[PATCH 0/3] iio:adc:at91-sama5d2: add support for signed conversion

STALE3838d

7 messages, 2 authors, 2016-03-05 · open the first message on its own page

[PATCH 0/3] iio:adc:at91-sama5d2: add support for signed conversion

From: Ludovic Desroches <hidden>
Date: 2016-03-03 16:08:51

Hi,

This set of patches does some cleanup in the code and export channels for
signed and unsigned conversions.

Ludovic Desroches (3):
  iio:adc:at91-sama5d2: fix typo
  iio:adc:at91-sama5d2: fix identation
  iio:adc:at91-sama5d2: add support for signed conversion

 drivers/iio/adc/at91-sama5d2_adc.c | 101 ++++++++++++++++++++++++++++---------
 1 file changed, 77 insertions(+), 24 deletions(-)

-- 
2.5.0

[PATCH 1/3] iio:adc:at91-sama5d2: fix typo

From: Ludovic Desroches <hidden>
Date: 2016-03-03 16:09:13

Fix typo in the name of a macro.

Signed-off-by: Ludovic Desroches <redacted>
---
 drivers/iio/adc/at91-sama5d2_adc.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index dbee13a..33bacec 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c

@@ -140,7 +140,7 @@
 /* Version Register */
 #define AT91_SAMA5D2_VERSION	0xfc
 
-#define AT91_AT91_SAMA5D2_CHAN(num, addr)				\
+#define AT91_SAMA5D2_CHAN(num, addr)					\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.channel = num,						\

@@ -185,18 +185,18 @@ struct at91_adc_state {
 };
 
 static const struct iio_chan_spec at91_adc_channels[] = {
-	AT91_AT91_SAMA5D2_CHAN(0, 0x50),
-	AT91_AT91_SAMA5D2_CHAN(1, 0x54),
-	AT91_AT91_SAMA5D2_CHAN(2, 0x58),
-	AT91_AT91_SAMA5D2_CHAN(3, 0x5c),
-	AT91_AT91_SAMA5D2_CHAN(4, 0x60),
-	AT91_AT91_SAMA5D2_CHAN(5, 0x64),
-	AT91_AT91_SAMA5D2_CHAN(6, 0x68),
-	AT91_AT91_SAMA5D2_CHAN(7, 0x6c),
-	AT91_AT91_SAMA5D2_CHAN(8, 0x70),
-	AT91_AT91_SAMA5D2_CHAN(9, 0x74),
-	AT91_AT91_SAMA5D2_CHAN(10, 0x78),
-	AT91_AT91_SAMA5D2_CHAN(11, 0x7c),
+	AT91_SAMA5D2_CHAN(0, 0x50),
+	AT91_SAMA5D2_CHAN(1, 0x54),
+	AT91_SAMA5D2_CHAN(2, 0x58),
+	AT91_SAMA5D2_CHAN(3, 0x5c),
+	AT91_SAMA5D2_CHAN(4, 0x60),
+	AT91_SAMA5D2_CHAN(5, 0x64),
+	AT91_SAMA5D2_CHAN(6, 0x68),
+	AT91_SAMA5D2_CHAN(7, 0x6c),
+	AT91_SAMA5D2_CHAN(8, 0x70),
+	AT91_SAMA5D2_CHAN(9, 0x74),
+	AT91_SAMA5D2_CHAN(10, 0x78),
+	AT91_SAMA5D2_CHAN(11, 0x7c),
 };
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,

-- 
2.5.0

[PATCH 2/3] iio:adc:at91-sama5d2: fix identation

From: Ludovic Desroches <hidden>
Date: 2016-03-03 16:09:37

Remove some extra tabs.

Signed-off-by: Ludovic Desroches <redacted>
---
 drivers/iio/adc/at91-sama5d2_adc.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 33bacec..5bc038f 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c

@@ -92,13 +92,13 @@
 /* Last Converted Data Register */
 #define AT91_SAMA5D2_LCDR	0x20
 /* Interrupt Enable Register */
-#define AT91_SAMA5D2_IER		0x24
+#define AT91_SAMA5D2_IER	0x24
 /* Interrupt Disable Register */
-#define AT91_SAMA5D2_IDR		0x28
+#define AT91_SAMA5D2_IDR	0x28
 /* Interrupt Mask Register */
-#define AT91_SAMA5D2_IMR		0x2c
+#define AT91_SAMA5D2_IMR	0x2c
 /* Interrupt Status Register */
-#define AT91_SAMA5D2_ISR		0x30
+#define AT91_SAMA5D2_ISR	0x30
 /* Last Channel Trigger Mode Register */
 #define AT91_SAMA5D2_LCTMR	0x34
 /* Last Channel Compare Window Register */

@@ -106,17 +106,17 @@
 /* Overrun Status Register */
 #define AT91_SAMA5D2_OVER	0x3c
 /* Extended Mode Register */
-#define AT91_SAMA5D2_EMR		0x40
+#define AT91_SAMA5D2_EMR	0x40
 /* Compare Window Register */
-#define AT91_SAMA5D2_CWR		0x44
+#define AT91_SAMA5D2_CWR	0x44
 /* Channel Gain Register */
-#define AT91_SAMA5D2_CGR		0x48
+#define AT91_SAMA5D2_CGR	0x48
 /* Channel Offset Register */
-#define AT91_SAMA5D2_COR		0x4c
+#define AT91_SAMA5D2_COR	0x4c
 /* Channel Data Register 0 */
 #define AT91_SAMA5D2_CDR0	0x50
 /* Analog Control Register */
-#define AT91_SAMA5D2_ACR		0x94
+#define AT91_SAMA5D2_ACR	0x94
 /* Touchscreen Mode Register */
 #define AT91_SAMA5D2_TSMR	0xb0
 /* Touchscreen X Position Register */

@@ -130,7 +130,7 @@
 /* Correction Select Register */
 #define AT91_SAMA5D2_COSR	0xd0
 /* Correction Value Register */
-#define AT91_SAMA5D2_CVR		0xd4
+#define AT91_SAMA5D2_CVR	0xd4
 /* Channel Error Correction Register */
 #define AT91_SAMA5D2_CECR	0xd8
 /* Write Protection Mode Register */

-- 
2.5.0

[PATCH 3/3] iio:adc:at91-sama5d2: add support for signed conversion

From: Ludovic Desroches <hidden>
Date: 2016-03-03 16:10:00

The at91-sama5d2 ADC controller can achieve unsigned and signed
conversion. For each channel, a signed and an unsigned variant are
created.
We can't set the sign mode for each channel. For that reason, the
controller has to be configured upon conversion requests.

Signed-off-by: Ludovic Desroches <redacted>
---
 drivers/iio/adc/at91-sama5d2_adc.c | 81 +++++++++++++++++++++++++++++++-------
 1 file changed, 67 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 5bc038f..d4bf73f 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c

@@ -105,8 +105,26 @@
 #define AT91_SAMA5D2_LCCWR	0x38
 /* Overrun Status Register */
 #define AT91_SAMA5D2_OVER	0x3c
+
 /* Extended Mode Register */
 #define AT91_SAMA5D2_EMR	0x40
+/* Sign Mode */
+#define AT91_SAMA5D2_EMR_SIGNMODE(v)		((v) << 25)
+/*
+ * Single-Ended channels: Unsigned conversions.
+ * Differential channels: Signed conversions.
+ */
+#define AT91_SAMA5D2_EMR_SE_UNSG_DF_SIGN	0
+/*
+ * Single-Ended channels: Signed conversions.
+ * Differential channels: Unsigned conversions.
+ */
+#define AT91_SAMA5D2_EMR_SE_SIGN_DF_UNSG	1
+/* All channels: Unsigned conversions */
+#define AT91_SAMA5D2_EMR_ALL_UNSIGNED		2
+/* All channels: Signed conversions */
+#define AT91_SAMA5D2_EMR_ALL_SIGNED		3
+
 /* Compare Window Register */
 #define AT91_SAMA5D2_CWR	0x44
 /* Channel Gain Register */

@@ -140,13 +158,14 @@
 /* Version Register */
 #define AT91_SAMA5D2_VERSION	0xfc
 
-#define AT91_SAMA5D2_CHAN(num, addr)					\
+#define AT91_SAMA5D2_VOLTAGE_CHANNEL(num, addr, sign_mode)		\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.channel = num,						\
 		.address = addr,					\
+		.extend_name = (sign_mode == 's') ? "signed" : "unsigned",\
 		.scan_type = {						\
-			.sign = 'u',					\
+			.sign = sign_mode,				\
 			.realbits = 12,					\
 		},							\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\

@@ -156,6 +175,12 @@
 		.indexed = 1,						\
 	}
 
+#define AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(num, addr)		\
+	AT91_SAMA5D2_VOLTAGE_CHANNEL(num, addr, 's')
+
+#define AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(num, addr)	\
+	AT91_SAMA5D2_VOLTAGE_CHANNEL(num, addr, 'u')
+
 #define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
 #define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)

@@ -185,18 +210,30 @@ struct at91_adc_state {
 };
 
 static const struct iio_chan_spec at91_adc_channels[] = {
-	AT91_SAMA5D2_CHAN(0, 0x50),
-	AT91_SAMA5D2_CHAN(1, 0x54),
-	AT91_SAMA5D2_CHAN(2, 0x58),
-	AT91_SAMA5D2_CHAN(3, 0x5c),
-	AT91_SAMA5D2_CHAN(4, 0x60),
-	AT91_SAMA5D2_CHAN(5, 0x64),
-	AT91_SAMA5D2_CHAN(6, 0x68),
-	AT91_SAMA5D2_CHAN(7, 0x6c),
-	AT91_SAMA5D2_CHAN(8, 0x70),
-	AT91_SAMA5D2_CHAN(9, 0x74),
-	AT91_SAMA5D2_CHAN(10, 0x78),
-	AT91_SAMA5D2_CHAN(11, 0x7c),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(0, 0x50),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(1, 0x54),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(2, 0x58),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(3, 0x5c),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(4, 0x60),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(5, 0x64),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(6, 0x68),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(7, 0x6c),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(8, 0x70),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(9, 0x74),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(10, 0x78),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(11, 0x7c),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(0, 0x50),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(1, 0x54),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(2, 0x58),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(3, 0x5c),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(4, 0x60),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(5, 0x64),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(6, 0x68),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(7, 0x6c),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(8, 0x70),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(9, 0x74),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(10, 0x78),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(11, 0x7c),
 };
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,

@@ -278,6 +315,7 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 			     int *val, int *val2, long mask)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
+	u32 emr;
 	int ret;
 
 	switch (mask) {

@@ -286,6 +324,19 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 
 		st->chan = chan;
 
+		/* Read EMR register and clear 'sign mode' field */
+		emr = at91_adc_readl(st, AT91_SAMA5D2_EMR)
+		      & AT91_SAMA5D2_EMR_SIGNMODE(0);
+		/*
+		 * Check if the user requested a conversion on a signed or
+		 * unsigned channel.
+		 */
+		if (chan->scan_type.sign == 's')
+			emr |= AT91_SAMA5D2_EMR_SIGNMODE(AT91_SAMA5D2_EMR_ALL_SIGNED);
+		else
+			emr |= AT91_SAMA5D2_EMR_SIGNMODE(AT91_SAMA5D2_EMR_ALL_UNSIGNED);
+
+		at91_adc_writel(st, AT91_SAMA5D2_EMR, emr);
 		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
 		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
 		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);

@@ -298,6 +349,8 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 
 		if (ret > 0) {
 			*val = st->conversion_value;
+			if (chan->scan_type.sign == 's')
+				*val = sign_extend32(*val, 11);
 			ret = IIO_VAL_INT;
 			st->conversion_done = false;
 		}

-- 
2.5.0

Re: [PATCH 1/3] iio:adc:at91-sama5d2: fix typo

From: Jonathan Cameron <jic23@kernel.org>
Date: 2016-03-05 15:02:51

On 03/03/16 16:09, Ludovic Desroches wrote:

Fix typo in the name of a macro.

Signed-off-by: Ludovic Desroches <redacted>

Oops ;)

Applied to the togreg branch of iio.git - initially pushed out as testing
for the autobuilders to play with it.  Not sure if I will be doing another pull
request to Greg this cycle though...

Jonathan

quoted hunk

---
 drivers/iio/adc/at91-sama5d2_adc.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index dbee13a..33bacec 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c

@@ -140,7 +140,7 @@
 /* Version Register */
 #define AT91_SAMA5D2_VERSION	0xfc
 
-#define AT91_AT91_SAMA5D2_CHAN(num, addr)				\
+#define AT91_SAMA5D2_CHAN(num, addr)					\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.channel = num,						\

@@ -185,18 +185,18 @@ struct at91_adc_state {
 };
 
 static const struct iio_chan_spec at91_adc_channels[] = {
-	AT91_AT91_SAMA5D2_CHAN(0, 0x50),
-	AT91_AT91_SAMA5D2_CHAN(1, 0x54),
-	AT91_AT91_SAMA5D2_CHAN(2, 0x58),
-	AT91_AT91_SAMA5D2_CHAN(3, 0x5c),
-	AT91_AT91_SAMA5D2_CHAN(4, 0x60),
-	AT91_AT91_SAMA5D2_CHAN(5, 0x64),
-	AT91_AT91_SAMA5D2_CHAN(6, 0x68),
-	AT91_AT91_SAMA5D2_CHAN(7, 0x6c),
-	AT91_AT91_SAMA5D2_CHAN(8, 0x70),
-	AT91_AT91_SAMA5D2_CHAN(9, 0x74),
-	AT91_AT91_SAMA5D2_CHAN(10, 0x78),
-	AT91_AT91_SAMA5D2_CHAN(11, 0x7c),
+	AT91_SAMA5D2_CHAN(0, 0x50),
+	AT91_SAMA5D2_CHAN(1, 0x54),
+	AT91_SAMA5D2_CHAN(2, 0x58),
+	AT91_SAMA5D2_CHAN(3, 0x5c),
+	AT91_SAMA5D2_CHAN(4, 0x60),
+	AT91_SAMA5D2_CHAN(5, 0x64),
+	AT91_SAMA5D2_CHAN(6, 0x68),
+	AT91_SAMA5D2_CHAN(7, 0x6c),
+	AT91_SAMA5D2_CHAN(8, 0x70),
+	AT91_SAMA5D2_CHAN(9, 0x74),
+	AT91_SAMA5D2_CHAN(10, 0x78),
+	AT91_SAMA5D2_CHAN(11, 0x7c),
 };
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,

Re: [PATCH 2/3] iio:adc:at91-sama5d2: fix identation

From: Jonathan Cameron <jic23@kernel.org>
Date: 2016-03-05 15:03:41

On 03/03/16 16:09, Ludovic Desroches wrote:

Remove some extra tabs.

Signed-off-by: Ludovic Desroches <redacted>

I find it hard to care about this sort of patch, but whatever.

Applied to the togreg branch of iio.git - pushed out as testing.. etc etc.

Jonathan

quoted hunk

---
 drivers/iio/adc/at91-sama5d2_adc.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 33bacec..5bc038f 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c

@@ -92,13 +92,13 @@
 /* Last Converted Data Register */
 #define AT91_SAMA5D2_LCDR	0x20
 /* Interrupt Enable Register */
-#define AT91_SAMA5D2_IER		0x24
+#define AT91_SAMA5D2_IER	0x24
 /* Interrupt Disable Register */
-#define AT91_SAMA5D2_IDR		0x28
+#define AT91_SAMA5D2_IDR	0x28
 /* Interrupt Mask Register */
-#define AT91_SAMA5D2_IMR		0x2c
+#define AT91_SAMA5D2_IMR	0x2c
 /* Interrupt Status Register */
-#define AT91_SAMA5D2_ISR		0x30
+#define AT91_SAMA5D2_ISR	0x30
 /* Last Channel Trigger Mode Register */
 #define AT91_SAMA5D2_LCTMR	0x34
 /* Last Channel Compare Window Register */

@@ -106,17 +106,17 @@
 /* Overrun Status Register */
 #define AT91_SAMA5D2_OVER	0x3c
 /* Extended Mode Register */
-#define AT91_SAMA5D2_EMR		0x40
+#define AT91_SAMA5D2_EMR	0x40
 /* Compare Window Register */
-#define AT91_SAMA5D2_CWR		0x44
+#define AT91_SAMA5D2_CWR	0x44
 /* Channel Gain Register */
-#define AT91_SAMA5D2_CGR		0x48
+#define AT91_SAMA5D2_CGR	0x48
 /* Channel Offset Register */
-#define AT91_SAMA5D2_COR		0x4c
+#define AT91_SAMA5D2_COR	0x4c
 /* Channel Data Register 0 */
 #define AT91_SAMA5D2_CDR0	0x50
 /* Analog Control Register */
-#define AT91_SAMA5D2_ACR		0x94
+#define AT91_SAMA5D2_ACR	0x94
 /* Touchscreen Mode Register */
 #define AT91_SAMA5D2_TSMR	0xb0
 /* Touchscreen X Position Register */

@@ -130,7 +130,7 @@
 /* Correction Select Register */
 #define AT91_SAMA5D2_COSR	0xd0
 /* Correction Value Register */
-#define AT91_SAMA5D2_CVR		0xd4
+#define AT91_SAMA5D2_CVR	0xd4
 /* Channel Error Correction Register */
 #define AT91_SAMA5D2_CECR	0xd8
 /* Write Protection Mode Register */

Re: [PATCH 3/3] iio:adc:at91-sama5d2: add support for signed conversion

From: Jonathan Cameron <jic23@kernel.org>
Date: 2016-03-05 15:16:20

On 03/03/16 16:09, Ludovic Desroches wrote:

The at91-sama5d2 ADC controller can achieve unsigned and signed
conversion. For each channel, a signed and an unsigned variant are
created.
We can't set the sign mode for each channel. For that reason, the
controller has to be configured upon conversion requests.

Signed-off-by: Ludovic Desroches <redacted>

Hmm. This should have a documentation patch as well as it breaks with
standard ABI.  I really don't like using the extended name for this.
Firstly, doing so changes the presented ABI to userspace and makes
it non standard and secondly the channels are only differentiated at
some levels (sysfs attribute naming for example.)  This really isn't
a generic enough approach.

I'd argue that we need a cleaner way of supporting this. Easy enough to add
an infomask element for this (I thought about an enum but _singed is clear
enough).

In this driver, that is all that would be needed.  Gets more interesting
for buffered drivers, where we'd need to provide an alternative to how
the channel type readback works (probably an optional callback in iio_info).
(was envisioning this from the first, but have never implemented it).

Anyhow, I guess we need to do this generically at somepoint.  Right now
all we need is the ABI for configuring on non buffered devices.

in_voltageX_signed with 1 and 0 as possible values should do the job I think...

Jonathan

quoted hunk

---
 drivers/iio/adc/at91-sama5d2_adc.c | 81 +++++++++++++++++++++++++++++++-------
 1 file changed, 67 insertions(+), 14 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 5bc038f..d4bf73f 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c

@@ -105,8 +105,26 @@
 #define AT91_SAMA5D2_LCCWR	0x38
 /* Overrun Status Register */
 #define AT91_SAMA5D2_OVER	0x3c
+
 /* Extended Mode Register */
 #define AT91_SAMA5D2_EMR	0x40
+/* Sign Mode */
+#define AT91_SAMA5D2_EMR_SIGNMODE(v)		((v) << 25)
+/*
+ * Single-Ended channels: Unsigned conversions.
+ * Differential channels: Signed conversions.
+ */
+#define AT91_SAMA5D2_EMR_SE_UNSG_DF_SIGN	0
+/*
+ * Single-Ended channels: Signed conversions.
+ * Differential channels: Unsigned conversions.
+ */
+#define AT91_SAMA5D2_EMR_SE_SIGN_DF_UNSG	1
+/* All channels: Unsigned conversions */
+#define AT91_SAMA5D2_EMR_ALL_UNSIGNED		2
+/* All channels: Signed conversions */
+#define AT91_SAMA5D2_EMR_ALL_SIGNED		3
+
 /* Compare Window Register */
 #define AT91_SAMA5D2_CWR	0x44
 /* Channel Gain Register */

@@ -140,13 +158,14 @@
 /* Version Register */
 #define AT91_SAMA5D2_VERSION	0xfc
 
-#define AT91_SAMA5D2_CHAN(num, addr)					\
+#define AT91_SAMA5D2_VOLTAGE_CHANNEL(num, addr, sign_mode)		\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.channel = num,						\
 		.address = addr,					\
+		.extend_name = (sign_mode == 's') ? "signed" : "unsigned",\
 		.scan_type = {						\
-			.sign = 'u',					\
+			.sign = sign_mode,				\
 			.realbits = 12,					\
 		},							\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\

@@ -156,6 +175,12 @@
 		.indexed = 1,						\
 	}
 
+#define AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(num, addr)		\
+	AT91_SAMA5D2_VOLTAGE_CHANNEL(num, addr, 's')
+
+#define AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(num, addr)	\
+	AT91_SAMA5D2_VOLTAGE_CHANNEL(num, addr, 'u')
+
 #define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
 #define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)

@@ -185,18 +210,30 @@ struct at91_adc_state {
 };
 
 static const struct iio_chan_spec at91_adc_channels[] = {
-	AT91_SAMA5D2_CHAN(0, 0x50),
-	AT91_SAMA5D2_CHAN(1, 0x54),
-	AT91_SAMA5D2_CHAN(2, 0x58),
-	AT91_SAMA5D2_CHAN(3, 0x5c),
-	AT91_SAMA5D2_CHAN(4, 0x60),
-	AT91_SAMA5D2_CHAN(5, 0x64),
-	AT91_SAMA5D2_CHAN(6, 0x68),
-	AT91_SAMA5D2_CHAN(7, 0x6c),
-	AT91_SAMA5D2_CHAN(8, 0x70),
-	AT91_SAMA5D2_CHAN(9, 0x74),
-	AT91_SAMA5D2_CHAN(10, 0x78),
-	AT91_SAMA5D2_CHAN(11, 0x7c),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(0, 0x50),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(1, 0x54),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(2, 0x58),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(3, 0x5c),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(4, 0x60),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(5, 0x64),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(6, 0x68),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(7, 0x6c),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(8, 0x70),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(9, 0x74),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(10, 0x78),
+	AT91_SAMA5D2_UNSIGNED_VOLTAGE_CHANNEL(11, 0x7c),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(0, 0x50),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(1, 0x54),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(2, 0x58),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(3, 0x5c),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(4, 0x60),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(5, 0x64),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(6, 0x68),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(7, 0x6c),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(8, 0x70),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(9, 0x74),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(10, 0x78),
+	AT91_SAMA5D2_SIGNED_VOLTAGE_CHANNEL(11, 0x7c),
 };
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,

@@ -278,6 +315,7 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 			     int *val, int *val2, long mask)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
+	u32 emr;
 	int ret;
 
 	switch (mask) {

@@ -286,6 +324,19 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 
 		st->chan = chan;
 
+		/* Read EMR register and clear 'sign mode' field */
+		emr = at91_adc_readl(st, AT91_SAMA5D2_EMR)
+		      & AT91_SAMA5D2_EMR_SIGNMODE(0);
+		/*
+		 * Check if the user requested a conversion on a signed or
+		 * unsigned channel.
+		 */
+		if (chan->scan_type.sign == 's')
+			emr |= AT91_SAMA5D2_EMR_SIGNMODE(AT91_SAMA5D2_EMR_ALL_SIGNED);
+		else
+			emr |= AT91_SAMA5D2_EMR_SIGNMODE(AT91_SAMA5D2_EMR_ALL_UNSIGNED);
+
+		at91_adc_writel(st, AT91_SAMA5D2_EMR, emr);
 		at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
 		at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
 		at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);

@@ -298,6 +349,8 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 
 		if (ret > 0) {
 			*val = st->conversion_value;
+			if (chan->scan_type.sign == 's')
+				*val = sign_extend32(*val, 11);
 			ret = IIO_VAL_INT;
 			st->conversion_done = false;
 		}

`h`	back out one level
`j`	next message in thread
`k`	previous message in thread
`l`	drill in
`Esc`	close help / fold thread tree
`?`	toggle this help