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ACPI / PMIC: xpower: Block P-Unit I2C access during read-modify-write

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intel_xpower_pmic_update_power() does a read-modify-write of the output
control register. The i2c-designware code blocks the P-Unit I2C access
during the read and write by taking the P-Unit's PMIC bus semaphore.
But between the read and the write that semaphore is released and the
P-Unit could make changes to the register which we then end up overwriting.

This commit makes intel_xpower_pmic_update_power() take the semaphore
itself so that it is held over the entire read-modify-write, avoiding this
race.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Hans de Goede 2018-10-11 16:29:10 +02:00 committed by Rafael J. Wysocki
parent e09db3d241
commit 3c670dba86
1 changed files with 15 additions and 6 deletions
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21
drivers/acpi/pmic/intel_pmic_xpower.c
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@ -8,8 +8,9 @@
#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/mfd/axp20x.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/platform_device.h>
#include <asm/iosf_mbi.h>
#include "intel_pmic.h"
#define XPOWER_GPADC_LOW 0x5b
@ -172,15 +173,21 @@ static int intel_xpower_pmic_get_power(struct regmap *regmap, int reg,
static int intel_xpower_pmic_update_power(struct regmap *regmap, int reg,
int bit, bool on)
{
int data;
int data, ret;
/* GPIO1 LDO regulator needs special handling */
if (reg == XPOWER_GPI1_CTRL)
return regmap_update_bits(regmap, reg, GPI1_LDO_MASK,
on ? GPI1_LDO_ON : GPI1_LDO_OFF);
if (regmap_read(regmap, reg, &data))
return -EIO;
ret = iosf_mbi_block_punit_i2c_access();
if (ret)
return ret;
if (regmap_read(regmap, reg, &data)) {
ret = -EIO;
goto out;
}
if (on)
data |= BIT(bit);
@ -188,9 +195,11 @@ static int intel_xpower_pmic_update_power(struct regmap *regmap, int reg,
data &= ~BIT(bit);
if (regmap_write(regmap, reg, data))
return -EIO;
ret = -EIO;
out:
iosf_mbi_unblock_punit_i2c_access();
return 0;
return ret;
}
/**