[PATCH v5] drivers: ipmi: Support raw i2c packet in IPMB

[Asmaa Mnebhi]

-----Original Message-----
From: Vijay Khemka <vijaykhemka at fb.com> 
Sent: Thursday, November 14, 2019 1:54 PM
To: Jonathan Corbet <corbet at lwn.net>; Corey Minyard <minyard at acm.org>; Arnd Bergmann <arnd at arndb.de>; Greg Kroah-Hartman <gregkh at linuxfoundation.org>; linux-doc at vger.kernel.org; linux-kernel at vger.kernel.org; openipmi-developer at lists.sourceforge.net
Cc: vijaykhemka at fb.com; cminyard at mvista.com; Asmaa Mnebhi <Asmaa at mellanox.com>; joel at jms.id.au; linux-aspeed at lists.ozlabs.org; sdasari at fb.com
Subject: [PATCH v5] 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.

Asmaa >> It would be good if you can rephrase the above description as follows:
"The ipmb_dev_int driver only supports the smbus protocol at the moment. Add support for the i2c protocol as well. There will be a variable passed by the device tree or ACPI table which determines whether the protocol is i2c or smbus."

Or at least fix the following: 
"Many IPMB devices doesn't" -> "Many IPMB devices don't"
"current driver support" -> "current driver supports"

Besides my above comment:
Reviewed-by: Asmaa Mnebhi <asmaa at mellanox.com>

Signed-off-by: Vijay Khemka <vijaykhemka at fb.com>
---
 Documentation/IPMB.txt           |  4 ++++
 drivers/char/ipmi/ipmb_dev_int.c | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/Documentation/IPMB.txt b/Documentation/IPMB.txt index a6ed8b68bd0f..7a023beff976 100644
--- a/Documentation/IPMB.txt
+++ b/Documentation/IPMB.txt
@@ -71,9 +71,13 @@ b) Example for device tree:
          ipmb at 10 {
                  compatible = "ipmb-dev";
                  reg = <0x10>;
+                 i2c-protocol;
          };
 };
 
+If xmit of data to be done using raw i2c block vs smbus then 
+"i2c-protocol" needs to be defined as above.
+
 2) Manually from Linux:
 modprobe ipmb-dev-int
 
diff --git a/drivers/char/ipmi/ipmb_dev_int.c b/drivers/char/ipmi/ipmb_dev_int.c
index ae3bfba27526..68a254c0dd92 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, u8 addr) 
+{
+	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 = addr;
+	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, rq_sa);
+		return (ret == 1) ? count : ret;
+	}
+
 	/*
 	 * subtract rq_sa and netf_rq_lun from the length of the msg passed to
 	 * i2c_smbus_xfer
@@ -302,6 +328,9 @@ static int ipmb_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
+	ipmb_dev->is_i2c_protocol
+		= device_property_read_bool(&client->dev, "i2c-protocol");
+
 	ipmb_dev->client = client;
 	i2c_set_clientdata(client, ipmb_dev);
 	ret = i2c_slave_register(client, ipmb_slave_cb);
--
2.17.1