diff options
Diffstat (limited to 'drivers/w1')
| -rw-r--r-- | drivers/w1/w1.h | 2 | ||||
| -rw-r--r-- | drivers/w1/w1_io.c | 26 |
2 files changed, 28 insertions, 0 deletions
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h index d8a9709f3449..f804eba89b7b 100644 --- a/drivers/w1/w1.h +++ b/drivers/w1/w1.h @@ -55,6 +55,7 @@ struct w1_reg_num #define W1_READ_ROM 0x33 #define W1_READ_PSUPPLY 0xB4 #define W1_MATCH_ROM 0x55 +#define W1_RESUME_CMD 0xA5 #define W1_SLAVE_ACTIVE 0 @@ -213,6 +214,7 @@ void w1_write_block(struct w1_master *, const u8 *, int); void w1_touch_block(struct w1_master *, u8 *, int); u8 w1_read_block(struct w1_master *, u8 *, int); int w1_reset_select_slave(struct w1_slave *sl); +int w1_reset_resume_command(struct w1_master *); void w1_next_pullup(struct w1_master *, int); static inline struct w1_slave* dev_to_w1_slave(struct device *dev) diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c index 3ebe9726a9e5..8e8b64cfafb6 100644 --- a/drivers/w1/w1_io.c +++ b/drivers/w1/w1_io.c @@ -390,6 +390,32 @@ int w1_reset_select_slave(struct w1_slave *sl) EXPORT_SYMBOL_GPL(w1_reset_select_slave); /** + * When the workflow with a slave amongst many requires several + * successive commands a reset between each, this function is similar + * to doing a reset then a match ROM for the last matched ROM. The + * advantage being that the matched ROM step is skipped in favor of the + * resume command. The slave must support the command of course. + * + * If the bus has only one slave, traditionnaly the match ROM is skipped + * and a "SKIP ROM" is done for efficiency. On multi-slave busses, this + * doesn't work of course, but the resume command is the next best thing. + * + * The w1 master lock must be held. + * + * @param dev the master device + */ +int w1_reset_resume_command(struct w1_master *dev) +{ + if (w1_reset_bus(dev)) + return -1; + + /* This will make only the last matched slave perform a skip ROM. */ + w1_write_8(dev, W1_RESUME_CMD); + return 0; +} +EXPORT_SYMBOL_GPL(w1_reset_resume_command); + +/** * Put out a strong pull-up of the specified duration after the next write * operation. Not all hardware supports strong pullups. Hardware that * doesn't support strong pullups will sleep for the given time after the |