drivers/misc/arm-charlcd.c - android_kernel_htc_msm8960 - Gitiles

 /*
  * Driver for the on-board character LCD found on some ARM reference boards
  * This is basically an Hitachi HD44780 LCD with a custom IP block to drive it
  * http://en.wikipedia.org/wiki/HD44780_Character_LCD
  * Currently it will just display the text "ARM Linux" and the linux version
  *
  * License terms: GNU General Public License (GPL) version 2
  * Author: Linus Walleij <triad@df.lth.se>
  */
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include <generated/utsrelease.h>

 #define DRIVERNAME "arm-charlcd"
 #define CHARLCD_TIMEOUT (msecs_to_jiffies(1000))

 /* Offsets to registers */
 #define CHAR_COM	0x00U
 #define CHAR_DAT	0x04U
 #define CHAR_RD		0x08U
 #define CHAR_RAW	0x0CU
 #define CHAR_MASK	0x10U
 #define CHAR_STAT	0x14U

 #define CHAR_RAW_CLEAR	0x00000000U
 #define CHAR_RAW_VALID	0x00000100U

 /* Hitachi HD44780 display commands */
 #define HD_CLEAR			0x01U
 #define HD_HOME				0x02U
 #define HD_ENTRYMODE			0x04U
 #define HD_ENTRYMODE_INCREMENT		0x02U
 #define HD_ENTRYMODE_SHIFT		0x01U
 #define HD_DISPCTRL			0x08U
 #define HD_DISPCTRL_ON			0x04U
 #define HD_DISPCTRL_CURSOR_ON		0x02U
 #define HD_DISPCTRL_CURSOR_BLINK	0x01U
 #define HD_CRSR_SHIFT			0x10U
 #define HD_CRSR_SHIFT_DISPLAY		0x08U
 #define HD_CRSR_SHIFT_DISPLAY_RIGHT	0x04U
 #define HD_FUNCSET			0x20U
 #define HD_FUNCSET_8BIT			0x10U
 #define HD_FUNCSET_2_LINES		0x08U
 #define HD_FUNCSET_FONT_5X10		0x04U
 #define HD_SET_CGRAM			0x40U
 #define HD_SET_DDRAM			0x80U
 #define HD_BUSY_FLAG			0x80U

 /**
  * @dev: a pointer back to containing device
  * @phybase: the offset to the controller in physical memory
  * @physize: the size of the physical page
  * @virtbase: the offset to the controller in virtual memory
  * @irq: reserved interrupt number
  * @complete: completion structure for the last LCD command
  */
 struct charlcd {
 	struct device *dev;
 	u32 phybase;
 	u32 physize;
 	void __iomem *virtbase;
 	int irq;
 	struct completion complete;
 	struct delayed_work init_work;
 };

 static irqreturn_t charlcd_interrupt(int irq, void *data)
 {
 	struct charlcd *lcd = data;
 	u8 status;

 	status = readl(lcd->virtbase + CHAR_STAT) & 0x01;
 	/* Clear IRQ */
 	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
 	if (status)
 		complete(&lcd->complete);
 	else
 		dev_info(lcd->dev, "Spurious IRQ (%02x)\n", status);
 	return IRQ_HANDLED;
 }


 static void charlcd_wait_complete_irq(struct charlcd *lcd)
 {
 	int ret;

 	ret = wait_for_completion_interruptible_timeout(&lcd->complete,
 							CHARLCD_TIMEOUT);
 	/* Disable IRQ after completion */
 	writel(0x00, lcd->virtbase + CHAR_MASK);

 	if (ret < 0) {
 		dev_err(lcd->dev,
 			"wait_for_completion_interruptible_timeout() "
 			"returned %d waiting for ready\n", ret);
 		return;
 	}

 	if (ret == 0) {
 		dev_err(lcd->dev, "charlcd controller timed out "
 			"waiting for ready\n");
 		return;
 	}
 }

 static u8 charlcd_4bit_read_char(struct charlcd *lcd)
 {
 	u8 data;
 	u32 val;
 	int i;

 	/* If we can, use an IRQ to wait for the data, else poll */
 	if (lcd->irq >= 0)
 		charlcd_wait_complete_irq(lcd);
 	else {
 		i = 0;
 		val = 0;
 		while (!(val & CHAR_RAW_VALID) && i < 10) {
 			udelay(100);
 			val = readl(lcd->virtbase + CHAR_RAW);
 			i++;
 		}

 		writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
 	}
 	msleep(1);

 	/* Read the 4 high bits of the data */
 	data = readl(lcd->virtbase + CHAR_RD) & 0xf0;

 	/*
 	 * The second read for the low bits does not trigger an IRQ
 	 * so in this case we have to poll for the 4 lower bits
 	 */
 	i = 0;
 	val = 0;
 	while (!(val & CHAR_RAW_VALID) && i < 10) {
 		udelay(100);
 		val = readl(lcd->virtbase + CHAR_RAW);
 		i++;
 	}
 	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
 	msleep(1);

 	/* Read the 4 low bits of the data */
 	data |= (readl(lcd->virtbase + CHAR_RD) >> 4) & 0x0f;

 	return data;
 }

 static bool charlcd_4bit_read_bf(struct charlcd *lcd)
 {
 	if (lcd->irq >= 0) {
 		/*
 		 * If we'll use IRQs to wait for the busyflag, clear any
 		 * pending flag and enable IRQ
 		 */
 		writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
 		init_completion(&lcd->complete);
 		writel(0x01, lcd->virtbase + CHAR_MASK);
 	}
 	readl(lcd->virtbase + CHAR_COM);
 	return charlcd_4bit_read_char(lcd) & HD_BUSY_FLAG ? true : false;
 }

 static void charlcd_4bit_wait_busy(struct charlcd *lcd)
 {
 	int retries = 50;

 	udelay(100);
 	while (charlcd_4bit_read_bf(lcd) && retries)
 		retries--;
 	if (!retries)
 		dev_err(lcd->dev, "timeout waiting for busyflag\n");
 }

 static void charlcd_4bit_command(struct charlcd *lcd, u8 cmd)
 {
 	u32 cmdlo = (cmd << 4) & 0xf0;
 	u32 cmdhi = (cmd & 0xf0);

 	writel(cmdhi, lcd->virtbase + CHAR_COM);
 	udelay(10);
 	writel(cmdlo, lcd->virtbase + CHAR_COM);
 	charlcd_4bit_wait_busy(lcd);
 }

 static void charlcd_4bit_char(struct charlcd *lcd, u8 ch)
 {
 	u32 chlo = (ch << 4) & 0xf0;
 	u32 chhi = (ch & 0xf0);

 	writel(chhi, lcd->virtbase + CHAR_DAT);
 	udelay(10);
 	writel(chlo, lcd->virtbase + CHAR_DAT);
 	charlcd_4bit_wait_busy(lcd);
 }

 static void charlcd_4bit_print(struct charlcd *lcd, int line, const char *str)
 {
 	u8 offset;
 	int i;

 	/*
 	 * We support line 0, 1
 	 * Line 1 runs from 0x00..0x27
 	 * Line 2 runs from 0x28..0x4f
 	 */
 	if (line == 0)
 		offset = 0;
 	else if (line == 1)
 		offset = 0x28;
 	else
 		return;

 	/* Set offset */
 	charlcd_4bit_command(lcd, HD_SET_DDRAM | offset);

 	/* Send string */
 	for (i = 0; i < strlen(str) && i < 0x28; i++)
 		charlcd_4bit_char(lcd, str[i]);
 }

 static void charlcd_4bit_init(struct charlcd *lcd)
 {
 	/* These commands cannot be checked with the busy flag */
 	writel(HD_FUNCSET | HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
 	msleep(5);
 	writel(HD_FUNCSET | HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
 	udelay(100);
 	writel(HD_FUNCSET | HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
 	udelay(100);
 	/* Go to 4bit mode */
 	writel(HD_FUNCSET, lcd->virtbase + CHAR_COM);
 	udelay(100);
 	/*
 	 * 4bit mode, 2 lines, 5x8 font, after this the number of lines
 	 * and the font cannot be changed until the next initialization sequence
 	 */
 	charlcd_4bit_command(lcd, HD_FUNCSET | HD_FUNCSET_2_LINES);
 	charlcd_4bit_command(lcd, HD_DISPCTRL | HD_DISPCTRL_ON);
 	charlcd_4bit_command(lcd, HD_ENTRYMODE | HD_ENTRYMODE_INCREMENT);
 	charlcd_4bit_command(lcd, HD_CLEAR);
 	charlcd_4bit_command(lcd, HD_HOME);
 	/* Put something useful in the display */
 	charlcd_4bit_print(lcd, 0, "ARM Linux");
 	charlcd_4bit_print(lcd, 1, UTS_RELEASE);
 }

 static void charlcd_init_work(struct work_struct *work)
 {
 	struct charlcd *lcd =
 		container_of(work, struct charlcd, init_work.work);

 	charlcd_4bit_init(lcd);
 }

 static int __init charlcd_probe(struct platform_device *pdev)
 {
 	int ret;
 	struct charlcd *lcd;
 	struct resource *res;

 	lcd = kzalloc(sizeof(struct charlcd), GFP_KERNEL);
 	if (!lcd)
 		return -ENOMEM;

 	lcd->dev = &pdev->dev;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		ret = -ENOENT;
 		goto out_no_resource;
 	}
 	lcd->phybase = res->start;
 	lcd->physize = resource_size(res);

 	if (request_mem_region(lcd->phybase, lcd->physize,
 			       DRIVERNAME) == NULL) {
 		ret = -EBUSY;
 		goto out_no_memregion;
 	}

 	lcd->virtbase = ioremap(lcd->phybase, lcd->physize);
 	if (!lcd->virtbase) {
 		ret = -ENOMEM;
 		goto out_no_remap;
 	}

 	lcd->irq = platform_get_irq(pdev, 0);
 	/* If no IRQ is supplied, we'll survive without it */
 	if (lcd->irq >= 0) {
 		if (request_irq(lcd->irq, charlcd_interrupt, IRQF_DISABLED,
 				DRIVERNAME, lcd)) {
 			ret = -EIO;
 			goto out_no_irq;
 		}
 	}

 	platform_set_drvdata(pdev, lcd);

 	/*
 	 * Initialize the display in a delayed work, because
 	 * it is VERY slow and would slow down the boot of the system.
 	 */
 	INIT_DELAYED_WORK(&lcd->init_work, charlcd_init_work);
 	schedule_delayed_work(&lcd->init_work, 0);

 	dev_info(&pdev->dev, "initalized ARM character LCD at %08x\n",
 		lcd->phybase);

 	return 0;

 out_no_irq:
 	iounmap(lcd->virtbase);
 out_no_remap:
 	platform_set_drvdata(pdev, NULL);
 out_no_memregion:
 	release_mem_region(lcd->phybase, SZ_4K);
 out_no_resource:
 	kfree(lcd);
 	return ret;
 }

 static int __exit charlcd_remove(struct platform_device *pdev)
 {
 	struct charlcd *lcd = platform_get_drvdata(pdev);

 	if (lcd) {
 		free_irq(lcd->irq, lcd);
 		iounmap(lcd->virtbase);
 		release_mem_region(lcd->phybase, lcd->physize);
 		platform_set_drvdata(pdev, NULL);
 		kfree(lcd);
 	}

 	return 0;
 }

 static int charlcd_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct charlcd *lcd = platform_get_drvdata(pdev);

 	/* Power the display off */
 	charlcd_4bit_command(lcd, HD_DISPCTRL);
 	return 0;
 }

 static int charlcd_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct charlcd *lcd = platform_get_drvdata(pdev);

 	/* Turn the display back on */
 	charlcd_4bit_command(lcd, HD_DISPCTRL | HD_DISPCTRL_ON);
 	return 0;
 }

 static const struct dev_pm_ops charlcd_pm_ops = {
 	.suspend = charlcd_suspend,
 	.resume = charlcd_resume,
 };

 static struct platform_driver charlcd_driver = {
 	.driver = {
 		.name = DRIVERNAME,
 		.owner = THIS_MODULE,
 		.pm = &charlcd_pm_ops,
 	},
 	.remove = __exit_p(charlcd_remove),
 };

 static int __init charlcd_init(void)
 {
 	return platform_driver_probe(&charlcd_driver, charlcd_probe);
 }

 static void __exit charlcd_exit(void)
 {
 	platform_driver_unregister(&charlcd_driver);
 }

 module_init(charlcd_init);
 module_exit(charlcd_exit);

 MODULE_AUTHOR("Linus Walleij <triad@df.lth.se>");
 MODULE_DESCRIPTION("ARM Character LCD Driver");
 MODULE_LICENSE("GPL v2");
	/*
	* Driver for the on-board character LCD found on some ARM reference boards
	* This is basically an Hitachi HD44780 LCD with a custom IP block to drive it
	* http://en.wikipedia.org/wiki/HD44780_Character_LCD
	* Currently it will just display the text "ARM Linux" and the linux version
	*
	* License terms: GNU General Public License (GPL) version 2
	* Author: Linus Walleij <triad@df.lth.se>
	*/
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/completion.h>
	#include <linux/delay.h>
	#include <linux/io.h>
	#include <linux/slab.h>
	#include <linux/workqueue.h>
	#include <generated/utsrelease.h>

	#define DRIVERNAME "arm-charlcd"
	#define CHARLCD_TIMEOUT (msecs_to_jiffies(1000))

	/* Offsets to registers */
	#define CHAR_COM 0x00U
	#define CHAR_DAT 0x04U
	#define CHAR_RD 0x08U
	#define CHAR_RAW 0x0CU
	#define CHAR_MASK 0x10U
	#define CHAR_STAT 0x14U

	#define CHAR_RAW_CLEAR 0x00000000U
	#define CHAR_RAW_VALID 0x00000100U

	/* Hitachi HD44780 display commands */
	#define HD_CLEAR 0x01U
	#define HD_HOME 0x02U
	#define HD_ENTRYMODE 0x04U
	#define HD_ENTRYMODE_INCREMENT 0x02U
	#define HD_ENTRYMODE_SHIFT 0x01U
	#define HD_DISPCTRL 0x08U
	#define HD_DISPCTRL_ON 0x04U
	#define HD_DISPCTRL_CURSOR_ON 0x02U
	#define HD_DISPCTRL_CURSOR_BLINK 0x01U
	#define HD_CRSR_SHIFT 0x10U
	#define HD_CRSR_SHIFT_DISPLAY 0x08U
	#define HD_CRSR_SHIFT_DISPLAY_RIGHT 0x04U
	#define HD_FUNCSET 0x20U
	#define HD_FUNCSET_8BIT 0x10U
	#define HD_FUNCSET_2_LINES 0x08U
	#define HD_FUNCSET_FONT_5X10 0x04U
	#define HD_SET_CGRAM 0x40U
	#define HD_SET_DDRAM 0x80U
	#define HD_BUSY_FLAG 0x80U

	/**
	* @dev: a pointer back to containing device
	* @phybase: the offset to the controller in physical memory
	* @physize: the size of the physical page
	* @virtbase: the offset to the controller in virtual memory
	* @irq: reserved interrupt number
	* @complete: completion structure for the last LCD command
	*/
	struct charlcd {
	struct device *dev;
	u32 phybase;
	u32 physize;
	void __iomem *virtbase;
	int irq;
	struct completion complete;
	struct delayed_work init_work;
	};

	static irqreturn_t charlcd_interrupt(int irq, void *data)
	{
	struct charlcd *lcd = data;
	u8 status;

	status = readl(lcd->virtbase + CHAR_STAT) & 0x01;
	/* Clear IRQ */
	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
	if (status)
	complete(&lcd->complete);
	else
	dev_info(lcd->dev, "Spurious IRQ (%02x)\n", status);
	return IRQ_HANDLED;
	}


	static void charlcd_wait_complete_irq(struct charlcd *lcd)
	{
	int ret;

	ret = wait_for_completion_interruptible_timeout(&lcd->complete,
	CHARLCD_TIMEOUT);
	/* Disable IRQ after completion */
	writel(0x00, lcd->virtbase + CHAR_MASK);

	if (ret < 0) {
	dev_err(lcd->dev,
	"wait_for_completion_interruptible_timeout() "
	"returned %d waiting for ready\n", ret);
	return;
	}

	if (ret == 0) {
	dev_err(lcd->dev, "charlcd controller timed out "
	"waiting for ready\n");
	return;
	}
	}

	static u8 charlcd_4bit_read_char(struct charlcd *lcd)
	{
	u8 data;
	u32 val;
	int i;

	/* If we can, use an IRQ to wait for the data, else poll */
	if (lcd->irq >= 0)
	charlcd_wait_complete_irq(lcd);
	else {
	i = 0;
	val = 0;
	while (!(val & CHAR_RAW_VALID) && i < 10) {
	udelay(100);
	val = readl(lcd->virtbase + CHAR_RAW);
	i++;
	}

	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
	}
	msleep(1);

	/* Read the 4 high bits of the data */
	data = readl(lcd->virtbase + CHAR_RD) & 0xf0;

	/*
	* The second read for the low bits does not trigger an IRQ
	* so in this case we have to poll for the 4 lower bits
	*/
	i = 0;
	val = 0;
	while (!(val & CHAR_RAW_VALID) && i < 10) {
	udelay(100);
	val = readl(lcd->virtbase + CHAR_RAW);
	i++;
	}
	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
	msleep(1);

	/* Read the 4 low bits of the data */
	data \|= (readl(lcd->virtbase + CHAR_RD) >> 4) & 0x0f;

	return data;
	}

	static bool charlcd_4bit_read_bf(struct charlcd *lcd)
	{
	if (lcd->irq >= 0) {
	/*
	* If we'll use IRQs to wait for the busyflag, clear any
	* pending flag and enable IRQ
	*/
	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
	init_completion(&lcd->complete);
	writel(0x01, lcd->virtbase + CHAR_MASK);
	}
	readl(lcd->virtbase + CHAR_COM);
	return charlcd_4bit_read_char(lcd) & HD_BUSY_FLAG ? true : false;
	}

	static void charlcd_4bit_wait_busy(struct charlcd *lcd)
	{
	int retries = 50;

	udelay(100);
	while (charlcd_4bit_read_bf(lcd) && retries)
	retries--;
	if (!retries)
	dev_err(lcd->dev, "timeout waiting for busyflag\n");
	}

	static void charlcd_4bit_command(struct charlcd *lcd, u8 cmd)
	{
	u32 cmdlo = (cmd << 4) & 0xf0;
	u32 cmdhi = (cmd & 0xf0);

	writel(cmdhi, lcd->virtbase + CHAR_COM);
	udelay(10);
	writel(cmdlo, lcd->virtbase + CHAR_COM);
	charlcd_4bit_wait_busy(lcd);
	}

	static void charlcd_4bit_char(struct charlcd *lcd, u8 ch)
	{
	u32 chlo = (ch << 4) & 0xf0;
	u32 chhi = (ch & 0xf0);

	writel(chhi, lcd->virtbase + CHAR_DAT);
	udelay(10);
	writel(chlo, lcd->virtbase + CHAR_DAT);
	charlcd_4bit_wait_busy(lcd);
	}

	static void charlcd_4bit_print(struct charlcd lcd, int line, const char str)
	{
	u8 offset;
	int i;

	/*
	* We support line 0, 1
	* Line 1 runs from 0x00..0x27
	* Line 2 runs from 0x28..0x4f
	*/
	if (line == 0)
	offset = 0;
	else if (line == 1)
	offset = 0x28;
	else
	return;

	/* Set offset */
	charlcd_4bit_command(lcd, HD_SET_DDRAM \| offset);

	/* Send string */
	for (i = 0; i < strlen(str) && i < 0x28; i++)
	charlcd_4bit_char(lcd, str[i]);
	}

	static void charlcd_4bit_init(struct charlcd *lcd)
	{
	/* These commands cannot be checked with the busy flag */
	writel(HD_FUNCSET \| HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
	msleep(5);
	writel(HD_FUNCSET \| HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
	udelay(100);
	writel(HD_FUNCSET \| HD_FUNCSET_8BIT, lcd->virtbase + CHAR_COM);
	udelay(100);
	/* Go to 4bit mode */
	writel(HD_FUNCSET, lcd->virtbase + CHAR_COM);
	udelay(100);
	/*
	* 4bit mode, 2 lines, 5x8 font, after this the number of lines
	* and the font cannot be changed until the next initialization sequence
	*/
	charlcd_4bit_command(lcd, HD_FUNCSET \| HD_FUNCSET_2_LINES);
	charlcd_4bit_command(lcd, HD_DISPCTRL \| HD_DISPCTRL_ON);
	charlcd_4bit_command(lcd, HD_ENTRYMODE \| HD_ENTRYMODE_INCREMENT);
	charlcd_4bit_command(lcd, HD_CLEAR);
	charlcd_4bit_command(lcd, HD_HOME);
	/* Put something useful in the display */
	charlcd_4bit_print(lcd, 0, "ARM Linux");
	charlcd_4bit_print(lcd, 1, UTS_RELEASE);
	}

	static void charlcd_init_work(struct work_struct *work)
	{
	struct charlcd *lcd =
	container_of(work, struct charlcd, init_work.work);

	charlcd_4bit_init(lcd);
	}

	static int __init charlcd_probe(struct platform_device *pdev)
	{
	int ret;
	struct charlcd *lcd;
	struct resource *res;

	lcd = kzalloc(sizeof(struct charlcd), GFP_KERNEL);
	if (!lcd)
	return -ENOMEM;

	lcd->dev = &pdev->dev;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	ret = -ENOENT;
	goto out_no_resource;
	}
	lcd->phybase = res->start;
	lcd->physize = resource_size(res);

	if (request_mem_region(lcd->phybase, lcd->physize,
	DRIVERNAME) == NULL) {
	ret = -EBUSY;
	goto out_no_memregion;
	}

	lcd->virtbase = ioremap(lcd->phybase, lcd->physize);
	if (!lcd->virtbase) {
	ret = -ENOMEM;
	goto out_no_remap;
	}

	lcd->irq = platform_get_irq(pdev, 0);
	/* If no IRQ is supplied, we'll survive without it */
	if (lcd->irq >= 0) {
	if (request_irq(lcd->irq, charlcd_interrupt, IRQF_DISABLED,
	DRIVERNAME, lcd)) {
	ret = -EIO;
	goto out_no_irq;
	}
	}

	platform_set_drvdata(pdev, lcd);

	/*
	* Initialize the display in a delayed work, because
	* it is VERY slow and would slow down the boot of the system.
	*/
	INIT_DELAYED_WORK(&lcd->init_work, charlcd_init_work);
	schedule_delayed_work(&lcd->init_work, 0);

	dev_info(&pdev->dev, "initalized ARM character LCD at %08x\n",
	lcd->phybase);

	return 0;

	out_no_irq:
	iounmap(lcd->virtbase);
	out_no_remap:
	platform_set_drvdata(pdev, NULL);
	out_no_memregion:
	release_mem_region(lcd->phybase, SZ_4K);
	out_no_resource:
	kfree(lcd);
	return ret;
	}

	static int __exit charlcd_remove(struct platform_device *pdev)
	{
	struct charlcd *lcd = platform_get_drvdata(pdev);

	if (lcd) {
	free_irq(lcd->irq, lcd);
	iounmap(lcd->virtbase);
	release_mem_region(lcd->phybase, lcd->physize);
	platform_set_drvdata(pdev, NULL);
	kfree(lcd);
	}

	return 0;
	}

	static int charlcd_suspend(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct charlcd *lcd = platform_get_drvdata(pdev);

	/* Power the display off */
	charlcd_4bit_command(lcd, HD_DISPCTRL);
	return 0;
	}

	static int charlcd_resume(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct charlcd *lcd = platform_get_drvdata(pdev);

	/* Turn the display back on */
	charlcd_4bit_command(lcd, HD_DISPCTRL \| HD_DISPCTRL_ON);
	return 0;
	}

	static const struct dev_pm_ops charlcd_pm_ops = {
	.suspend = charlcd_suspend,
	.resume = charlcd_resume,
	};

	static struct platform_driver charlcd_driver = {
	.driver = {
	.name = DRIVERNAME,
	.owner = THIS_MODULE,
	.pm = &charlcd_pm_ops,
	},
	.remove = __exit_p(charlcd_remove),
	};

	static int __init charlcd_init(void)
	{
	return platform_driver_probe(&charlcd_driver, charlcd_probe);
	}

	static void __exit charlcd_exit(void)
	{
	platform_driver_unregister(&charlcd_driver);
	}

	module_init(charlcd_init);
	module_exit(charlcd_exit);

	MODULE_AUTHOR("Linus Walleij <triad@df.lth.se>");
	MODULE_DESCRIPTION("ARM Character LCD Driver");
	MODULE_LICENSE("GPL v2");