[PATCH V2 0/2] iio: mxs-lradc: check ranges of ts properties

[PATCH V2 0/2] iio: mxs-lradc: check ranges of ts properties

[Stefan Wahren]

These patch series fixes off-by-one issues of the touchscreen DT properties
and finally adds a range check during probe.

Only the range check has been tested by myself, because i don't have a
touchscreen. So a functional test is very welcome.

Changes since V1:
- fix format specifier in error message
- fix minor style issues

Changes since RFC:
- add fix for off-by-one issues
- first check DT properties and then assign a value
- adapt range check to better represent DT binding
- add important note from the reference manual as comment

Stefan Wahren (2):
  DT: mxs-lradc: fix ranges of ts properties
  iio: mxs-lradc: check ranges of ts properties

 .../bindings/staging/iio/adc/mxs-lradc.txt         |    4 +-
 drivers/staging/iio/adc/mxs-lradc.c                |   45 +++++++++++++++-----
 2 files changed, 37 insertions(+), 12 deletions(-)

-- 
1.7.9.5

[PATCH V2 1/2] DT: mxs-lradc: fix ranges of ts properties

[Stefan Wahren]

This patch fixes off-by-one issues in the devicetree binding of
mxs-lradc.

According to the i.MX23 and i.MX28 reference manuals [1][2] the range of
NUM_SAMPLES is 0..31, but property ave-ctrl is substracted by 1 before used.

Considering all limitations the range of DELAY is 1..2047, but also
property ave-delay is substracted by 1 before used.

The patch has been suggested by Hartmut Knaack and Kristina Martsenko.

[1] - http://cache.freescale.com/files/dsp/doc/ref_manual/IMX23RM.pdf
[2] - http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf

Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
---
 .../bindings/staging/iio/adc/mxs-lradc.txt         |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt b/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
index ee05dc3..3075377 100644
--- a/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
+++ b/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
@@ -12,9 +12,9 @@ Optional properties:
                                property is not present, then the touchscreen is
                                disabled. 5 wires is valid for i.MX28 SoC only.
 - fsl,ave-ctrl: number of samples per direction to calculate an average value.
-                Allowed value is 1 ... 31, default is 4
+                Allowed value is 1 ... 32, default is 4
 - fsl,ave-delay: delay between consecutive samples. Allowed value is
-                 1 ... 2047. It is used if 'fsl,ave-ctrl' > 1, counts at
+                 2 ... 2048. It is used if 'fsl,ave-ctrl' > 1, counts at
                  2 kHz and its default is 2 (= 1 ms)
 - fsl,settling: delay between plate switch to next sample. Allowed value is
                 1 ... 2047. It counts at 2 kHz and its default is
-- 
1.7.9.5

[PATCH V2 2/2] iio: mxs-lradc: check ranges of ts properties

[Stefan Wahren]

The devicetree binding for mxs-lradc defines ranges for the
touchscreen properties. In order to avoid unexpected behavior like
division by zero, we better check these ranges during probe and
abort in error case.

Additionally this patch adds an important note from the reference
manual about the range of sample delay.

Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
Reviewed-by: Marek Vasut <marex-ynQEQJNshbs@public.gmane.org>
---
 drivers/staging/iio/adc/mxs-lradc.c |   45 +++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index f053535..d9d6fad 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -436,7 +436,14 @@ static void mxs_lradc_setup_ts_channel(struct mxs_lradc *lradc, unsigned ch)
 	 */
 	mxs_lradc_reg_clear(lradc, LRADC_CH_VALUE_MASK, LRADC_CH(ch));
 
-	/* prepare the delay/loop unit according to the oversampling count */
+	/*
+	 * prepare the delay/loop unit according to the oversampling count
+	 *
+	 * from the datasheet:
+	 * "The DELAY fields in HW_LRADC_DELAY0, HW_LRADC_DELAY1,
+	 * HW_LRADC_DELAY2, and HW_LRADC_DELAY3 must be non-zero; otherwise,
+	 * the LRADC will not trigger the delay group."
+	 */
 	mxs_lradc_reg_wrt(lradc, LRADC_DELAY_TRIGGER(1 << ch) |
 		LRADC_DELAY_TRIGGER_DELAYS(0) |
 		LRADC_DELAY_LOOP(lradc->over_sample_cnt - 1) |
@@ -1495,20 +1502,38 @@ static int mxs_lradc_probe_touchscreen(struct mxs_lradc *lradc,
 		return -EINVAL;
 	}
 
-	lradc->over_sample_cnt = 4;
-	ret = of_property_read_u32(lradc_node, "fsl,ave-ctrl", &adapt);
-	if (ret == 0)
+	if (of_property_read_u32(lradc_node, "fsl,ave-ctrl", &adapt)) {
+		lradc->over_sample_cnt = 4;
+	} else {
+		if (adapt < 1 || adapt > 32) {
+			dev_err(lradc->dev, "Invalid sample count (%u)\n",
+				adapt);
+			return -EINVAL;
+		}
 		lradc->over_sample_cnt = adapt;
+	}
 
-	lradc->over_sample_delay = 2;
-	ret = of_property_read_u32(lradc_node, "fsl,ave-delay", &adapt);
-	if (ret == 0)
+	if (of_property_read_u32(lradc_node, "fsl,ave-delay", &adapt)) {
+		lradc->over_sample_delay = 2;
+	} else {
+		if (adapt < 2 || adapt > LRADC_DELAY_DELAY_MASK + 1) {
+			dev_err(lradc->dev, "Invalid sample delay (%u)\n",
+				adapt);
+			return -EINVAL;
+		}
 		lradc->over_sample_delay = adapt;
+	}
 
-	lradc->settling_delay = 10;
-	ret = of_property_read_u32(lradc_node, "fsl,settling", &adapt);
-	if (ret == 0)
+	if (of_property_read_u32(lradc_node, "fsl,settling", &adapt)) {
+		lradc->settling_delay = 10;
+	} else {
+		if (adapt < 1 || adapt > LRADC_DELAY_DELAY_MASK) {
+			dev_err(lradc->dev, "Invalid settling delay (%u)\n",
+				adapt);
+			return -EINVAL;
+		}
 		lradc->settling_delay = adapt;
+	}
 
 	return 0;
 }
-- 
1.7.9.5

Re: [PATCH V2 1/2] DT: mxs-lradc: fix ranges of ts properties

[Jonathan Cameron]

On 29/12/14 10:27, Stefan Wahren wrote:
> This patch fixes off-by-one issues in the devicetree binding of
> mxs-lradc.
> 
> According to the i.MX23 and i.MX28 reference manuals [1][2] the range of
> NUM_SAMPLES is 0..31, but property ave-ctrl is substracted by 1 before used.
> 
> Considering all limitations the range of DELAY is 1..2047, but also
> property ave-delay is substracted by 1 before used.
> 
> The patch has been suggested by Hartmut Knaack and Kristina Martsenko.
> 
> [1] - http://cache.freescale.com/files/dsp/doc/ref_manual/IMX23RM.pdf
> [2] - http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf
> 
> Signed-off-by: Stefan Wahren <stefan.wahren-eS4NqCHxEME@public.gmane.org>
Hmm.  I debated whether to take these through the fixes tree.  Whilst they
are technically fixing the driver, it is only a fashion that makes it a little
more flexible and the devicetree binding more resilient.  Good stuff, but
can probably wait a cycle.

Anyhow, as such - applied to the togreg branch of iio.git.
Initially pushed out as testing for the autobuilders to play.

Thanks,

Jonathan
> ---
>  .../bindings/staging/iio/adc/mxs-lradc.txt         |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt b/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
> index ee05dc3..3075377 100644
> --- a/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
> +++ b/Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt
> @@ -12,9 +12,9 @@ Optional properties:
>                                 property is not present, then the touchscreen is
>                                 disabled. 5 wires is valid for i.MX28 SoC only.
>  - fsl,ave-ctrl: number of samples per direction to calculate an average value.
> -                Allowed value is 1 ... 31, default is 4
> +                Allowed value is 1 ... 32, default is 4
>  - fsl,ave-delay: delay between consecutive samples. Allowed value is
> -                 1 ... 2047. It is used if 'fsl,ave-ctrl' > 1, counts at
> +                 2 ... 2048. It is used if 'fsl,ave-ctrl' > 1, counts at
>                   2 kHz and its default is 2 (= 1 ms)
>  - fsl,settling: delay between plate switch to next sample. Allowed value is
>                  1 ... 2047. It counts at 2 kHz and its default is
>