Merge branch 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6

* 'i2c-for-linus' of git://jdelvare.pck.nerim.net/jdelvare-2.6:
  i2c/eeprom: Recognize VGN as a valid Sony Vaio name prefix
  i2c/eeprom: Hide Sony Vaio serial numbers
  i2c-pasemi: Fix NACK detection
  i2c-pasemi: Replace obsolete "driverfs" reference with "sysfs"
  i2c: Make i2c_check_addr static
  i2c-dev: Unbound new-style i2c clients aren't busy
  i2c-dev: "how does it work" comments

4 files changed, 115 insertions, 18 deletions

diff --git a/drivers/i2c/busses/i2c-pasemi.c b/drivers/i2c/busses/i2c-pasemi.c
index 58e32714afb5..ca18e0be4901 100644
--- a/drivers/i2c/busses/i2c-pasemi.c
+++ b/drivers/i2c/busses/i2c-pasemi.c
@@ -51,6 +51,7 @@ struct pasemi_smbus {
 #define MRXFIFO_DATA_M	0x000000ff
 
 #define SMSTA_XEN	0x08000000
+#define SMSTA_MTN	0x00200000
 
 #define CTL_MRR		0x00000400
 #define CTL_MTR		0x00000200
@@ -98,6 +99,10 @@ static unsigned int pasemi_smb_waitready(struct pasemi_smbus *smbus)
 		status = reg_read(smbus, REG_SMSTA);
 	}
 
+	/* Got NACK? */
+	if (status & SMSTA_MTN)
+		return -ENXIO;
+
 	if (timeout < 0) {
 		dev_warn(&smbus->dev->dev, "Timeout, status 0x%08x\n", status);
 		reg_write(smbus, REG_SMSTA, status);
@@ -364,7 +369,7 @@ static int __devinit pasemi_smb_probe(struct pci_dev *dev,
 	smbus->adapter.algo = &smbus_algorithm;
 	smbus->adapter.algo_data = smbus;
 
-	/* set up the driverfs linkage to our parent device */
+	/* set up the sysfs linkage to our parent device */
 	smbus->adapter.dev.parent = &dev->dev;
 
 	reg_write(smbus, REG_CTL, (CTL_MTR | CTL_MRR |
diff --git a/drivers/i2c/chips/eeprom.c b/drivers/i2c/chips/eeprom.c
index d3da1fb05b9b..1a7eeebac506 100644
--- a/drivers/i2c/chips/eeprom.c
+++ b/drivers/i2c/chips/eeprom.c
@@ -128,13 +128,20 @@ static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr,
 	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 		eeprom_update_client(client, slice);
 
-	/* Hide Vaio security settings to regular users (16 first bytes) */
-	if (data->nature == VAIO && off < 16 && !capable(CAP_SYS_ADMIN)) {
-		size_t in_row1 = 16 - off;
-		in_row1 = min(in_row1, count);
-		memset(buf, 0, in_row1);
-		if (count - in_row1 > 0)
-			memcpy(buf + in_row1, &data->data[16], count - in_row1);
+	/* Hide Vaio private settings to regular users:
+	   - BIOS passwords: bytes 0x00 to 0x0f
+	   - UUID: bytes 0x10 to 0x1f
+	   - Serial number: 0xc0 to 0xdf */
+	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
+		int i;
+
+		for (i = 0; i < count; i++) {
+			if ((off + i <= 0x1f) ||
+			    (off + i >= 0xc0 && off + i <= 0xdf))
+				buf[i] = 0;
+			else
+				buf[i] = data->data[off + i];
+		}
 	} else {
 		memcpy(buf, &data->data[off], count);
 	}
@@ -197,14 +204,18 @@ static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind)
 		goto exit_kfree;
 
 	/* Detect the Vaio nature of EEPROMs.
-	   We use the "PCG-" prefix as the signature. */
+	   We use the "PCG-" or "VGN-" prefix as the signature. */
 	if (address == 0x57) {
-		if (i2c_smbus_read_byte_data(new_client, 0x80) == 'P'
-		 && i2c_smbus_read_byte(new_client) == 'C'
-		 && i2c_smbus_read_byte(new_client) == 'G'
-		 && i2c_smbus_read_byte(new_client) == '-') {
+		char name[4];
+
+		name[0] = i2c_smbus_read_byte_data(new_client, 0x80);
+		name[1] = i2c_smbus_read_byte(new_client);
+		name[2] = i2c_smbus_read_byte(new_client);
+		name[3] = i2c_smbus_read_byte(new_client);
+
+		if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
 			dev_info(&new_client->dev, "Vaio EEPROM detected, "
-				"enabling password protection\n");
+				 "enabling privacy protection\n");
 			data->nature = VAIO;
 		}
 	}
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 1a4e8dc03b36..b5e13e405e72 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -673,7 +673,7 @@ static int __i2c_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 	return 0;
 }
 
-int i2c_check_addr(struct i2c_adapter *adapter, int addr)
+static int i2c_check_addr(struct i2c_adapter *adapter, int addr)
 {
 	int rval;
 
@@ -683,7 +683,6 @@ int i2c_check_addr(struct i2c_adapter *adapter, int addr)
 
 	return rval;
 }
-EXPORT_SYMBOL(i2c_check_addr);
 
 int i2c_attach_client(struct i2c_client *client)
 {
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 5a15e50748de..c21ae20ae362 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -38,6 +38,15 @@
 
 static struct i2c_driver i2cdev_driver;
 
+/*
+ * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
+ * slave (i2c_client) with which messages will be exchanged.  It's coupled
+ * with a character special file which is accessed by user mode drivers.
+ *
+ * The list of i2c_dev structures is parallel to the i2c_adapter lists
+ * maintained by the driver model, and is updated using notifications
+ * delivered to the i2cdev_driver.
+ */
 struct i2c_dev {
 	struct list_head list;
 	struct i2c_adapter *adap;
@@ -103,6 +112,25 @@ static ssize_t show_adapter_name(struct device *dev,
 }
 static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);
 
+/* ------------------------------------------------------------------------- */
+
+/*
+ * After opening an instance of this character special file, a file
+ * descriptor starts out associated only with an i2c_adapter (and bus).
+ *
+ * Using the I2C_RDWR ioctl(), you can then *immediately* issue i2c_msg
+ * traffic to any devices on the bus used by that adapter.  That's because
+ * the i2c_msg vectors embed all the addressing information they need, and
+ * are submitted directly to an i2c_adapter.  However, SMBus-only adapters
+ * don't support that interface.
+ *
+ * To use read()/write() system calls on that file descriptor, or to use
+ * SMBus interfaces (and work with SMBus-only hosts!), you must first issue
+ * an I2C_SLAVE (or I2C_SLAVE_FORCE) ioctl.  That configures an anonymous
+ * (never registered) i2c_client so it holds the addressing information
+ * needed by those system calls and by this SMBus interface.
+ */
+
 static ssize_t i2cdev_read (struct file *file, char __user *buf, size_t count,
                             loff_t *offset)
 {
@@ -154,6 +182,29 @@ static ssize_t i2cdev_write (struct file *file, const char __user *buf, size_t c
 	return ret;
 }
 
+/* This address checking function differs from the one in i2c-core
+   in that it considers an address with a registered device, but no
+   bounded driver, as NOT busy. */
+static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
+{
+	struct list_head *item;
+	struct i2c_client *client;
+	int res = 0;
+
+	mutex_lock(&adapter->clist_lock);
+	list_for_each(item, &adapter->clients) {
+		client = list_entry(item, struct i2c_client, list);
+		if (client->addr == addr) {
+			if (client->driver)
+				res = -EBUSY;
+			break;
+		}
+	}
+	mutex_unlock(&adapter->clist_lock);
+
+	return res;
+}
+
 static int i2cdev_ioctl(struct inode *inode, struct file *file,
 		unsigned int cmd, unsigned long arg)
 {
@@ -172,11 +223,22 @@ static int i2cdev_ioctl(struct inode *inode, struct file *file,
 	switch ( cmd ) {
 	case I2C_SLAVE:
 	case I2C_SLAVE_FORCE:
+		/* NOTE:  devices set up to work with "new style" drivers
+		 * can't use I2C_SLAVE, even when the device node is not
+		 * bound to a driver.  Only I2C_SLAVE_FORCE will work.
+		 *
+		 * Setting the PEC flag here won't affect kernel drivers,
+		 * which will be using the i2c_client node registered with
+		 * the driver model core.  Likewise, when that client has
+		 * the PEC flag already set, the i2c-dev driver won't see
+		 * (or use) this setting.
+		 */
 		if ((arg > 0x3ff) ||
 		    (((client->flags & I2C_M_TEN) == 0) && arg > 0x7f))
 			return -EINVAL;
-		if ((cmd == I2C_SLAVE) && i2c_check_addr(client->adapter,arg))
+		if (cmd == I2C_SLAVE && i2cdev_check_addr(client->adapter, arg))
 			return -EBUSY;
+		/* REVISIT: address could become busy later */
 		client->addr = arg;
 		return 0;
 	case I2C_TENBIT:
@@ -386,6 +448,13 @@ static int i2cdev_open(struct inode *inode, struct file *file)
 	if (!adap)
 		return -ENODEV;
 
+	/* This creates an anonymous i2c_client, which may later be
+	 * pointed to some address using I2C_SLAVE or I2C_SLAVE_FORCE.
+	 *
+	 * This client is ** NEVER REGISTERED ** with the driver model
+	 * or I2C core code!!  It just holds private copies of addressing
+	 * information and maybe a PEC flag.
+	 */
 	client = kzalloc(sizeof(*client), GFP_KERNEL);
 	if (!client) {
 		i2c_put_adapter(adap);
@@ -394,7 +463,6 @@ static int i2cdev_open(struct inode *inode, struct file *file)
 	snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
 	client->driver = &i2cdev_driver;
 
-	/* registered with adapter, passed as client to user */
 	client->adapter = adap;
 	file->private_data = client;
 
@@ -422,6 +490,14 @@ static const struct file_operations i2cdev_fops = {
 	.release	= i2cdev_release,
 };
 
+/* ------------------------------------------------------------------------- */
+
+/*
+ * The legacy "i2cdev_driver" is used primarily to get notifications when
+ * I2C adapters are added or removed, so that each one gets an i2c_dev
+ * and is thus made available to userspace driver code.
+ */
+
 static struct class *i2c_dev_class;
 
 static int i2cdev_attach_adapter(struct i2c_adapter *adap)
@@ -486,6 +562,12 @@ static struct i2c_driver i2cdev_driver = {
 	.detach_client	= i2cdev_detach_client,
 };
 
+/* ------------------------------------------------------------------------- */
+
+/*
+ * module load/unload record keeping
+ */
+
 static int __init i2c_dev_init(void)
 {
 	int res;