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 5563253..a6179b7 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -80,7 +80,8 @@
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 */
@@ -135,6 +136,16 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
* 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 @@
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 @@
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 @@
{
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");