@@ -16,6 +16,7 @@
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
+#include <linux/lockdep.h>
#define ATR_MAX_ADAPTERS 100 /* Just a sanity limit */
#define ATR_MAX_SYMLINK_LEN 11 /* Longest name is 10 chars: "channel-99" */
@@ -27,9 +28,17 @@
* @alias: I2C alias address assigned by the driver.
* This is the address that will be used to issue I2C transactions
* on the parent (physical) bus.
+ * @fixed: Alias pair cannot be replaced during dynamic address attachment.
+ * This flag is necessary for situations where a single I2C transaction
+ * contains more distinct target addresses than the ATR channel can handle.
+ * It marks addresses that have already been attached to an alias so
+ * that their alias pair is not evicted by a subsequent address in the same
+ * transaction.
+ *
*/
struct i2c_atr_alias_pair {
struct list_head node;
+ bool fixed;
u16 addr;
u16 alias;
};
@@ -58,6 +67,7 @@ struct i2c_atr_alias_pool {
* @adap: The &struct i2c_adapter for the channel
* @atr: The parent I2C ATR
* @chan_id: The ID of this channel
+ * @alias_pairs_lock: Mutex protecting @alias_pairs
* @alias_pairs: List of @struct i2c_atr_alias_pair containing the
* assigned aliases
* @alias_pool: Pool of available client aliases
@@ -71,6 +81,8 @@ struct i2c_atr_chan {
struct i2c_atr *atr;
u32 chan_id;
+ /* Lock alias_pairs during attach/detach */
+ struct mutex alias_pairs_lock;
struct list_head alias_pairs;
struct i2c_atr_alias_pool *alias_pool;
@@ -155,16 +167,132 @@ static void i2c_atr_free_alias_pool(struct i2c_atr_alias_pool *alias_pool)
kfree(alias_pool);
}
+/* Must be called with alias_pairs_lock held */
+static struct i2c_atr_alias_pair *i2c_atr_create_c2a(struct i2c_atr_chan *chan,
+ u16 alias, u16 addr)
+{
+ struct i2c_atr_alias_pair *c2a;
+
+ lockdep_assert_held(&chan->alias_pairs_lock);
+
+ c2a = kzalloc(sizeof(*c2a), GFP_KERNEL);
+ if (!c2a)
+ return NULL;
+
+ c2a->addr = addr;
+ c2a->alias = alias;
+
+ list_add(&c2a->node, &chan->alias_pairs);
+
+ return c2a;
+}
+
+/* Must be called with alias_pairs_lock held */
+static void i2c_atr_destroy_c2a(struct i2c_atr_alias_pair **pc2a)
+{
+ list_del(&(*pc2a)->node);
+ kfree(*pc2a);
+ *pc2a = NULL;
+}
+
+static int i2c_atr_reserve_alias(struct i2c_atr_alias_pool *alias_pool)
+{
+ unsigned long idx;
+ u16 alias;
+
+ spin_lock(&alias_pool->lock);
+
+ idx = find_first_zero_bit(alias_pool->use_mask, alias_pool->size);
+ if (idx >= alias_pool->size) {
+ spin_unlock(&alias_pool->lock);
+ return -EBUSY;
+ }
+
+ set_bit(idx, alias_pool->use_mask);
+
+ alias = alias_pool->aliases[idx];
+
+ spin_unlock(&alias_pool->lock);
+ return alias;
+}
+
+static void i2c_atr_release_alias(struct i2c_atr_alias_pool *alias_pool, u16 alias)
+{
+ unsigned int idx;
+
+ spin_lock(&alias_pool->lock);
+
+ for (idx = 0; idx < alias_pool->size; ++idx) {
+ if (alias_pool->aliases[idx] == alias) {
+ clear_bit(idx, alias_pool->use_mask);
+ spin_unlock(&alias_pool->lock);
+ return;
+ }
+ }
+
+ spin_unlock(&alias_pool->lock);
+}
+
+/* Must be called with alias_pairs_lock held */
static struct i2c_atr_alias_pair *
-i2c_atr_find_mapping_by_addr(const struct list_head *list, u16 phys_addr)
+i2c_atr_find_mapping_by_addr(struct i2c_atr_chan *chan, u16 addr)
{
+ struct i2c_atr *atr = chan->atr;
struct i2c_atr_alias_pair *c2a;
+ struct list_head *alias_pairs;
+ u16 alias;
+ int ret;
+
+ lockdep_assert_held(&chan->alias_pairs_lock);
- list_for_each_entry(c2a, list, node) {
- if (c2a->addr == phys_addr)
+ alias_pairs = &chan->alias_pairs;
+
+ list_for_each_entry(c2a, alias_pairs, node) {
+ if (c2a->addr == addr)
return c2a;
}
+ ret = i2c_atr_reserve_alias(chan->alias_pool);
+ if (ret < 0) {
+ // If no free aliases are left, replace an existing one
+ if (unlikely(list_empty(alias_pairs)))
+ return NULL;
+
+ list_for_each_entry_reverse(c2a, alias_pairs, node)
+ if (!c2a->fixed)
+ break;
+
+ if (c2a->fixed)
+ return NULL;
+
+ atr->ops->detach_addr(atr, chan->chan_id, c2a->addr);
+ c2a->addr = addr;
+
+ // Move updated entry to beginning of list
+ list_move(&c2a->node, alias_pairs);
+
+ alias = c2a->alias;
+ } else {
+ alias = ret;
+
+ c2a = i2c_atr_create_c2a(chan, alias, addr);
+ if (!c2a)
+ goto err_release_alias;
+ }
+
+ ret = atr->ops->attach_addr(atr, chan->chan_id, c2a->addr, c2a->alias);
+ if (ret) {
+ dev_err(atr->dev, "failed to attach 0x%02x on channel %d: err %d\n",
+ addr, chan->chan_id, ret);
+ goto err_del_c2a;
+ }
+
+ return c2a;
+
+err_del_c2a:
+ i2c_atr_destroy_c2a(&c2a);
+err_release_alias:
+ i2c_atr_release_alias(chan->alias_pool, alias);
return NULL;
}
@@ -180,7 +308,7 @@ static int i2c_atr_map_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs,
{
struct i2c_atr *atr = chan->atr;
static struct i2c_atr_alias_pair *c2a;
- int i;
+ int i, ret = 0;
/* Ensure we have enough room to save the original addresses */
if (unlikely(chan->orig_addrs_size < num)) {
@@ -196,11 +324,13 @@ static int i2c_atr_map_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs,
chan->orig_addrs_size = num;
}
+ mutex_lock(&chan->alias_pairs_lock);
+
for (i = 0; i < num; i++) {
chan->orig_addrs[i] = msgs[i].addr;
- c2a = i2c_atr_find_mapping_by_addr(&chan->alias_pairs,
- msgs[i].addr);
+ c2a = i2c_atr_find_mapping_by_addr(chan, msgs[i].addr);
+
if (!c2a) {
dev_err(atr->dev, "client 0x%02x not mapped!\n",
msgs[i].addr);
@@ -208,13 +338,19 @@ static int i2c_atr_map_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs,
while (i--)
msgs[i].addr = chan->orig_addrs[i];
- return -ENXIO;
+ ret = -ENXIO;
+ goto out_unlock;
}
+ // Prevent c2a from being overwritten by another client in this transaction
+ c2a->fixed = true;
+
msgs[i].addr = c2a->alias;
}
- return 0;
+out_unlock:
+ mutex_unlock(&chan->alias_pairs_lock);
+ return ret;
}
/*
@@ -227,10 +363,24 @@ static int i2c_atr_map_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs,
static void i2c_atr_unmap_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs,
int num)
{
+ struct i2c_atr_alias_pair *c2a;
int i;
for (i = 0; i < num; i++)
msgs[i].addr = chan->orig_addrs[i];
+
+ mutex_lock(&chan->alias_pairs_lock);
+
+ if (unlikely(list_empty(&chan->alias_pairs)))
+ goto out_unlock;
+
+ // unfix c2a entries so that subsequent transfers can reuse their aliases
+ list_for_each_entry(c2a, &chan->alias_pairs, node) {
+ c2a->fixed = false;
+ }
+
+out_unlock:
+ mutex_unlock(&chan->alias_pairs_lock);
}
static int i2c_atr_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
@@ -268,14 +418,23 @@ static int i2c_atr_smbus_xfer(struct i2c_adapter *adap, u16 addr,
struct i2c_atr *atr = chan->atr;
struct i2c_adapter *parent = atr->parent;
struct i2c_atr_alias_pair *c2a;
+ u16 alias;
+
+ mutex_lock(&chan->alias_pairs_lock);
+
+ c2a = i2c_atr_find_mapping_by_addr(chan, addr);
- c2a = i2c_atr_find_mapping_by_addr(&chan->alias_pairs, addr);
if (!c2a) {
dev_err(atr->dev, "client 0x%02x not mapped!\n", addr);
+ mutex_unlock(&chan->alias_pairs_lock);
return -ENXIO;
}
- return i2c_smbus_xfer(parent, c2a->alias, flags, read_write, command,
+ alias = c2a->alias;
+
+ mutex_unlock(&chan->alias_pairs_lock);
+
+ return i2c_smbus_xfer(parent, alias, flags, read_write, command,
size, data);
}
@@ -317,44 +476,6 @@ static const struct i2c_lock_operations i2c_atr_lock_ops = {
.unlock_bus = i2c_atr_unlock_bus,
};
-static int i2c_atr_reserve_alias(struct i2c_atr_alias_pool *alias_pool)
-{
- unsigned long idx;
- u16 alias;
-
- spin_lock(&alias_pool->lock);
-
- idx = find_first_zero_bit(alias_pool->use_mask, alias_pool->size);
- if (idx >= alias_pool->size) {
- spin_unlock(&alias_pool->lock);
- return -EBUSY;
- }
-
- set_bit(idx, alias_pool->use_mask);
-
- alias = alias_pool->aliases[idx];
-
- spin_unlock(&alias_pool->lock);
- return alias;
-}
-
-static void i2c_atr_release_alias(struct i2c_atr_alias_pool *alias_pool, u16 alias)
-{
- unsigned int idx;
-
- spin_lock(&alias_pool->lock);
-
- for (idx = 0; idx < alias_pool->size; ++idx) {
- if (alias_pool->aliases[idx] == alias) {
- clear_bit(idx, alias_pool->use_mask);
- spin_unlock(&alias_pool->lock);
- return;
- }
- }
-
- spin_unlock(&alias_pool->lock);
-}
-
static int i2c_atr_attach_addr(struct i2c_adapter *adapter,
u16 addr)
{
@@ -372,7 +493,9 @@ static int i2c_atr_attach_addr(struct i2c_adapter *adapter,
alias = ret;
- c2a = kzalloc(sizeof(*c2a), GFP_KERNEL);
+ mutex_lock(&chan->alias_pairs_lock);
+
+ c2a = i2c_atr_create_c2a(chan, alias, addr);
if (!c2a) {
ret = -ENOMEM;
goto err_release_alias;
@@ -380,22 +503,19 @@ static int i2c_atr_attach_addr(struct i2c_adapter *adapter,
ret = atr->ops->attach_addr(atr, chan->chan_id, addr, alias);
if (ret)
- goto err_free;
+ goto err_del_c2a;
dev_dbg(atr->dev, "chan%u: using alias 0x%02x for addr 0x%02x\n",
chan->chan_id, alias, addr);
- c2a->addr = addr;
- c2a->alias = alias;
- list_add(&c2a->node, &chan->alias_pairs);
-
- return 0;
+ goto out_unlock;
-err_free:
- kfree(c2a);
+err_del_c2a:
+ i2c_atr_destroy_c2a(&c2a);
err_release_alias:
i2c_atr_release_alias(chan->alias_pool, alias);
-
+out_unlock:
+ mutex_unlock(&chan->alias_pairs_lock);
return ret;
}
@@ -408,21 +528,25 @@ static void i2c_atr_detach_addr(struct i2c_adapter *adapter,
atr->ops->detach_addr(atr, chan->chan_id, addr);
- c2a = i2c_atr_find_mapping_by_addr(&chan->alias_pairs, addr);
+ mutex_lock(&chan->alias_pairs_lock);
+
+ c2a = i2c_atr_find_mapping_by_addr(chan, addr);
if (!c2a) {
/* This should never happen */
dev_warn(atr->dev, "Unable to find address mapping\n");
+ mutex_unlock(&chan->alias_pairs_lock);
return;
}
+ mutex_unlock(&chan->alias_pairs_lock);
+
i2c_atr_release_alias(chan->alias_pool, c2a->alias);
dev_dbg(atr->dev,
"chan%u: detached alias 0x%02x from addr 0x%02x\n",
chan->chan_id, c2a->alias, addr);
- list_del(&c2a->node);
- kfree(c2a);
+ i2c_atr_destroy_c2a(&c2a);
}
static int i2c_atr_bus_notifier_call(struct notifier_block *nb,
@@ -633,6 +757,7 @@ int i2c_atr_add_adapter(struct i2c_atr *atr, struct i2c_atr_adap_desc *desc)
chan->atr = atr;
chan->chan_id = chan_id;
INIT_LIST_HEAD(&chan->alias_pairs);
+ mutex_init(&chan->alias_pairs_lock);
mutex_init(&chan->orig_addrs_lock);
snprintf(chan->adap.name, sizeof(chan->adap.name), "i2c-%d-atr-%d",
@@ -709,6 +834,7 @@ int i2c_atr_add_adapter(struct i2c_atr *atr, struct i2c_atr_adap_desc *desc)
err_fwnode_put:
fwnode_handle_put(dev_fwnode(&chan->adap.dev));
mutex_destroy(&chan->orig_addrs_lock);
+ mutex_destroy(&chan->alias_pairs_lock);
kfree(chan);
return ret;
}
@@ -745,6 +871,7 @@ void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id)
fwnode_handle_put(fwnode);
mutex_destroy(&chan->orig_addrs_lock);
+ mutex_destroy(&chan->alias_pairs_lock);
kfree(chan->orig_addrs);
kfree(chan);
}