Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752172AbdFZTaW (ORCPT ); Mon, 26 Jun 2017 15:30:22 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:43533 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752070AbdFZT3z (ORCPT ); Mon, 26 Jun 2017 15:29:55 -0400 From: Eddie James To: linux-kernel@vger.kernel.org Cc: linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, wsa@the-dreams.de, robh+dt@kernel.org, gregkh@linuxfoundation.org, jk@ozlabs.org, joel@jms.id.au, andrew@aj.id.au, eajames@linux.vnet.ibm.com, "Edward A. James" Subject: [PATCH 4/6] drivers/i2c: Add I2C master locking to FSI algorithm Date: Mon, 26 Jun 2017 14:29:33 -0500 X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1498505375-1454-1-git-send-email-eajames@linux.vnet.ibm.com> References: <1498505375-1454-1-git-send-email-eajames@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17062619-0028-0000-0000-000007E44161 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007281; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00879079; UDB=6.00438095; IPR=6.00659233; BA=6.00005443; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015957; XFM=3.00000015; UTC=2017-06-26 19:29:53 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17062619-0029-0000-0000-0000366624CA Message-Id: <1498505375-1454-5-git-send-email-eajames@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-06-26_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1706260319 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2504 Lines: 101 From: "Edward A. James" Since there are many ports per master, each with it's own adapter and chardev, we need some locking to prevent transfers from changing the\ master state while other transfers are in progress. Signed-off-by: Edward A. James --- drivers/i2c/busses/i2c-fsi.c | 41 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 37 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c index 007f104..41193be 100644 --- a/drivers/i2c/busses/i2c-fsi.c +++ b/drivers/i2c/busses/i2c-fsi.c @@ -136,6 +136,8 @@ struct fsi_i2c_master { u8 fifo_size; struct list_head ports; struct ida ida; + wait_queue_head_t wait; + struct semaphore lock; }; struct fsi_i2c_port { @@ -171,6 +173,29 @@ static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg, return fsi_device_write(fsi, reg, &data_be, sizeof(data_be)); } +static int fsi_i2c_lock_master(struct fsi_i2c_master *i2c, int timeout) +{ + int rc; + + rc = down_trylock(&i2c->lock); + if (!rc) + return 0; + + rc = wait_event_interruptible_timeout(i2c->wait, + !down_trylock(&i2c->lock), + timeout); + if (rc > 0) + return 0; + + return -EBUSY; +} + +static void fsi_i2c_unlock_master(struct fsi_i2c_master *i2c) +{ + up(&i2c->lock); + wake_up(&i2c->wait); +} + static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c) { int rc; @@ -412,25 +437,31 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, struct fsi_i2c_port *port = adap->algo_data; struct i2c_msg *msg; - rc = fsi_i2c_set_port(port); + rc = fsi_i2c_lock_master(port->master, adap->timeout); if (rc) return rc; + rc = fsi_i2c_set_port(port); + if (rc) + goto unlock; + for (i = 0; i < num; ++i) { msg = msgs + i; start_time = jiffies; rc = fsi_i2c_start(port, msg, i == num - 1); if (rc) - return rc; + goto unlock; rc = fsi_i2c_wait(port, msg, adap->timeout - (jiffies - start_time)); if (rc) - return rc; + goto unlock; } - return 0; +unlock: + fsi_i2c_unlock_master(port->master); + return rc; } static u32 fsi_i2c_functionality(struct i2c_adapter *adap) @@ -455,6 +486,8 @@ static int fsi_i2c_probe(struct device *dev) if (!i2c) return -ENOMEM; + init_waitqueue_head(&i2c->wait); + sema_init(&i2c->lock, 1); i2c->fsi = to_fsi_dev(dev); i2c->idx = ida_simple_get(&fsi_i2c_ida, 1, INT_MAX, GFP_KERNEL); ida_init(&i2c->ida); -- 1.8.3.1