1 files changed, 368 insertions, 0 deletions
diff --git a/drivers/auxdisplay/arm-charlcd.c b/drivers/auxdisplay/arm-charlcd.c
new file mode 100644
index 000000000000..b3176ee92b90
--- /dev/null
+++ b/drivers/auxdisplay/arm-charlcd.c
@@ -0,0 +1,368 @@
+/*
+ * 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/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/of.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_memregion;
+	}
+
+	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, 0,
+				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, "initialized ARM character LCD at %08x\n",
+		lcd->phybase);
+
+	return 0;
+
+out_no_irq:
+	iounmap(lcd->virtbase);
+out_no_memregion:
+	release_mem_region(lcd->phybase, SZ_4K);
+out_no_resource:
+	kfree(lcd);
+	return ret;
+}
+
+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 const struct of_device_id charlcd_match[] = {
+	{ .compatible = "arm,versatile-lcd", },
+	{}
+};
+
+static struct platform_driver charlcd_driver = {
+	.driver = {
+		.name = DRIVERNAME,
+		.pm = &charlcd_pm_ops,
+		.suppress_bind_attrs = true,
+		.of_match_table = of_match_ptr(charlcd_match),
+	},
+};
+builtin_platform_driver_probe(charlcd_driver, charlcd_probe);