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>

// #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);

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 actualy 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, PROG_KBD, PROG_PRI, BYPASS, ACTIVE, STATE_COUNT};

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

struct lw35ioc_packet {
	enum lw35ioc_packet_state state;
};

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

#define UART_BUF_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;

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

	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;

#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;
			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:
			dev_info(&serdev->dev, "Printer not yet implemented.\n");
			priv->packet.state = SYNC;
			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;

	if (priv->state == ACTIVE)
		return lw35ioc_process_buf(serdev, data, count);

	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");

		if (priv->state != ACTIVE &&
				priv->state != PASSIVE) {
			lw35ioc_reset_ioc_hw(serdev);

			switch (priv->state) {
			case PROG_KBD:
				serdev_device_write(serdev, "X", 1, 0);
				dev_info(&serdev->dev, "Put ioc into programming mode: keyboard.\n");
				break;
			case PROG_PRI:
				serdev_device_write(serdev, "Y", 1, 0);
				dev_info(&serdev->dev, "Put ioc into programming mode: printer.\n");
				break;
			case BYPASS:
				serdev_device_write(serdev, "XX", 2, 0);
				dev_info(&serdev->dev, "Put ioc into bypass mode.\n");
				break;
			default:
				/* For other modes, we just wait for the reset to be over */
				usleep_range(1000000, 1010000);
				break;
			}
		}
	} else {
		dev_err(&serdev->dev, "Rejected. Device may only be opened once.\n");
		//return -EBUSY;
	}

	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;
		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);

	if (len > 256) {
		len = 256;
	}
	copy_from_user(msg, buffer, len);
	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;
}



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_err(&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 = PASSIVE;
	priv->uart_buf_rx_rd = priv->uart_buf_rx;
	priv->uart_buf_rx_wr = priv->uart_buf_rx;

	priv->serdev = serdev;
	static_serdev = serdev;
	priv->packet.state = SYNC;
	serdev_device_set_drvdata(serdev, priv);
	serdev_device_set_client_ops(serdev, &lw35ioc_serdev_ops);

	/* 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;
	}

	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);

	device_destroy(priv->chardev.class, MKDEV(priv->chardev.major_number, 0));
	class_unregister(priv->chardev.class);
	class_destroy(priv->chardev.class);
	unregister_chrdev(priv->chardev.major_number, DEVICE_NAME);

	lw35ioc_set_hw_reset(serdev, 1);
	gpiod_put(priv->gpio_rst);
	serdev_device_close(priv->serdev);
	input_unregister_device(priv->input_dev);

	dev_info(&serdev->dev, "remove\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);