[PATCH v3 1/4] iio: adc: rockchip_saradc: reset saradc controller before programming it

Caesar Wang
2016-07-27T14:24:04Z

SARADC controller needs to be reset before programming it, otherwise
it will not function properly.

Signed-off-by: Caesar Wang <wxt-TNX95d0MmH7DzftRWevZcw@public.gmane.org>
Cc: Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Heiko Stuebner <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>
Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Tested-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>

---

Changes in v3:
- %s/devm_reset_control_get_optional()/devm_reset_control_get()
- add Guente's test tag.

Changes in v2:
- Make the reset as an optional property, since it should work
with old devicetrees as well.

.../bindings/iio/adc/rockchip-saradc.txt | 7 +++++
drivers/iio/adc/Kconfig | 1 +
drivers/iio/adc/rockchip_saradc.c | 30 ++++++++++++++++++++++
3 files changed, 38 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
index bf99e2f..205593f 100644
--- a/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/rockchip-saradc.txt
@@ -16,6 +16,11 @@ Required properties:
- vref-supply: The regulator supply ADC reference voltage.
- #io-channel-cells: Should be 1, see ../iio-bindings.txt

+Optional properties:
+- resets: Must contain an entry for each entry in reset-names if need support
+ this option. See ../reset/reset.txt for details.
+- reset-names: Must include the name "saradc-apb".
+
Example:
saradc: saradc@2006c000 {
compatible = "rockchip,saradc";
@@ -23,6 +28,8 @@ Example:
interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&cru SCLK_SARADC>, <&cru PCLK_SARADC>;
clock-names = "saradc", "apb_pclk";
+ resets = <&cru SRST_SARADC>;
+ reset-names = "saradc-apb";
#io-channel-cells = <1>;
vref-supply = <&vcc18>;
};
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 1de31bd..7675772 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -389,6 +389,7 @@ config QCOM_SPMI_VADC
config ROCKCHIP_SARADC
tristate "Rockchip SARADC driver"
depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)
+ depends on RESET_CONTROLLER
help
Say yes here to build support for the SARADC found in SoCs from
Rockchip.
diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
index f9ad6c2..85d7012 100644
--- a/drivers/iio/adc/rockchip_saradc.c
+++ b/drivers/iio/adc/rockchip_saradc.c
@@ -21,6 +21,8 @@
#include <linux/of_device.h>
#include <linux/clk.h>
#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/reset.h>
#include <linux/regulator/consumer.h>
#include <linux/iio/iio.h>

@@ -53,6 +55,7 @@ struct rockchip_saradc {
struct clk *clk;
struct completion completion;
struct regulator *vref;
+ struct reset_control *reset;
const struct rockchip_saradc_data *data;
u16 last_val;
};
@@ -190,6 +193,16 @@ static const struct of_device_id rockchip_saradc_match[] = {
};
MODULE_DEVICE_TABLE(of, rockchip_saradc_match);

+/**
+ * Reset SARADC Controller.
+ */
+static void rockchip_saradc_reset_controller(struct reset_control *reset)
+{
+ reset_control_assert(reset);
+ usleep_range(10, 20);
+ reset_control_deassert(reset);
+}
+
static int rockchip_saradc_probe(struct platform_device *pdev)
{
struct rockchip_saradc *info = NULL;
@@ -218,6 +231,20 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
if (IS_ERR(info->regs))
return PTR_ERR(info->regs);

+ /*
+ * The reset should be an optional property, as it should work
+ * with old devicetrees as well
+ */
+ info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
+ if (IS_ERR(info->reset)) {
+ ret = PTR_ERR(info->reset);
+ if (ret != -ENOENT)
+ return ret;
+
+ dev_dbg(&pdev->dev, "no reset control found\n");
+ info->reset = NULL;
+ }
+
init_completion(&info->completion);

irq = platform_get_irq(pdev, 0);
@@ -252,6 +279,9 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
return PTR_ERR(info->vref);
}

+ if (info->reset)
+ rockchip_saradc_reset_controller(info->reset);
+
/*
* Use a default value for the converter clock.
* This may become user-configurable in the future.
--
1.9.1