Extcon: support mutually exclusive relation between cables.
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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/extcon/extcon_class.c b/drivers/extcon/extcon_class.c
index 403933b..3bc4b8a 100644
--- a/drivers/extcon/extcon_class.c
+++ b/drivers/extcon/extcon_class.c
@@ -72,6 +72,39 @@
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)
{
@@ -100,7 +133,7 @@
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)
{
@@ -112,7 +145,7 @@
if (ret == 0)
ret = -EINVAL;
else
- extcon_set_state(edev, state);
+ ret = extcon_set_state(edev, state);
if (ret < 0)
return ret;
@@ -191,7 +224,7 @@
* 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];
@@ -206,6 +239,12 @@
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;
@@ -247,6 +286,8 @@
/* No changes */
spin_unlock_irqrestore(&edev->lock, flags);
}
+
+ return 0;
}
EXPORT_SYMBOL_GPL(extcon_update_state);
@@ -258,9 +299,9 @@
* 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);
@@ -334,8 +375,7 @@
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_);
@@ -511,6 +551,14 @@
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);
@@ -533,6 +581,7 @@
extcon_cleanup(edev, true);
}
+static const char *muex_name = "mutually_exclusive";
static void dummy_sysfs_dev_release(struct device *dev)
{
}
@@ -625,10 +674,58 @@
}
}
+ 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;
@@ -640,6 +737,9 @@
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;
}
@@ -672,6 +772,13 @@
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: