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From d1fb9431676f37ddf2a8673f84368793e5a88ab0 Mon Sep 17 00:00:00 2001
From: Zhikui Ren <zhikui.ren@intel.com>
Date: Mon, 14 Sep 2020 12:02:03 -0700
Subject: [PATCH] Igore 0x3FF in aspeed_adc driver
ADC are 10 bits, 0x3FF means voltage exceeded reference voltage
Several ADC voltages reported rare transient events corresponding
to this value. Aspeed was consulted and did not identify possible
root causes. As a work around, igore these valuse and return
previous readings. If there were real issues, a slightly different
reading like 0x3FE will still be returned and resulted in a sensor
event.
Signed-off-by: Zhikui Ren <zhikui.ren@intel.com>
---
drivers/iio/adc/aspeed_adc.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
index 1dd5a97a16bc..c115797c4cc5 100644
--- a/drivers/iio/adc/aspeed_adc.c
+++ b/drivers/iio/adc/aspeed_adc.c
@@ -53,6 +53,9 @@
#define ASPEED_ADC_INIT_POLLING_TIME 500
#define ASPEED_ADC_INIT_TIMEOUT 500000
+#define ASPEED_ADC_CHANNELS_MAX 16
+#define ASPEED_ADC_RAW_VALUE_MAX 0x3ff
+
struct aspeed_adc_model_data {
const char *model_name;
unsigned int min_sampling_rate; // Hz
@@ -71,6 +74,7 @@ struct aspeed_adc_data {
struct clk_hw *clk_scaler;
struct reset_control *rst;
int cv;
+ int channel_raw_value[ASPEED_ADC_CHANNELS_MAX];
};
#define ASPEED_CHAN(_idx, _data_reg_addr) { \
@@ -124,6 +128,13 @@ static int aspeed_adc_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_RAW:
*val = readw(data->base + chan->address);
+ if (*val == ASPEED_ADC_RAW_VALUE_MAX) {
+ *val = data->channel_raw_value[chan->channel];
+ pr_err("aspeed_adc: channel %d drop invalid raw reading 0x3FF %d\n",
+ chan->channel, ASPEED_ADC_RAW_VALUE_MAX);
+ } else {
+ data->channel_raw_value[chan->channel] = *val;
+ }
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
@@ -206,6 +217,7 @@ static int aspeed_adc_probe(struct platform_device *pdev)
int ret;
u32 eng_ctrl = 0;
u32 adc_engine_control_reg_val;
+ int i;
indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
if (!indio_dev)
@@ -298,6 +310,9 @@ static int aspeed_adc_probe(struct platform_device *pdev)
data->cv = 0x200 - (readl(data->base + 0x10) & GENMASK(9, 0));
+ for (i = 0; i < ASPEED_ADC_CHANNELS_MAX; i++)
+ data->channel_raw_value[i] = ASPEED_ADC_RAW_VALUE_MAX;
+
writel(eng_ctrl | ASPEED_OPERATION_MODE_NORMAL |
ASPEED_ENGINE_ENABLE | ASPEED_AUTOPENSATING, data->base + ASPEED_REG_ENGINE_CONTROL);
printk(KERN_INFO "aspeed_adc: cv %d \n", data->cv);
--
2.17.1
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