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Subject[PATCH v6 5/5] Extcon: support mutually exclusive relation between cables.
Date
There could be cables that t recannot be attaches simulatenously. Extcon
device drivers may express such information via mutually_exclusive in
struct extcon_dev.

For example, for an extcon device with 16 cables (bits 0 to 15 are
available), if mutually_exclusive = { 0x7, 0xC0, 0x81, 0 }, then, the
following attachments are prohibitted.
{0, 1}
{0, 2}
{1, 2}
{6, 7}
{0, 7}
and every attachment set that are superset of one of the above.
For the detail, please refer to linux/include/linux/extcon.h.
The concept is suggested by NeilBrown <neilb@suse.de>

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

--
Changes from V5:
- Updated sysfs format
---
Documentation/ABI/testing/sysfs-class-extcon | 22 +++++
drivers/extcon/extcon_class.c | 123 ++++++++++++++++++++++++--
include/linux/extcon.h | 28 +++++-
3 files changed, 160 insertions(+), 13 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-class-extcon b/Documentation/ABI/testing/sysfs-class-extcon
index 19b18e9..20ab361 100644
--- a/Documentation/ABI/testing/sysfs-class-extcon
+++ b/Documentation/ABI/testing/sysfs-class-extcon
@@ -15,6 +15,10 @@ Description:
may have both HDMI and Charger attached, or analog audio,
video, and USB cables attached simulteneously.

+ If there are cables mutually exclusive with each other,
+ such binary relations may be expressed with extcon_dev's
+ mutually_exclusive array.
+
What: /sys/class/extcon/.../name
Date: February 2012
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
@@ -73,3 +77,21 @@ Description:
state of cable "x" (integer between 0 and 31) of an extcon
device. The state value is either 0 (detached) or 1
(attached).
+
+What: /sys/class/extcon/.../mutually_exclusive/...
+Date: December 2011
+Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
+Description:
+ Shows the relations of mutually exclusiveness. For example,
+ if the mutually_exclusive array of extcon_dev is
+ {0x3, 0x5, 0xC, 0x0}, the, the output is:
+ # ls mutually_exclusive/
+ 0x3
+ 0x5
+ 0xc
+ #
+
+ Note that mutually_exclusive is a sub-directory of the extcon
+ device and the file names under the mutually_exclusive
+ directory show the mutually-exclusive sets, not the contents
+ of the files.
diff --git a/drivers/extcon/extcon_class.c b/drivers/extcon/extcon_class.c
index 55f19c2..fb8d3a4 100644
--- a/drivers/extcon/extcon_class.c
+++ b/drivers/extcon/extcon_class.c
@@ -69,6 +69,39 @@ struct class *extcon_class;
static LIST_HEAD(extcon_dev_list);
static DEFINE_MUTEX(extcon_dev_list_lock);

+/**
+ * check_mutually_exclusive - Check if new_state violates mutually_exclusive
+ * condition.
+ * @edev: the extcon device
+ * @new_state: new cable attach status for @edev
+ *
+ * Returns 0 if nothing violates. Returns the index + 1 for the first
+ * violated condition.
+ */
+static int check_mutually_exclusive(struct extcon_dev *edev, u32 new_state)
+{
+ int i = 0;
+
+ if (!edev->mutually_exclusive)
+ return 0;
+
+ for (i = 0; edev->mutually_exclusive[i]; i++) {
+ int count = 0, j;
+ u32 correspondants = new_state & edev->mutually_exclusive[i];
+ u32 exp = 1;
+
+ for (j = 0; j < 32; j++) {
+ if (exp & correspondants)
+ count++;
+ if (count > 1)
+ return i + 1;
+ exp <<= 1;
+ }
+ }
+
+ return 0;
+}
+
static ssize_t state_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -97,7 +130,7 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr,
return count;
}

-void extcon_set_state(struct extcon_dev *edev, u32 state);
+int 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)
{
@@ -109,7 +142,7 @@ static ssize_t state_store(struct device *dev, struct device_attribute *attr,
if (ret == 0)
ret = -EINVAL;
else
- extcon_set_state(edev, state);
+ ret = extcon_set_state(edev, state);

if (ret < 0)
return ret;
@@ -188,7 +221,7 @@ static ssize_t cable_state_store(struct device *dev,
* Note that the notifier provides which bits are changed in the state
* variable with the val parameter (second) to the callback.
*/
-void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
+int extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
{
char name_buf[120];
char state_buf[120];
@@ -203,6 +236,12 @@ void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
if (edev->state != ((edev->state & ~mask) | (state & mask))) {
u32 old_state = edev->state;

+ if (check_mutually_exclusive(edev, (edev->state & ~mask) |
+ (state & mask))) {
+ spin_unlock_irqrestore(&edev->lock, flags);
+ return -EPERM;
+ }
+
edev->state &= ~mask;
edev->state |= state & mask;

@@ -244,6 +283,8 @@ void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
/* No changes */
spin_unlock_irqrestore(&edev->lock, flags);
}
+
+ return 0;
}
EXPORT_SYMBOL_GPL(extcon_update_state);

@@ -255,9 +296,9 @@ EXPORT_SYMBOL_GPL(extcon_update_state);
* 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)
+int extcon_set_state(struct extcon_dev *edev, u32 state)
{
- extcon_update_state(edev, 0xffffffff, state);
+ return extcon_update_state(edev, 0xffffffff, state);
}
EXPORT_SYMBOL_GPL(extcon_set_state);

@@ -331,8 +372,7 @@ int extcon_set_cable_state_(struct extcon_dev *edev,
return -EINVAL;

state = cable_state ? (1 << index) : 0;
- extcon_update_state(edev, 1 << index, state);
- return 0;
+ return extcon_update_state(edev, 1 << index, state);
}
EXPORT_SYMBOL_GPL(extcon_set_cable_state_);

@@ -506,6 +546,14 @@ static void extcon_cleanup(struct extcon_dev *edev, bool skip)
if (!skip && get_device(edev->dev)) {
int index;

+ if (edev->mutually_exclusive && edev->max_supported) {
+ for (index = 0; edev->mutually_exclusive[index];
+ index++)
+ kfree(edev->d_attrs_muex[index].attr.name);
+ kfree(edev->d_attrs_muex);
+ kfree(edev->attrs_muex);
+ }
+
for (index = 0; index < edev->max_supported; index++)
kfree(edev->cables[index].attr_g.name);

@@ -528,6 +576,7 @@ static void extcon_dev_release(struct device *dev)
extcon_cleanup(edev, true);
}

+static const char *muex_name = "mutually_exclusive";
static void dummy_sysfs_dev_release(struct device *dev)
{
}
@@ -620,10 +669,58 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
}
}

+ if (edev->max_supported && edev->mutually_exclusive) {
+ char buf[80];
+ char *name;
+
+ /* Count the size of mutually_exclusive array */
+ for (index = 0; edev->mutually_exclusive[index]; index++)
+ ;
+
+ edev->attrs_muex = kzalloc(sizeof(struct attribute *) *
+ (index + 1), GFP_KERNEL);
+ if (!edev->attrs_muex) {
+ ret = -ENOMEM;
+ goto err_muex;
+ }
+
+ edev->d_attrs_muex = kzalloc(sizeof(struct device_attribute) *
+ index, GFP_KERNEL);
+ if (!edev->d_attrs_muex) {
+ ret = -ENOMEM;
+ kfree(edev->attrs_muex);
+ goto err_muex;
+ }
+
+ for (index = 0; edev->mutually_exclusive[index]; index++) {
+ sprintf(buf, "0x%x", edev->mutually_exclusive[index]);
+ name = kzalloc(sizeof(char) * (strlen(buf) + 1),
+ GFP_KERNEL);
+ if (!name) {
+ for (index--; index >= 0; index--) {
+ kfree(edev->d_attrs_muex[index].attr.
+ name);
+ }
+ kfree(edev->d_attrs_muex);
+ kfree(edev->attrs_muex);
+ ret = -ENOMEM;
+ goto err_muex;
+ }
+ strcpy(name, buf);
+ edev->d_attrs_muex[index].attr.name = name;
+ edev->d_attrs_muex[index].attr.mode = 0000;
+ edev->attrs_muex[index] = &edev->d_attrs_muex[index]
+ .attr;
+ }
+ edev->attr_g_muex.name = muex_name;
+ edev->attr_g_muex.attrs = edev->attrs_muex;
+
+ }
+
if (edev->max_supported) {
edev->extcon_dev_type.groups =
kzalloc(sizeof(struct attribute_group *) *
- (edev->max_supported + 1), GFP_KERNEL);
+ (edev->max_supported + 2), GFP_KERNEL);
if (!edev->extcon_dev_type.groups) {
ret = -ENOMEM;
goto err_alloc_groups;
@@ -635,6 +732,9 @@ int extcon_dev_register(struct extcon_dev *edev, struct device *dev)
for (index = 0; index < edev->max_supported; index++)
edev->extcon_dev_type.groups[index] =
&edev->cables[index].attr_g;
+ if (edev->mutually_exclusive)
+ edev->extcon_dev_type.groups[index] =
+ &edev->attr_g_muex;

edev->dev->type = &edev->extcon_dev_type;
}
@@ -662,6 +762,13 @@ err_dev:
if (edev->max_supported)
kfree(edev->extcon_dev_type.groups);
err_alloc_groups:
+ if (edev->max_supported && edev->mutually_exclusive) {
+ for (index = 0; edev->mutually_exclusive[index]; index++)
+ kfree(edev->d_attrs_muex[index].attr.name);
+ kfree(edev->d_attrs_muex);
+ kfree(edev->attrs_muex);
+ }
+err_muex:
for (index = 0; index < edev->max_supported; index++)
kfree(edev->cables[index].attr_g.name);
err_alloc_cables:
diff --git a/include/linux/extcon.h b/include/linux/extcon.h
index 99ff60e..c9e2de8 100644
--- a/include/linux/extcon.h
+++ b/include/linux/extcon.h
@@ -78,6 +78,14 @@ struct extcon_cable;
* @supported_cable Array of supported cable name ending with NULL.
* If supported_cable is NULL, cable name related APIs
* are disabled.
+ * @mutually_exclusive Array of mutually exclusive set of cables that cannot
+ * be attached simultaneously. The array should be
+ * ending with NULL or be NULL (no mutually exclusive
+ * cables). For example, if it is { 0x7, 0x30, 0}, then,
+ * {0, 1}, {0, 1, 2}, {0, 2}, {1, 2}, or {4, 5} cannot
+ * be attached simulataneously. {0x7, 0} is equivalent to
+ * {0x3, 0x6, 0x5, 0}. If it is {0xFFFFFFFF, 0}, there
+ * can be no simultaneous connections.
* @print_name An optional callback to override the method to print the
* name of the extcon device.
* @print_state An optional callback to override the method to print the
@@ -103,6 +111,7 @@ struct extcon_dev {
/* --- Optional user initializing data --- */
const char *name;
const char **supported_cable;
+ const u32 *mutually_exclusive;

/* --- Optional callbacks to override class functions --- */
ssize_t (*print_name)(struct extcon_dev *edev, char *buf);
@@ -119,6 +128,10 @@ struct extcon_dev {
/* /sys/class/extcon/.../cable.n/... */
struct device_type extcon_dev_type;
struct extcon_cable *cables;
+ /* /sys/class/extcon/.../mutually_exclusive/... */
+ struct attribute_group attr_g_muex;
+ struct attribute **attrs_muex;
+ struct device_attribute *d_attrs_muex;
};

/**
@@ -179,8 +192,8 @@ static inline u32 extcon_get_state(struct extcon_dev *edev)
return edev->state;
}

-extern void extcon_set_state(struct extcon_dev *edev, u32 state);
-extern void extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state);
+extern int extcon_set_state(struct extcon_dev *edev, u32 state);
+extern int extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state);

/*
* get/set_cable_state access each bit of the 32b encoded state value.
@@ -235,11 +248,16 @@ static inline u32 extcon_get_state(struct extcon_dev *edev)
return 0;
}

-static inline void extcon_set_state(struct extcon_dev *edev, u32 state) { }
+static inline int extcon_set_state(struct extcon_dev *edev, u32 state)
+{
+ return 0;
+}

-static inline void extcon_update_state(struct extcon_dev *edev, u32 mask,
+static inline int extcon_update_state(struct extcon_dev *edev, u32 mask,
u32 state)
-{ }
+{
+ return 0;
+}

static inline int extcon_find_cable_index(struct extcon_dev *edev,
const char *cable_name)
--
1.7.4.1


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