@@ -12,6 +12,8 @@ Required properties:
- interrupts: The interrupt number for the ADC device.
- #io-channel-cells: Number of cells in an IIO specifier.
- hwlocks: Reference to a phandle of a hwlock provider node.
+- nvmem-cells: A phandle to the calibration cells provided by eFuse device.
+- nvmem-cell-names: Should be "big_scale_calib", "small_scale_calib".
Example:
@@ -32,5 +34,7 @@ Example:
interrupts = <0 IRQ_TYPE_LEVEL_HIGH>;
#io-channel-cells = <1>;
hwlocks = <&hwlock 4>;
+ nvmem-cells = <&adc_big_scale>, <&adc_small_scale>;
+ nvmem-cell-names = "big_scale_calib", "small_scale_calib";
};
};
@@ -5,6 +5,7 @@
#include <linux/iio/iio.h>
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
@@ -87,16 +88,48 @@ struct sc27xx_adc_linear_graph {
* should use the small-scale graph, and if more than 1.2v, we should use the
* big-scale graph.
*/
-static const struct sc27xx_adc_linear_graph big_scale_graph = {
+static struct sc27xx_adc_linear_graph big_scale_graph = {
4200, 3310,
3600, 2832,
};
-static const struct sc27xx_adc_linear_graph small_scale_graph = {
+static struct sc27xx_adc_linear_graph small_scale_graph = {
1000, 3413,
100, 341,
};
+static const struct sc27xx_adc_linear_graph big_scale_graph_calib = {
+ 4200, 856,
+ 3600, 733,
+};
+
+static const struct sc27xx_adc_linear_graph small_scale_graph_calib = {
+ 1000, 833,
+ 100, 80,
+};
+
+static int sc27xx_adc_get_calib_data(u32 calib_data, int calib_adc)
+{
+ return ((calib_data & 0xff) + calib_adc - 128) * 4;
+}
+
+static void
+sc27xx_adc_scale_calibration(const struct sc27xx_adc_linear_graph *calib_graph,
+ u32 calib_data, bool big_scale)
+{
+ struct sc27xx_adc_linear_graph *graph;
+
+ if (big_scale)
+ graph = &big_scale_graph;
+ else
+ graph = &small_scale_graph;
+
+ /* Only need to calibrate the adc values in the linear graph. */
+ graph->adc0 = sc27xx_adc_get_calib_data(calib_data, calib_graph->adc0);
+ graph->adc1 = sc27xx_adc_get_calib_data(calib_data >> 8,
+ calib_graph->adc1);
+}
+
static int sc27xx_adc_get_ratio(int channel, int scale)
{
switch (channel) {
@@ -209,7 +242,7 @@ static void sc27xx_adc_volt_ratio(struct sc27xx_adc_data *data,
*div_denominator = ratio & SC27XX_RATIO_DENOMINATOR_MASK;
}
-static int sc27xx_adc_to_volt(const struct sc27xx_adc_linear_graph *graph,
+static int sc27xx_adc_to_volt(struct sc27xx_adc_linear_graph *graph,
int raw_adc)
{
int tmp;
@@ -371,6 +404,7 @@ static int sc27xx_adc_write_raw(struct iio_dev *indio_dev,
static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
{
+ u32 val;
int ret;
ret = regmap_update_bits(data->regmap, SC27XX_MODULE_EN,
@@ -390,6 +424,18 @@ static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
if (ret)
goto disable_clk;
+ /* ADC channel scales' calibration from nvmem device */
+ ret = nvmem_cell_read_u32(data->dev, "big_scale_calib", &val);
+ if (ret)
+ goto disable_clk;
+
+ sc27xx_adc_scale_calibration(&big_scale_graph_calib, val, true);
+
+ ret = nvmem_cell_read_u32(data->dev, "small_scale_calib", &val);
+ if (ret)
+ goto disable_clk;
+
+ sc27xx_adc_scale_calibration(&small_scale_graph_calib, val, false);
return 0;
disable_clk:
This patch adds support to read calibration values from the eFuse controller to calibrate the ADC channel scales, which can make ADC sample data more accurate. Signed-off-by: Baolin Wang <baolin.wang@linaro.org> --- .../bindings/iio/adc/sprd,sc27xx-adc.txt | 4 ++ drivers/iio/adc/sc27xx_adc.c | 52 ++++++++++++++++++-- 2 files changed, 53 insertions(+), 3 deletions(-) -- 1.7.9.5