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dilingerdilinger
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Platform: OLPC: allow EC cmd to be overridden, and create a workqueue to call it
This provides a new API allows different OLPC architectures to override the EC driver. x86 and ARM OLPC machines use completely different EC backends. The olpc_ec_cmd is synchronous, and waits for the workqueue to send the command to the EC. Multiple callers can run olpc_ec_cmd() at once, and they will by serialized and sleep while only one executes on the EC at a time. We don't provide an unregister function, as that doesn't make sense within the context of OLPC machines - there's only ever 1 EC, it's critical to functionality, and it certainly not hotpluggable. Signed-off-by: Andres Salomon <dilinger@queued.net> Acked-by: Paul Fox <pgf@laptop.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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‎drivers/platform/olpc/olpc-ec.c

Lines changed: 110 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -5,12 +5,120 @@
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*
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* Licensed under the GPL v2 or later.
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*/
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#include <linux/completion.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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#include <linux/workqueue.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/olpc-ec.h>
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#include <asm/olpc.h>
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struct ec_cmd_desc {
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u8 cmd;
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u8 *inbuf, *outbuf;
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size_t inlen, outlen;
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int err;
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struct completion finished;
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struct list_head node;
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void *priv;
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};
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static void olpc_ec_worker(struct work_struct *w);
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static DECLARE_WORK(ec_worker, olpc_ec_worker);
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static LIST_HEAD(ec_cmd_q);
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static DEFINE_SPINLOCK(ec_cmd_q_lock);
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static struct olpc_ec_driver *ec_driver;
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static void *ec_cb_arg;
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static DEFINE_MUTEX(ec_cb_lock);
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void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
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{
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ec_driver = drv;
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ec_cb_arg = arg;
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}
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EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
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static void olpc_ec_worker(struct work_struct *w)
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{
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struct ec_cmd_desc *desc = NULL;
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unsigned long flags;
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/* Grab the first pending command from the queue */
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spin_lock_irqsave(&ec_cmd_q_lock, flags);
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if (!list_empty(&ec_cmd_q)) {
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desc = list_first_entry(&ec_cmd_q, struct ec_cmd_desc, node);
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list_del(&desc->node);
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}
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spin_unlock_irqrestore(&ec_cmd_q_lock, flags);
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/* Do we actually have anything to do? */
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if (!desc)
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return;
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/* Protect the EC hw with a mutex; only run one cmd at a time */
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mutex_lock(&ec_cb_lock);
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desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
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desc->outbuf, desc->outlen, ec_cb_arg);
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mutex_unlock(&ec_cb_lock);
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/* Finished, wake up olpc_ec_cmd() */
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complete(&desc->finished);
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/* Run the worker thread again in case there are more cmds pending */
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schedule_work(&ec_worker);
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}
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/*
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* Throw a cmd descripter onto the list. We now have SMP OLPC machines, so
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* locking is pretty critical.
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*/
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static void queue_ec_descriptor(struct ec_cmd_desc *desc)
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{
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unsigned long flags;
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INIT_LIST_HEAD(&desc->node);
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spin_lock_irqsave(&ec_cmd_q_lock, flags);
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list_add_tail(&desc->node, &ec_cmd_q);
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spin_unlock_irqrestore(&ec_cmd_q_lock, flags);
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schedule_work(&ec_worker);
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}
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int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
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{
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/* Currently a stub; this will be expanded upon later. */
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return olpc_ec_cmd_x86(cmd, inbuf, inlen, outbuf, outlen);
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struct ec_cmd_desc desc;
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/* XXX: this will be removed in later patches */
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/* Are we using old-style callers? */
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if (!ec_driver || !ec_driver->ec_cmd)
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return olpc_ec_cmd_x86(cmd, inbuf, inlen, outbuf, outlen);
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/* Ensure a driver and ec hook have been registered */
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if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
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return -ENODEV;
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might_sleep();
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desc.cmd = cmd;
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desc.inbuf = inbuf;
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desc.outbuf = outbuf;
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desc.inlen = inlen;
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desc.outlen = outlen;
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desc.err = 0;
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init_completion(&desc.finished);
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queue_ec_descriptor(&desc);
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/* Timeouts must be handled in the platform-specific EC hook */
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wait_for_completion(&desc.finished);
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/* The worker thread dequeues the cmd; no need to do anything here */
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return desc.err;
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}
16124
EXPORT_SYMBOL_GPL(olpc_ec_cmd);

‎include/linux/olpc-ec.h

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -14,8 +14,14 @@
1414
#define EC_SCI_QUERY 0x84
1515
#define EC_EXT_SCI_QUERY 0x85
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struct olpc_ec_driver {
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int (*ec_cmd)(u8, u8 *, size_t, u8 *, size_t, void *);
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};
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#ifdef CONFIG_OLPC
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extern void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg);
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1925
extern int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf,
2026
size_t outlen);
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