| Message ID | cc6b76c5d660818d3ff7833ea5be4f32ed960f54.1535103920.git.baolin.wang@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] iio: adc: sc27xx: Add raw data support | expand |
On Fri, 24 Aug 2018 17:53:16 +0800 Baolin Wang <baolin.wang@linaro.org> wrote: > 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> This looks good to me. I'll leave it for now though given open questions on patch 1 and to allow others time to comment on this if they wish - particularly as it includes a binding addition. Jonathan > --- > .../bindings/iio/adc/sprd,sc27xx-adc.txt | 4 ++ > drivers/iio/adc/sc27xx_adc.c | 52 ++++++++++++++++++-- > 2 files changed, 53 insertions(+), 3 deletions(-) > > diff --git a/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt b/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt > index 8aad960..b4daa15 100644 > --- a/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt > +++ b/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt > @@ -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"; > }; > }; > diff --git a/drivers/iio/adc/sc27xx_adc.c b/drivers/iio/adc/sc27xx_adc.c > index 153c311..7ac78eda 100644 > --- a/drivers/iio/adc/sc27xx_adc.c > +++ b/drivers/iio/adc/sc27xx_adc.c > @@ -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:
Hi Jonathan, On 25 August 2018 at 16:43, Jonathan Cameron <jic23@kernel.org> wrote: > On Fri, 24 Aug 2018 17:53:16 +0800 > Baolin Wang <baolin.wang@linaro.org> wrote: > >> 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> > This looks good to me. I'll leave it for now though given open questions > on patch 1 and to allow others time to comment on this if they wish - > particularly as it includes a binding addition. Thanks for your reviewing. But after more testing, we found one issue when reading calibration data from efuse, which is not always 4 bytes (sizeof(u32)). So I will change to use nvmem_cell_read() instead of nvmem_cell_read_u32() in next version.
diff --git a/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt b/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt index 8aad960..b4daa15 100644 --- a/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt +++ b/Documentation/devicetree/bindings/iio/adc/sprd,sc27xx-adc.txt @@ -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"; }; }; diff --git a/drivers/iio/adc/sc27xx_adc.c b/drivers/iio/adc/sc27xx_adc.c index 153c311..7ac78eda 100644 --- a/drivers/iio/adc/sc27xx_adc.c +++ b/drivers/iio/adc/sc27xx_adc.c @@ -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(-)