@@ -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";
};
};
@@ -5,10 +5,12 @@
#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>
#include <linux/regmap.h>
+#include <linux/slab.h>
/* PMIC global registers definition */
#define SC27XX_MODULE_EN 0xc08
@@ -87,16 +89,73 @@ 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 int sc27xx_adc_scale_calibration(struct sc27xx_adc_data *data,
+ bool big_scale)
+{
+ const struct sc27xx_adc_linear_graph *calib_graph;
+ struct sc27xx_adc_linear_graph *graph;
+ struct nvmem_cell *cell;
+ const char *cell_name;
+ u32 calib_data = 0;
+ void *buf;
+ size_t len;
+
+ if (big_scale) {
+ calib_graph = &big_scale_graph_calib;
+ graph = &big_scale_graph;
+ cell_name = "big_scale_calib";
+ } else {
+ calib_graph = &small_scale_graph_calib;
+ graph = &small_scale_graph;
+ cell_name = "small_scale_calib";
+ }
+
+ cell = nvmem_cell_get(data->dev, cell_name);
+ if (IS_ERR(cell))
+ return PTR_ERR(cell);
+
+ buf = nvmem_cell_read(cell, &len);
+ nvmem_cell_put(cell);
+
+ if (IS_ERR(buf))
+ return PTR_ERR(buf);
+
+ memcpy(&calib_data, buf, min(len, sizeof(u32)));
+
+ /* 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);
+
+ kfree(buf);
+ return 0;
+}
+
static int sc27xx_adc_get_ratio(int channel, int scale)
{
switch (channel) {
@@ -209,7 +268,7 @@ 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;
@@ -390,6 +449,15 @@ static int sc27xx_adc_enable(struct sc27xx_adc_data *data)
if (ret)
goto disable_clk;
+ /* ADC channel scales' calibration from nvmem device */
+ ret = sc27xx_adc_scale_calibration(data, true);
+ if (ret)
+ goto disable_clk;
+
+ ret = sc27xx_adc_scale_calibration(data, false);
+ if (ret)
+ goto disable_clk;
+
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> --- Changes from v1: - Use nvmem_cell_read() instead of nvmem_cell_read_u32(). --- .../bindings/iio/adc/sprd,sc27xx-adc.txt | 4 ++ drivers/iio/adc/sc27xx_adc.c | 74 +++++++++++++++++++- 2 files changed, 75 insertions(+), 3 deletions(-) -- 1.7.9.5