Revert "Staging: olpc_dcon: Remove obsolete driver"

This reverts commit 82ef33af9dd30075adbd9f3dd161b606b8ba88ac.  It turns
out these machines are still out there, and the original patch broke
them.  So revert it, adding back the driver, so people's machines still
work properly.

Reported-by: James Cameron <quozl@laptop.org>
Cc: Shraddha Barke <shraddha.6596@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 813 insertions, 0 deletions

diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
new file mode 100644
index 000000000000..f45b2ef05f48
--- /dev/null
+++ b/drivers/staging/olpc_dcon/olpc_dcon.c
@@ -0,0 +1,813 @@
+/*
+ * Mainly by David Woodhouse, somewhat modified by Jordan Crouse
+ *
+ * Copyright © 2006-2007  Red Hat, Inc.
+ * Copyright © 2006-2007  Advanced Micro Devices, Inc.
+ * Copyright © 2009       VIA Technology, Inc.
+ * Copyright (c) 2010-2011  Andres Salomon <dilinger@queued.net>
+ *
+ * This program is free software.  You can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/fb.h>
+#include <linux/console.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/backlight.h>
+#include <linux/device.h>
+#include <linux/uaccess.h>
+#include <linux/ctype.h>
+#include <linux/reboot.h>
+#include <linux/olpc-ec.h>
+#include <asm/tsc.h>
+#include <asm/olpc.h>
+
+#include "olpc_dcon.h"
+
+/* Module definitions */
+
+static ushort resumeline = 898;
+module_param(resumeline, ushort, 0444);
+
+static struct dcon_platform_data *pdata;
+
+/* I2C structures */
+
+/* Platform devices */
+static struct platform_device *dcon_device;
+
+static unsigned short normal_i2c[] = { 0x0d, I2C_CLIENT_END };
+
+static s32 dcon_write(struct dcon_priv *dcon, u8 reg, u16 val)
+{
+	return i2c_smbus_write_word_data(dcon->client, reg, val);
+}
+
+static s32 dcon_read(struct dcon_priv *dcon, u8 reg)
+{
+	return i2c_smbus_read_word_data(dcon->client, reg);
+}
+
+/* ===== API functions - these are called by a variety of users ==== */
+
+static int dcon_hw_init(struct dcon_priv *dcon, int is_init)
+{
+	u16 ver;
+	int rc = 0;
+
+	ver = dcon_read(dcon, DCON_REG_ID);
+	if ((ver >> 8) != 0xDC) {
+		pr_err("DCON ID not 0xDCxx: 0x%04x instead.\n", ver);
+		rc = -ENXIO;
+		goto err;
+	}
+
+	if (is_init) {
+		pr_info("Discovered DCON version %x\n", ver & 0xFF);
+		rc = pdata->init(dcon);
+		if (rc != 0) {
+			pr_err("Unable to init.\n");
+			goto err;
+		}
+	}
+
+	if (ver < 0xdc02) {
+		dev_err(&dcon->client->dev,
+				"DCON v1 is unsupported, giving up..\n");
+		rc = -ENODEV;
+		goto err;
+	}
+
+	/* SDRAM setup/hold time */
+	dcon_write(dcon, 0x3a, 0xc040);
+	dcon_write(dcon, DCON_REG_MEM_OPT_A, 0x0000);  /* clear option bits */
+	dcon_write(dcon, DCON_REG_MEM_OPT_A,
+				MEM_DLL_CLOCK_DELAY | MEM_POWER_DOWN);
+	dcon_write(dcon, DCON_REG_MEM_OPT_B, MEM_SOFT_RESET);
+
+	/* Colour swizzle, AA, no passthrough, backlight */
+	if (is_init) {
+		dcon->disp_mode = MODE_PASSTHRU | MODE_BL_ENABLE |
+				MODE_CSWIZZLE | MODE_COL_AA;
+	}
+	dcon_write(dcon, DCON_REG_MODE, dcon->disp_mode);
+
+	/* Set the scanline to interrupt on during resume */
+	dcon_write(dcon, DCON_REG_SCAN_INT, resumeline);
+
+err:
+	return rc;
+}
+
+/*
+ * The smbus doesn't always come back due to what is believed to be
+ * hardware (power rail) bugs.  For older models where this is known to
+ * occur, our solution is to attempt to wait for the bus to stabilize;
+ * if it doesn't happen, cut power to the dcon, repower it, and wait
+ * for the bus to stabilize.  Rinse, repeat until we have a working
+ * smbus.  For newer models, we simply BUG(); we want to know if this
+ * still happens despite the power fixes that have been made!
+ */
+static int dcon_bus_stabilize(struct dcon_priv *dcon, int is_powered_down)
+{
+	unsigned long timeout;
+	u8 pm;
+	int x;
+
+power_up:
+	if (is_powered_down) {
+		pm = 1;
+		x = olpc_ec_cmd(EC_DCON_POWER_MODE, &pm, 1, NULL, 0);
+		if (x) {
+			pr_warn("unable to force dcon to power up: %d!\n", x);
+			return x;
+		}
+		usleep_range(10000, 11000);  /* we'll be conservative */
+	}
+
+	pdata->bus_stabilize_wiggle();
+
+	for (x = -1, timeout = 50; timeout && x < 0; timeout--) {
+		usleep_range(1000, 1100);
+		x = dcon_read(dcon, DCON_REG_ID);
+	}
+	if (x < 0) {
+		pr_err("unable to stabilize dcon's smbus, reasserting power and praying.\n");
+		BUG_ON(olpc_board_at_least(olpc_board(0xc2)));
+		pm = 0;
+		olpc_ec_cmd(EC_DCON_POWER_MODE, &pm, 1, NULL, 0);
+		msleep(100);
+		is_powered_down = 1;
+		goto power_up;	/* argh, stupid hardware.. */
+	}
+
+	if (is_powered_down)
+		return dcon_hw_init(dcon, 0);
+	return 0;
+}
+
+static void dcon_set_backlight(struct dcon_priv *dcon, u8 level)
+{
+	dcon->bl_val = level;
+	dcon_write(dcon, DCON_REG_BRIGHT, dcon->bl_val);
+
+	/* Purposely turn off the backlight when we go to level 0 */
+	if (dcon->bl_val == 0) {
+		dcon->disp_mode &= ~MODE_BL_ENABLE;
+		dcon_write(dcon, DCON_REG_MODE, dcon->disp_mode);
+	} else if (!(dcon->disp_mode & MODE_BL_ENABLE)) {
+		dcon->disp_mode |= MODE_BL_ENABLE;
+		dcon_write(dcon, DCON_REG_MODE, dcon->disp_mode);
+	}
+}
+
+/* Set the output type to either color or mono */
+static int dcon_set_mono_mode(struct dcon_priv *dcon, bool enable_mono)
+{
+	if (dcon->mono == enable_mono)
+		return 0;
+
+	dcon->mono = enable_mono;
+
+	if (enable_mono) {
+		dcon->disp_mode &= ~(MODE_CSWIZZLE | MODE_COL_AA);
+		dcon->disp_mode |= MODE_MONO_LUMA;
+	} else {
+		dcon->disp_mode &= ~(MODE_MONO_LUMA);
+		dcon->disp_mode |= MODE_CSWIZZLE | MODE_COL_AA;
+	}
+
+	dcon_write(dcon, DCON_REG_MODE, dcon->disp_mode);
+	return 0;
+}
+
+/* For now, this will be really stupid - we need to address how
+ * DCONLOAD works in a sleep and account for it accordingly
+ */
+
+static void dcon_sleep(struct dcon_priv *dcon, bool sleep)
+{
+	int x;
+
+	/* Turn off the backlight and put the DCON to sleep */
+
+	if (dcon->asleep == sleep)
+		return;
+
+	if (!olpc_board_at_least(olpc_board(0xc2)))
+		return;
+
+	if (sleep) {
+		u8 pm = 0;
+
+		x = olpc_ec_cmd(EC_DCON_POWER_MODE, &pm, 1, NULL, 0);
+		if (x)
+			pr_warn("unable to force dcon to power down: %d!\n", x);
+		else
+			dcon->asleep = sleep;
+	} else {
+		/* Only re-enable the backlight if the backlight value is set */
+		if (dcon->bl_val != 0)
+			dcon->disp_mode |= MODE_BL_ENABLE;
+		x = dcon_bus_stabilize(dcon, 1);
+		if (x)
+			pr_warn("unable to reinit dcon hardware: %d!\n", x);
+		else
+			dcon->asleep = sleep;
+
+		/* Restore backlight */
+		dcon_set_backlight(dcon, dcon->bl_val);
+	}
+
+	/* We should turn off some stuff in the framebuffer - but what? */
+}
+
+/* the DCON seems to get confused if we change DCONLOAD too
+ * frequently -- i.e., approximately faster than frame time.
+ * normally we don't change it this fast, so in general we won't
+ * delay here.
+ */
+static void dcon_load_holdoff(struct dcon_priv *dcon)
+{
+	ktime_t delta_t, now;
+
+	while (1) {
+		now = ktime_get();
+		delta_t = ktime_sub(now, dcon->load_time);
+		if (ktime_to_ns(delta_t) > NSEC_PER_MSEC * 20)
+			break;
+		mdelay(4);
+	}
+}
+
+static bool dcon_blank_fb(struct dcon_priv *dcon, bool blank)
+{
+	int err;
+
+	console_lock();
+	if (!lock_fb_info(dcon->fbinfo)) {
+		console_unlock();
+		dev_err(&dcon->client->dev, "unable to lock framebuffer\n");
+		return false;
+	}
+
+	dcon->ignore_fb_events = true;
+	err = fb_blank(dcon->fbinfo,
+			blank ? FB_BLANK_POWERDOWN : FB_BLANK_UNBLANK);
+	dcon->ignore_fb_events = false;
+	unlock_fb_info(dcon->fbinfo);
+	console_unlock();
+
+	if (err) {
+		dev_err(&dcon->client->dev, "couldn't %sblank framebuffer\n",
+				blank ? "" : "un");
+		return false;
+	}
+	return true;
+}
+
+/* Set the source of the display (CPU or DCON) */
+static void dcon_source_switch(struct work_struct *work)
+{
+	struct dcon_priv *dcon = container_of(work, struct dcon_priv,
+			switch_source);
+	int source = dcon->pending_src;
+
+	if (dcon->curr_src == source)
+		return;
+
+	dcon_load_holdoff(dcon);
+
+	dcon->switched = false;
+
+	switch (source) {
+	case DCON_SOURCE_CPU:
+		pr_info("dcon_source_switch to CPU\n");
+		/* Enable the scanline interrupt bit */
+		if (dcon_write(dcon, DCON_REG_MODE,
+				dcon->disp_mode | MODE_SCAN_INT))
+			pr_err("couldn't enable scanline interrupt!\n");
+		else
+			/* Wait up to one second for the scanline interrupt */
+			wait_event_timeout(dcon->waitq, dcon->switched, HZ);
+
+		if (!dcon->switched)
+			pr_err("Timeout entering CPU mode; expect a screen glitch.\n");
+
+		/* Turn off the scanline interrupt */
+		if (dcon_write(dcon, DCON_REG_MODE, dcon->disp_mode))
+			pr_err("couldn't disable scanline interrupt!\n");
+
+		/*
+		 * Ideally we'd like to disable interrupts here so that the
+		 * fb unblanking and DCON turn on happen at a known time value;
+		 * however, we can't do that right now with fb_blank
+		 * messing with semaphores.
+		 *
+		 * For now, we just hope..
+		 */
+		if (!dcon_blank_fb(dcon, false)) {
+			pr_err("Failed to enter CPU mode\n");
+			dcon->pending_src = DCON_SOURCE_DCON;
+			return;
+		}
+
+		/* And turn off the DCON */
+		pdata->set_dconload(1);
+		dcon->load_time = ktime_get();
+
+		pr_info("The CPU has control\n");
+		break;
+	case DCON_SOURCE_DCON:
+	{
+		ktime_t delta_t;
+
+		pr_info("dcon_source_switch to DCON\n");
+
+		/* Clear DCONLOAD - this implies that the DCON is in control */
+		pdata->set_dconload(0);
+		dcon->load_time = ktime_get();
+
+		wait_event_timeout(dcon->waitq, dcon->switched, HZ/2);
+
+		if (!dcon->switched) {
+			pr_err("Timeout entering DCON mode; expect a screen glitch.\n");
+		} else {
+			/* sometimes the DCON doesn't follow its own rules,
+			 * and doesn't wait for two vsync pulses before
+			 * ack'ing the frame load with an IRQ.  the result
+			 * is that the display shows the *previously*
+			 * loaded frame.  we can detect this by looking at
+			 * the time between asserting DCONLOAD and the IRQ --
+			 * if it's less than 20msec, then the DCON couldn't
+			 * have seen two VSYNC pulses.  in that case we
+			 * deassert and reassert, and hope for the best.
+			 * see http://dev.laptop.org/ticket/9664
+			 */
+			delta_t = ktime_sub(dcon->irq_time, dcon->load_time);
+			if (dcon->switched && ktime_to_ns(delta_t)
+			    < NSEC_PER_MSEC * 20) {
+				pr_err("missed loading, retrying\n");
+				pdata->set_dconload(1);
+				mdelay(41);
+				pdata->set_dconload(0);
+				dcon->load_time = ktime_get();
+				mdelay(41);
+			}
+		}
+
+		dcon_blank_fb(dcon, true);
+		pr_info("The DCON has control\n");
+		break;
+	}
+	default:
+		BUG();
+	}
+
+	dcon->curr_src = source;
+}
+
+static void dcon_set_source(struct dcon_priv *dcon, int arg)
+{
+	if (dcon->pending_src == arg)
+		return;
+
+	dcon->pending_src = arg;
+
+	if (dcon->curr_src != arg)
+		schedule_work(&dcon->switch_source);
+}
+
+static void dcon_set_source_sync(struct dcon_priv *dcon, int arg)
+{
+	dcon_set_source(dcon, arg);
+	flush_scheduled_work();
+}
+
+static ssize_t dcon_mode_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct dcon_priv *dcon = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%4.4X\n", dcon->disp_mode);
+}
+
+static ssize_t dcon_sleep_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct dcon_priv *dcon = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", dcon->asleep);
+}
+
+static ssize_t dcon_freeze_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct dcon_priv *dcon = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", dcon->curr_src == DCON_SOURCE_DCON ? 1 : 0);
+}
+
+static ssize_t dcon_mono_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct dcon_priv *dcon = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", dcon->mono);
+}
+
+static ssize_t dcon_resumeline_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", resumeline);
+}
+
+static ssize_t dcon_mono_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	unsigned long enable_mono;
+	int rc;
+
+	rc = kstrtoul(buf, 10, &enable_mono);
+	if (rc)
+		return rc;
+
+	dcon_set_mono_mode(dev_get_drvdata(dev), enable_mono ? true : false);
+
+	return count;
+}
+
+static ssize_t dcon_freeze_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct dcon_priv *dcon = dev_get_drvdata(dev);
+	unsigned long output;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &output);
+	if (ret)
+		return ret;
+
+	pr_info("dcon_freeze_store: %lu\n", output);
+
+	switch (output) {
+	case 0:
+		dcon_set_source(dcon, DCON_SOURCE_CPU);
+		break;
+	case 1:
+		dcon_set_source_sync(dcon, DCON_SOURCE_DCON);
+		break;
+	case 2:  /* normally unused */
+		dcon_set_source(dcon, DCON_SOURCE_DCON);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+static ssize_t dcon_resumeline_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	unsigned short rl;
+	int rc;
+
+	rc = kstrtou16(buf, 10, &rl);
+	if (rc)
+		return rc;
+
+	resumeline = rl;
+	dcon_write(dev_get_drvdata(dev), DCON_REG_SCAN_INT, resumeline);
+
+	return count;
+}
+
+static ssize_t dcon_sleep_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	unsigned long output;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &output);
+	if (ret)
+		return ret;
+
+	dcon_sleep(dev_get_drvdata(dev), output ? true : false);
+	return count;
+}
+
+static struct device_attribute dcon_device_files[] = {
+	__ATTR(mode, 0444, dcon_mode_show, NULL),
+	__ATTR(sleep, 0644, dcon_sleep_show, dcon_sleep_store),
+	__ATTR(freeze, 0644, dcon_freeze_show, dcon_freeze_store),
+	__ATTR(monochrome, 0644, dcon_mono_show, dcon_mono_store),
+	__ATTR(resumeline, 0644, dcon_resumeline_show, dcon_resumeline_store),
+};
+
+static int dcon_bl_update(struct backlight_device *dev)
+{
+	struct dcon_priv *dcon = bl_get_data(dev);
+	u8 level = dev->props.brightness & 0x0F;
+
+	if (dev->props.power != FB_BLANK_UNBLANK)
+		level = 0;
+
+	if (level != dcon->bl_val)
+		dcon_set_backlight(dcon, level);
+
+	/* power down the DCON when the screen is blanked */
+	if (!dcon->ignore_fb_events)
+		dcon_sleep(dcon, !!(dev->props.state & BL_CORE_FBBLANK));
+
+	return 0;
+}
+
+static int dcon_bl_get(struct backlight_device *dev)
+{
+	struct dcon_priv *dcon = bl_get_data(dev);
+
+	return dcon->bl_val;
+}
+
+static const struct backlight_ops dcon_bl_ops = {
+	.update_status = dcon_bl_update,
+	.get_brightness = dcon_bl_get,
+};
+
+static struct backlight_properties dcon_bl_props = {
+	.max_brightness = 15,
+	.type = BACKLIGHT_RAW,
+	.power = FB_BLANK_UNBLANK,
+};
+
+static int dcon_reboot_notify(struct notifier_block *nb,
+			      unsigned long foo, void *bar)
+{
+	struct dcon_priv *dcon = container_of(nb, struct dcon_priv, reboot_nb);
+
+	if (!dcon || !dcon->client)
+		return NOTIFY_DONE;
+
+	/* Turn off the DCON. Entirely. */
+	dcon_write(dcon, DCON_REG_MODE, 0x39);
+	dcon_write(dcon, DCON_REG_MODE, 0x32);
+	return NOTIFY_DONE;
+}
+
+static int unfreeze_on_panic(struct notifier_block *nb,
+			     unsigned long e, void *p)
+{
+	pdata->set_dconload(1);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block dcon_panic_nb = {
+	.notifier_call = unfreeze_on_panic,
+};
+
+static int dcon_detect(struct i2c_client *client, struct i2c_board_info *info)
+{
+	strlcpy(info->type, "olpc_dcon", I2C_NAME_SIZE);
+
+	return 0;
+}
+
+static int dcon_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+	struct dcon_priv *dcon;
+	int rc, i, j;
+
+	if (!pdata)
+		return -ENXIO;
+
+	dcon = kzalloc(sizeof(*dcon), GFP_KERNEL);
+	if (!dcon)
+		return -ENOMEM;
+
+	dcon->client = client;
+	init_waitqueue_head(&dcon->waitq);
+	INIT_WORK(&dcon->switch_source, dcon_source_switch);
+	dcon->reboot_nb.notifier_call = dcon_reboot_notify;
+	dcon->reboot_nb.priority = -1;
+
+	i2c_set_clientdata(client, dcon);
+
+	if (num_registered_fb < 1) {
+		dev_err(&client->dev, "DCON driver requires a registered fb\n");
+		rc = -EIO;
+		goto einit;
+	}
+	dcon->fbinfo = registered_fb[0];
+
+	rc = dcon_hw_init(dcon, 1);
+	if (rc)
+		goto einit;
+
+	/* Add the DCON device */
+
+	dcon_device = platform_device_alloc("dcon", -1);
+
+	if (!dcon_device) {
+		pr_err("Unable to create the DCON device\n");
+		rc = -ENOMEM;
+		goto eirq;
+	}
+	rc = platform_device_add(dcon_device);
+	platform_set_drvdata(dcon_device, dcon);
+
+	if (rc) {
+		pr_err("Unable to add the DCON device\n");
+		goto edev;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(dcon_device_files); i++) {
+		rc = device_create_file(&dcon_device->dev,
+					&dcon_device_files[i]);
+		if (rc) {
+			dev_err(&dcon_device->dev, "Cannot create sysfs file\n");
+			goto ecreate;
+		}
+	}
+
+	dcon->bl_val = dcon_read(dcon, DCON_REG_BRIGHT) & 0x0F;
+
+	/* Add the backlight device for the DCON */
+	dcon_bl_props.brightness = dcon->bl_val;
+	dcon->bl_dev = backlight_device_register("dcon-bl", &dcon_device->dev,
+		dcon, &dcon_bl_ops, &dcon_bl_props);
+	if (IS_ERR(dcon->bl_dev)) {
+		dev_err(&client->dev, "cannot register backlight dev (%ld)\n",
+				PTR_ERR(dcon->bl_dev));
+		dcon->bl_dev = NULL;
+	}
+
+	register_reboot_notifier(&dcon->reboot_nb);
+	atomic_notifier_chain_register(&panic_notifier_list, &dcon_panic_nb);
+
+	return 0;
+
+ ecreate:
+	for (j = 0; j < i; j++)
+		device_remove_file(&dcon_device->dev, &dcon_device_files[j]);
+ edev:
+	platform_device_unregister(dcon_device);
+	dcon_device = NULL;
+ eirq:
+	free_irq(DCON_IRQ, dcon);
+ einit:
+	kfree(dcon);
+	return rc;
+}
+
+static int dcon_remove(struct i2c_client *client)
+{
+	struct dcon_priv *dcon = i2c_get_clientdata(client);
+
+	unregister_reboot_notifier(&dcon->reboot_nb);
+	atomic_notifier_chain_unregister(&panic_notifier_list, &dcon_panic_nb);
+
+	free_irq(DCON_IRQ, dcon);
+
+	backlight_device_unregister(dcon->bl_dev);
+
+	if (dcon_device)
+		platform_device_unregister(dcon_device);
+	cancel_work_sync(&dcon->switch_source);
+
+	kfree(dcon);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int dcon_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct dcon_priv *dcon = i2c_get_clientdata(client);
+
+	if (!dcon->asleep) {
+		/* Set up the DCON to have the source */
+		dcon_set_source_sync(dcon, DCON_SOURCE_DCON);
+	}
+
+	return 0;
+}
+
+static int dcon_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct dcon_priv *dcon = i2c_get_clientdata(client);
+
+	if (!dcon->asleep) {
+		dcon_bus_stabilize(dcon, 0);
+		dcon_set_source(dcon, DCON_SOURCE_CPU);
+	}
+
+	return 0;
+}
+
+#else
+
+#define dcon_suspend NULL
+#define dcon_resume NULL
+
+#endif /* CONFIG_PM */
+
+irqreturn_t dcon_interrupt(int irq, void *id)
+{
+	struct dcon_priv *dcon = id;
+	u8 status;
+
+	if (pdata->read_status(&status))
+		return IRQ_NONE;
+
+	switch (status & 3) {
+	case 3:
+		pr_debug("DCONLOAD_MISSED interrupt\n");
+		break;
+
+	case 2:	/* switch to DCON mode */
+	case 1: /* switch to CPU mode */
+		dcon->switched = true;
+		dcon->irq_time = ktime_get();
+		wake_up(&dcon->waitq);
+		break;
+
+	case 0:
+		/* workaround resume case:  the DCON (on 1.5) doesn't
+		 * ever assert status 0x01 when switching to CPU mode
+		 * during resume.  this is because DCONLOAD is de-asserted
+		 * _immediately_ upon exiting S3, so the actual release
+		 * of the DCON happened long before this point.
+		 * see http://dev.laptop.org/ticket/9869
+		 */
+		if (dcon->curr_src != dcon->pending_src && !dcon->switched) {
+			dcon->switched = true;
+			dcon->irq_time = ktime_get();
+			wake_up(&dcon->waitq);
+			pr_debug("switching w/ status 0/0\n");
+		} else {
+			pr_debug("scanline interrupt w/CPU\n");
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static const struct dev_pm_ops dcon_pm_ops = {
+	.suspend = dcon_suspend,
+	.resume = dcon_resume,
+};
+
+static const struct i2c_device_id dcon_idtable[] = {
+	{ "olpc_dcon",  0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, dcon_idtable);
+
+static struct i2c_driver dcon_driver = {
+	.driver = {
+		.name	= "olpc_dcon",
+		.pm = &dcon_pm_ops,
+	},
+	.class = I2C_CLASS_DDC | I2C_CLASS_HWMON,
+	.id_table = dcon_idtable,
+	.probe = dcon_probe,
+	.remove = dcon_remove,
+	.detect = dcon_detect,
+	.address_list = normal_i2c,
+};
+
+static int __init olpc_dcon_init(void)
+{
+#ifdef CONFIG_FB_OLPC_DCON_1_5
+	/* XO-1.5 */
+	if (olpc_board_at_least(olpc_board(0xd0)))
+		pdata = &dcon_pdata_xo_1_5;
+#endif
+#ifdef CONFIG_FB_OLPC_DCON_1
+	if (!pdata)
+		pdata = &dcon_pdata_xo_1;
+#endif
+
+	return i2c_add_driver(&dcon_driver);
+}
+
+static void __exit olpc_dcon_exit(void)
+{
+	i2c_del_driver(&dcon_driver);
+}
+
+module_init(olpc_dcon_init);
+module_exit(olpc_dcon_exit);
+
+MODULE_LICENSE("GPL");