[PATCH 1/3] i2c: append hardware lock with bus lock
From: Ben Dooks <hidden>
Date: 2011-05-02 09:27:44
Also in:
linux-i2c, lkml
Possibly related (same subject, not in this thread)
- 2011-04-28 · Re: [PATCH 1/3] i2c: append hardware lock with bus lock · Haojian Zhuang <haojian.zhuang@gmail.com>
- 2011-04-28 · Re: [PATCH 1/3] i2c: append hardware lock with bus lock · Russell King - ARM Linux <hidden>
- 2011-04-28 · Re: [PATCH 1/3] i2c: append hardware lock with bus lock · Haojian Zhuang <haojian.zhuang@gmail.com>
- 2011-04-28 · Re: [PATCH 1/3] i2c: append hardware lock with bus lock · Jean Delvare <hidden>
- 2011-04-28 · Re: [PATCH 1/3] i2c: append hardware lock with bus lock · Eric Miao <hidden>
On Thu, Apr 28, 2011 at 11:15:44PM +0800, Haojian Zhuang wrote:
Both AP and CP are contained in Marvell PXA910 silicon. These two ARM cores are sharing one pair of I2C pins. In order to keep I2C transaction operated with atomic, hardware lock (RIPC) is required. Because of this, bus lock in AP side can't afford this requirement. Now hardware lock is appended. Signed-off-by: Haojian Zhuang <redacted> Cc: Ben Dooks <ben-linux@fluff.org> Cc: Jean Delvare <redacted>
Right, this looks like a reasonable explanation of what is going on here and if Jean is happy with the core changes I'll look at where the driver change can go.
quoted hunk ↗ jump to hunk
--- drivers/i2c/i2c-core.c | 22 ++++++++++++++++++---- include/linux/i2c.h | 3 +++ 2 files changed, 21 insertions(+), 4 deletions(-)diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 045ba6e..132d46c 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c@@ -448,8 +448,11 @@ void i2c_lock_adapter(struct i2c_adapter *adapter) if (parent) i2c_lock_adapter(parent); - else + else { rt_mutex_lock(&adapter->bus_lock); + if (adapter->hardware_lock) + adapter->hardware_lock(adapter); + } } EXPORT_SYMBOL_GPL(i2c_lock_adapter);@@ -460,11 +463,19 @@ EXPORT_SYMBOL_GPL(i2c_lock_adapter); static int i2c_trylock_adapter(struct i2c_adapter *adapter) { struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); + int ret = 0; if (parent) return i2c_trylock_adapter(parent); - else - return rt_mutex_trylock(&adapter->bus_lock); + else { + ret = rt_mutex_trylock(&adapter->bus_lock); + if (ret && adapter->hardware_trylock) { + ret = adapter->hardware_trylock(adapter); + if (!ret) + i2c_unlock_adapter(adapter); + } + return ret; + } } /**@@ -477,8 +488,11 @@ void i2c_unlock_adapter(struct i2c_adapter *adapter) if (parent) i2c_unlock_adapter(parent); - else + else { + if (adapter->hardware_unlock) + adapter->hardware_unlock(adapter); rt_mutex_unlock(&adapter->bus_lock); + } } EXPORT_SYMBOL_GPL(i2c_unlock_adapter);diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 06a8d9c..f4ef5b0 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h@@ -361,6 +361,9 @@ struct i2c_adapter { /* data fields that are valid for all devices */ struct rt_mutex bus_lock; + void (*hardware_lock)(struct i2c_adapter *); + void (*hardware_unlock)(struct i2c_adapter *); + int (*hardware_trylock)(struct i2c_adapter *); int timeout; /* in jiffies */ int retries;-- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Ben Dooks, ben at fluff.org, http://www.fluff.org/ben/ Large Hadron Colada: A large Pina Colada that makes the universe disappear.