linux-kernel - [RFC PATCH 2/3] drivers: mfd: vexpress: add timeout API to vexpress config interface

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Date:	Fri, 24 May 2013 13:53:05 +0100
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:	devicetree-discuss@...ts.ozlabs.org,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Achin Gupta <achin.gupta@....com>,
	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>,
	Pawel Moll <pawel.moll@....com>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Jon Medhurst <tixy@...aro.org>
Subject: [RFC PATCH 2/3] drivers: mfd: vexpress: add timeout API to vexpress config interface

In case some transactions to the Serial Power Controller (SPC) are lost owing
to multiple operations handled at once by the M3 controller the OS needs to
rely on a configuration API that can time out so that failures do not result
in an unusable system.

This patch adds a timeout API to the vexpress config programming interface,
and refactors the existing read/write functions so that they can be reused
seamlessly on top of the newly defined API.

Cc: Samuel Ortiz <sameo@...ux.intel.com>
Cc: Achin Gupta <achin.gupta@....com>
Cc: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
Cc: Pawel Moll <pawel.moll@....com>
Cc: Nicolas Pitre <nicolas.pitre@...aro.org>
Cc: Amit Kucheria <amit.kucheria@...aro.org>
Cc: Jon Medhurst <tixy@...aro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
---
 drivers/mfd/vexpress-config.c | 26 +++++++---
 include/linux/vexpress.h      | 23 ++++++--
 2 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/mfd/vexpress-config.c b/drivers/mfd/vexpress-config.c
index 1af2b0e..6f4aa5a 100644
--- a/drivers/mfd/vexpress-config.c
+++ b/drivers/mfd/vexpress-config.c
@@ -266,8 +266,18 @@ int vexpress_config_wait(struct vexpress_config_trans *trans)
 }
 EXPORT_SYMBOL(vexpress_config_wait);
 
-int vexpress_config_read(struct vexpress_config_func *func, int offset,
-		u32 *data)
+int vexpress_config_wait_timeout(struct vexpress_config_trans *trans,
+			long jiffies)
+{
+	int ret;
+	ret = wait_for_completion_timeout(&trans->completion, jiffies);
+
+	return ret ? trans->status : -ETIMEDOUT;
+}
+EXPORT_SYMBOL(vexpress_config_wait_timeout);
+
+int vexpress_config_read_timeout(struct vexpress_config_func *func, int offset,
+		u32 *data, long jiffies)
 {
 	struct vexpress_config_trans trans = {
 		.func = func,
@@ -279,14 +289,14 @@ int vexpress_config_read(struct vexpress_config_func *func, int offset,
 	int status = vexpress_config_schedule(&trans);
 
 	if (status == VEXPRESS_CONFIG_STATUS_WAIT)
-		status = vexpress_config_wait(&trans);
+		status = vexpress_config_wait_timeout(&trans, jiffies);
 
 	return status;
 }
-EXPORT_SYMBOL(vexpress_config_read);
+EXPORT_SYMBOL(vexpress_config_read_timeout);
 
-int vexpress_config_write(struct vexpress_config_func *func, int offset,
-		u32 data)
+int vexpress_config_write_timeout(struct vexpress_config_func *func,
+				  int offset, u32 data, long jiffies)
 {
 	struct vexpress_config_trans trans = {
 		.func = func,
@@ -298,8 +308,8 @@ int vexpress_config_write(struct vexpress_config_func *func, int offset,
 	int status = vexpress_config_schedule(&trans);
 
 	if (status == VEXPRESS_CONFIG_STATUS_WAIT)
-		status = vexpress_config_wait(&trans);
+		status = vexpress_config_wait_timeout(&trans, jiffies);
 
 	return status;
 }
-EXPORT_SYMBOL(vexpress_config_write);
+EXPORT_SYMBOL(vexpress_config_write_timeout);
diff --git a/include/linux/vexpress.h b/include/linux/vexpress.h
index 50368e0..e5015d8 100644
--- a/include/linux/vexpress.h
+++ b/include/linux/vexpress.h
@@ -15,6 +15,7 @@
 #define _LINUX_VEXPRESS_H
 
 #include <linux/device.h>
+#include <linux/sched.h>
 
 #define VEXPRESS_SITE_MB		0
 #define VEXPRESS_SITE_DB1		1
@@ -102,10 +103,24 @@ struct vexpress_config_func *__vexpress_config_func_get(
 void vexpress_config_func_put(struct vexpress_config_func *func);
 
 /* Both may sleep! */
-int vexpress_config_read(struct vexpress_config_func *func, int offset,
-		u32 *data);
-int vexpress_config_write(struct vexpress_config_func *func, int offset,
-		u32 data);
+int vexpress_config_read_timeout(struct vexpress_config_func *func, int offset,
+		u32 *data, long jiffies);
+int vexpress_config_write_timeout(struct vexpress_config_func *func,
+		int offset, u32 data, long jiffies);
+
+static inline int vexpress_config_read(struct vexpress_config_func *func,
+				 int offset, u32 *data)
+{
+	return vexpress_config_read_timeout(func, offset, data,
+					     MAX_SCHEDULE_TIMEOUT);
+}
+
+static inline int vexpress_config_write(struct vexpress_config_func *func,
+				 int offset, u32 data)
+{
+	return vexpress_config_write_timeout(func, offset, data,
+					     MAX_SCHEDULE_TIMEOUT);
+}
 
 /* Platform control */
 
-- 
1.8.2.2


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