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Message-ID: <1458662926-8791-2-git-send-email-ludovic.desroches@atmel.com>
Date: Tue, 22 Mar 2016 17:08:46 +0100
From: Ludovic Desroches <ludovic.desroches@...el.com>
To: <jic23@...nel.org>
CC: <lars@...afoo.de>, <linux-iio@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <nicolas.ferre@...el.com>,
<alexandre.belloni@...e-electrons.com>,
<linux-arm-kernel@...ts.infradead.org>,
Ludovic Desroches <ludovic.desroches@...el.com>
Subject: [PATCH 2/2] iio:adc:at91-sama5d2: add support for differential conversions
Add signed differential channels and update the voltage scale for
differential conversions.
Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
---
This patch is based on:
iio:adc:at91-sama5d2: fix identation
iio:adc:at91-sama5d2: fix typo
drivers/iio/adc/at91-sama5d2_adc.c | 71 ++++++++++++++++++++++++++++++--------
1 file changed, 56 insertions(+), 15 deletions(-)
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 01ba106..07adb10 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -113,8 +113,11 @@
#define AT91_SAMA5D2_CWR 0x44
/* Channel Gain Register */
#define AT91_SAMA5D2_CGR 0x48
+
/* Channel Offset Register */
#define AT91_SAMA5D2_COR 0x4c
+#define AT91_SAMA5D2_COR_DIFF_OFFSET 16
+
/* Channel Data Register 0 */
#define AT91_SAMA5D2_CDR0 0x50
/* Analog Control Register */
@@ -142,7 +145,7 @@
/* Version Register */
#define AT91_SAMA5D2_VERSION 0xfc
-#define AT91_SAMA5D2_CHAN(num, addr) \
+#define AT91_SAMA5D2_CHAN_SINGLE(num, addr) \
{ \
.type = IIO_VOLTAGE, \
.channel = num, \
@@ -158,6 +161,24 @@
.indexed = 1, \
}
+#define AT91_SAMA5D2_CHAN_DIFF(num, num2, addr) \
+ { \
+ .type = IIO_VOLTAGE, \
+ .differential = 1, \
+ .channel = num, \
+ .channel2 = num2, \
+ .address = addr, \
+ .scan_type = { \
+ .sign = 's', \
+ .realbits = 12, \
+ }, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
+ .datasheet_name = "CH"#num"-CH"#num2, \
+ .indexed = 1, \
+ }
+
#define at91_adc_readl(st, reg) readl_relaxed(st->base + reg)
#define at91_adc_writel(st, reg, val) writel_relaxed(val, st->base + reg)
@@ -187,18 +208,24 @@ 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_CHAN_SINGLE(0, 0x50),
+ AT91_SAMA5D2_CHAN_SINGLE(1, 0x54),
+ AT91_SAMA5D2_CHAN_SINGLE(2, 0x58),
+ AT91_SAMA5D2_CHAN_SINGLE(3, 0x5c),
+ AT91_SAMA5D2_CHAN_SINGLE(4, 0x60),
+ AT91_SAMA5D2_CHAN_SINGLE(5, 0x64),
+ AT91_SAMA5D2_CHAN_SINGLE(6, 0x68),
+ AT91_SAMA5D2_CHAN_SINGLE(7, 0x6c),
+ AT91_SAMA5D2_CHAN_SINGLE(8, 0x70),
+ AT91_SAMA5D2_CHAN_SINGLE(9, 0x74),
+ AT91_SAMA5D2_CHAN_SINGLE(10, 0x78),
+ AT91_SAMA5D2_CHAN_SINGLE(11, 0x7c),
+ AT91_SAMA5D2_CHAN_DIFF(0, 1, 0x50),
+ AT91_SAMA5D2_CHAN_DIFF(2, 3, 0x58),
+ AT91_SAMA5D2_CHAN_DIFF(4, 5, 0x60),
+ AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
+ AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
+ AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
};
static unsigned at91_adc_startup_time(unsigned startup_time_min,
@@ -281,6 +308,7 @@ 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 cor = 0;
int ret;
switch (mask) {
@@ -289,6 +317,11 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
st->chan = chan;
+ if (chan->differential)
+ cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
+ AT91_SAMA5D2_COR_DIFF_OFFSET;
+
+ at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
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);
@@ -301,6 +334,8 @@ 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;
}
@@ -313,6 +348,8 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
case IIO_CHAN_INFO_SCALE:
*val = st->vref_uv / 1000;
+ if (chan->differential)
+ *val *= 2;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
@@ -447,8 +484,12 @@ static int at91_adc_probe(struct platform_device *pdev)
at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
at91_adc_writel(st, AT91_SAMA5D2_IDR, 0xffffffff);
- /* Transfer field must be set to 2 according to the datasheet. */
- at91_adc_writel(st, AT91_SAMA5D2_MR, AT91_SAMA5D2_MR_TRANSFER(2));
+ /*
+ * Transfer field must be set to 2 according to the datasheet and
+ * allows different analog settings for each channel.
+ */
+ at91_adc_writel(st, AT91_SAMA5D2_MR,
+ AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
--
2.5.0
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