// SPDX-License-Identifier: GPL-2.0+
// Expose the Chromebook Pixel lightbar to userspace
//
// Copyright (C) 2014 Google, Inc.

#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/platform_data/cros_ec_commands.h>
#include <linux/platform_data/cros_ec_proto.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/slab.h>

#define DRV_NAME "cros-ec-lightbar"

/* Rate-limit the lightbar interface to prevent DoS. */
static unsigned long lb_interval_jiffies = 50 * HZ / 1000;

/*
 * Whether or not we have given userspace control of the lightbar.
 * If this is true, we won't do anything during suspend/resume.
 */
static bool userspace_control;

static ssize_t interval_msec_show(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        unsigned long msec = lb_interval_jiffies * 1000 / HZ;

        return scnprintf(buf, PAGE_SIZE, "%lu\n", msec);
}

static ssize_t interval_msec_store(struct device *dev,
                                   struct device_attribute *attr,
                                   const char *buf, size_t count)
{
        unsigned long msec;

        if (kstrtoul(buf, 0, &msec))
                return -EINVAL;

        lb_interval_jiffies = msec * HZ / 1000;

        return count;
}

static DEFINE_MUTEX(lb_mutex);
/* Return 0 if able to throttle correctly, error otherwise */
static int lb_throttle(void)
{
        static unsigned long last_access;
        unsigned long now, next_timeslot;
        long delay;
        int ret = 0;

        mutex_lock(&lb_mutex);

        now = jiffies;
        next_timeslot = last_access + lb_interval_jiffies;

        if (time_before(now, next_timeslot)) {
                delay = (long)(next_timeslot) - (long)now;
                set_current_state(TASK_INTERRUPTIBLE);
                if (schedule_timeout(delay) > 0) {
                        /* interrupted - just abort */
                        ret = -EINTR;
                        goto out;
                }
                now = jiffies;
        }

        last_access = now;
out:
        mutex_unlock(&lb_mutex);

        return ret;
}

static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
{
        struct cros_ec_command *msg;
        int len;

        len = max(sizeof(struct ec_params_lightbar),
                  sizeof(struct ec_response_lightbar));

        msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
        if (!msg)
                return NULL;

        msg->version = 0;
        msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
        msg->outsize = sizeof(struct ec_params_lightbar);
        msg->insize = sizeof(struct ec_response_lightbar);

        return msg;
}

static int get_lightbar_version(struct cros_ec_dev *ec,
                                uint32_t *ver_ptr, uint32_t *flg_ptr)
{
        struct ec_params_lightbar *param;
        struct ec_response_lightbar *resp;
        struct cros_ec_command *msg;
        int ret;

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return 0;

        param = (struct ec_params_lightbar *)msg->data;
        param->cmd = LIGHTBAR_CMD_VERSION;
        msg->outsize = sizeof(param->cmd);
        msg->result = sizeof(resp->version);
        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0 && ret != -EINVAL) {
                ret = 0;
                goto exit;
        }

        switch (msg->result) {
        case EC_RES_INVALID_PARAM:
                /* Pixel had no version command. */
                if (ver_ptr)
                        *ver_ptr = 0;
                if (flg_ptr)
                        *flg_ptr = 0;
                ret = 1;
                goto exit;

        case EC_RES_SUCCESS:
                resp = (struct ec_response_lightbar *)msg->data;

                /* Future devices w/lightbars should implement this command */
                if (ver_ptr)
                        *ver_ptr = resp->version.num;
                if (flg_ptr)
                        *flg_ptr = resp->version.flags;
                ret = 1;
                goto exit;
        }

        /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
        ret = 0;
exit:
        kfree(msg);
        return ret;
}

static ssize_t version_show(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        uint32_t version = 0, flags = 0;
        struct cros_ec_dev *ec = to_cros_ec_dev(dev);
        int ret;

        ret = lb_throttle();
        if (ret)
                return ret;

        /* This should always succeed, because we check during init. */
        if (!get_lightbar_version(ec, &version, &flags))
                return -EIO;

        return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
}

static ssize_t brightness_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct ec_params_lightbar *param;
        struct cros_ec_command *msg;
        int ret;
        unsigned int val;
        struct cros_ec_dev *ec = to_cros_ec_dev(dev);

        if (kstrtouint(buf, 0, &val))
                return -EINVAL;

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        param = (struct ec_params_lightbar *)msg->data;
        param->cmd = LIGHTBAR_CMD_SET_BRIGHTNESS;
        param->set_brightness.num = val;
        ret = lb_throttle();
        if (ret)
                goto exit;

        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0)
                goto exit;

        ret = count;
exit:
        kfree(msg);
        return ret;
}


/*
 * We expect numbers, and we'll keep reading until we find them, skipping over
 * any whitespace (sysfs guarantees that the input is null-terminated). Every
 * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
 * parsing error, if we don't parse any numbers, or if we have numbers left
 * over.
 */
static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        struct ec_params_lightbar *param;
        struct cros_ec_command *msg;
        struct cros_ec_dev *ec = to_cros_ec_dev(dev);
        unsigned int val[4];
        int ret, i = 0, j = 0, ok = 0;

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        do {
                /* Skip any whitespace */
                while (*buf && isspace(*buf))
                        buf++;

                if (!*buf)
                        break;

                ret = sscanf(buf, "%i", &val[i++]);
                if (ret == 0)
                        goto exit;

                if (i == 4) {
                        param = (struct ec_params_lightbar *)msg->data;
                        param->cmd = LIGHTBAR_CMD_SET_RGB;
                        param->set_rgb.led = val[0];
                        param->set_rgb.red = val[1];
                        param->set_rgb.green = val[2];
                        param->set_rgb.blue = val[3];
                        /*
                         * Throttle only the first of every four transactions,
                         * so that the user can update all four LEDs at once.
                         */
                        if ((j++ % 4) == 0) {
                                ret = lb_throttle();
                                if (ret)
                                        goto exit;
                        }

                        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
                        if (ret < 0)
                                goto exit;

                        i = 0;
                        ok = 1;
                }

                /* Skip over the number we just read */
                while (*buf && !isspace(*buf))
                        buf++;

        } while (*buf);

exit:
        kfree(msg);
        return (ok && i == 0) ? count : -EINVAL;
}

static char const *seqname[] = {
        "ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
        "S0S3", "S3S5", "STOP", "RUN", "KONAMI",
        "TAP", "PROGRAM",
};

static ssize_t sequence_show(struct device *dev,
                             struct device_attribute *attr, char *buf)
{
        struct ec_params_lightbar *param;
        struct ec_response_lightbar *resp;
        struct cros_ec_command *msg;
        int ret;
        struct cros_ec_dev *ec = to_cros_ec_dev(dev);

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        param = (struct ec_params_lightbar *)msg->data;
        param->cmd = LIGHTBAR_CMD_GET_SEQ;
        ret = lb_throttle();
        if (ret)
                goto exit;

        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0) {
                ret = scnprintf(buf, PAGE_SIZE, "XFER / EC ERROR %d / %d\n",
                                ret, msg->result);
                goto exit;
        }

        resp = (struct ec_response_lightbar *)msg->data;
        if (resp->get_seq.num >= ARRAY_SIZE(seqname))
                ret = scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
        else
                ret = scnprintf(buf, PAGE_SIZE, "%s\n",
                                seqname[resp->get_seq.num]);

exit:
        kfree(msg);
        return ret;
}

static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
{
        struct ec_params_lightbar *param;
        struct cros_ec_command *msg;
        int ret;

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        param = (struct ec_params_lightbar *)msg->data;
        param->cmd = cmd;

        ret = lb_throttle();
        if (ret)
                goto error;

        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0)
                goto error;

        ret = 0;
error:
        kfree(msg);

        return ret;
}

static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
{
        struct ec_params_lightbar *param;
        struct cros_ec_command *msg;
        int ret;

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        param = (struct ec_params_lightbar *)msg->data;

        param->cmd = LIGHTBAR_CMD_MANUAL_SUSPEND_CTRL;
        param->manual_suspend_ctrl.enable = enable;

        ret = lb_throttle();
        if (ret)
                goto error;

        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0)
                goto error;

        ret = 0;
error:
        kfree(msg);

        return ret;
}

static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
                              const char *buf, size_t count)
{
        struct ec_params_lightbar *param;
        struct cros_ec_command *msg;
        unsigned int num;
        int ret, len;
        struct cros_ec_dev *ec = to_cros_ec_dev(dev);

        for (len = 0; len < count; len++)
                if (!isalnum(buf[len]))
                        break;

        for (num = 0; num < ARRAY_SIZE(seqname); num++)
                if (!strncasecmp(seqname[num], buf, len))
                        break;

        if (num >= ARRAY_SIZE(seqname)) {
                ret = kstrtouint(buf, 0, &num);
                if (ret)
                        return ret;
        }

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        param = (struct ec_params_lightbar *)msg->data;
        param->cmd = LIGHTBAR_CMD_SEQ;
        param->seq.num = num;
        ret = lb_throttle();
        if (ret)
                goto exit;

        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0)
                goto exit;

        ret = count;
exit:
        kfree(msg);
        return ret;
}

static ssize_t program_store(struct device *dev, struct device_attribute *attr,
                             const char *buf, size_t count)
{
        int extra_bytes, max_size, ret;
        struct ec_params_lightbar *param;
        struct cros_ec_command *msg;
        struct cros_ec_dev *ec = to_cros_ec_dev(dev);

        /*
         * We might need to reject the program for size reasons. The EC
         * enforces a maximum program size, but we also don't want to try
         * and send a program that is too big for the protocol. In order
         * to ensure the latter, we also need to ensure we have extra bytes
         * to represent the rest of the packet.
         */
        extra_bytes = sizeof(*param) - sizeof(param->set_program.data);
        max_size = min(EC_LB_PROG_LEN, ec->ec_dev->max_request - extra_bytes);
        if (count > max_size) {
                dev_err(dev, "Program is %u bytes, too long to send (max: %u)",
                        (unsigned int)count, max_size);

                return -EINVAL;
        }

        msg = alloc_lightbar_cmd_msg(ec);
        if (!msg)
                return -ENOMEM;

        ret = lb_throttle();
        if (ret)
                goto exit;

        dev_info(dev, "Copying %zu byte program to EC", count);

        param = (struct ec_params_lightbar *)msg->data;
        param->cmd = LIGHTBAR_CMD_SET_PROGRAM;

        param->set_program.size = count;
        memcpy(param->set_program.data, buf, count);

        /*
         * We need to set the message size manually or else it will use
         * EC_LB_PROG_LEN. This might be too long, and the program
         * is unlikely to use all of the space.
         */
        msg->outsize = count + extra_bytes;

        ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
        if (ret < 0)
                goto exit;

        ret = count;
exit:
        kfree(msg);

        return ret;
}

static ssize_t userspace_control_show(struct device *dev,
                                      struct device_attribute *attr,
                                      char *buf)
{
        return scnprintf(buf, PAGE_SIZE, "%d\n", userspace_control);
}

static ssize_t userspace_control_store(struct device *dev,
                                       struct device_attribute *attr,
                                       const char *buf,
                                       size_t count)
{
        bool enable;
        int ret;

        ret = strtobool(buf, &enable);
        if (ret < 0)
                return ret;

        userspace_control = enable;

        return count;
}

/* Module initialization */

static DEVICE_ATTR_RW(interval_msec);
static DEVICE_ATTR_RO(version);
static DEVICE_ATTR_WO(brightness);
static DEVICE_ATTR_WO(led_rgb);
static DEVICE_ATTR_RW(sequence);
static DEVICE_ATTR_WO(program);
static DEVICE_ATTR_RW(userspace_control);

static struct attribute *__lb_cmds_attrs[] = {
        &dev_attr_interval_msec.attr,
        &dev_attr_version.attr,
        &dev_attr_brightness.attr,
        &dev_attr_led_rgb.attr,
        &dev_attr_sequence.attr,
        &dev_attr_program.attr,
        &dev_attr_userspace_control.attr,
        NULL,
};

static const struct attribute_group cros_ec_lightbar_attr_group = {
        .name = "lightbar",
        .attrs = __lb_cmds_attrs,
};

static int cros_ec_lightbar_probe(struct platform_device *pd)
{
        struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
        struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
        struct device *dev = &pd->dev;
        int ret;

        /*
         * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
         * devices like 'cros_pd' doesn't have a lightbar.
         */
        if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
                return -ENODEV;

        /*
         * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
         * doesn't have a lightbar.
         */
        if (!get_lightbar_version(ec_dev, NULL, NULL))
                return -ENODEV;

        /* Take control of the lightbar from the EC. */
        lb_manual_suspend_ctrl(ec_dev, 1);

        ret = sysfs_create_group(&ec_dev->class_dev.kobj,
                                 &cros_ec_lightbar_attr_group);
        if (ret < 0)
                dev_err(dev, "failed to create %s attributes. err=%d\n",
                        cros_ec_lightbar_attr_group.name, ret);

        return ret;
}

static int cros_ec_lightbar_remove(struct platform_device *pd)
{
        struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);

        sysfs_remove_group(&ec_dev->class_dev.kobj,
                           &cros_ec_lightbar_attr_group);

        /* Let the EC take over the lightbar again. */
        lb_manual_suspend_ctrl(ec_dev, 0);

        return 0;
}

static int __maybe_unused cros_ec_lightbar_resume(struct device *dev)
{
        struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);

        if (userspace_control)
                return 0;

        return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_RESUME);
}

static int __maybe_unused cros_ec_lightbar_suspend(struct device *dev)
{
        struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);

        if (userspace_control)
                return 0;

        return lb_send_empty_cmd(ec_dev, LIGHTBAR_CMD_SUSPEND);
}

static SIMPLE_DEV_PM_OPS(cros_ec_lightbar_pm_ops,
                         cros_ec_lightbar_suspend, cros_ec_lightbar_resume);

static struct platform_driver cros_ec_lightbar_driver = {
        .driver = {
                .name = DRV_NAME,
                .pm = &cros_ec_lightbar_pm_ops,
        },
        .probe = cros_ec_lightbar_probe,
        .remove = cros_ec_lightbar_remove,
};

module_platform_driver(cros_ec_lightbar_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Expose the Chromebook Pixel's lightbar to userspace");
MODULE_ALIAS("platform:" DRV_NAME);