION("LW-35 I/O Controller Driver");
MODULE_VERSION("0.1");

static int debug_level = 0;
module_param(debug_level, int, 0);
MODULE_PARM_DESC(debug_level, "Debug level");

/* Only for chrdev... man they really suck! */
static struct serdev_device *static_serdev = NULL;
static DECLARE_WAIT_QUEUE_HEAD(wq);

void pbuf_work_handler(struct work_struct *work);
DECLARE_WORK(pbuf_work, pbuf_work_handler);

static DEFINE_SPINLOCK(printer_status_lock);

static struct of_device_id lw35ioc_dt_ids[] = {
{ .compatible = "brother,lw35", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, lw35ioc_dt_ids);

/* Chardev */
#define DEVICE_NAME "lw35"
#define CLASS_NAME "lw35ioc"

/* Only used for initialization, not for actual keycode mapping */
static int keycode_map[] = {
	KEY_A, KEY_B, KEY_C, KEY_D, KEY_E, KEY_F, KEY_G, KEY_H, KEY_I, KEY_J,
	KEY_K, KEY_L, KEY_M, KEY_N, KEY_O, KEY_P, KEY_Q, KEY_R, KEY_S, KEY_T,
	KEY_U, KEY_V, KEY_W, KEY_X, KEY_Y, KEY_Z,
	KEY_0, KEY_1, KEY_2, KEY_3, KEY_4, KEY_5, KEY_6, KEY_7, KEY_8, KEY_9,
	KEY_F1, KEY_F2, KEY_F3, KEY_F4, KEY_F5, KEY_F6, KEY_F7, KEY_F8, KEY_F9,
	KEY_F10, KEY_F11, KEY_F12,
	KEY_UP, KEY_DOWN, KEY_RIGHT, KEY_LEFT, KEY_PAGEUP, KEY_PAGEDOWN,
	KEY_102ND, KEY_INSERT, KEY_HOME, KEY_END, KEY_PRINT,
	KEY_CAPSLOCK, KEY_LEFTCTRL, KEY_LEFTSHIFT, KEY_LEFTALT, KEY_TAB,
	KEY_MINUS, KEY_COMMA, KEY_SEMICOLON, KEY_RIGHTBRACE, KEY_LEFTBRACE,
	KEY_GRAVE, KEY_SPACE, KEY_EQUAL, KEY_DOT, KEY_SLASH, KEY_APOSTROPHE,
	KEY_BACKSLASH,
	KEY_DELETE, KEY_ESC, KEY_ENTER, KEY_BACKSPACE,
	KEY_SYSRQ
};

enum lw35ioc_state {PASSIVE = 0, INIT, PROG_KBD, PROG_PRI, BYPASS, ACTIVE, STATE_COUNT};

enum lw35ioc_packet_state {SYNC, TYPE, KEYBOARD, PRINTER};

struct lw35ioc_packet {
	enum lw35ioc_packet_state state;
	int payload_offset;
};

struct lw35ioc_chardev {
	int major_number;
	struct class* class;
	struct device* device;
	int open_count;
};

struct lw35ioc_printer_status{
	int buffer_free;
	int status;
	int reserved0;
	int reserved1;
};

#define UART_BUF_SIZE 256
#define PBUF_SIZE 256

struct lw35ioc_priv {
	struct serdev_device *serdev;
	struct input_dev *input_dev;
	struct gpio_desc *gpio_rst; /* GPIO to reset both AVRs */
	struct lw35ioc_chardev chardev;

	struct lw35ioc_printer_status printer_status_temp;
	struct lw35ioc_printer_status printer_status;

	char uart_buf_rx[UART_BUF_SIZE];
	char *uart_buf_rx_rd;
	char *uart_buf_rx_wr;

	char pbuf[PBUF_SIZE];
	unsigned long pbuf_tail;
	unsigned long pbuf_head;

	enum lw35ioc_state state;
	struct lw35ioc_packet packet;
};


static int lw35ioc_process_buf(struct serdev_device *serdev,
			       const unsigned char *data,
			       size_t count)
{
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);
	unsigned char c;
	int ev;
	int i;
	unsigned long lock_flags;

#ifdef ENABLE_DEBUG
	dev_info(&serdev->dev, "IRQ.\n");
#endif
	for (i = 0; i < count; ++i) {
		c = data[i];
#ifdef ENABLE_DEBUG
		dev_info(&serdev->dev, "  RX [%d]: %02x\n", priv->packet.state, c);
#endif
		switch (priv->packet.state) {
		case SYNC:
			if (c == 0xFF)
				priv->packet.state = TYPE;
			break;

		case TYPE:
			if (c == 0x55)
				priv->packet.state = KEYBOARD;
			else if (c == 0xAA)
				priv->packet.state = PRINTER;
			else
				priv->packet.state = SYNC;
			priv->packet.payload_offset = 0;
			break;

		case KEYBOARD:
			if (c > 127) {
				c -= 128;
				ev = 1;
			} else {
				ev = 0;
			}
			input_report_key(priv->input_dev, c, ev);
			input_sync(priv->input_dev);
			priv->packet.state = SYNC;
			break;

		case PRINTER:
			switch (priv->packet.payload_offset) {
			case 0: /* Status */
				priv->printer_status_temp.status = (int)c;
				break;
			case 1: /* Buffer status */
				priv->printer_status_temp.buffer_free = (int)c;
				break;
			case 2: /* Reserved */
				priv->printer_status_temp.reserved0 = (int)c;
				break;
			case 3: /* Reserved */
				priv->printer_status_temp.reserved1 = (int)c;

				dev_info(&serdev->dev,
					 "New printer status. status=0x%02X buffer_free=0x%02X [0x%02X,0x%02X].\n",
					 priv->printer_status_temp.status,
					 priv->printer_status_temp.buffer_free,
					 priv->printer_status_temp.reserved0,
					 priv->printer_status_temp.reserved1);
				if (priv->printer_status_temp.status == 0xFF) {
					dev_err(&serdev->dev,
						"HARDFAULT in printer firmware! Reset required.\n");
				}
				spin_lock_irqsave(&printer_status_lock, lock_flags);
				memcpy(&priv->printer_status,
				       &priv->printer_status_temp,
				       sizeof(priv->printer_status));
				spin_unlock_irqrestore(&printer_status_lock, lock_flags);

				if (priv->printer_status_temp.buffer_free > 0)
					schedule_work(&pbuf_work);

				priv->packet.state = SYNC;
				break;
			default:
				break;
			}
			priv->packet.payload_offset++;
			break;
		}
	}

	return i;
}

static int lw35ioc_receive_buf(struct serdev_device *serdev,
			       const unsigned char *data,
			       size_t count)
{
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);
	int i;

	switch (priv->state) {
	case ACTIVE:
		return lw35ioc_process_buf(serdev, data, count);
		break;
	case PASSIVE:
		break;
	default:
		/* Pass data directly to chardev */
		for (i = 0; i < count; ++i) {
#ifdef ENABLE_DEBUG
			dev_info(&serdev->dev, "  RX [PSV]: %02x\n", data[i]);
#endif
			*(priv->uart_buf_rx_wr) = data[i];
			if (priv->uart_buf_rx_wr == priv->uart_buf_rx + UART_BUF_SIZE - 1)
				priv->uart_buf_rx_wr = priv->uart_buf_rx;
			else
				priv->uart_buf_rx_wr++;

			if (priv->uart_buf_rx_rd == priv->uart_buf_rx_wr) {
				dev_err(&serdev->dev, "UART RX buffer overflow.\n");
			}
		}

		wake_up_interruptible(&wq);
	}

	return count; /* Pretend we read all data */
}

static void lw35ioc_write_wakeup(struct serdev_device *serdev)
{
	// schedule work here
}

static struct serdev_device_ops lw35ioc_serdev_ops = {
	.receive_buf = lw35ioc_receive_buf,
	.write_wakeup = lw35ioc_write_wakeup,
};

static void lw35ioc_set_hw_reset(struct serdev_device *serdev,
				 int reset_active)
{
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	gpiod_set_value(priv->gpio_rst, !!reset_active);
}

static void lw35ioc_reset_ioc_hw(struct serdev_device *serdev)
{
	dev_info(&serdev->dev, "Resetting IOC...\n");
	lw35ioc_set_hw_reset(serdev, 1);
	usleep_range(90000, 100000);
	lw35ioc_set_hw_reset(serdev, 0);
	usleep_range(90000, 100000);
}

/* Chardev */
static int lw35ioc_chardev_open(struct inode *inodep, struct file *filep) {
	struct serdev_device *serdev = static_serdev;
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	filep->private_data = serdev;

	if (!priv->chardev.open_count) {
		dev_info(&serdev->dev, "Opened chardev.\n");

		switch (priv->state) {
		case PROG_KBD:
			lw35ioc_reset_ioc_hw(serdev);
			serdev_device_write(serdev, "X", 1, 0);
			dev_info(&serdev->dev, "Put ioc into programming mode: keyboard.\n");
			break;
		case PROG_PRI:
			lw35ioc_reset_ioc_hw(serdev);
			serdev_device_write(serdev, "Y", 1, 0);
			dev_info(&serdev->dev, "Put ioc into programming mode: printer.\n");
			break;
		case BYPASS:
			lw35ioc_reset_ioc_hw(serdev);
			serdev_device_write(serdev, "XX", 2, 0);
			dev_info(&serdev->dev, "Put ioc into bypass mode.\n");
			break;
		case INIT:
		case PASSIVE:
			lw35ioc_reset_ioc_hw(serdev);
			usleep_range(2100000, 2210000);
			dev_info(&serdev->dev, "Put ioc into active mode.\n");
			if (priv->state == INIT) {
				serdev_device_write(serdev, "\xFF", 1, 0);
				priv->state = ACTIVE;
			}
			break;
		case ACTIVE:
			/* Don't do anything when active */
			break;
		default:
			break;
		}

	} else {
		dev_err(&serdev->dev, "Rejected. Device may only be opened once.\n");
		//return -EBUSY; // TODO
	}

	priv->chardev.open_count++;

	return 0;
}

static ssize_t lw35ioc_chardev_read(struct file *filep, char *buffer, size_t len, loff_t *offset) {
	struct serdev_device *serdev = filep->private_data;
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);
	int error_count;
	int available;

	available = priv->uart_buf_rx_wr - priv->uart_buf_rx_rd;
	if (available < 0)
		available = 1;
	if (!available) { /* Wait for data to become available */
		wait_event_interruptible(wq, priv->uart_buf_rx_rd != priv->uart_buf_rx_wr);
		available = priv->uart_buf_rx_wr - priv->uart_buf_rx_rd;
		if (available < 0)
			available = 1; /* TODO: We should calculate the remaining block until wraparound here... */
		if (!available)
			return -EAGAIN;
	}

	if (available < len)
		len = available;

	error_count = copy_to_user(buffer, priv->uart_buf_rx_rd, len);
	len -= error_count;
	priv->uart_buf_rx_rd += len;
	if (priv->uart_buf_rx_rd >= priv->uart_buf_rx + UART_BUF_SIZE) {
		priv->uart_buf_rx_rd -= UART_BUF_SIZE;
	}

	if (error_count == 0) {
		return len;
	} else {
		dev_err(&serdev->dev, "Failed to read %d characters to chardev.\n",
			error_count);
		return -EFAULT;
	}
}

char msg[256]; // TODO
static ssize_t lw35ioc_chardev_write(struct file *filep, const char *buffer, size_t len, loff_t *offset) {
	struct serdev_device *serdev = filep->private_data;
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);
	unsigned long tail;
	int i;
	int ret;

	switch (priv->state) {
	case ACTIVE:
		/* Put data into pbuf */
		// TODO: spinlock
		if (CIRC_SPACE(priv->pbuf_head, READ_ONCE(priv->pbuf_tail), PBUF_SIZE) < 1) {
			dev_err(&serdev->dev, "chdev write: Waiting for space...\n");
			if (ret = (wait_event_interruptible(wq, CIRC_SPACE(priv->pbuf_head, priv->pbuf_tail, PBUF_SIZE) >= 1))) { // TODO: Accessing pbuf_tail without any protection... this might be bad?
				dev_err(&serdev->dev,
					"chdev write: device closed while waiting. ret: %d\n",
					ret);
				// TODO: This is not proper handling of this I guess...
				return len;
			}
			dev_err(&serdev->dev, "chdev write: done waiting...\n");
		}

		tail = READ_ONCE(priv->pbuf_tail);
		for (i = 0; i < len; ++i) { // TODO: Block copy would be faster...
			if (CIRC_SPACE(priv->pbuf_head, tail, PBUF_SIZE) >= 1) {
				ret = copy_from_user(priv->pbuf + priv->pbuf_head,
						     buffer + i,
						     1);
				if (ret) {
					dev_err(&serdev->dev, "chdev write: copy_from_user failed (%d).\n",
						ret);
					i = len - 1;
				}
				smp_store_release(&(priv->pbuf_head),
						  (priv->pbuf_head + 1) & (PBUF_SIZE - 1));
			} else {
				dev_warn(&serdev->dev, "chdev write: ring buffer full.\n");
				break;
			}
		}
		len = i;

		schedule_work(&pbuf_work);
		dev_info(&serdev->dev,
			 "Copied %d bytes to FIFO (FIFO free: %d)",
			 len, CIRC_SPACE(priv->pbuf_head, tail, PBUF_SIZE));
		break;
	case PASSIVE:
		len = -EBUSY; // TODO: Can I do this?
		break;
	default: /* Pass-through */
		if (len > 256) {
			len = 256;
		}
		copy_from_user(msg, buffer, len); // TODO: Return value
		serdev_device_write_buf(serdev, msg, len);
	}

	return len;
}

static int lw35ioc_chardev_release(struct inode *inodep, struct file *filep){
	struct serdev_device *serdev = filep->private_data;
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	priv->chardev.open_count--;

	dev_info(&serdev->dev, "Device successfully closed\n");
	return 0;
}

#define IOCTL_SET_MODE 42

static long lw35ioc_chardev_ioctl(struct file *filep, unsigned int cmd,
				  unsigned long arg)
{
	struct serdev_device *serdev = filep->private_data;
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	switch (cmd) {
	case IOCTL_SET_MODE:
		if (arg >= STATE_COUNT || arg < 0) {
			dev_err(&serdev->dev, "Invalid driver mode: %lu", arg);
			return -1;
		}
		priv->state = arg;
		dev_info(&serdev->dev, "Switched driver mode to: %lu. Will be applied with next open().\n", arg);
		break;
	default:
		dev_info(&serdev->dev, "Ignoring IOCTL %u(%lu)\n", cmd, arg);
		break;
	}

	return 0;
}

__poll_t poll(struct file *filep, struct poll_table_struct *ptab)
{
	struct serdev_device *serdev = filep->private_data;
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	poll_wait(filep, &wq, ptab);

	if (priv->uart_buf_rx_wr != priv->uart_buf_rx_rd)
		return EPOLLIN | EPOLLRDNORM;

	return 0;
}

#define PRINTER_READY_MASK (0b00011111)
int printer_ready_for_data(struct lw35ioc_printer_status printer_status)
{
	return ((printer_status.status & PRINTER_READY_MASK) == PRINTER_READY_MASK);
}

void pbuf_work_handler(struct work_struct *work)
{
	// TODO: get private data using container_of(): https://linux-kernel-labs.github.io/master/labs/deferred_work.html
	struct serdev_device *serdev = static_serdev; // Not cool, but whatever...
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);
	unsigned long head;
	unsigned long tail;
	unsigned long lock_flags;
	int bsize = 0;
	int i;
	int locked = 0;

	while (1) {
		// TODO: We are the only consumer, so we should be fine without a spinlock, right?
		head = smp_load_acquire(&priv->pbuf_head);
		tail = priv->pbuf_tail;
		bsize = CIRC_CNT(head, tail, PBUF_SIZE);
		//dev_info(&serdev->dev, "CIRC CNT=%d\n", bsize);
		if (bsize == 0)
			break;

		spin_lock_irqsave(&printer_status_lock, lock_flags);
		locked = 1;
		if (!printer_ready_for_data(priv->printer_status)) {
			dev_warn(&serdev->dev, "Cannot transmit data to device. Device is not ready.\n");
			break;
		}
		if (bsize > priv->printer_status.buffer_free)
			bsize = priv->printer_status.buffer_free;
		if (bsize > CIRC_CNT_TO_END(head, tail, PBUF_SIZE))
			bsize = CIRC_CNT_TO_END(head, tail, PBUF_SIZE);
		if (bsize > priv->printer_status.buffer_free - 20)
			bsize = priv->printer_status.buffer_free - 20; // TODO: Bug workaround
		dev_info(&serdev->dev, "TX %d of %d bytes [%d bytes free on device].\n",
			 bsize,
			 CIRC_CNT(head, tail, PBUF_SIZE),
			 priv->printer_status.buffer_free);
		priv->printer_status.buffer_free-=bsize;
		spin_unlock_irqrestore(&printer_status_lock, lock_flags);
		locked = 0;
		if (bsize == 0) {
			dev_warn(&serdev->dev, "Cannot transmit data to device. Device buffer is full.\n");
			break;
		}

		serdev_device_write_buf(serdev,
					priv->pbuf + tail,
					bsize);
#ifdef ENABLE_DEBUG
		for (i=0; i<bsize; ++i) {
			dev_info(&serdev->dev,
				 "UART TX: %c\n",
				 priv->pbuf[tail + i]);
		}
#endif
		smp_store_release(&priv->pbuf_tail,
				  (tail + bsize) & (PBUF_SIZE - 1));
	}
	if (locked)
		spin_unlock_irqrestore(&printer_status_lock, lock_flags);
	wake_up_interruptible(&wq); // There's some space available in the FIFO now, so wake up chardev write
}


static struct file_operations fops =
{
	.open = lw35ioc_chardev_open,
	.read = lw35ioc_chardev_read,
	.write = lw35ioc_chardev_write,
	.release = lw35ioc_chardev_release,
	.unlocked_ioctl = lw35ioc_chardev_ioctl,
	.poll = poll,
};


static int lw35ioc_cdev_init(struct serdev_device *serdev)
{
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	priv->chardev.open_count = 0;

	// Try to dynamically allocate a major number for the device
	priv->chardev.major_number = register_chrdev(0, DEVICE_NAME, &fops);
	if (priv->chardev.major_number < 0) {
		dev_err(&serdev->dev, "Failed to register a major number\n");
		return priv->chardev.major_number;
	}
	dev_info(&serdev->dev, "Registered correctly with major number %d\n", priv->chardev.major_number);

	// Register the device class
	priv->chardev.class = class_create(THIS_MODULE, CLASS_NAME);
	if (IS_ERR(priv->chardev.class)) {
		unregister_chrdev(priv->chardev.major_number, DEVICE_NAME);
		dev_err(&serdev->dev, "Failed to register device class\n");
		return PTR_ERR(priv->chardev.class);
	}
	dev_info(&serdev->dev, "Device class registered correctly\n");

	// Register the device driver
	priv->chardev.device = device_create(priv->chardev.class, NULL, MKDEV(priv->chardev.major_number, 0), NULL, DEVICE_NAME);
	if (IS_ERR(priv->chardev.device)) {
		class_destroy(priv->chardev.class);
		unregister_chrdev(priv->chardev.major_number, DEVICE_NAME);
		dev_err(&serdev->dev, "Failed to create the device\n");
		return PTR_ERR(priv->chardev.device);
	}

	dev_info(&serdev->dev, "Device class created correctly\n");
	return 0;
}

static int lw35ioc_probe(struct serdev_device *serdev)
{
	struct lw35ioc_priv *priv = NULL;
	int ret = 0;
	int i;
	u32 speed = 19200;
	struct input_dev *input_dev;

	printk(KERN_INFO "lw35ioc: probe\n");

	if (static_serdev) {
		printk(KERN_ERR "lw35ioc: Can only be loaded once.\n");
		goto fail_multicheck;
	}

	/* Allocate memory */
	priv = devm_kzalloc(&serdev->dev,
			    sizeof(struct lw35ioc_priv),
			    GFP_KERNEL);
	if (!priv) {
		printk(KERN_ERR "lw35ioc: Not enough memory.\n");
		return -ENOMEM;
	}

	priv->state = ACTIVE; // TODO: This should be passive
	priv->uart_buf_rx_rd = priv->uart_buf_rx;
	priv->uart_buf_rx_wr = priv->uart_buf_rx;

	priv->pbuf_tail = 0;
	priv->pbuf_head = 0;

	priv->printer_status.buffer_free = 0;
	priv->printer_status.status = 0;

	priv->serdev = serdev;
	static_serdev = serdev;
	priv->packet.state = SYNC;
	serdev_device_set_drvdata(serdev, priv);

	/* Register input device */
	input_dev = devm_input_allocate_device(&serdev->dev);
	if (!input_dev) {
		dev_err(&serdev->dev, "Unable to allocate input device.\n");
		return -ENOMEM;
	}
	priv->input_dev = input_dev;
	input_dev->name = "lw35ioc";
	input_dev->phys = "lw35ioc/input1";
	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
	__set_bit(EV_KEY, input_dev->evbit);
	__set_bit(EV_REP, input_dev->evbit);
	for (i = 0; i < ARRAY_SIZE(keycode_map); i++)
		__set_bit(keycode_map[i], input_dev->keybit);
	ret = input_register_device(input_dev);
	if (ret) {
		dev_err(&serdev->dev, "Unable to register input device.\n");
		goto fail_input;
	}

	serdev_device_set_client_ops(serdev, &lw35ioc_serdev_ops);

	ret = serdev_device_open(serdev);
	if (ret) {
		dev_err(&serdev->dev, "Unable to open device.\n");
		goto fail_serdev;
	}
	speed = serdev_device_set_baudrate(serdev, speed);
	dev_info(&serdev->dev, "Using baudrate: %u\n", speed);

	/* Register GPIO */
	priv->gpio_rst = gpiod_get_index(&serdev->dev,
					 "rst",
					 0,
					 GPIOD_OUT_HIGH);

	/* Register character device */
	ret = lw35ioc_cdev_init(serdev);
	if (ret) {
		dev_err(&serdev->dev, "Unable to initialize character device.\n");
		goto fail_gpio;
	}

	if (IS_ERR(priv->gpio_rst)) {
		dev_err(&serdev->dev, "Unable to get reset GPIO.\n");
		ret = -ENODEV; /* TODO */
		goto fail_gpio;
	}

	lw35ioc_reset_ioc_hw(serdev);

	dev_info(&serdev->dev, "Loaded driver.\n");

	return 0;
fail_gpio:
fail_serdev:
	input_unregister_device(input_dev);
fail_input:
	devm_kfree(&serdev->dev, input_dev);
fail_multicheck:
	return ret;
}

static void lw35ioc_remove(struct serdev_device *serdev)
{
	struct lw35ioc_priv *priv = serdev_device_get_drvdata(serdev);

	dev_info(&serdev->dev, "remove\n");
	dev_info(&serdev->dev, "  cdev class: %p\n", priv->chardev.class);

	device_destroy(priv->chardev.class, MKDEV(priv->chardev.major_number, 0));
	dev_info(&serdev->dev, "unreg\n");
	class_unregister(priv->chardev.class);
	dev_info(&serdev->dev, "destroy: SKIP\n");
	//class_destroy(priv->chardev.class);
	dev_info(&serdev->dev, "unreg-dev\n");
	unregister_chrdev(priv->chardev.major_number, DEVICE_NAME);

	dev_info(&serdev->dev, "  gpio rst: %p\n", priv->gpio_rst);
	dev_info(&serdev->dev, "  serdev: %p\n", priv->serdev);
	dev_info(&serdev->dev, "  input dev: %p\n", priv->input_dev);
	lw35ioc_set_hw_reset(serdev, 1);
	usleep_range(90000, 100000); // Make sure the reset actually happens
	gpiod_put(priv->gpio_rst);
	serdev_device_close(priv->serdev);
	input_unregister_device(priv->input_dev);

	dev_info(&serdev->dev, "done.\n");
	return;
}

static struct serdev_device_driver lw35ioc_driver = {
	.probe = lw35ioc_probe,
	.remove = lw35ioc_remove,
	.driver = {
		.name = "lw35ioc",
		.owner = THIS_MODULE,
		.of_match_table = of_match_ptr(lw35ioc_dt_ids),
	},
};

module_serdev_device_driver(lw35ioc_driver);