[PATCH 1/3] ARM: AT91: IIO: add low and high res support for adc
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Wed Dec 19 13:37:10 EST 2012
From: Ludovic Desroches <ludovic.desroches at atmel.com>
at91 adc offers the choice between two resolutions: low and high.
The low and high resolution values depends on adc IP version, as many IP
properties have been exposed through device tree, these settings have also
been added to the dt bindings.
Update at the same time the dtsi.
Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
[plagnioj at jcrosoft.com: udpate current adc dt support]
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
Cc: linux-iio at vger.kernel.org
Cc: Nicolas Ferre <nicolas.ferre at atmel.com>
---
.../devicetree/bindings/arm/atmel-adc.txt | 11 +++
arch/arm/boot/dts/at91sam9260.dtsi | 3 +
arch/arm/boot/dts/at91sam9g45.dtsi | 3 +
arch/arm/boot/dts/at91sam9x5.dtsi | 3 +
drivers/iio/adc/at91_adc.c | 74 ++++++++++++++++++--
5 files changed, 90 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/arm/atmel-adc.txt b/Documentation/devicetree/bindings/arm/atmel-adc.txt
index c63097d..fd2d69e 100644
--- a/Documentation/devicetree/bindings/arm/atmel-adc.txt
+++ b/Documentation/devicetree/bindings/arm/atmel-adc.txt
@@ -14,9 +14,17 @@ Required properties:
- atmel,adc-status-register: Offset of the Interrupt Status Register
- atmel,adc-trigger-register: Offset of the Trigger Register
- atmel,adc-vref: Reference voltage in millivolts for the conversions
+ - atmel,adc-res: List of resolution in bits supported by the ADC. List size
+ must be two at least.
+ - atmel,adc-res-names: Contains one identifier string for each resolution
+ in atmel,adc-res property. "lowres" and "highres"
+ identifiers are required.
Optional properties:
- atmel,adc-use-external: Boolean to enable of external triggers
+ - atmel,adc-use-res: String corresponding to an identifier from
+ atmel,adc-res-names property. If not specified, the highest
+ resolution will be used.
Optional trigger Nodes:
- Required properties:
@@ -40,6 +48,9 @@ adc0: adc at fffb0000 {
atmel,adc-trigger-register = <0x08>;
atmel,adc-use-external;
atmel,adc-vref = <3300>;
+ atmel,adc-res = <8 10>;
+ atmel,adc-res-names = "lowres", "highres";
+ atmel,adc-use-res = "lowres";
trigger at 0 {
trigger-name = "external-rising";
diff --git a/arch/arm/boot/dts/at91sam9260.dtsi b/arch/arm/boot/dts/at91sam9260.dtsi
index cca34bc..7c605d2 100644
--- a/arch/arm/boot/dts/at91sam9260.dtsi
+++ b/arch/arm/boot/dts/at91sam9260.dtsi
@@ -506,6 +506,9 @@
atmel,adc-drdy-mask = <0x10000>;
atmel,adc-status-register = <0x1c>;
atmel,adc-trigger-register = <0x04>;
+ atmel,adc-res = <8 10>;
+ atmel,adc-res-names = "lowres", "highres";
+ atmel,adc-use-res = "highres";
trigger at 0 {
trigger-name = "timer-counter-0";
diff --git a/arch/arm/boot/dts/at91sam9g45.dtsi b/arch/arm/boot/dts/at91sam9g45.dtsi
index 253afed..70c776e 100644
--- a/arch/arm/boot/dts/at91sam9g45.dtsi
+++ b/arch/arm/boot/dts/at91sam9g45.dtsi
@@ -488,6 +488,9 @@
atmel,adc-drdy-mask = <0x10000>;
atmel,adc-status-register = <0x1c>;
atmel,adc-trigger-register = <0x08>;
+ atmel,adc-res = <8 10>;
+ atmel,adc-res-names = "lowres", "highres";
+ atmel,adc-use-res = "highres";
trigger at 0 {
trigger-name = "external-rising";
diff --git a/arch/arm/boot/dts/at91sam9x5.dtsi b/arch/arm/boot/dts/at91sam9x5.dtsi
index 70c1f5d..e52862d 100644
--- a/arch/arm/boot/dts/at91sam9x5.dtsi
+++ b/arch/arm/boot/dts/at91sam9x5.dtsi
@@ -469,6 +469,9 @@
atmel,adc-drdy-mask = <0x1000000>;
atmel,adc-status-register = <0x30>;
atmel,adc-trigger-register = <0xc0>;
+ atmel,adc-res = <8 10>;
+ atmel,adc-res-names = "lowres", "highres";
+ atmel,adc-use-res = "highres";
trigger at 0 {
trigger-name = "external-rising";
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 315bed1..f175a86 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -57,6 +57,8 @@ struct at91_adc_state {
u32 trigger_number;
bool use_external;
u32 vref_mv;
+ u32 res; /* resolution used for convertions */
+ bool low_res; /* the resolution corresponds to the lowest one */
wait_queue_head_t wq_data_avail;
};
@@ -138,7 +140,7 @@ static int at91_adc_channel_init(struct iio_dev *idev)
chan->channel = bit;
chan->scan_index = idx;
chan->scan_type.sign = 'u';
- chan->scan_type.realbits = 10;
+ chan->scan_type.realbits = st->res;
chan->scan_type.storagebits = 16;
chan->info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT |
IIO_CHAN_INFO_RAW_SEPARATE_BIT;
@@ -372,6 +374,59 @@ static int at91_adc_read_raw(struct iio_dev *idev,
return -EINVAL;
}
+static int at91_adc_of_get_resolution(struct at91_adc_state *st,
+ struct platform_device *pdev)
+{
+ struct iio_dev *idev = iio_priv_to_dev(st);
+ struct device_node *np = pdev->dev.of_node;
+ int count, i, ret = 0;
+ char *res_name, *s;
+ u32 *resolutions;
+
+ count = of_property_count_strings(np, "atmel,adc-res-names");
+ if (count < 2) {
+ dev_err(&idev->dev, "You must specified at least two resolution names for "
+ "adc-res-names property in the DT\n");
+ return count;
+ }
+
+ resolutions = kmalloc(count * sizeof(*resolutions), GFP_KERNEL);
+ if (!resolutions)
+ return -ENOMEM;
+
+ if (of_property_read_u32_array(np, "atmel,adc-res", resolutions, count)) {
+ dev_err(&idev->dev, "Missing adc-res property in the DT.\n");
+ ret = -ENODEV;
+ goto ret;
+ }
+
+ if (of_property_read_string(np, "atmel,adc-use-res", (const char **)&res_name))
+ res_name = "highres";
+
+ for (i = 0; i < count; i++) {
+ if (of_property_read_string_index(np, "atmel,adc-res-names", i, (const char **)&s))
+ continue;
+
+ if (strcmp(res_name, s))
+ continue;
+
+ st->res = resolutions[i];
+ if (!strcmp(res_name, "lowres"))
+ st->low_res = true;
+ else
+ st->low_res = false;
+
+ dev_info(&idev->dev, "Resolution used: %u bits\n", st->res);
+ goto ret;
+ }
+
+ dev_err(&idev->dev, "There is no resolution for %s\n", res_name);
+
+ret:
+ kfree(resolutions);
+ return ret;
+}
+
static int at91_adc_probe_dt(struct at91_adc_state *st,
struct platform_device *pdev)
{
@@ -415,6 +470,10 @@ static int at91_adc_probe_dt(struct at91_adc_state *st,
}
st->vref_mv = prop;
+ ret = at91_adc_of_get_resolution(st, pdev);
+ if (ret)
+ goto error_ret;
+
st->registers = devm_kzalloc(&idev->dev,
sizeof(struct at91_adc_reg_desc),
GFP_KERNEL);
@@ -628,9 +687,16 @@ static int __devinit at91_adc_probe(struct platform_device *pdev)
*/
ticks = round_up((st->startup_time * adc_clk /
1000000) - 1, 8) / 8;
- at91_adc_writel(st, AT91_ADC_MR,
- (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
- (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
+
+ if (st->low_res)
+ at91_adc_writel(st, AT91_ADC_MR,
+ AT91_ADC_LOWRES |
+ (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
+ (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
+ else
+ at91_adc_writel(st, AT91_ADC_MR,
+ (AT91_ADC_PRESCAL_(prsc) & AT91_ADC_PRESCAL) |
+ (AT91_ADC_STARTUP_(ticks) & AT91_ADC_STARTUP));
/* Setup the ADC channels available on the board */
ret = at91_adc_channel_init(idev);
--
1.7.10.4
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