Extcon: support multiple states at a device.

One switch device (e.g., MUIC(MAX8997, MAX77686, ...), and some 30-pin
devices) may have multiple cables attached. For example, one
30-pin port may inhabit a USB cable, an HDMI cable, and a mic.
Thus, one switch device requires multiple state bits each representing
a type of cable.

For such purpose, we use the 32bit state variable; thus, up to 32
different type of cables may be defined for a switch device. The list of
possible cables is defined by the array of cable names in the switch_dev
struct given to the class.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

--
Changes from V7
- Bugfixed in _call_per_cable() (incorrect nb) (Chanwoo Choi)
- Compiler error in header for !CONFIG_EXTCON (Chanwoo Choi)

Changes from V5
- Sysfs style reformed: subdirectory per cable.
- Updated standard cable names
- Removed unnecessary printf
- Bugfixes after testing

Changes from V4
- Bugfixes after more testing at Exynos4412 boards with userspace
  processses.

Changes from V3
- Bugfixes after more testing at Exynos4412 boards.

Changes from V2
- State can be stored by user
- Documentation updated

Changes from RFC
- Switch is renamed to extcon
- Added kerneldoc comments
- Added APIs to support "standard" cable names
- Added helper APIs to support notifier block registration with cable
  name.
- Regrouped function list in the header file.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 426 insertions, 13 deletions

diff --git a/drivers/extcon/extcon_class.c b/drivers/extcon/extcon_class.c
index 83a088f1edc4..403933bc3e9c 100644
--- a/drivers/extcon/extcon_class.c
+++ b/drivers/extcon/extcon_class.c
@@ -31,6 +31,39 @@
 #include <linux/extcon.h>
 #include <linux/slab.h>
 
+/*
+ * extcon_cable_name suggests the standard cable names for commonly used
+ * cable types.
+ *
+ * However, please do not use extcon_cable_name directly for extcon_dev
+ * struct's supported_cable pointer unless your device really supports
+ * every single port-type of the following cable names. Please choose cable
+ * names that are actually used in your extcon device.
+ */
+const char *extcon_cable_name[] = {
+        [EXTCON_USB]            = "USB",
+        [EXTCON_USB_HOST]       = "USB-Host",
+        [EXTCON_TA]             = "TA",
+        [EXTCON_FAST_CHARGER]   = "Fast-charger",
+        [EXTCON_SLOW_CHARGER]   = "Slow-charger",
+        [EXTCON_CHARGE_DOWNSTREAM]      = "Charge-downstream",
+        [EXTCON_HDMI]           = "HDMI",
+        [EXTCON_MHL]            = "MHL",
+        [EXTCON_DVI]            = "DVI",
+        [EXTCON_VGA]            = "VGA",
+        [EXTCON_DOCK]           = "Dock",
+        [EXTCON_LINE_IN]        = "Line-in",
+        [EXTCON_LINE_OUT]       = "Line-out",
+        [EXTCON_MIC_IN]         = "Microphone",
+        [EXTCON_HEADPHONE_OUT]  = "Headphone",
+        [EXTCON_SPDIF_IN]       = "SPDIF-in",
+        [EXTCON_SPDIF_OUT]      = "SPDIF-out",
+        [EXTCON_VIDEO_IN]       = "Video-in",
+        [EXTCON_VIDEO_OUT]      = "Video-out",
+
+        NULL,
+};
+
 struct class *extcon_class;
 #if defined(CONFIG_ANDROID) && !defined(CONFIG_ANDROID_SWITCH)
 static struct class_compat *switch_class;
@@ -42,6 +75,7 @@ static DEFINE_MUTEX(extcon_dev_list_lock);
 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
                           char *buf)
 {
+        int i, count = 0;
         struct extcon_dev *edev = (struct extcon_dev *) dev_get_drvdata(dev);
 
         if (edev->print_state) {
@@ -51,7 +85,39 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
                         return ret;
                 /* Use default if failed */
         }
-        return sprintf(buf, "%u\n", edev->state);
+
+        if (edev->max_supported == 0)
+                return sprintf(buf, "%u\n", edev->state);
+
+        for (i = 0; i < SUPPORTED_CABLE_MAX; i++) {
+                if (!edev->supported_cable[i])
+                        break;
+                count += sprintf(buf + count, "%s=%d\n",
+                                 edev->supported_cable[i],
+                                 !!(edev->state & (1 << i)));
+        }
+
+        return count;
+}
+
+void extcon_set_state(struct extcon_dev *edev, u32 state);
+static ssize_t state_store(struct device *dev, struct device_attribute *attr,
+                           const char *buf, size_t count)
+{
+        u32 state;
+        ssize_t ret = 0;
+        struct extcon_dev *edev = (struct extcon_dev *) dev_get_drvdata(dev);
+
+        ret = sscanf(buf, "0x%x", &state);
+        if (ret == 0)
+                ret = -EINVAL;
+        else
+                extcon_set_state(edev, state);
+
+        if (ret < 0)
+                return ret;
+
+        return count;
 }
 
 static ssize_t name_show(struct device *dev, struct device_attribute *attr,
@@ -69,9 +135,52 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
         return sprintf(buf, "%s\n", dev_name(edev->dev));
 }
 
+static ssize_t cable_name_show(struct device *dev,
+                               struct device_attribute *attr, char *buf)
+{
+        struct extcon_cable *cable = container_of(attr, struct extcon_cable,
+                                                  attr_name);
+
+        return sprintf(buf, "%s\n",
+                       cable->edev->supported_cable[cable->cable_index]);
+}
+
+static ssize_t cable_state_show(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        struct extcon_cable *cable = container_of(attr, struct extcon_cable,
+                                                  attr_state);
+
+        return sprintf(buf, "%d\n",
+                       extcon_get_cable_state_(cable->edev,
+                                               cable->cable_index));
+}
+
+static ssize_t cable_state_store(struct device *dev,
+                                 struct device_attribute *attr, const char *buf,
+                                 size_t count)
+{
+        struct extcon_cable *cable = container_of(attr, struct extcon_cable,
+                                                  attr_state);
+        int ret, state;
+
+        ret = sscanf(buf, "%d", &state);
+        if (ret == 0)
+                ret = -EINVAL;
+        else
+                ret = extcon_set_cable_state_(cable->edev, cable->cable_index,
+                                              state);
+
+        if (ret < 0)
+                return ret;
+        return count;
+}
+
 /**
- * extcon_set_state() - Set the cable attach states of the extcon device.
+ * extcon_update_state() - Update the cable attach states of the extcon device
+ *                      only for the masked bits.
  * @edev:       the extcon device
+ * @mask:       the bit mask to designate updated bits.
  * @state:      new cable attach status for @edev
  *
  * Changing the state sends uevent with environment variable containing
@@ -79,10 +188,10 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr,
  * Tizen uses this format for extcon device to get events from ports.
  * Android uses this format as well.
  *
- * Note that notifier provides the which bits are changes in the state
- * variable with "val" to the callback.
+ * Note that the notifier provides which bits are changed in the state
+ * variable with the val parameter (second) to the callback.
  */
-void extcon_set_state(struct extcon_dev *edev, u32 state)
+void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
 {
         char name_buf[120];
         char state_buf[120];
@@ -90,15 +199,20 @@ void extcon_set_state(struct extcon_dev *edev, u32 state)
         char *envp[3];
         int env_offset = 0;
         int length;
-        u32 old_state = edev->state;
+        unsigned long flags;
 
-        if (edev->state != state) {
-                edev->state = state;
+        spin_lock_irqsave(&edev->lock, flags);
 
-                raw_notifier_call_chain(&edev->nh, old_state ^ edev->state,
-                                        edev);
+        if (edev->state != ((edev->state & ~mask) | (state & mask))) {
+                u32 old_state = edev->state;
 
-                prop_buf = (char *)get_zeroed_page(GFP_KERNEL);
+                edev->state &= ~mask;
+                edev->state |= state & mask;
+
+                raw_notifier_call_chain(&edev->nh, old_state, edev);
+
+                /* This could be in interrupt handler */
+                prop_buf = (char *)get_zeroed_page(GFP_ATOMIC);
                 if (prop_buf) {
                         length = name_show(edev->dev, NULL, prop_buf);
                         if (length > 0) {
@@ -117,17 +231,132 @@ void extcon_set_state(struct extcon_dev *edev, u32 state)
                                 envp[env_offset++] = state_buf;
                         }
                         envp[env_offset] = NULL;
+                        /* Unlock early before uevent */
+                        spin_unlock_irqrestore(&edev->lock, flags);
+
                         kobject_uevent_env(&edev->dev->kobj, KOBJ_CHANGE, envp);
                         free_page((unsigned long)prop_buf);
                 } else {
+                        /* Unlock early before uevent */
+                        spin_unlock_irqrestore(&edev->lock, flags);
+
                         dev_err(edev->dev, "out of memory in extcon_set_state\n");
                         kobject_uevent(&edev->dev->kobj, KOBJ_CHANGE);
                 }
+        } else {
+                /* No changes */
+                spin_unlock_irqrestore(&edev->lock, flags);
         }
 }
+EXPORT_SYMBOL_GPL(extcon_update_state);
+
+/**
+ * extcon_set_state() - Set the cable attach states of the extcon device.
+ * @edev:       the extcon device
+ * @state:      new cable attach status for @edev
+ *
+ * Note that notifier provides which bits are changed in the state
+ * variable with the val parameter (second) to the callback.
+ */
+void extcon_set_state(struct extcon_dev *edev, u32 state)
+{
+        extcon_update_state(edev, 0xffffffff, state);
+}
 EXPORT_SYMBOL_GPL(extcon_set_state);
 
 /**
+ * extcon_find_cable_index() - Get the cable index based on the cable name.
+ * @edev:       the extcon device that has the cable.
+ * @cable_name: cable name to be searched.
+ *
+ * Note that accessing a cable state based on cable_index is faster than
+ * cable_name because using cable_name induces a loop with strncmp().
+ * Thus, when get/set_cable_state is repeatedly used, using cable_index
+ * is recommended.
+ */
+int extcon_find_cable_index(struct extcon_dev *edev, const char *cable_name)
+{
+        int i;
+
+        if (edev->supported_cable) {
+                for (i = 0; edev->supported_cable[i]; i++) {
+                        if (!strncmp(edev->supported_cable[i],
+                                cable_name, CABLE_NAME_MAX))
+                                return i;
+                }
+        }
+
+        return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(extcon_find_cable_index);
+
+/**
+ * extcon_get_cable_state_() - Get the status of a specific cable.
+ * @edev:       the extcon device that has the cable.
+ * @index:      cable index that can be retrieved by extcon_find_cable_index().
+ */
+int extcon_get_cable_state_(struct extcon_dev *edev, int index)
+{
+        if (index < 0 || (edev->max_supported && edev->max_supported <= index))
+                return -EINVAL;
+
+        return !!(edev->state & (1 << index));
+}
+EXPORT_SYMBOL_GPL(extcon_get_cable_state_);
+
+/**
+ * extcon_get_cable_state() - Get the status of a specific cable.
+ * @edev:       the extcon device that has the cable.
+ * @cable_name: cable name.
+ *
+ * Note that this is slower than extcon_get_cable_state_.
+ */
+int extcon_get_cable_state(struct extcon_dev *edev, const char *cable_name)
+{
+        return extcon_get_cable_state_(edev, extcon_find_cable_index
+                                                (edev, cable_name));
+}
+EXPORT_SYMBOL_GPL(extcon_get_cable_state);
+
+/**
+ * extcon_get_cable_state_() - Set the status of a specific cable.
+ * @edev:       the extcon device that has the cable.
+ * @index:      cable index that can be retrieved by extcon_find_cable_index().
+ * @cable_state:        the new cable status. The default semantics is
+ *                      true: attached / false: detached.
+ */
+int extcon_set_cable_state_(struct extcon_dev *edev,
+                        int index, bool cable_state)
+{
+        u32 state;
+
+        if (index < 0 || (edev->max_supported && edev->max_supported <= index))
+                return -EINVAL;
+
+        state = cable_state ? (1 << index) : 0;
+        extcon_update_state(edev, 1 << index, state);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(extcon_set_cable_state_);
+
+/**
+ * extcon_get_cable_state() - Set the status of a specific cable.
+ * @edev:       the extcon device that has the cable.
+ * @cable_name: cable name.
+ * @cable_state:        the new cable status. The default semantics is
+ *                      true: attached / false: detached.
+ *
+ * Note that this is slower than extcon_set_cable_state_.
+ */
+int extcon_set_cable_state(struct extcon_dev *edev,
+                        const char *cable_name, bool cable_state)
+{
+        return extcon_set_cable_state_(edev, extcon_find_cable_index
+                                        (edev, cable_name), cable_state);
+}
+EXPORT_SYMBOL_GPL(extcon_set_cable_state);
+
+/**
  * extcon_get_extcon_dev() - Get the extcon device instance from the name
  * @extcon_name:        The extcon name provided with extcon_dev_register()
  */
@@ -147,11 +376,88 @@ out:
 }
 EXPORT_SYMBOL_GPL(extcon_get_extcon_dev);
 
+static int _call_per_cable(struct notifier_block *nb, unsigned long val,
+                           void *ptr)
+{
+        struct extcon_specific_cable_nb *obj = container_of(nb,
+                        struct extcon_specific_cable_nb, internal_nb);
+        struct extcon_dev *edev = ptr;
+
+        if ((val & (1 << obj->cable_index)) !=
+            (edev->state & (1 << obj->cable_index))) {
+                obj->previous_value = val;
+                return obj->user_nb->notifier_call(obj->user_nb, val, ptr);
+        }
+
+        return NOTIFY_OK;
+}
+
+/**
+ * extcon_register_interest() - Register a notifier for a state change of a
+ *                            specific cable, not a entier set of cables of a
+ *                            extcon device.
+ * @obj:        an empty extcon_specific_cable_nb object to be returned.
+ * @extcon_name:        the name of extcon device.
+ * @cable_name:         the target cable name.
+ * @nb:         the notifier block to get notified.
+ *
+ * Provide an empty extcon_specific_cable_nb. extcon_register_interest() sets
+ * the struct for you.
+ *
+ * extcon_register_interest is a helper function for those who want to get
+ * notification for a single specific cable's status change. If a user wants
+ * to get notification for any changes of all cables of a extcon device,
+ * he/she should use the general extcon_register_notifier().
+ *
+ * Note that the second parameter given to the callback of nb (val) is
+ * "old_state", not the current state. The current state can be retrieved
+ * by looking at the third pameter (edev pointer)'s state value.
+ */
+int extcon_register_interest(struct extcon_specific_cable_nb *obj,
+                             const char *extcon_name, const char *cable_name,
+                             struct notifier_block *nb)
+{
+        if (!obj || !extcon_name || !cable_name || !nb)
+                return -EINVAL;
+
+        obj->edev = extcon_get_extcon_dev(extcon_name);
+        if (!obj->edev)
+                return -ENODEV;
+
+        obj->cable_index = extcon_find_cable_index(obj->edev, cable_name);
+        if (obj->cable_index < 0)
+                return -ENODEV;
+
+        obj->user_nb = nb;
+
+        obj->internal_nb.notifier_call = _call_per_cable;
+
+        return raw_notifier_chain_register(&obj->edev->nh, &obj->internal_nb);
+}
+
+/**
+ * extcon_unregister_interest() - Unregister the notifier registered by
+ *                              extcon_register_interest().
+ * @obj:        the extcon_specific_cable_nb object returned by
+ *              extcon_register_interest().
+ */
+int extcon_unregister_interest(struct extcon_specific_cable_nb *obj)
+{
+        if (!obj)
+                return -EINVAL;
+
+        return raw_notifier_chain_unregister(&obj->edev->nh, &obj->internal_nb);
+}
+
 /**
  * extcon_register_notifier() - Register a notifee to get notified by
  *                            any attach status changes from the extcon.
  * @edev:       the extcon device.
  * @nb:         a notifier block to be registered.
+ *
+ * Note that the second parameter given to the callback of nb (val) is
+ * "old_state", not the current state. The current state can be retrieved
+ * by looking at the third pameter (edev pointer)'s state value.
  */
 int extcon_register_notifier(struct extcon_dev *edev,
                         struct notifier_block *nb)
@@ -173,8 +479,9 @@ int extcon_unregister_notifier(struct extcon_dev *edev,
 EXPORT_SYMBOL_GPL(extcon_unregister_notifier);
 
 static struct device_attribute extcon_attrs[] = {
-        __ATTR_RO(state),
+        __ATTR(state, S_IRUGO | S_IWUSR, state_show, state_store),
         __ATTR_RO(name),
+        __ATTR_NULL,
 };
 
 static int create_extcon_class(void)
@@ -202,6 +509,16 @@ static void extcon_cleanup(struct extcon_dev *edev, bool skip)
         mutex_unlock(&extcon_dev_list_lock);
 
         if (!skip && get_device(edev->dev)) {
+                int index;
+
+                for (index = 0; index < edev->max_supported; index++)
+                        kfree(edev->cables[index].attr_g.name);
+
+                if (edev->max_supported) {
+                        kfree(edev->extcon_dev_type.groups);
+                        kfree(edev->cables);
+                }
+
                 device_unregister(edev->dev);
                 put_device(edev->dev);
         }
@@ -216,6 +533,10 @@ static void extcon_dev_release(struct device *dev)
         extcon_cleanup(edev, true);
 }
 
+static void dummy_sysfs_dev_release(struct device *dev)
+{
+}
+
 /**
  * extcon_dev_register() - Register a new extcon device
  * @edev        : the new extcon device (should be allocated before calling)
@@ -228,7 +549,7 @@ static void extcon_dev_release(struct device *dev)
  */
 int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
 {
-        int ret;
+        int ret, index = 0;
 
         if (!extcon_class) {
                 ret = create_extcon_class();
@@ -236,12 +557,93 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
                         return ret;
         }
 
+        if (edev->supported_cable) {
+                /* Get size of array */
+                for (index = 0; edev->supported_cable[index]; index++)
+                        ;
+                edev->max_supported = index;
+        } else {
+                edev->max_supported = 0;
+        }
+
+        if (index > SUPPORTED_CABLE_MAX) {
+                dev_err(edev->dev, "extcon: maximum number of supported cables exceeded.\n");
+                return -EINVAL;
+        }
+
         edev->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
         edev->dev->parent = dev;
         edev->dev->class = extcon_class;
         edev->dev->release = extcon_dev_release;
 
         dev_set_name(edev->dev, edev->name ? edev->name : dev_name(dev));
+
+        if (edev->max_supported) {
+                char buf[10];
+                char *str;
+                struct extcon_cable *cable;
+
+                edev->cables = kzalloc(sizeof(struct extcon_cable) *
+                                       edev->max_supported, GFP_KERNEL);
+                if (!edev->cables) {
+                        ret = -ENOMEM;
+                        goto err_sysfs_alloc;
+                }
+                for (index = 0; index < edev->max_supported; index++) {
+                        cable = &edev->cables[index];
+
+                        snprintf(buf, 10, "cable.%d", index);
+                        str = kzalloc(sizeof(char) * (strlen(buf) + 1),
+                                      GFP_KERNEL);
+                        if (!str) {
+                                for (index--; index >= 0; index--) {
+                                        cable = &edev->cables[index];
+                                        kfree(cable->attr_g.name);
+                                }
+                                ret = -ENOMEM;
+
+                                goto err_alloc_cables;
+                        }
+                        strcpy(str, buf);
+
+                        cable->edev = edev;
+                        cable->cable_index = index;
+                        cable->attrs[0] = &cable->attr_name.attr;
+                        cable->attrs[1] = &cable->attr_state.attr;
+                        cable->attrs[2] = NULL;
+                        cable->attr_g.name = str;
+                        cable->attr_g.attrs = cable->attrs;
+
+                        cable->attr_name.attr.name = "name";
+                        cable->attr_name.attr.mode = 0444;
+                        cable->attr_name.show = cable_name_show;
+
+                        cable->attr_state.attr.name = "state";
+                        cable->attr_state.attr.mode = 0644;
+                        cable->attr_state.show = cable_state_show;
+                        cable->attr_state.store = cable_state_store;
+                }
+        }
+
+        if (edev->max_supported) {
+                edev->extcon_dev_type.groups =
+                        kzalloc(sizeof(struct attribute_group *) *
+                                (edev->max_supported + 1), GFP_KERNEL);
+                if (!edev->extcon_dev_type.groups) {
+                        ret = -ENOMEM;
+                        goto err_alloc_groups;
+                }
+
+                edev->extcon_dev_type.name = dev_name(edev->dev);
+                edev->extcon_dev_type.release = dummy_sysfs_dev_release;
+
+                for (index = 0; index < edev->max_supported; index++)
+                        edev->extcon_dev_type.groups[index] =
+                                &edev->cables[index].attr_g;
+
+                edev->dev->type = &edev->extcon_dev_type;
+        }
+
         ret = device_register(edev->dev);
         if (ret) {
                 put_device(edev->dev);
@@ -253,6 +655,8 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
                                                dev);
 #endif /* CONFIG_ANDROID && !defined(CONFIG_ANDROID_SWITCH) */
 
+        spin_lock_init(&edev->lock);
+
         RAW_INIT_NOTIFIER_HEAD(&edev->nh);
 
         dev_set_drvdata(edev->dev, edev);
@@ -265,6 +669,15 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
         return 0;
 
 err_dev:
+        if (edev->max_supported)
+                kfree(edev->extcon_dev_type.groups);
+err_alloc_groups:
+        for (index = 0; index < edev->max_supported; index++)
+                kfree(edev->cables[index].attr_g.name);
+err_alloc_cables:
+        if (edev->max_supported)
+                kfree(edev->cables);
+err_sysfs_alloc:
         kfree(edev->dev);
         return ret;
 }