[PATCH 1/4] i2c: Add detection capability to new-style drivers

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

Add a mechanism to let new-style i2c drivers auto-detect devices they
would support and ask i2c-core to instantiate them. This is a
replacement for legacy drivers, much cleaner.

Signed-off-by: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
---
This patch depends on:
http://khali.linux-fr.org/devel/linux-2.6/jdelvare-i2c/i2c-use-class_for_each_device.patch
http://khali.linux-fr.org/devel/linux-2.6/jdelvare-i2c/i2c-simplify-i2c_del_driver.patch

Implementation note: i2c_detect and i2c_detect_address are basically
clones of i2c_probe and i2c_probe_address but operating on a callback
with a slightly different prototype. This duplicated code accounts
for a large part of the patch, but once legacy drivers are gone,
i2c_probe and i2c_probe_address will be removed, so this is no
long-term duplication.

 drivers/i2c/i2c-core.c |  207 +++++++++++++++++++++++++++++++++++++++++++++---
 include/linux/i2c.h    |   14 +++
 2 files changed, 210 insertions(+), 11 deletions(-)

--- linux-2.6.26-rc5.orig/include/linux/i2c.h	2008-06-05 21:04:35.000000000 +0200
+++ linux-2.6.26-rc5/include/linux/i2c.h	2008-06-05 21:54:49.000000000 +0200
@@ -43,6 +43,7 @@ struct i2c_adapter;
 struct i2c_client;
 struct i2c_driver;
 union i2c_smbus_data;
+struct i2c_board_info;
 
 /*
  * The master routines are the ones normally used to transmit data to devices
@@ -99,6 +100,11 @@ extern s32 i2c_smbus_write_i2c_block_dat
  *
  * The driver.owner field should be set to the module owner of this driver.
  * The driver.name field should be set to the name of this driver.
+ *
+ * @class: What kind of i2c device we may instantiate
+ * @detect: Callback for device detection
+ * @address_data: The I2C addresses to probe, ignore or force
+ * @clients: List of detected clients we created
  */
 
 struct i2c_driver {
@@ -140,6 +146,12 @@ struct i2c_driver {
 
 	struct device_driver driver;
 	const struct i2c_device_id *id_table;
+
+	/* Device detection callback for automatic device creation */
+	int (*detect)(struct i2c_adapter *, int address, int kind,
+		      struct i2c_board_info *);
+	const struct i2c_client_address_data *address_data;
+	struct list_head clients;
 };
 #define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
 
@@ -155,6 +167,7 @@ struct i2c_driver {
  * @dev: Driver model device node for the slave.
  * @irq: indicates the IRQ generated by this device (if any)
  * @list: list of active/busy clients (DEPRECATED)
+ * @detected: member of a i2c_driver.clients list
  * @released: used to synchronize client releases & detaches and references
  *
  * An i2c_client identifies a single device (i.e. chip) connected to an
@@ -172,6 +185,7 @@ struct i2c_client {
 	struct device dev;		/* the device structure		*/
 	int irq;			/* irq issued by device (or -1) */
 	struct list_head list;		/* DEPRECATED */
+	struct list_head detected;
 	struct completion released;
 };
 #define to_i2c_client(d) container_of(d, struct i2c_client, dev)
--- linux-2.6.26-rc5.orig/drivers/i2c/i2c-core.c	2008-06-05 21:04:35.000000000 +0200
+++ linux-2.6.26-rc5/drivers/i2c/i2c-core.c	2008-06-06 14:04:40.000000000 +0200
@@ -42,7 +42,9 @@
 static DEFINE_MUTEX(core_lock);
 static DEFINE_IDR(i2c_adapter_idr);
 
-#define is_newstyle_driver(d) ((d)->probe || (d)->remove)
+#define is_newstyle_driver(d) ((d)->probe || (d)->remove || (d)->detect)
+
+static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
 
 /* ------------------------------------------------------------------------- */
 
@@ -409,6 +411,10 @@ static int i2c_do_add_adapter(struct dev
 	struct i2c_driver *driver = to_i2c_driver(d);
 	struct i2c_adapter *adap = data;
 
+	/* Detect supported devices on that bus, and instantiate them */
+	i2c_detect(adap, driver);
+
+	/* Let legacy drivers scan this bus for matching devices */
 	if (driver->attach_adapter) {
 		/* We ignore the return code; if it fails, too bad */
 		driver->attach_adapter(adap);
@@ -448,7 +454,7 @@ static int i2c_register_adapter(struct i
 	if (adap->nr < __i2c_first_dynamic_bus_num)
 		i2c_scan_static_board_info(adap);
 
-	/* let legacy drivers scan this bus for matching devices */
+	/* Notify drivers */
 	dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
 				 i2c_do_add_adapter);
 
@@ -554,14 +560,26 @@ static int i2c_do_del_adapter(struct dev
 {
 	struct i2c_driver *driver = to_i2c_driver(d);
 	struct i2c_adapter *adapter = data;
+	struct i2c_client *client, *_n;
 	int res;
 
+	/* Remove the devices we created ourselves */
+	list_for_each_entry_safe(client, _n, &driver->clients, detected) {
+		if (client->adapter == adapter) {
+			dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
+				client->name, client->addr);
+			list_del(&client->detected);
+			i2c_unregister_device(client);
+		}
+	}
+
 	if (!driver->detach_adapter)
 		return 0;
 	res = driver->detach_adapter(adapter);
 	if (res)
 		dev_err(&adapter->dev, "detach_adapter failed (%d) "
 			"for driver [%s]\n", res, driver->driver.name);
+
 	return res;
 }
 
@@ -642,7 +660,10 @@ static int __attach_adapter(struct devic
 	struct i2c_adapter *adapter = to_i2c_adapter(dev);
 	struct i2c_driver *driver = data;
 
-	driver->attach_adapter(adapter);
+	i2c_detect(adapter, driver);
+
+	if (driver->attach_adapter)
+		driver->attach_adapter(adapter);
 
 	return 0;
 }
@@ -686,10 +707,10 @@ int i2c_register_driver(struct module *o
 
 	pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);
 
-	/* legacy drivers scan i2c busses directly */
-	if (driver->attach_adapter)
-		class_for_each_device(&i2c_adapter_class, driver,
-				      __attach_adapter);
+	INIT_LIST_HEAD(&driver->clients);
+	/* Walk the adapters that are already present */
+	class_for_each_device(&i2c_adapter_class, driver,
+			      __attach_adapter);
 
 	mutex_unlock(&core_lock);
 	return 0;
@@ -700,6 +721,17 @@ static int __detach_adapter(struct devic
 {
 	struct i2c_adapter *adapter = to_i2c_adapter(dev);
 	struct i2c_driver *driver = data;
+	struct i2c_client *client, *_n;
+
+	list_for_each_entry_safe(client, _n, &driver->clients, detected) {
+		dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
+			client->name, client->addr);
+		list_del(&client->detected);
+		i2c_unregister_device(client);
+	}
+
+	if (is_newstyle_driver(driver))
+		return 0;
 
 	/* Have a look at each adapter, if clients of this driver are still
 	 * attached. If so, detach them to be able to kill the driver
@@ -738,10 +770,7 @@ void i2c_del_driver(struct i2c_driver *d
 {
 	mutex_lock(&core_lock);
 
-	/* legacy driver? */
-	if (!is_newstyle_driver(driver))
-		class_for_each_device(&i2c_adapter_class, driver,
-				      __detach_adapter);
+	class_for_each_device(&i2c_adapter_class, driver, __detach_adapter);
 
 	driver_unregister(&driver->driver);
 	pr_debug("i2c-core: driver [%s] unregistered\n", driver->driver.name);
@@ -1196,6 +1225,162 @@ int i2c_probe(struct i2c_adapter *adapte
 }
 EXPORT_SYMBOL(i2c_probe);
 
+/* Separate detection function for new-style drivers */
+static int i2c_detect_address(struct i2c_adapter *adapter,
+			      int addr, int kind, struct i2c_driver *driver)
+{
+	struct i2c_board_info info;
+	struct i2c_client *client;
+	int err;
+
+	/* Make sure the address is valid */
+	if (addr < 0x03 || addr > 0x77) {
+		dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
+			 addr);
+		return -EINVAL;
+	}
+
+	/* Skip if already in use */
+	if (i2c_check_addr(adapter, addr))
+		return 0;
+
+	/* Make sure there is something at this address, unless forced */
+	if (kind < 0) {
+		if (i2c_smbus_xfer(adapter, addr, 0, 0, 0,
+				   I2C_SMBUS_QUICK, NULL) < 0)
+			return 0;
+
+		/* prevent 24RF08 corruption */
+		if ((addr & ~0x0f) == 0x50)
+			i2c_smbus_xfer(adapter, addr, 0, 0, 0,
+				       I2C_SMBUS_QUICK, NULL);
+	}
+
+	/* Finally call the custom detection function */
+	memset(&info, 0, sizeof(struct i2c_board_info));
+	err = driver->detect(adapter, addr, kind, &info);
+	if (err) {
+		/* -ENODEV can be returned if there is a chip at the given address
+		   but it isn't supported by this chip driver. We catch it here as
+		   this isn't an error. */
+		return err == -ENODEV ? 0 : err;
+	}
+
+	/* Consistency check */
+	if (info.type[0] == '\0' || info.addr != addr) {
+		dev_err(&adapter->dev, "Detection function returned "
+			"inconsistent data for 0x%x\n", addr);
+	} else {
+		/* Detection succeeded, instantiate the device */
+		dev_dbg(&adapter->dev, "Creating %s at 0x%x\n",
+			info.type, info.addr);
+		client = i2c_new_device(adapter, &info);
+		list_add_tail(&client->detected, &driver->clients);
+	}
+	return 0;
+}
+
+static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
+{
+	const struct i2c_client_address_data *address_data;
+	int i, err;
+	int adap_id = i2c_adapter_id(adapter);
+
+	if (!driver->detect)
+		return 0;
+	address_data = driver->address_data;
+
+	/* Force entries are done first, and are not affected by ignore
+	   entries */
+	if (address_data->forces) {
+		const unsigned short * const *forces = address_data->forces;
+		int kind;
+
+		for (kind = 0; forces[kind]; kind++) {
+			for (i = 0; forces[kind][i] != I2C_CLIENT_END;
+			     i += 2) {
+				if (forces[kind][i] == adap_id
+				 || forces[kind][i] == ANY_I2C_BUS) {
+					dev_dbg(&adapter->dev, "found force "
+						"parameter for adapter %d, "
+						"addr 0x%02x, kind %d\n",
+						adap_id, forces[kind][i + 1],
+						kind);
+					err = i2c_detect_address(adapter,
+						forces[kind][i + 1],
+						kind, driver);
+					if (err)
+						return err;
+				}
+			}
+		}
+	}
+
+	/* Stop here if we can't use SMBUS_QUICK */
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_QUICK)) {
+		if (address_data->probe[0] == I2C_CLIENT_END
+		 && address_data->normal_i2c[0] == I2C_CLIENT_END)
+			return 0;
+
+		dev_warn(&adapter->dev, "SMBus Quick command not supported, "
+			 "can't probe for chips\n");
+		return -EOPNOTSUPP;
+	}
+
+	/* Probe entries are done second, and are not affected by ignore
+	   entries either */
+	for (i = 0; address_data->probe[i] != I2C_CLIENT_END; i += 2) {
+		if (address_data->probe[i] == adap_id
+		 || address_data->probe[i] == ANY_I2C_BUS) {
+			dev_dbg(&adapter->dev, "found probe parameter for "
+				"adapter %d, addr 0x%02x\n", adap_id,
+				address_data->probe[i + 1]);
+			err = i2c_detect_address(adapter,
+						 address_data->probe[i + 1],
+						 -1, driver);
+			if (err)
+				return err;
+		}
+	}
+
+	/* Stop here if the classes do not match */
+	if (!(adapter->class & driver->class))
+		return 0;
+
+	/* Normal entries are done last, unless shadowed by an ignore entry */
+	for (i = 0; address_data->normal_i2c[i] != I2C_CLIENT_END; i += 1) {
+		int j, ignore;
+
+		ignore = 0;
+		for (j = 0; address_data->ignore[j] != I2C_CLIENT_END;
+		     j += 2) {
+			if ((address_data->ignore[j] == adap_id ||
+			     address_data->ignore[j] == ANY_I2C_BUS)
+			 && address_data->ignore[j + 1]
+			    == address_data->normal_i2c[i]) {
+				dev_dbg(&adapter->dev, "found ignore "
+					"parameter for adapter %d, "
+					"addr 0x%02x\n", adap_id,
+					address_data->ignore[j + 1]);
+				ignore = 1;
+				break;
+			}
+		}
+		if (ignore)
+			continue;
+
+		dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
+			"addr 0x%02x\n", adap_id,
+			address_data->normal_i2c[i]);
+		err = i2c_detect_address(adapter, address_data->normal_i2c[i],
+					 -1, driver);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 struct i2c_client *
 i2c_new_probed_device(struct i2c_adapter *adap,
 		      struct i2c_board_info *info,

-- 
Jean Delvare

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