1 files changed, 396 insertions, 0 deletions

diff --git a/drivers/misc/arm-charlcd.c b/drivers/misc/arm-charlcd.c
new file mode 100644
index 000000000000..9e3879ef58f2
--- /dev/null
+++ b/drivers/misc/arm-charlcd.c
@@ -0,0 +1,396 @@
+/*
+ * 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");