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Commit ad479e7f authored by Lv Zheng's avatar Lv Zheng Committed by Rafael J. Wysocki
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ACPI / EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag 



By using the 2 flags, we can indicate an inter-mediate state where the
current transactions should be completed while the new transactions should
be dropped.

The comparison of the old flag and the new flags:
  Old			New
  about to set BLOCKED	STOPPED set / STARTED set
  BLOCKED set		STOPPED clear / STARTED clear
  BLOCKED clear		STOPPED clear / STARTED set
A new period can be indicated by the 2 flags. The new period is between the
point where we are about to set BLOCKED and the point when the BLOCKED is
set. The new flags facilitate us with acpi_ec_started() check to allow the
EC transaction to be submitted during the new period. This period thus can
be used as a grace period for the EC transaction flushing.

The only functional change after applying this patch is:
1. The GPE enabling/disabling is protected by the EC specific lock. We can
   do this because of recent ACPICA GPE API enhancement. This is reasonable
   as the GPE disabling/enabling state should only be determined by the EC
   driver's state machine which is protected by the EC spinlock.

Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
Tested-by: default avatarOrtwin Glück <odi@odi.ch>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent a8d4fc22

drivers/acpi/ec.c

+54 −11
Original line number Diff line number Diff line
@@ -80,7 +80,8 @@ enum { 
	EC_FLAGS_GPE_STORM,		/* GPE storm detected */

	EC_FLAGS_HANDLERS_INSTALLED,	/* Handlers for GPE and

					 * OpReg are installed */

	EC_FLAGS_BLOCKED,		/* Transactions are blocked */

	EC_FLAGS_STARTED,		/* Driver is started */

	EC_FLAGS_STOPPED,		/* Driver is stopped */

};



#define ACPI_EC_COMMAND_POLL		0x01 /* Available for command byte */
@@ -134,6 +135,16 @@ static int EC_FLAGS_SKIP_DSDT_SCAN; /* Not all BIOS survive early DSDT scan */ 
static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */

static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */



/* --------------------------------------------------------------------------

 *                           Device Flags

 * -------------------------------------------------------------------------- */



static bool acpi_ec_started(struct acpi_ec *ec)

{

	return test_bit(EC_FLAGS_STARTED, &ec->flags) &&

	       !test_bit(EC_FLAGS_STOPPED, &ec->flags);

}



/* --------------------------------------------------------------------------

 *                           EC Registers

 * -------------------------------------------------------------------------- */
@@ -415,6 +426,10 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, 
		udelay(ACPI_EC_MSI_UDELAY);

	/* start transaction */

	spin_lock_irqsave(&ec->lock, tmp);

	if (!acpi_ec_started(ec)) {

		ret = -EINVAL;

		goto unlock;

	}

	/* following two actions should be kept atomic */

	ec->curr = t;

	pr_debug("***** Command(%s) started *****\n",
@@ -426,6 +441,7 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, 
	pr_debug("***** Command(%s) stopped *****\n",

		 acpi_ec_cmd_string(t->command));

	ec->curr = NULL;

unlock:

	spin_unlock_irqrestore(&ec->lock, tmp);

	return ret;

}
@@ -440,10 +456,6 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) 
	if (t->rdata)

		memset(t->rdata, 0, t->rlen);

	mutex_lock(&ec->mutex);

	if (test_bit(EC_FLAGS_BLOCKED, &ec->flags)) {

		status = -EINVAL;

		goto unlock;

	}

	if (ec->global_lock) {

		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);

		if (ACPI_FAILURE(status)) {
@@ -595,6 +607,37 @@ static void acpi_ec_clear(struct acpi_ec *ec) 
		pr_info("%d stale EC events cleared\n", i);

}



static void acpi_ec_start(struct acpi_ec *ec, bool resuming)

{

	unsigned long flags;



	spin_lock_irqsave(&ec->lock, flags);

	if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {

		pr_debug("+++++ Starting EC +++++\n");

		if (!resuming)

			acpi_ec_enable_gpe(ec, true);

		pr_info("+++++ EC started +++++\n");

	}

	spin_unlock_irqrestore(&ec->lock, flags);

}



static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)

{

	unsigned long flags;



	spin_lock_irqsave(&ec->lock, flags);

	if (acpi_ec_started(ec)) {

		pr_debug("+++++ Stopping EC +++++\n");

		set_bit(EC_FLAGS_STOPPED, &ec->flags);

		if (!suspending)

			acpi_ec_disable_gpe(ec, true);

		clear_bit(EC_FLAGS_STARTED, &ec->flags);

		clear_bit(EC_FLAGS_STOPPED, &ec->flags);

		pr_info("+++++ EC stopped +++++\n");

	}

	spin_unlock_irqrestore(&ec->lock, flags);

}



void acpi_ec_block_transactions(void)

{

	struct acpi_ec *ec = first_ec;
@@ -604,7 +647,7 @@ void acpi_ec_block_transactions(void) 


	mutex_lock(&ec->mutex);

	/* Prevent transactions from being carried out */

	set_bit(EC_FLAGS_BLOCKED, &ec->flags);

	acpi_ec_stop(ec, true);

	mutex_unlock(&ec->mutex);

}
@@ -616,7 +659,7 @@ void acpi_ec_unblock_transactions(void) 
		return;



	/* Allow transactions to be carried out again */

	clear_bit(EC_FLAGS_BLOCKED, &ec->flags);

	acpi_ec_start(ec, true);



	if (EC_FLAGS_CLEAR_ON_RESUME)

		acpi_ec_clear(ec);
@@ -629,7 +672,7 @@ void acpi_ec_unblock_transactions_early(void) 
	 * atomic context during wakeup, so we don't need to acquire the mutex).

	 */

	if (first_ec)

		clear_bit(EC_FLAGS_BLOCKED, &first_ec->flags);

		acpi_ec_start(first_ec, true);

}



/* --------------------------------------------------------------------------
@@ -894,7 +937,7 @@ static int ec_install_handlers(struct acpi_ec *ec) 
	if (ACPI_FAILURE(status))

		return -ENODEV;



	acpi_ec_enable_gpe(ec, true);

	acpi_ec_start(ec, false);

	status = acpi_install_address_space_handler(ec->handle,

						    ACPI_ADR_SPACE_EC,

						    &acpi_ec_space_handler,
@@ -909,7 +952,7 @@ static int ec_install_handlers(struct acpi_ec *ec) 
			pr_err("Fail in evaluating the _REG object"

				" of EC device. Broken bios is suspected.\n");

		} else {

			acpi_ec_disable_gpe(ec, true);

			acpi_ec_stop(ec, false);

			acpi_remove_gpe_handler(NULL, ec->gpe,

				&acpi_ec_gpe_handler);

			return -ENODEV;
@@ -924,7 +967,7 @@ static void ec_remove_handlers(struct acpi_ec *ec) 
{

	if (!test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))

		return;

	acpi_ec_disable_gpe(ec, true);

	acpi_ec_stop(ec, false);

	if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,

				ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))

		pr_err("failed to remove space handler\n");