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/*
* Generic driver for the OLPC Embedded Controller.
*
* Copyright (C) 2011-2012 One Laptop per Child Foundation.
*
* Licensed under the GPL v2 or later.
*/
#include <linux/completion.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/olpc-ec.h>
#include <asm/olpc.h>
struct ec_cmd_desc {
u8 cmd;
u8 *inbuf, *outbuf;
size_t inlen, outlen;
int err;
struct completion finished;
struct list_head node;
void *priv;
};
struct olpc_ec_priv {
struct olpc_ec_driver *drv;
/*
* Running an EC command while suspending means we don't always finish
* the command before the machine suspends. This means that the EC
* is expecting the command protocol to finish, but we after a period
* of time (while the OS is asleep) the EC times out and restarts its
* idle loop. Meanwhile, the OS wakes up, thinks it's still in the
* middle of the command protocol, starts throwing random things at
* the EC... and everyone's uphappy.
*/
bool suspended;
};
static void olpc_ec_worker(struct work_struct *w);
static DECLARE_WORK(ec_worker, olpc_ec_worker);
static LIST_HEAD(ec_cmd_q);
static DEFINE_SPINLOCK(ec_cmd_q_lock);
static struct olpc_ec_driver *ec_driver;
static struct olpc_ec_priv *ec_priv;
static void *ec_cb_arg;
static DEFINE_MUTEX(ec_cb_lock);
void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
{
ec_driver = drv;
ec_cb_arg = arg;
}
EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
static void olpc_ec_worker(struct work_struct *w)
{
struct ec_cmd_desc *desc = NULL;
unsigned long flags;
/* Grab the first pending command from the queue */
spin_lock_irqsave(&ec_cmd_q_lock, flags);
if (!list_empty(&ec_cmd_q)) {
desc = list_first_entry(&ec_cmd_q, struct ec_cmd_desc, node);
list_del(&desc->node);
}
spin_unlock_irqrestore(&ec_cmd_q_lock, flags);
/* Do we actually have anything to do? */
if (!desc)
return;
/* Protect the EC hw with a mutex; only run one cmd at a time */
mutex_lock(&ec_cb_lock);
desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
desc->outbuf, desc->outlen, ec_cb_arg);
mutex_unlock(&ec_cb_lock);
/* Finished, wake up olpc_ec_cmd() */
complete(&desc->finished);
/* Run the worker thread again in case there are more cmds pending */
schedule_work(&ec_worker);
}
/*
* Throw a cmd descripter onto the list. We now have SMP OLPC machines, so
* locking is pretty critical.
*/
static void queue_ec_descriptor(struct ec_cmd_desc *desc)
{
unsigned long flags;
INIT_LIST_HEAD(&desc->node);
spin_lock_irqsave(&ec_cmd_q_lock, flags);
list_add_tail(&desc->node, &ec_cmd_q);
spin_unlock_irqrestore(&ec_cmd_q_lock, flags);
schedule_work(&ec_worker);
}
int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
{
struct olpc_ec_priv *ec = ec_priv;
struct ec_cmd_desc desc;
/* Ensure a driver and ec hook have been registered */
if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
return -ENODEV;
if (!ec)
return -ENOMEM;
/* Suspending in the middle of a command hoses things really badly */
if (WARN_ON(ec->suspended))
return -EBUSY;
might_sleep();
desc.cmd = cmd;
desc.inbuf = inbuf;
desc.outbuf = outbuf;
desc.inlen = inlen;
desc.outlen = outlen;
desc.err = 0;
init_completion(&desc.finished);
queue_ec_descriptor(&desc);
/* Timeouts must be handled in the platform-specific EC hook */
wait_for_completion(&desc.finished);
/* The worker thread dequeues the cmd; no need to do anything here */
return desc.err;
}
EXPORT_SYMBOL_GPL(olpc_ec_cmd);
static int olpc_ec_probe(struct platform_device *pdev)
{
struct olpc_ec_priv *ec;
int err;
if (!ec_driver)
return -ENODEV;
ec = kzalloc(sizeof(*ec), GFP_KERNEL);
if (!ec)
return -ENOMEM;
ec->drv = ec_driver;
ec_priv = ec;
platform_set_drvdata(pdev, ec);
err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
return err;
}
static int olpc_ec_suspend(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
int err = 0;
if (ec_driver->suspend)
err = ec_driver->suspend(pdev);
if (!err)
ec->suspended = true;
return err;
}
static int olpc_ec_resume(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
ec->suspended = false;
return ec_driver->resume ? ec_driver->resume(pdev) : 0;
}
static const struct dev_pm_ops olpc_ec_pm_ops = {
.suspend_late = olpc_ec_suspend,
.resume_early = olpc_ec_resume,
};
static struct platform_driver olpc_ec_plat_driver = {
.probe = olpc_ec_probe,
.driver = {
.name = "olpc-ec",
.pm = &olpc_ec_pm_ops,
},
};
static int __init olpc_ec_init_module(void)
{
return platform_driver_register(&olpc_ec_plat_driver);
}
module_init(olpc_ec_init_module);
MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
MODULE_LICENSE("GPL");
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