ACPI: EC: do transaction from interrupt context

commit 7c6db4e050601f359081fde418ca6dc4fc2d0011 upstream.

It is easier and faster to do transaction directly from interrupt context
rather than waking control thread.
Also, cleaner GPE storm avoidance is implemented.
References: 	http://bugzilla.kernel.org/show_bug.cgi?id=9998
		http://bugzilla.kernel.org/show_bug.cgi?id=10724
		http://bugzilla.kernel.org/show_bug.cgi?id=10919
		http://bugzilla.kernel.org/show_bug.cgi?id=11309
		http://bugzilla.kernel.org/show_bug.cgi?id=11549

Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 149 insertions, 160 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 13593f9f219..7f0d81c0ec9 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1,7 +1,7 @@
 /*
- *  ec.c - ACPI Embedded Controller Driver (v2.0)
+ *  ec.c - ACPI Embedded Controller Driver (v2.1)
  *
- *  Copyright (C) 2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
+ *  Copyright (C) 2006-2008 Alexey Starikovskiy <astarikovskiy@suse.de>
  *  Copyright (C) 2006 Denis Sadykov <denis.m.sadykov@intel.com>
  *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
@@ -26,7 +26,7 @@
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
 
-/* Uncomment next line to get verbose print outs*/
+/* Uncomment next line to get verbose printout */
 /* #define DEBUG */
 
 #include <linux/kernel.h>
@@ -38,6 +38,7 @@
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/list.h>
+#include <linux/spinlock.h>
 #include <asm/io.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
@@ -65,22 +66,21 @@ enum ec_command {
 	ACPI_EC_COMMAND_QUERY = 0x84,
 };
 
-/* EC events */
-enum ec_event {
-	ACPI_EC_EVENT_OBF_1 = 1,	/* Output buffer full */
-	ACPI_EC_EVENT_IBF_0,		/* Input buffer empty */
-};
-
 #define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
 #define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
 #define ACPI_EC_UDELAY		100	/* Wait 100us before polling EC again */
 
+#define ACPI_EC_STORM_THRESHOLD 20	/* number of false interrupts
+					   per one transaction */
+
 enum {
-	EC_FLAGS_WAIT_GPE = 0,		/* Don't check status until GPE arrives */
 	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
-	EC_FLAGS_GPE_MODE,		/* Expect GPE to be sent for status change */
+	EC_FLAGS_GPE_MODE,		/* Expect GPE to be sent
+					 * for status change */
 	EC_FLAGS_NO_GPE,		/* Don't use GPE mode */
-	EC_FLAGS_RESCHEDULE_POLL	/* Re-schedule poll */
+	EC_FLAGS_GPE_STORM,		/* GPE storm detected */
+	EC_FLAGS_HANDLERS_INSTALLED	/* Handlers for GPE and
+					 * OpReg are installed */
 };
 
 /* If we find an EC via the ECDT, we need to keep a ptr to its context */
@@ -95,6 +95,14 @@ struct acpi_ec_query_handler {
 	u8 query_bit;
 };
 
+struct transaction_data {
+	const u8 *wdata;
+	u8 *rdata;
+	unsigned short irq_count;
+	u8 wlen;
+	u8 rlen;
+};
+
 static struct acpi_ec {
 	acpi_handle handle;
 	unsigned long gpe;
@@ -105,9 +113,8 @@ static struct acpi_ec {
 	struct mutex lock;
 	wait_queue_head_t wait;
 	struct list_head list;
-	struct delayed_work work;
-	atomic_t irq_count;
-	u8 handlers_installed;
+	struct transaction_data *t;
+	spinlock_t t_lock;
 } *boot_ec, *first_ec;
 
 /* 
@@ -150,7 +157,7 @@ static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
 {
 	u8 x = inb(ec->data_addr);
 	pr_debug(PREFIX "---> data = 0x%2.2x\n", x);
-	return inb(ec->data_addr);
+	return x;
 }
 
 static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
@@ -165,68 +172,79 @@ static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
 	outb(data, ec->data_addr);
 }
 
-static inline int acpi_ec_check_status(struct acpi_ec *ec, enum ec_event event)
+static int ec_transaction_done(struct acpi_ec *ec)
 {
-	if (test_bit(EC_FLAGS_WAIT_GPE, &ec->flags))
-		return 0;
-	if (event == ACPI_EC_EVENT_OBF_1) {
-		if (acpi_ec_read_status(ec) & ACPI_EC_FLAG_OBF)
-			return 1;
-	} else if (event == ACPI_EC_EVENT_IBF_0) {
-		if (!(acpi_ec_read_status(ec) & ACPI_EC_FLAG_IBF))
-			return 1;
-	}
-
-	return 0;
+	unsigned long flags;
+	int ret = 0;
+	spin_lock_irqsave(&ec->t_lock, flags);
+	if (!ec->t || (!ec->t->wlen && !ec->t->rlen))
+		ret = 1;
+	spin_unlock_irqrestore(&ec->t_lock, flags);
+	return ret;
 }
 
-static void ec_schedule_ec_poll(struct acpi_ec *ec)
+static void gpe_transaction(struct acpi_ec *ec, u8 status)
 {
-	if (test_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags))
-		schedule_delayed_work(&ec->work,
-				      msecs_to_jiffies(ACPI_EC_DELAY));
+	unsigned long flags;
+	spin_lock_irqsave(&ec->t_lock, flags);
+	if (!ec->t)
+		goto unlock;
+	if (ec->t->wlen > 0) {
+		if ((status & ACPI_EC_FLAG_IBF) == 0) {
+			acpi_ec_write_data(ec, *(ec->t->wdata++));
+			--ec->t->wlen;
+		} else
+			/* false interrupt, state didn't change */
+			++ec->t->irq_count;
+
+	} else if (ec->t->rlen > 0) {
+		if ((status & ACPI_EC_FLAG_OBF) == 1) {
+			*(ec->t->rdata++) = acpi_ec_read_data(ec);
+			--ec->t->rlen;
+		} else
+			/* false interrupt, state didn't change */
+			++ec->t->irq_count;
+	}
+unlock:
+	spin_unlock_irqrestore(&ec->t_lock, flags);
 }
 
-static void ec_switch_to_poll_mode(struct acpi_ec *ec)
+static int acpi_ec_wait(struct acpi_ec *ec)
 {
+	if (wait_event_timeout(ec->wait, ec_transaction_done(ec),
+			       msecs_to_jiffies(ACPI_EC_DELAY)))
+		return 0;
+	/* missing GPEs, switch back to poll mode */
+	if (printk_ratelimit())
+		pr_info(PREFIX "missing confirmations, "
+				"switch off interrupt mode.\n");
 	set_bit(EC_FLAGS_NO_GPE, &ec->flags);
 	clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
-	acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
-	set_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
+	return 1;
 }
 
-static int acpi_ec_wait(struct acpi_ec *ec, enum ec_event event, int force_poll)
+static void acpi_ec_gpe_query(void *ec_cxt);
+
+static int ec_check_sci(struct acpi_ec *ec, u8 state)
 {
-	atomic_set(&ec->irq_count, 0);
-	if (likely(test_bit(EC_FLAGS_GPE_MODE, &ec->flags)) &&
-	    likely(!force_poll)) {
-		if (wait_event_timeout(ec->wait, acpi_ec_check_status(ec, event),
-				       msecs_to_jiffies(ACPI_EC_DELAY)))
-			return 0;
-		clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		if (acpi_ec_check_status(ec, event)) {
-			/* missing GPEs, switch back to poll mode */
-			if (printk_ratelimit())
-				pr_info(PREFIX "missing confirmations, "
-						"switch off interrupt mode.\n");
-			ec_switch_to_poll_mode(ec);
-			ec_schedule_ec_poll(ec);
-			return 0;
-		}
-	} else {
-		unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
-		clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		while (time_before(jiffies, delay)) {
-			if (acpi_ec_check_status(ec, event))
-				return 0;
-			msleep(1);
-		}
-		if (acpi_ec_check_status(ec,event))
+	if (state & ACPI_EC_FLAG_SCI) {
+		if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
+			return acpi_os_execute(OSL_EC_BURST_HANDLER,
+				acpi_ec_gpe_query, ec);
+	}
+	return 0;
+}
+
+static int ec_poll(struct acpi_ec *ec)
+{
+	unsigned long delay = jiffies + msecs_to_jiffies(ACPI_EC_DELAY);
+	msleep(1);
+	while (time_before(jiffies, delay)) {
+		gpe_transaction(ec, acpi_ec_read_status(ec));
+		msleep(1);
+		if (ec_transaction_done(ec))
 			return 0;
 	}
-	pr_err(PREFIX "acpi_ec_wait timeout, status = 0x%2.2x, event = %s\n",
-		acpi_ec_read_status(ec),
-		(event == ACPI_EC_EVENT_OBF_1) ? "\"b0=1\"" : "\"b1=0\"");
 	return -ETIME;
 }
 
@@ -235,45 +253,51 @@ static int acpi_ec_transaction_unlocked(struct acpi_ec *ec, u8 command,
 					u8 * rdata, unsigned rdata_len,
 					int force_poll)
 {
-	int result = 0;
-	set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
+	unsigned long tmp;
+	struct transaction_data t = {.wdata = wdata, .rdata = rdata,
+				     .wlen = wdata_len, .rlen = rdata_len,
+				     .irq_count = 0};
+	int ret = 0;
 	pr_debug(PREFIX "transaction start\n");
-	acpi_ec_write_cmd(ec, command);
-	for (; wdata_len > 0; --wdata_len) {
-		result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, force_poll);
-		if (result) {
-			pr_err(PREFIX
-			       "write_cmd timeout, command = %d\n", command);
-			goto end;
-		}
-		set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		acpi_ec_write_data(ec, *(wdata++));
+	/* disable GPE during transaction if storm is detected */
+	if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+		clear_bit(EC_FLAGS_GPE_MODE, &ec->flags);
+		acpi_disable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
 	}
-
-	if (!rdata_len) {
-		result = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, force_poll);
-		if (result) {
-			pr_err(PREFIX
-			       "finish-write timeout, command = %d\n", command);
-			goto end;
-		}
-	} else if (command == ACPI_EC_COMMAND_QUERY)
+	/* start transaction */
+	spin_lock_irqsave(&ec->t_lock, tmp);
+	/* following two actions should be kept atomic */
+	ec->t = &t;
+	acpi_ec_write_cmd(ec, command);
+	if (command == ACPI_EC_COMMAND_QUERY)
 		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
-
-	for (; rdata_len > 0; --rdata_len) {
-		result = acpi_ec_wait(ec, ACPI_EC_EVENT_OBF_1, force_poll);
-		if (result) {
-			pr_err(PREFIX "read timeout, command = %d\n", command);
-			goto end;
-		}
-		/* Don't expect GPE after last read */
-		if (rdata_len > 1)
-			set_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-		*(rdata++) = acpi_ec_read_data(ec);
-	}
-      end:
+	spin_unlock_irqrestore(&ec->t_lock, tmp);
+	/* if we selected poll mode or failed in GPE-mode do a poll loop */
+	if (force_poll ||
+	    !test_bit(EC_FLAGS_GPE_MODE, &ec->flags) ||
+	    acpi_ec_wait(ec))
+		ret = ec_poll(ec);
 	pr_debug(PREFIX "transaction end\n");
-	return result;
+	spin_lock_irqsave(&ec->t_lock, tmp);
+	ec->t = NULL;
+	spin_unlock_irqrestore(&ec->t_lock, tmp);
+	if (test_bit(EC_FLAGS_GPE_STORM, &ec->flags)) {
+		/* check if we received SCI during transaction */
+		ec_check_sci(ec, acpi_ec_read_status(ec));
+		/* it is safe to enable GPE outside of transaction */
+		acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
+	} else if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
+		   t.irq_count > ACPI_EC_STORM_THRESHOLD) {
+		pr_debug(PREFIX "GPE storm detected\n");
+		set_bit(EC_FLAGS_GPE_STORM, &ec->flags);
+	}
+	return ret;
+}
+
+static int ec_check_ibf0(struct acpi_ec *ec)
+{
+	u8 status = acpi_ec_read_status(ec);
+	return (status & ACPI_EC_FLAG_IBF) == 0;
 }
 
 static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
@@ -283,40 +307,34 @@ static int acpi_ec_transaction(struct acpi_ec *ec, u8 command,
 {
 	int status;
 	u32 glk;
-
 	if (!ec || (wdata_len && !wdata) || (rdata_len && !rdata))
 		return -EINVAL;
-
 	if (rdata)
 		memset(rdata, 0, rdata_len);
-
 	mutex_lock(&ec->lock);
 	if (ec->global_lock) {
 		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
 		if (ACPI_FAILURE(status)) {
-			mutex_unlock(&ec->lock);
-			return -ENODEV;
+			status = -ENODEV;
+			goto unlock;
 		}
 	}
-
-	status = acpi_ec_wait(ec, ACPI_EC_EVENT_IBF_0, 0);
-	if (status) {
+	if (!wait_event_timeout(ec->wait, ec_check_ibf0(ec),
+				msecs_to_jiffies(ACPI_EC_DELAY))) {
 		pr_err(PREFIX "input buffer is not empty, "
 				"aborting transaction\n");
+		status = -ETIME;
 		goto end;
 	}
-
 	status = acpi_ec_transaction_unlocked(ec, command,
 					      wdata, wdata_len,
 					      rdata, rdata_len,
 					      force_poll);
-
-      end:
-
+end:
 	if (ec->global_lock)
 		acpi_release_global_lock(glk);
+unlock:
 	mutex_unlock(&ec->lock);
-
 	return status;
 }
 
@@ -332,7 +350,9 @@ int acpi_ec_burst_enable(struct acpi_ec *ec)
 
 int acpi_ec_burst_disable(struct acpi_ec *ec)
 {
-	return acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE, NULL, 0, NULL, 0, 0);
+	return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
+		acpi_ec_transaction(ec, ACPI_EC_BURST_DISABLE,
+			NULL, 0, NULL, 0, 0) : 0;
 }
 
 static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 * data)
@@ -513,46 +533,26 @@ static void acpi_ec_gpe_query(void *ec_cxt)
 
 static u32 acpi_ec_gpe_handler(void *data)
 {
-	acpi_status status = AE_OK;
 	struct acpi_ec *ec = data;
-	u8 state = acpi_ec_read_status(ec);
+	u8 status;
 
 	pr_debug(PREFIX "~~~> interrupt\n");
-	atomic_inc(&ec->irq_count);
-	if (atomic_read(&ec->irq_count) > 5) {
-		pr_err(PREFIX "GPE storm detected, disabling EC GPE\n");
-		ec_switch_to_poll_mode(ec);
-		goto end;
-	}
-	clear_bit(EC_FLAGS_WAIT_GPE, &ec->flags);
-	if (test_bit(EC_FLAGS_GPE_MODE, &ec->flags))
+	status = acpi_ec_read_status(ec);
+
+	gpe_transaction(ec, status);
+	if (ec_transaction_done(ec) && (status & ACPI_EC_FLAG_IBF) == 0)
 		wake_up(&ec->wait);
 
-	if (state & ACPI_EC_FLAG_SCI) {
-		if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
-			status = acpi_os_execute(OSL_EC_BURST_HANDLER,
-				acpi_ec_gpe_query, ec);
-	} else if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
-		   !test_bit(EC_FLAGS_NO_GPE, &ec->flags) &&
-		   in_interrupt()) {
+	ec_check_sci(ec, status);
+	if (!test_bit(EC_FLAGS_GPE_MODE, &ec->flags) &&
+	    !test_bit(EC_FLAGS_NO_GPE, &ec->flags)) {
 		/* this is non-query, must be confirmation */
 		if (printk_ratelimit())
 			pr_info(PREFIX "non-query interrupt received,"
 				" switching to interrupt mode\n");
 		set_bit(EC_FLAGS_GPE_MODE, &ec->flags);
-		clear_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
 	}
-end:
-	ec_schedule_ec_poll(ec);
-	return ACPI_SUCCESS(status) ?
-	    ACPI_INTERRUPT_HANDLED : ACPI_INTERRUPT_NOT_HANDLED;
-}
-
-static void do_ec_poll(struct work_struct *work)
-{
-	struct acpi_ec *ec = container_of(work, struct acpi_ec, work.work);
-	atomic_set(&ec->irq_count, 0);
-	(void)acpi_ec_gpe_handler(ec);
+	return ACPI_INTERRUPT_HANDLED;
 }
 
 /* --------------------------------------------------------------------------
@@ -696,8 +696,7 @@ static struct acpi_ec *make_acpi_ec(void)
 	mutex_init(&ec->lock);
 	init_waitqueue_head(&ec->wait);
 	INIT_LIST_HEAD(&ec->list);
-	INIT_DELAYED_WORK_DEFERRABLE(&ec->work, do_ec_poll);
-	atomic_set(&ec->irq_count, 0);
+	spin_lock_init(&ec->t_lock);
 	return ec;
 }
 
@@ -736,22 +735,15 @@ ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
 	return AE_CTRL_TERMINATE;
 }
 
-static void ec_poll_stop(struct acpi_ec *ec)
-{
-	clear_bit(EC_FLAGS_RESCHEDULE_POLL, &ec->flags);
-	cancel_delayed_work(&ec->work);
-}
-
 static void ec_remove_handlers(struct acpi_ec *ec)
 {
-	ec_poll_stop(ec);
 	if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
 				ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
 		pr_err(PREFIX "failed to remove space handler\n");
 	if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
 				&acpi_ec_gpe_handler)))
 		pr_err(PREFIX "failed to remove gpe handler\n");
-	ec->handlers_installed = 0;
+	clear_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
 }
 
 static int acpi_ec_add(struct acpi_device *device)
@@ -846,17 +838,15 @@ ec_parse_io_ports(struct acpi_resource *resource, void *context)
 static int ec_install_handlers(struct acpi_ec *ec)
 {
 	acpi_status status;
-	if (ec->handlers_installed)
+	if (test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))
 		return 0;
 	status = acpi_install_gpe_handler(NULL, ec->gpe,
-					  ACPI_GPE_EDGE_TRIGGERED,
-					  &acpi_ec_gpe_handler, ec);
+				  ACPI_GPE_EDGE_TRIGGERED,
+				  &acpi_ec_gpe_handler, ec);
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
-
 	acpi_set_gpe_type(NULL, ec->gpe, ACPI_GPE_TYPE_RUNTIME);
 	acpi_enable_gpe(NULL, ec->gpe, ACPI_NOT_ISR);
-
 	status = acpi_install_address_space_handler(ec->handle,
 						    ACPI_ADR_SPACE_EC,
 						    &acpi_ec_space_handler,
@@ -866,7 +856,7 @@ static int ec_install_handlers(struct acpi_ec *ec)
 		return -ENODEV;
 	}
 
-	ec->handlers_installed = 1;
+	set_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
 	return 0;
 }
 
@@ -887,7 +877,6 @@ static int acpi_ec_start(struct acpi_device *device)
 
 	/* EC is fully operational, allow queries */
 	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
-	ec_schedule_ec_poll(ec);
 	return ret;
 }
 
@@ -906,7 +895,7 @@ static int acpi_ec_stop(struct acpi_device *device, int type)
 
 int __init acpi_boot_ec_enable(void)
 {
-	if (!boot_ec || boot_ec->handlers_installed)
+	if (!boot_ec || test_bit(EC_FLAGS_HANDLERS_INSTALLED, &boot_ec->flags))
 		return 0;
 	if (!ec_install_handlers(boot_ec)) {
 		first_ec = boot_ec;