From eef5ba1aa148ca5e6deb1e0aa1de797fa4e12cb7 Mon Sep 17 00:00:00 2001 From: Peter Rosin Date: Wed, 20 Jun 2018 10:51:53 +0200 Subject: [PATCH] i2c: smbus: add unlocked __i2c_smbus_xfer variant Removes all locking from i2c_smbus_xfer and renames it to __i2c_smbus_xfer, then adds a new i2c_smbus_xfer function that simply grabs the lock while calling the unlocked variant. This is not perfectly equivalent, since i2c_smbus_xfer was callable from atomic/irq context if you happened to end up emulating SMBus with an I2C transfer, and that is no longer the case with this patch. It is unknown (to me) if anything depends on that quirk, but it seems fragile enough to simply break those cases and require them to call i2c_transfer directly instead. While at it, for consistency rename the 2nd to last argument (size) of the i2c_smbus_xfer declaration to protocol and remove the surplus extern marker. Signed-off-by: Peter Rosin Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core-smbus.c | 28 ++++++++++++++++++++-------- include/linux/i2c.h | 11 ++++++++--- 2 files changed, 28 insertions(+), 11 deletions(-) diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 51970ba..9cd66ca 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -463,7 +463,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr, msg[num-1].len++; } - status = i2c_transfer(adapter, msg, num); + status = __i2c_transfer(adapter, msg, num); if (status < 0) goto cleanup; if (status != num) { @@ -524,9 +524,24 @@ cleanup: * This executes an SMBus protocol operation, and returns a negative * errno code else zero on success. */ -s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, - char read_write, u8 command, int protocol, - union i2c_smbus_data *data) +s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, + unsigned short flags, char read_write, + u8 command, int protocol, union i2c_smbus_data *data) +{ + s32 res; + + i2c_lock_bus(adapter, I2C_LOCK_SEGMENT); + res = __i2c_smbus_xfer(adapter, addr, flags, read_write, + command, protocol, data); + i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT); + + return res; +} +EXPORT_SYMBOL(i2c_smbus_xfer); + +s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, + unsigned short flags, char read_write, + u8 command, int protocol, union i2c_smbus_data *data) { unsigned long orig_jiffies; int try; @@ -543,8 +558,6 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB; if (adapter->algo->smbus_xfer) { - i2c_lock_bus(adapter, I2C_LOCK_SEGMENT); - /* Retry automatically on arbitration loss */ orig_jiffies = jiffies; for (res = 0, try = 0; try <= adapter->retries; try++) { @@ -557,7 +570,6 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, orig_jiffies + adapter->timeout)) break; } - i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT); if (res != -EOPNOTSUPP || !adapter->algo->master_xfer) goto trace; @@ -579,7 +591,7 @@ trace: return res; } -EXPORT_SYMBOL(i2c_smbus_xfer); +EXPORT_SYMBOL(__i2c_smbus_xfer); /** * i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate diff --git a/include/linux/i2c.h b/include/linux/i2c.h index 254cd34..465afb0 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -140,9 +140,14 @@ extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, and probably just as fast. Note that we use i2c_adapter here, because you do not need a specific smbus adapter to call this function. */ -extern s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, - unsigned short flags, char read_write, u8 command, - int size, union i2c_smbus_data *data); +s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, + unsigned short flags, char read_write, u8 command, + int protocol, union i2c_smbus_data *data); + +/* Unlocked flavor */ +s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, + unsigned short flags, char read_write, u8 command, + int protocol, union i2c_smbus_data *data); /* Now follow the 'nice' access routines. These also document the calling conventions of i2c_smbus_xfer. */ -- 2.7.4