Re: [PATCH 1/2] drivers: ipmi: Support raw i2c packet in IPMB

[Vijay Khemka <vijaykhemka@fb.com>]

On 11/12/19, 10:41 AM, "Corey Minyard" <cminyard@mvista.com> wrote:

    On Tue, Nov 12, 2019 at 05:57:25PM +0000, Vijay Khemka wrote:
    > 
    > 
    > On 11/12/19, 4:36 AM, "Corey Minyard" <tcminyard@gmail.com on behalf of minyard@acm.org> wrote:
    > 
    >     On Mon, Nov 11, 2019 at 06:36:09PM -0800, Vijay Khemka wrote:
    >     > Many IPMB devices doesn't support smbus protocol and current driver
    >     > support only smbus devices. So added support for raw i2c packets.
    >     
    >     I haven't reviewed this, really, because I have a more general
    >     concern...
    >     
    >     Is it possible to not do this with a config item?  Can you add something
    >     to the device tree and/or via an ioctl to make this dynamically
    >     configurable?  That's more flexible (it can support mixed devices) and
    >     is friendlier to users (don't have to get the config right).
    > I agree with you, I was also not comfortable using config and couldn't find other 
    > Options, I will look into more option now and update patch.
    
    IMHO, device tree is the right way to do this.  You should also have a
    sysfs setting for this, I think.

I think ioctl is also a good option and can control from application. I have already 
wrote ioctl  approach. Testing the same and will send new patch once verified.
    
    -corey
    
    >     
    >     Config items for adding new functionality are generally ok.  Config
    >     items for choosing between two mutually exclusive choices are
    >     generally not.
    >     
    >     -corey
    >     
    >     > 
    >     > Signed-off-by: Vijay Khemka <vijaykhemka@fb.com>
    >     > ---
    >     >  drivers/char/ipmi/Kconfig        |  6 ++++++
    >     >  drivers/char/ipmi/ipmb_dev_int.c | 30 ++++++++++++++++++++++++++++++
    >     >  2 files changed, 36 insertions(+)
    >     > 
    >     > diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
    >     > index a9cfe4c05e64..e5268443b478 100644
    >     > --- a/drivers/char/ipmi/Kconfig
    >     > +++ b/drivers/char/ipmi/Kconfig
    >     > @@ -139,3 +139,9 @@ config IPMB_DEVICE_INTERFACE
    >     >  	  Provides a driver for a device (Satellite MC) to
    >     >  	  receive requests and send responses back to the BMC via
    >     >  	  the IPMB interface. This module requires I2C support.
    >     > +
    >     > +config IPMB_SMBUS_DISABLE
    >     > +	bool 'Disable SMBUS protocol for sending packet to IPMB device'
    >     > +	depends on IPMB_DEVICE_INTERFACE
    >     > +	help
    >     > +	  provides functionality of sending raw i2c packets to IPMB device.
    >     > diff --git a/drivers/char/ipmi/ipmb_dev_int.c b/drivers/char/ipmi/ipmb_dev_int.c
    >     > index ae3bfba27526..2419b9a928b2 100644
    >     > --- a/drivers/char/ipmi/ipmb_dev_int.c
    >     > +++ b/drivers/char/ipmi/ipmb_dev_int.c
    >     > @@ -118,6 +118,10 @@ static ssize_t ipmb_write(struct file *file, const char __user *buf,
    >     >  	struct ipmb_dev *ipmb_dev = to_ipmb_dev(file);
    >     >  	u8 rq_sa, netf_rq_lun, msg_len;
    >     >  	union i2c_smbus_data data;
    >     > +#ifdef CONFIG_IPMB_SMBUS_DISABLE
    >     > +	unsigned char *i2c_buf;
    >     > +	struct i2c_msg i2c_msg;
    >     > +#endif
    >     >  	u8 msg[MAX_MSG_LEN];
    >     >  	ssize_t ret;
    >     >  
    >     > @@ -133,6 +137,31 @@ static ssize_t ipmb_write(struct file *file, const char __user *buf,
    >     >  	rq_sa = GET_7BIT_ADDR(msg[RQ_SA_8BIT_IDX]);
    >     >  	netf_rq_lun = msg[NETFN_LUN_IDX];
    >     >  
    >     > +#ifdef CONFIG_IPMB_SMBUS_DISABLE
    >     > +	/*
    >     > +	 * subtract 1 byte (rq_sa) from the length of the msg passed to
    >     > +	 * raw i2c_transfer
    >     > +	 */
    >     > +	msg_len = msg[IPMB_MSG_LEN_IDX] - 1;
    >     > +
    >     > +	i2c_buf = kzalloc(msg_len, GFP_KERNEL);
    >     > +	if (!i2c_buf)
    >     > +		return -EFAULT;
    >     > +
    >     > +	/* Copy message to buffer except first 2 bytes (length and address) */
    >     > +	memcpy(i2c_buf, msg+2, msg_len);
    >     > +
    >     > +	i2c_msg.addr = rq_sa;
    >     > +	i2c_msg.flags = ipmb_dev->client->flags &
    >     > +			(I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB);
    >     > +	i2c_msg.len = msg_len;
    >     > +	i2c_msg.buf = i2c_buf;
    >     > +
    >     > +	ret = i2c_transfer(ipmb_dev->client->adapter, &i2c_msg, 1);
    >     > +	kfree(i2c_buf);
    >     > +
    >     > +	return (ret == 1) ? count : ret;
    >     > +#else
    >     >  	/*
    >     >  	 * subtract rq_sa and netf_rq_lun from the length of the msg passed to
    >     >  	 * i2c_smbus_xfer
    >     > @@ -149,6 +178,7 @@ static ssize_t ipmb_write(struct file *file, const char __user *buf,
    >     >  			     I2C_SMBUS_BLOCK_DATA, &data);
    >     >  
    >     >  	return ret ? : count;
    >     > +#endif
    >     >  }
    >     >  
    >     >  static unsigned int ipmb_poll(struct file *file, poll_table *wait)
    >     > -- 
    >     > 2.17.1
    >     > 
    >     
    >