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: Lv Zheng <lv.zheng@intel.com>
Tested-by: Ortwin Glück <odi@odi.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 55632539392d4adffe6a3000ecf83f9f70e901f6..a6179b71c5730dbfcb39c4a243ea49d9c7f5fd37 100644 (file)
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -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");