diff options
author | Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com> | 2016-03-26 10:28:13 +0200 |
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committer | Mark Brown <broonie@kernel.org> | 2016-03-28 10:39:58 +0100 |
commit | 2330b05c095bdeaaf1261c54cd2d4b9127496996 (patch) | |
tree | f746457ae21a732018cd6ba84ecbd1395399da67 | |
parent | f55532a0c0b8bb6148f4e07853b876ef73bc69ca (diff) | |
download | linux-2330b05c095bdeaaf1261c54cd2d4b9127496996.tar.bz2 |
regulator: twl: Make sure we have access to powerbus before trying to write to it
According to the TRM, we need to enable i2c access to powerbus before
writing to it. Also, a new write to powerbus should not be attempted if
there is a pending transfer. The current code does not implement that
functionality and while there are no known problems caused by that, it is
better to follow what TRM says.
Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
-rw-r--r-- | drivers/regulator/twl-regulator.c | 78 |
1 files changed, 70 insertions, 8 deletions
diff --git a/drivers/regulator/twl-regulator.c b/drivers/regulator/twl-regulator.c index 955a6fb1355c..aad748b00e1a 100644 --- a/drivers/regulator/twl-regulator.c +++ b/drivers/regulator/twl-regulator.c @@ -21,7 +21,7 @@ #include <linux/regulator/machine.h> #include <linux/regulator/of_regulator.h> #include <linux/i2c/twl.h> - +#include <linux/delay.h> /* * The TWL4030/TW5030/TPS659x0/TWL6030 family chips include power management, a @@ -188,6 +188,74 @@ static int twl6030reg_is_enabled(struct regulator_dev *rdev) return grp && (val == TWL6030_CFG_STATE_ON); } +#define PB_I2C_BUSY BIT(0) +#define PB_I2C_BWEN BIT(1) + +/* Wait until buffer empty/ready to send a word on power bus. */ +static int twl4030_wait_pb_ready(void) +{ + + int ret; + int timeout = 10; + u8 val; + + do { + ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val, + TWL4030_PM_MASTER_PB_CFG); + if (ret < 0) + return ret; + + if (!(val & PB_I2C_BUSY)) + return 0; + + mdelay(1); + timeout--; + } while (timeout); + + return -ETIMEDOUT; +} + +/* Send a word over the powerbus */ +static int twl4030_send_pb_msg(unsigned msg) +{ + u8 val; + int ret; + + /* save powerbus configuration */ + ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val, + TWL4030_PM_MASTER_PB_CFG); + if (ret < 0) + return ret; + + /* Enable i2c access to powerbus */ + ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val | PB_I2C_BWEN, + TWL4030_PM_MASTER_PB_CFG); + if (ret < 0) + return ret; + + ret = twl4030_wait_pb_ready(); + if (ret < 0) + return ret; + + ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, msg >> 8, + TWL4030_PM_MASTER_PB_WORD_MSB); + if (ret < 0) + return ret; + + ret = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, msg & 0xff, + TWL4030_PM_MASTER_PB_WORD_LSB); + if (ret < 0) + return ret; + + ret = twl4030_wait_pb_ready(); + if (ret < 0) + return ret; + + /* Restore powerbus configuration */ + return twl_i2c_write_u8(TWL_MODULE_PM_MASTER, val, + TWL_MODULE_PM_MASTER); +} + static int twl4030reg_enable(struct regulator_dev *rdev) { struct twlreg_info *info = rdev_get_drvdata(rdev); @@ -324,13 +392,7 @@ static int twl4030reg_set_mode(struct regulator_dev *rdev, unsigned mode) if (!(status & (P3_GRP_4030 | P2_GRP_4030 | P1_GRP_4030))) return -EACCES; - status = twl_i2c_write_u8(TWL_MODULE_PM_MASTER, - message >> 8, TWL4030_PM_MASTER_PB_WORD_MSB); - if (status < 0) - return status; - - return twl_i2c_write_u8(TWL_MODULE_PM_MASTER, - message & 0xff, TWL4030_PM_MASTER_PB_WORD_LSB); + return twl4030_send_pb_msg(message); } static int twl6030reg_set_mode(struct regulator_dev *rdev, unsigned mode) |