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Message-Id: <1510862032-12394-5-git-send-email-eajames@linux.vnet.ibm.com>
Date: Thu, 16 Nov 2017 13:53:49 -0600
From: Eddie James <eajames@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
wsa@...-dreams.de, robh+dt@...nel.org, joel@....id.au,
eajames@...ux.vnet.ibm.com, "Edward A. James" <eajames@...ibm.com>
Subject: [PATCH v6 4/7] drivers/i2c: Add abort and hardware reset procedures
From: "Edward A. James" <eajames@...ibm.com>
Add abort procedure for failed transfers. Add engine and bus reset
procedures to recover from as many faults as possible.
Signed-off-by: Edward A. James <eajames@...ibm.com>
---
drivers/i2c/busses/i2c-fsi.c | 186 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 186 insertions(+)
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 4ad5d68..61609bce 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -9,14 +9,18 @@
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fsi.h>
#include <linux/i2c.h>
+#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
#define FSI_ENGID_I2C 0x7
@@ -129,10 +133,18 @@
#define I2C_ESTAT_SELF_BUSY 0x00000040
#define I2C_ESTAT_VERSION 0x0000001f
+#define I2C_PORT_BUSY_RESET 0x80000000
+
+#define I2C_LOCAL_WAIT_TIMEOUT 2 /* jiffies */
+
+/* choose timeout length from legacy driver; it's well tested */
+#define I2C_ABORT_TIMEOUT msecs_to_jiffies(100)
+
struct fsi_i2c_master {
struct fsi_device *fsi;
u8 fifo_size;
struct list_head ports;
+ spinlock_t reset_lock;
};
struct fsi_i2c_port {
@@ -224,6 +236,179 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
return rc;
}
+static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
+{
+ int i, rc;
+ u32 mode, stat, ext, dummy = 0;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ mode |= I2C_MODE_DIAG;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ for (i = 0; i < 9; ++i) {
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+ if (rc)
+ return rc;
+ }
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
+ if (rc)
+ return rc;
+
+ mode &= ~I2C_MODE_DIAG;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+ if (rc)
+ return rc;
+
+ /* check for hardware fault */
+ if (!(stat & I2C_STAT_SCL_IN) || !(stat & I2C_STAT_SDA_IN)) {
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_ESTAT, &ext);
+ if (rc)
+ return rc;
+
+ dev_err(&i2c->fsi->dev, "bus stuck status[%08X] ext[%08X]\n",
+ stat, ext);
+ }
+
+ return 0;
+}
+
+static int fsi_i2c_reset(struct fsi_i2c_master *i2c, u16 port)
+{
+ int rc;
+ u32 mode, stat, dummy = 0;
+ unsigned long flags;
+
+ /* disable pre-emption; bus won't get left in a bad state for long */
+ spin_lock_irqsave(&i2c->reset_lock, flags);
+
+ /* reset engine */
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+ if (rc)
+ goto done;
+
+ /* re-init engine */
+ rc = fsi_i2c_dev_init(i2c);
+ if (rc)
+ goto done;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ goto done;
+
+ /* set port; default after reset is 0 */
+ if (port) {
+ mode = SETFIELD(I2C_MODE_PORT, mode, port);
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ goto done;
+ }
+
+ /* reset busy register; hw workaround */
+ dummy = I2C_PORT_BUSY_RESET;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
+ if (rc)
+ goto done;
+
+ /* force bus reset */
+ rc = fsi_i2c_reset_bus(i2c);
+ if (rc)
+ goto done;
+
+ /* reset errors */
+ dummy = 0;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+ if (rc)
+ goto done;
+
+ /* wait for command complete; time from legacy driver */
+ udelay(1000);
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+ if (rc)
+ goto done;
+
+ if (stat & I2C_STAT_CMD_COMP)
+ goto done;
+
+ /* failed to get command complete; reset engine again */
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+ if (rc)
+ goto done;
+
+ /* re-init engine again */
+ rc = fsi_i2c_dev_init(i2c);
+
+done:
+ spin_unlock_irqrestore(&i2c->reset_lock, flags);
+ return rc;
+}
+
+static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
+{
+ int rc;
+ unsigned long start;
+ u32 cmd = I2C_CMD_WITH_STOP;
+ struct fsi_device *fsi = port->master->fsi;
+
+ rc = fsi_i2c_reset(port->master, port->port);
+ if (rc)
+ return rc;
+
+ /* skip final stop command for these errors */
+ if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))
+ return 0;
+
+ /* write stop command */
+ rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);
+ if (rc)
+ return rc;
+
+ /* wait until we see command complete in the master */
+ start = jiffies;
+
+ do {
+ rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);
+ if (rc)
+ return rc;
+
+ if (status & I2C_STAT_CMD_COMP)
+ return 0;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0)
+ return -EINTR;
+
+ } while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
+
+ return -ETIME;
+}
+
static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
@@ -260,6 +445,7 @@ static int fsi_i2c_probe(struct device *dev)
if (!i2c)
return -ENOMEM;
+ spin_lock_init(&i2c->reset_lock);
i2c->fsi = to_fsi_dev(dev);
INIT_LIST_HEAD(&i2c->ports);
--
1.8.3.1
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