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mfd: Read wm831x AUXADC conversion results before acknowledging interrupt

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Ensure that there's no possibility of loosing an AUXADC interrupt by reading
the conversion result in the IRQ handler when using interrupts. Otherwise
it's possible that under very heavy load a new conversion could be initiated
before the acknowledgement for a previous interrupt has happened.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Mark Brown 2011-06-02 19:18:52 +01:00 committed by Samuel Ortiz
parent 5c05a8d1f0
commit c1a82780b4
2 changed files with 32 additions and 16 deletions
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47
drivers/mfd/wm831x-core.c
View file

@ -376,6 +376,16 @@ int wm831x_auxadc_read(struct wm831x *wm831x, enum wm831x_auxadc input)
goto disable;
}
}
ret = wm831x_reg_read(wm831x, WM831X_AUXADC_DATA);
if (ret < 0) {
dev_err(wm831x->dev,
"Failed to read AUXADC data: %d\n", ret);
goto disable;
}
wm831x->auxadc_data = ret;
} else {
/* If we are using interrupts then wait for the
* interrupt to complete. Use an extremely long
@ -390,23 +400,18 @@ int wm831x_auxadc_read(struct wm831x *wm831x, enum wm831x_auxadc input)
}
}
ret = wm831x_reg_read(wm831x, WM831X_AUXADC_DATA);
if (ret < 0) {
dev_err(wm831x->dev, "Failed to read AUXADC data: %d\n", ret);
src = ((wm831x->auxadc_data & WM831X_AUX_DATA_SRC_MASK)
>> WM831X_AUX_DATA_SRC_SHIFT) - 1;
if (src == 14)
src = WM831X_AUX_CAL;
if (src != input) {
dev_err(wm831x->dev, "Data from source %d not %d\n",
src, input);
ret = -EINVAL;
} else {
src = ((ret & WM831X_AUX_DATA_SRC_MASK)
>> WM831X_AUX_DATA_SRC_SHIFT) - 1;
if (src == 14)
src = WM831X_AUX_CAL;
if (src != input) {
dev_err(wm831x->dev, "Data from source %d not %d\n",
src, input);
ret = -EINVAL;
} else {
ret &= WM831X_AUX_DATA_MASK;
}
ret = wm831x->auxadc_data & WM831X_AUX_DATA_MASK;
}
disable:
@ -420,6 +425,16 @@ EXPORT_SYMBOL_GPL(wm831x_auxadc_read);
static irqreturn_t wm831x_auxadc_irq(int irq, void *irq_data)
{
struct wm831x *wm831x = irq_data;
int ret;
ret = wm831x_reg_read(wm831x, WM831X_AUXADC_DATA);
if (ret < 0) {
dev_err(wm831x->dev,
"Failed to read AUXADC data: %d\n", ret);
wm831x->auxadc_data = 0xffff;
} else {
wm831x->auxadc_data = ret;
}
complete(&wm831x->auxadc_done);

1
include/linux/mfd/wm831x/core.h
View file

@ -278,6 +278,7 @@ struct wm831x {
struct mutex auxadc_lock;
struct completion auxadc_done;
u16 auxadc_data;
/* The WM831x has a security key blocking access to certain
* registers. The mutex is taken by the accessors for locking