| Edward A. James | 7bd8637 | 2017-05-15 12:28:44 -0500 | [diff] [blame] | 1 | From patchwork Wed May 10 15:52:40 2017 |
| 2 | Content-Type: text/plain; charset="utf-8" |
| 3 | MIME-Version: 1.0 |
| 4 | Content-Transfer-Encoding: 7bit |
| 5 | Subject: [linux, dev-4.10, v2, |
| 6 | 4/6] drivers: i2c: Add I2C master locking to FSI algorithm |
| 7 | From: eajames@linux.vnet.ibm.com |
| 8 | X-Patchwork-Id: 760699 |
| 9 | Message-Id: <1494431562-25101-5-git-send-email-eajames@linux.vnet.ibm.com> |
| 10 | To: openbmc@lists.ozlabs.org |
| 11 | Cc: "Edward A. James" <eajames@us.ibm.com>, cbostic@linux.vnet.ibm.com |
| 12 | Date: Wed, 10 May 2017 10:52:40 -0500 |
| 13 | |
| 14 | From: "Edward A. James" <eajames@us.ibm.com> |
| 15 | |
| 16 | Since there are many ports per master, each with it's own adapter and |
| 17 | chardev, we need some locking to prevent xfers from changing the master |
| 18 | state while other xfers are in progress. |
| 19 | |
| 20 | Signed-off-by: Edward A. James <eajames@us.ibm.com> |
| 21 | --- |
| 22 | drivers/i2c/busses/i2c-fsi.c | 41 +++++++++++++++++++++++++++++++++++++---- |
| 23 | 1 file changed, 37 insertions(+), 4 deletions(-) |
| 24 | |
| 25 | diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c |
| 26 | index f690b16..d757aee 100644 |
| 27 | --- a/drivers/i2c/busses/i2c-fsi.c |
| 28 | +++ b/drivers/i2c/busses/i2c-fsi.c |
| 29 | @@ -136,6 +136,8 @@ struct fsi_i2c_master { |
| 30 | u8 fifo_size; |
| 31 | struct list_head ports; |
| 32 | struct ida ida; |
| 33 | + wait_queue_head_t wait; |
| 34 | + struct semaphore lock; |
| 35 | }; |
| 36 | |
| 37 | struct fsi_i2c_port { |
| 38 | @@ -171,6 +173,29 @@ static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg, |
| 39 | return fsi_device_write(fsi, reg, &raw_data, sizeof(raw_data)); |
| 40 | } |
| 41 | |
| 42 | +static int fsi_i2c_lock_master(struct fsi_i2c_master *i2c, int timeout) |
| 43 | +{ |
| 44 | + int rc; |
| 45 | + |
| 46 | + rc = down_trylock(&i2c->lock); |
| 47 | + if (!rc) |
| 48 | + return 0; |
| 49 | + |
| 50 | + rc = wait_event_interruptible_timeout(i2c->wait, |
| 51 | + !down_trylock(&i2c->lock), |
| 52 | + timeout); |
| 53 | + if (rc > 0) |
| 54 | + return 0; |
| 55 | + |
| 56 | + return -EBUSY; |
| 57 | +} |
| 58 | + |
| 59 | +static void fsi_i2c_unlock_master(struct fsi_i2c_master *i2c) |
| 60 | +{ |
| 61 | + up(&i2c->lock); |
| 62 | + wake_up(&i2c->wait); |
| 63 | +} |
| 64 | + |
| 65 | static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c) |
| 66 | { |
| 67 | int rc; |
| 68 | @@ -410,25 +435,31 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, |
| 69 | struct fsi_i2c_port *port = adap->algo_data; |
| 70 | struct i2c_msg *msg; |
| 71 | |
| 72 | - rc = fsi_i2c_set_port(port); |
| 73 | + rc = fsi_i2c_lock_master(port->master, adap->timeout); |
| 74 | if (rc) |
| 75 | return rc; |
| 76 | |
| 77 | + rc = fsi_i2c_set_port(port); |
| 78 | + if (rc) |
| 79 | + goto unlock; |
| 80 | + |
| 81 | for (i = 0; i < num; ++i) { |
| 82 | msg = msgs + i; |
| 83 | start_time = jiffies; |
| 84 | |
| 85 | rc = fsi_i2c_start(port, msg, i == num - 1); |
| 86 | if (rc) |
| 87 | - return rc; |
| 88 | + goto unlock; |
| 89 | |
| 90 | rc = fsi_i2c_wait(port, msg, |
| 91 | adap->timeout - (jiffies - start_time)); |
| 92 | if (rc) |
| 93 | - return rc; |
| 94 | + goto unlock; |
| 95 | } |
| 96 | |
| 97 | - return 0; |
| 98 | +unlock: |
| 99 | + fsi_i2c_unlock_master(port->master); |
| 100 | + return rc; |
| 101 | } |
| 102 | |
| 103 | static u32 fsi_i2c_functionality(struct i2c_adapter *adap) |
| 104 | @@ -453,6 +484,8 @@ static int fsi_i2c_probe(struct device *dev) |
| 105 | if (!i2c) |
| 106 | return -ENOMEM; |
| 107 | |
| 108 | + init_waitqueue_head(&i2c->wait); |
| 109 | + sema_init(&i2c->lock, 1); |
| 110 | i2c->fsi = to_fsi_dev(dev); |
| 111 | i2c->idx = ida_simple_get(&fsi_i2c_ida, 1, INT_MAX, GFP_KERNEL); |
| 112 | ida_init(&i2c->ida); |