blob: f9119525f5570c2d041d563c0eefbc9a01e32c20 [file] [log] [blame]
* 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/debugfs.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;
struct work_struct worker;
struct mutex cmd_lock;
/* Pending EC commands */
struct list_head cmd_q;
spinlock_t cmd_q_lock;
struct dentry *dbgfs_dir;
* 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 struct olpc_ec_driver *ec_driver;
static struct olpc_ec_priv *ec_priv;
static void *ec_cb_arg;
void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
ec_driver = drv;
ec_cb_arg = arg;
static void olpc_ec_worker(struct work_struct *w)
struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
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);
spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
/* Do we actually have anything to do? */
if (!desc)
/* Protect the EC hw with a mutex; only run one cmd at a time */
desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
desc->outbuf, desc->outlen, ec_cb_arg);
/* Finished, wake up olpc_ec_cmd() */
/* Run the worker thread again in case there are more cmds pending */
* 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,
struct olpc_ec_priv *ec)
unsigned long flags;
spin_lock_irqsave(&ec->cmd_q_lock, flags);
list_add_tail(&desc->node, &ec->cmd_q);
spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
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;
desc.cmd = cmd;
desc.inbuf = inbuf;
desc.outbuf = outbuf;
desc.inlen = inlen;
desc.outlen = outlen;
desc.err = 0;
queue_ec_descriptor(&desc, ec);
/* Timeouts must be handled in the platform-specific EC hook */
/* The worker thread dequeues the cmd; no need to do anything here */
return desc.err;
* debugfs support for "generic commands", to allow sending
* arbitrary EC commands from userspace.
#define EC_MAX_CMD_ARGS (5 + 1) /* cmd byte + 5 args */
#define EC_MAX_CMD_REPLY (8)
static DEFINE_MUTEX(ec_dbgfs_lock);
static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
static unsigned int ec_dbgfs_resp_bytes;
static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
size_t size, loff_t *ppos)
int i, m;
unsigned char ec_cmd[EC_MAX_CMD_ARGS];
unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
char cmdbuf[64];
int ec_cmd_bytes;
size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
&ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
&ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
/* reset to prevent overflow on read */
ec_dbgfs_resp_bytes = 0;
pr_debug("olpc-ec: bad ec cmd: cmd:response-count [arg1 [arg2 ...]]\n");
size = -EINVAL;
goto out;
/* convert scanf'd ints to char */
ec_cmd_bytes = m - 2;
for (i = 0; i <= ec_cmd_bytes; i++)
ec_cmd[i] = ec_cmd_int[i];
pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %02x %02x %02x %02x %02x, want %d returns\n",
ec_cmd[0], ec_cmd_bytes, ec_cmd[1], ec_cmd[2],
ec_cmd[3], ec_cmd[4], ec_cmd[5], ec_dbgfs_resp_bytes);
olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
pr_debug("olpc-ec: response %02x %02x %02x %02x %02x %02x %02x %02x (%d bytes expected)\n",
ec_dbgfs_resp[0], ec_dbgfs_resp[1], ec_dbgfs_resp[2],
ec_dbgfs_resp[3], ec_dbgfs_resp[4], ec_dbgfs_resp[5],
ec_dbgfs_resp[6], ec_dbgfs_resp[7],
return size;
static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
size_t size, loff_t *ppos)
unsigned int i, r;
char *rp;
char respbuf[64];
rp = respbuf;
rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
for (i = 1; i < ec_dbgfs_resp_bytes; i++)
rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
rp += sprintf(rp, "\n");
r = rp - respbuf;
return simple_read_from_buffer(buf, size, ppos, respbuf, r);
static const struct file_operations ec_dbgfs_ops = {
.write = ec_dbgfs_cmd_write,
.read = ec_dbgfs_cmd_read,
static struct dentry *olpc_ec_setup_debugfs(void)
struct dentry *dbgfs_dir;
dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
if (IS_ERR_OR_NULL(dbgfs_dir))
return NULL;
debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
return dbgfs_dir;
static struct dentry *olpc_ec_setup_debugfs(void)
return NULL;
#endif /* CONFIG_DEBUG_FS */
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;
INIT_WORK(&ec->worker, olpc_ec_worker);
ec_priv = ec;
platform_set_drvdata(pdev, ec);
err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
if (err) {
ec_priv = NULL;
} else {
ec->dbgfs_dir = olpc_ec_setup_debugfs();
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_AUTHOR("Andres Salomon <>");