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| author | Eric Brower <ebrower@gmail.com> | 2008-07-14 22:38:31 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@mahadeva.delvare> | 2008-07-14 22:38:31 +0200 |
| commit | 0573d11b2bbd0e4774f33f4c1959c1939c055e96 (patch) | |
| tree | f78451f46dc192ec90f7d30e531633104dc7ae93 /drivers/i2c | |
| parent | 8a56ce1033073657572bd993595a56498baa4800 (diff) | |
| download | lwn-0573d11b2bbd0e4774f33f4c1959c1939c055e96.tar.gz lwn-0573d11b2bbd0e4774f33f4c1959c1939c055e96.zip | |
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>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/algos/i2c-algo-pcf.c | 48 |
1 files changed, 31 insertions, 17 deletions
diff --git a/drivers/i2c/algos/i2c-algo-pcf.c b/drivers/i2c/algos/i2c-algo-pcf.c index 8907b0191677..1e328d19cd6d 100644 --- a/drivers/i2c/algos/i2c-algo-pcf.c +++ b/drivers/i2c/algos/i2c-algo-pcf.c @@ -78,6 +78,36 @@ static void i2c_stop(struct i2c_algo_pcf_data *adap) 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 @@ static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) { *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 |