This is a note to let you know that I've just added the patch titled
iio: aspeed-adc: wait for initial sequence.
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 737cc2a593782df6846b3cab7e0f64384f58364a Mon Sep 17 00:00:00 2001
From: Mykola Kostenok <c_mykolak@xxxxxxxxxxxx>
Date: Mon, 17 Jul 2017 12:00:35 +0300
Subject: iio: aspeed-adc: wait for initial sequence.
This patch enables adc engine at initialization time and waits
for the initial sequence completion before enabling adc channels.
Without this code adc channels are not functional and shows
zeros for all connected channels.
Tested on mellanox msn platform.
v1 -> v2:
Pointed by Rick Altherr:
- Wait init sequence code enabled by bool
from OF match table.
Signed-off-by: Mykola Kostenok <c_mykolak@xxxxxxxxxxxx>
Reviewed-by: Rick Altherr <raltherr@xxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
---
drivers/iio/adc/aspeed_adc.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
index 62670cbfa2bb..87fd6e0ce5ee 100644
--- a/drivers/iio/adc/aspeed_adc.c
+++ b/drivers/iio/adc/aspeed_adc.c
@@ -22,6 +22,7 @@
#include <linux/iio/iio.h>
#include <linux/iio/driver.h>
+#include <linux/iopoll.h>
#define ASPEED_RESOLUTION_BITS 10
#define ASPEED_CLOCKS_PER_SAMPLE 12
@@ -38,11 +39,17 @@
#define ASPEED_ENGINE_ENABLE BIT(0)
+#define ASPEED_ADC_CTRL_INIT_RDY BIT(8)
+
+#define ASPEED_ADC_INIT_POLLING_TIME 500
+#define ASPEED_ADC_INIT_TIMEOUT 500000
+
struct aspeed_adc_model_data {
const char *model_name;
unsigned int min_sampling_rate; // Hz
unsigned int max_sampling_rate; // Hz
unsigned int vref_voltage; // mV
+ bool wait_init_sequence;
};
struct aspeed_adc_data {
@@ -211,6 +218,24 @@ static int aspeed_adc_probe(struct platform_device *pdev)
goto scaler_error;
}
+ model_data = of_device_get_match_data(&pdev->dev);
+
+ if (model_data->wait_init_sequence) {
+ /* Enable engine in normal mode. */
+ writel(ASPEED_OPERATION_MODE_NORMAL | ASPEED_ENGINE_ENABLE,
+ data->base + ASPEED_REG_ENGINE_CONTROL);
+
+ /* Wait for initial sequence complete. */
+ ret = readl_poll_timeout(data->base + ASPEED_REG_ENGINE_CONTROL,
+ adc_engine_control_reg_val,
+ adc_engine_control_reg_val &
+ ASPEED_ADC_CTRL_INIT_RDY,
+ ASPEED_ADC_INIT_POLLING_TIME,
+ ASPEED_ADC_INIT_TIMEOUT);
+ if (ret)
+ goto scaler_error;
+ }
+
/* Start all channels in normal mode. */
clk_prepare_enable(data->clk_scaler->clk);
adc_engine_control_reg_val = GENMASK(31, 16) |
@@ -270,6 +295,7 @@ static const struct aspeed_adc_model_data ast2500_model_data = {
.vref_voltage = 1800, // mV
.min_sampling_rate = 1,
.max_sampling_rate = 1000000,
+ .wait_init_sequence = true,
};
static const struct of_device_id aspeed_adc_matches[] = {
--
2.13.3