// SPDX-License-Identifier: GPL-2.0
/*
 * 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>
 */

#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();
        lock_fb_info(dcon->fbinfo);

        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("%s to CPU\n", __func__);
                /* 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("%s to DCON\n", __func__);

                /* 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;

        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)
{
        /* XO-1.5 */
        if (olpc_board_at_least(olpc_board(0xd0)))
                pdata = &dcon_pdata_xo_1_5;
        else
                pdata = &dcon_pdata_xo_1;

        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");