linux-kernel - Re: [PATCH v4] drivers: ipmi: Support raw i2c packet in IPMB

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Date:   Thu, 14 Nov 2019 18:03:27 +0000
From:   Vijay Khemka <vijaykhemka@...com>
To:     Asmaa Mnebhi <asmaa@...lanox.com>, Corey Minyard <minyard@....org>,
        "Arnd Bergmann" <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "openipmi-developer@...ts.sourceforge.net" 
        <openipmi-developer@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "cminyard@...sta.com" <cminyard@...sta.com>,
        "joel@....id.au" <joel@....id.au>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        Sai Dasari <sdasari@...com>
Subject: Re: [PATCH v4] drivers: ipmi: Support raw i2c packet in IPMB

Ok I will send another patch with acpi support.

On 11/14/19, 6:16 AM, "Asmaa Mnebhi" <asmaa@...lanox.com> wrote:

    Hi Vijay,
    
    You haven't addressed some of my comments.
    
    -----Original Message-----
    From: Vijay Khemka <vijaykhemka@...com> 
    Sent: Wednesday, November 13, 2019 6:42 PM
    To: Corey Minyard <minyard@....org>; Arnd Bergmann <arnd@...db.de>; Greg Kroah-Hartman <gregkh@...uxfoundation.org>; openipmi-developer@...ts.sourceforge.net; linux-kernel@...r.kernel.org
    Cc: vijaykhemka@...com; cminyard@...sta.com; Asmaa Mnebhi <Asmaa@...lanox.com>; joel@....id.au; linux-aspeed@...ts.ozlabs.org; sdasari@...com
    Subject: [PATCH v4] drivers: ipmi: Support raw i2c packet in IPMB
    
    Many IPMB devices doesn't support smbus protocol and current driver support only smbus devices. Added support for raw i2c packets.
    
    User can define i2c-protocol in device tree to use i2c raw transfer.
    
    A>> Please fix the description as suggested in previous comments
    
    Signed-off-by: Vijay Khemka <vijaykhemka@...com>
    ---
     drivers/char/ipmi/ipmb_dev_int.c | 32 ++++++++++++++++++++++++++++++++
     1 file changed, 32 insertions(+)
    
    diff --git a/drivers/char/ipmi/ipmb_dev_int.c b/drivers/char/ipmi/ipmb_dev_int.c
    index ae3bfba27526..10904bec1de0 100644
    --- a/drivers/char/ipmi/ipmb_dev_int.c
    +++ b/drivers/char/ipmi/ipmb_dev_int.c
    @@ -63,6 +63,7 @@ struct ipmb_dev {
     	spinlock_t lock;
     	wait_queue_head_t wait_queue;
     	struct mutex file_mutex;
    +	bool is_i2c_protocol;
     };
     
     static inline struct ipmb_dev *to_ipmb_dev(struct file *file) @@ -112,6 +113,25 @@ static ssize_t ipmb_read(struct file *file, char __user *buf, size_t count,
     	return ret < 0 ? ret : count;
     }
     
    +static int ipmb_i2c_write(struct i2c_client *client, u8 *msg) {
    +	struct i2c_msg i2c_msg;
    +
    +	/*
    +	 * subtract 1 byte (rq_sa) from the length of the msg passed to
    +	 * raw i2c_transfer
    +	 */
    +	i2c_msg.len = msg[IPMB_MSG_LEN_IDX] - 1;
    +
    +	/* Assign message to buffer except first 2 bytes (length and address) */
    +	i2c_msg.buf = msg + 2;
    +
    +	i2c_msg.addr = GET_7BIT_ADDR(msg[RQ_SA_8BIT_IDX]);
    
    You can have:
    i2c_msg.flags = addr;
    addr being an argument of the ipmb_i2c_write function and passed in ipmb_write. We already define it.
    
    +	i2c_msg.flags = client->flags & I2C_CLIENT_PEC;
    +
    +	return i2c_transfer(client->adapter, &i2c_msg, 1); }
    +
     static ssize_t ipmb_write(struct file *file, const char __user *buf,
     			size_t count, loff_t *ppos)
     {
    @@ -133,6 +153,12 @@ 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];
     
    +	/* Check i2c block transfer vs smbus */
    +	if (ipmb_dev->is_i2c_protocol) {
    +		ret = ipmb_i2c_write(ipmb_dev->client, msg);
    +		return (ret == 1) ? count : ret;
    +	}
    +
     	/*
     	 * subtract rq_sa and netf_rq_lun from the length of the msg passed to
     	 * i2c_smbus_xfer
    @@ -277,6 +303,7 @@ static int ipmb_probe(struct i2c_client *client,
     			const struct i2c_device_id *id)
     {
     	struct ipmb_dev *ipmb_dev;
    +	struct device_node *np;
     	int ret;
     
     	ipmb_dev = devm_kzalloc(&client->dev, sizeof(*ipmb_dev), @@ -302,6 +329,11 @@ static int ipmb_probe(struct i2c_client *client,
     	if (ret)
     		return ret;
     
    +	/* Check if i2c block xmit needs to use instead of smbus */
    +	np = client->dev.of_node;
    +	if (np && of_get_property(np, "i2c-protocol", NULL))
    +		ipmb_dev->is_i2c_protocol = true;
    
    I know Corey said that ACPI is not a priority but many companies (including mine) use ACPI and I would prefer if we implement it. All you need to do is use
    device_property_read_u32 function instead of of_get_property:
    ret = device_property_read_u32(&client->dev, "i2c-protocol", &ipmb_dev->is_i2c_protocol);
    This function does the job for both dt and acpi.
    
    +
     	ipmb_dev->client = client;
     	i2c_set_clientdata(client, ipmb_dev);
     	ret = i2c_slave_register(client, ipmb_slave_cb);
    --
    2.17.1