[PATCH v2 2/2] iio:adc:at91-sama5d2: add support for signed conversion
From: Ludovic Desroches
Date: Mon Mar 07 2016 - 09:30:40 EST
The at91-sama5d2 ADC controller can achieve unsigned and signed
conversions. For each channel, a signed and an unsigned variant are
created.
Sign mode is a global configuration, it is not tied to a specific
channel. For this reason, the controller has to be configured upon
conversion request.
Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
---
drivers/iio/adc/at91-sama5d2_adc.c | 125 ++++++++++++++++++++++++++++++-------
1 file changed, 102 insertions(+), 23 deletions(-)
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 5bc038f..0370c4f 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 */
@@ -140,22 +158,28 @@
/* 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, \
.scan_type = { \
- .sign = 'u', \
+ .sign = sign_mode, \
.realbits = 12, \
}, \
- .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_separate = (sign_mode == 's') ? BIT(IIO_CHAN_INFO_SIGNED) : 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, \
.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 +209,30 @@ 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,
@@ -273,6 +309,38 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
return IRQ_NONE;
}
+static int at91_adc_read_conversion_value(struct at91_adc_state *st)
+{
+ u32 emr;
+ int ret;
+
+ /* 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 (st->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(st->chan->channel));
+ at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(st->chan->channel));
+ at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
+
+ ret = wait_event_interruptible_timeout(st->wq_data_available,
+ st->conversion_done,
+ msecs_to_jiffies(1000));
+
+ at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(st->chan->channel));
+ at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(st->chan->channel));
+
+ return ret;
+}
+
static int at91_adc_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
@@ -286,13 +354,8 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
st->chan = chan;
- 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);
+ ret = at91_adc_read_conversion_value(st);
- ret = wait_event_interruptible_timeout(st->wq_data_available,
- st->conversion_done,
- msecs_to_jiffies(1000));
if (ret == 0)
ret = -ETIMEDOUT;
@@ -302,8 +365,24 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
st->conversion_done = false;
}
- at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
- at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+ mutex_unlock(&st->lock);
+ return ret;
+
+ case IIO_CHAN_INFO_SIGNED:
+ mutex_lock(&st->lock);
+
+ st->chan = chan;
+
+ ret = at91_adc_read_conversion_value(st);
+
+ if (ret == 0)
+ ret = -ETIMEDOUT;
+
+ if (ret > 0) {
+ *val = sign_extend32(st->conversion_value, 11);
+ ret = IIO_VAL_INT;
+ st->conversion_done = false;
+ }
mutex_unlock(&st->lock);
return ret;
--
2.5.0