linux-kernel - Re: [PATCH 19 5/5] Convert pfc8563 i2c driver from old style to new style

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Message-Id: <200804101114.18325.laurentp@cse-semaphore.com>
Date:	Thu, 10 Apr 2008 11:14:15 +0200
From:	Laurent Pinchart <laurentp@...-semaphore.com>
To:	linuxppc-dev@...abs.org
Cc:	Jon Smirl <jonsmirl@...il.com>, i2c@...sensors.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 19 5/5] Convert pfc8563 i2c driver from old style to new style

Hi Jon,

On Saturday 12 January 2008 03:47, Jon Smirl wrote:
> Convert pfc8563 i2c driver from old style to new style. The
> driver is also modified to support device tree names via the
> i2c mod alias mechanism.

The patch breaks the pfc8563 driver.

The old style driver allocated memory for a pcf8563 structure that
encapsulated an i2c_client instance. Various functions use container_of
on an i2c_client instance to get a pointer to the pcf8563 structure.

The new style driver gets rid of the pcf8563 structure allocation, as the
i2c_client structure is now allocated by I2C code.

Here is an incremental patch that fixes the issue.

From 1eac5a8e10e085c3a77c6ba7ed9dac9a39024915 Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurentp@...-semaphore.com>
Date: Thu, 10 Apr 2008 11:12:25 +0200
Subject: [PATCH] Fix pcf8563 breakage introduced by the conversion from old style to new style

The old style I2C driver used to allocate a pcf8563 instance that encapsulated
an i2c_client instance. The i2c_client instance is now allocated by I2C core.

This patch fixes the driver by storing the pcf8563 instance in the I2C client
data field.

Signed-off-by: Laurent Pinchart <laurentp@...-semaphore.com>
---
 drivers/rtc/rtc-pcf8563.c |   29 ++++++++++++++++++-----------
 1 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/rtc/rtc-pcf8563.c b/drivers/rtc/rtc-pcf8563.c
index e1ea2a0..7aab24e 100644
--- a/drivers/rtc/rtc-pcf8563.c
+++ b/drivers/rtc/rtc-pcf8563.c
@@ -50,7 +50,7 @@
 #define PCF8563_MO_C		0x80 /* century */
 
 struct pcf8563 {
-	struct i2c_client client;
+	struct rtc_device *rtc;
 	/*
 	 * The meaning of MO_C bit varies by the chip type.
 	 * From PCF8563 datasheet: this bit is toggled when the years
@@ -74,7 +74,7 @@ struct pcf8563 {
  */
 static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
-	struct pcf8563 *pcf8563 = container_of(client, struct pcf8563, client);
+	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 	unsigned char buf[13] = { PCF8563_REG_ST1 };
 
 	struct i2c_msg msgs[] = {
@@ -131,7 +131,7 @@ static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 
 static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
-	struct pcf8563 *pcf8563 = container_of(client, struct pcf8563, client);
+	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 	int i, err;
 	unsigned char buf[9];
 
@@ -252,10 +252,10 @@ static const struct rtc_class_ops pcf8563_rtc_ops = {
 
 static int pcf8563_remove(struct i2c_client *client)
 {
-	struct rtc_device *rtc = i2c_get_clientdata(client);
+	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 
-	if (rtc)
-		rtc_device_unregister(rtc);
+	if (pcf8563->rtc)
+		rtc_device_unregister(pcf8563->rtc);
 
 	return 0;
 }
@@ -274,26 +274,33 @@ static struct i2c_driver pcf8563_driver = {
 		.name	= "rtc-pcf8563",
 	},
 	.id		= I2C_DRIVERID_PCF8563,
-	.probe = &pcf8563_probe,
-	.remove = &pcf8563_remove,
+	.probe		= &pcf8563_probe,
+	.remove		= &pcf8563_remove,
 	.id_table	= pcf8563_id,
 };
 
 static int pcf8563_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
-	int result;
+	struct pcf8563 *pcf8563;
 	struct rtc_device *rtc;
+	int result;
 
 	result = pcf8563_validate_client(client);
 	if (result)
 		return result;
 
+	if ((pcf8563 = kzalloc(sizeof(*pcf8563), GFP_KERNEL)) == NULL)
+		return -ENOMEM;
+
 	rtc = rtc_device_register(pcf8563_driver.driver.name, &client->dev,
 				&pcf8563_rtc_ops, THIS_MODULE);
-	if (IS_ERR(rtc))
+	if (IS_ERR(rtc)) {
+		kfree(pcf8563);
 		return PTR_ERR(rtc);
+	}
 
-	i2c_set_clientdata(client, rtc);
+	pcf8563->rtc = rtc;
+	i2c_set_clientdata(client, pcf8563);
 
 	return 0;
 }
-- 
1.5.0

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussee de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
F +32 (2) 387 42 75

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