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regulator: twl: Make sure we have access to powerbus before trying to write to it

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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>
This commit is contained in:
Ivaylo Dimitrov 2016-03-26 10:28:13 +02:00 committed by Mark Brown
parent f55532a0c0
commit 2330b05c09
1 changed files with 70 additions and 8 deletions
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78
drivers/regulator/twl-regulator.c
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@ -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)