Platform: OLPC: add a suspended flag to the EC driver

A problem we've noticed on XO-1.75 is when we suspend in the middle of
an EC command.  Don't allow that.

In the process, create a private object for the generic EC driver to use;
we have a framework for passing around a struct, use that rather than a
proliferation of global variables.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Acked-by: Paul Fox <pgf@laptop.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 45 insertions, 1 deletions

diff --git a/drivers/platform/olpc/olpc-ec.c b/drivers/platform/olpc/olpc-ec.c
index d00523c65191..cfba41fb04de 100644
--- a/drivers/platform/olpc/olpc-ec.c
+++ b/drivers/platform/olpc/olpc-ec.c
@@ -9,6 +9,7 @@
 #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>
@@ -27,6 +28,21 @@ struct ec_cmd_desc {
         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);
@@ -34,6 +50,7 @@ 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);
 
@@ -93,6 +110,7 @@ static void queue_ec_descriptor(struct ec_cmd_desc *desc)
 
 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;
 
         /* XXX: this will be removed in later patches */
@@ -104,6 +122,13 @@ int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
         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;
@@ -126,11 +151,19 @@ 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;
@@ -139,12 +172,23 @@ static int olpc_ec_probe(struct platform_device *pdev)
 static int olpc_ec_suspend(struct device *dev)
 {
         struct platform_device *pdev = to_platform_device(dev);
-        return ec_driver->suspend ? ec_driver->suspend(pdev) : 0;
+        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;
 }