i2c-algo-pcf: Multi-master lost-arbitration improvement
Improve lost-arbitration handling of PCF8584. This is necessary for
support of a currently out-of-kernel driver for Sun Microsystems E250
environmental management; perhaps others.
Signed-off-by: Eric Brower <ebrower@gmail.com>
Acked-by: Dan Smolik <marvin@mydatex.cz>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/algos/i2c-algo-pcf.c b/drivers/i2c/algos/i2c-algo-pcf.c
index 8907b01..1e328d19 100644
--- a/drivers/i2c/algos/i2c-algo-pcf.c
+++ b/drivers/i2c/algos/i2c-algo-pcf.c
@@ -78,6 +78,36 @@
set_pcf(adap, 1, I2C_PCF_STOP);
}
+static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
+{
+ DEB2(printk(KERN_INFO
+ "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
+ *status));
+
+ /* Cleanup from LAB -- reset and enable ESO.
+ * This resets the PCF8584; since we've lost the bus, no
+ * further attempts should be made by callers to clean up
+ * (no i2c_stop() etc.)
+ */
+ set_pcf(adap, 1, I2C_PCF_PIN);
+ set_pcf(adap, 1, I2C_PCF_ESO);
+
+ /* We pause for a time period sufficient for any running
+ * I2C transaction to complete -- the arbitration logic won't
+ * work properly until the next START is seen.
+ * It is assumed the bus driver or client has set a proper value.
+ *
+ * REVISIT: should probably use msleep instead of mdelay if we
+ * know we can sleep.
+ */
+ if (adap->lab_mdelay)
+ mdelay(adap->lab_mdelay);
+
+ DEB2(printk(KERN_INFO
+ "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
+ get_pcf(adap, 1)));
+}
+
static int wait_for_bb(struct i2c_algo_pcf_data *adap) {
int timeout = DEF_TIMEOUT;
@@ -109,23 +139,7 @@
*status = get_pcf(adap, 1);
}
if (*status & I2C_PCF_LAB) {
- DEB2(printk(KERN_INFO
- "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
- *status));
- /* Cleanup from LAB-- reset and enable ESO.
- * This resets the PCF8584; since we've lost the bus, no
- * further attempts should be made by callers to clean up
- * (no i2c_stop() etc.)
- */
- set_pcf(adap, 1, I2C_PCF_PIN);
- set_pcf(adap, 1, I2C_PCF_ESO);
- /* TODO: we should pause for a time period sufficient for any
- * running I2C transaction to complete-- the arbitration
- * logic won't work properly until the next START is seen.
- */
- DEB2(printk(KERN_INFO
- "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
- get_pcf(adap,1)));
+ handle_lab(adap, status);
return(-EINTR);
}
#endif