1 files changed, 349 insertions, 56 deletions

diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
index 13e1bba45b..1fd2211e29 100644
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -4,7 +4,11 @@
  *
  * Copyright 2012-2020 Analog Devices Inc.
  */
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
 #include <linux/cleanup.h>
+#include <linux/debugfs.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/device.h>
@@ -100,6 +104,8 @@
 #define AD9467_DEF_OUTPUT_MODE		0x08
 #define AD9467_REG_VREF_MASK		0x0F
 
+#define AD9647_MAX_TEST_POINTS		32
+
 struct ad9467_chip_info {
 	const char		*name;
 	unsigned int		id;
@@ -110,6 +116,9 @@ struct ad9467_chip_info {
 	unsigned long		max_rate;
 	unsigned int		default_output_mode;
 	unsigned int		vref_mask;
+	unsigned int		num_lanes;
+	/* data clock output */
+	bool			has_dco;
 };
 
 struct ad9467_state {
@@ -119,13 +128,23 @@ struct ad9467_state {
 	struct clk			*clk;
 	unsigned int			output_mode;
 	unsigned int                    (*scales)[2];
-
+	/*
+	 * Times 2 because we may also invert the signal polarity and run the
+	 * calibration again. For some reference on the test points (ad9265) see:
+	 * https://www.analog.com/media/en/technical-documentation/data-sheets/ad9265.pdf
+	 * at page 38 for the dco output delay. On devices as ad9467, the
+	 * calibration is done at the backend level. For the ADI axi-adc:
+	 * https://wiki.analog.com/resources/fpga/docs/axi_adc_ip
+	 * at the io delay control section.
+	 */
+	DECLARE_BITMAP(calib_map, AD9647_MAX_TEST_POINTS * 2);
 	struct gpio_desc		*pwrdown_gpio;
 	/* ensure consistent state obtained on multiple related accesses */
 	struct mutex			lock;
+	u8				buf[3] __aligned(IIO_DMA_MINALIGN);
 };
 
-static int ad9467_spi_read(struct spi_device *spi, unsigned int reg)
+static int ad9467_spi_read(struct ad9467_state *st, unsigned int reg)
 {
 	unsigned char tbuf[2], rbuf[1];
 	int ret;
@@ -133,7 +152,7 @@ static int ad9467_spi_read(struct spi_device *spi, unsigned int reg)
 	tbuf[0] = 0x80 | (reg >> 8);
 	tbuf[1] = reg & 0xFF;
 
-	ret = spi_write_then_read(spi,
+	ret = spi_write_then_read(st->spi,
 				  tbuf, ARRAY_SIZE(tbuf),
 				  rbuf, ARRAY_SIZE(rbuf));
 
@@ -143,35 +162,32 @@ static int ad9467_spi_read(struct spi_device *spi, unsigned int reg)
 	return rbuf[0];
 }
 
-static int ad9467_spi_write(struct spi_device *spi, unsigned int reg,
+static int ad9467_spi_write(struct ad9467_state *st, unsigned int reg,
 			    unsigned int val)
 {
-	unsigned char buf[3];
-
-	buf[0] = reg >> 8;
-	buf[1] = reg & 0xFF;
-	buf[2] = val;
+	st->buf[0] = reg >> 8;
+	st->buf[1] = reg & 0xFF;
+	st->buf[2] = val;
 
-	return spi_write(spi, buf, ARRAY_SIZE(buf));
+	return spi_write(st->spi, st->buf, ARRAY_SIZE(st->buf));
 }
 
 static int ad9467_reg_access(struct iio_dev *indio_dev, unsigned int reg,
 			     unsigned int writeval, unsigned int *readval)
 {
 	struct ad9467_state *st = iio_priv(indio_dev);
-	struct spi_device *spi = st->spi;
 	int ret;
 
 	if (!readval) {
 		guard(mutex)(&st->lock);
-		ret = ad9467_spi_write(spi, reg, writeval);
+		ret = ad9467_spi_write(st, reg, writeval);
 		if (ret)
 			return ret;
-		return ad9467_spi_write(spi, AN877_ADC_REG_TRANSFER,
+		return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
 					AN877_ADC_TRANSFER_SYNC);
 	}
 
-	ret = ad9467_spi_read(spi, reg);
+	ret = ad9467_spi_read(st, reg);
 	if (ret < 0)
 		return ret;
 	*readval = ret;
@@ -242,6 +258,7 @@ static const struct ad9467_chip_info ad9467_chip_tbl = {
 	.num_channels = ARRAY_SIZE(ad9467_channels),
 	.default_output_mode = AD9467_DEF_OUTPUT_MODE,
 	.vref_mask = AD9467_REG_VREF_MASK,
+	.num_lanes = 8,
 };
 
 static const struct ad9467_chip_info ad9434_chip_tbl = {
@@ -254,6 +271,7 @@ static const struct ad9467_chip_info ad9434_chip_tbl = {
 	.num_channels = ARRAY_SIZE(ad9434_channels),
 	.default_output_mode = AD9434_DEF_OUTPUT_MODE,
 	.vref_mask = AD9434_REG_VREF_MASK,
+	.num_lanes = 6,
 };
 
 static const struct ad9467_chip_info ad9265_chip_tbl = {
@@ -266,6 +284,7 @@ static const struct ad9467_chip_info ad9265_chip_tbl = {
 	.num_channels = ARRAY_SIZE(ad9467_channels),
 	.default_output_mode = AD9265_DEF_OUTPUT_MODE,
 	.vref_mask = AD9265_REG_VREF_MASK,
+	.has_dco = true,
 };
 
 static int ad9467_get_scale(struct ad9467_state *st, int *val, int *val2)
@@ -274,7 +293,7 @@ static int ad9467_get_scale(struct ad9467_state *st, int *val, int *val2)
 	unsigned int i, vref_val;
 	int ret;
 
-	ret = ad9467_spi_read(st->spi, AN877_ADC_REG_VREF);
+	ret = ad9467_spi_read(st, AN877_ADC_REG_VREF);
 	if (ret < 0)
 		return ret;
 
@@ -309,18 +328,257 @@ static int ad9467_set_scale(struct ad9467_state *st, int val, int val2)
 			continue;
 
 		guard(mutex)(&st->lock);
-		ret = ad9467_spi_write(st->spi, AN877_ADC_REG_VREF,
+		ret = ad9467_spi_write(st, AN877_ADC_REG_VREF,
 				       info->scale_table[i][1]);
 		if (ret < 0)
 			return ret;
 
-		return ad9467_spi_write(st->spi, AN877_ADC_REG_TRANSFER,
+		return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
 					AN877_ADC_TRANSFER_SYNC);
 	}
 
 	return -EINVAL;
 }
 
+static int ad9467_outputmode_set(struct ad9467_state *st, unsigned int mode)
+{
+	int ret;
+
+	ret = ad9467_spi_write(st, AN877_ADC_REG_OUTPUT_MODE, mode);
+	if (ret < 0)
+		return ret;
+
+	return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
+				AN877_ADC_TRANSFER_SYNC);
+}
+
+static int ad9647_calibrate_prepare(struct ad9467_state *st)
+{
+	struct iio_backend_data_fmt data = {
+		.enable = false,
+	};
+	unsigned int c;
+	int ret;
+
+	ret = ad9467_spi_write(st, AN877_ADC_REG_TEST_IO,
+			       AN877_ADC_TESTMODE_PN9_SEQ);
+	if (ret)
+		return ret;
+
+	ret = ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
+			       AN877_ADC_TRANSFER_SYNC);
+	if (ret)
+		return ret;
+
+	ret = ad9467_outputmode_set(st, st->info->default_output_mode);
+	if (ret)
+		return ret;
+
+	for (c = 0; c < st->info->num_channels; c++) {
+		ret = iio_backend_data_format_set(st->back, c, &data);
+		if (ret)
+			return ret;
+	}
+
+	ret = iio_backend_test_pattern_set(st->back, 0,
+					   IIO_BACKEND_ADI_PRBS_9A);
+	if (ret)
+		return ret;
+
+	return iio_backend_chan_enable(st->back, 0);
+}
+
+static int ad9647_calibrate_polarity_set(struct ad9467_state *st,
+					 bool invert)
+{
+	enum iio_backend_sample_trigger trigger;
+
+	if (st->info->has_dco) {
+		unsigned int phase = AN877_ADC_OUTPUT_EVEN_ODD_MODE_EN;
+
+		if (invert)
+			phase |= AN877_ADC_INVERT_DCO_CLK;
+
+		return ad9467_spi_write(st, AN877_ADC_REG_OUTPUT_PHASE,
+					phase);
+	}
+
+	if (invert)
+		trigger = IIO_BACKEND_SAMPLE_TRIGGER_EDGE_FALLING;
+	else
+		trigger = IIO_BACKEND_SAMPLE_TRIGGER_EDGE_RISING;
+
+	return iio_backend_data_sample_trigger(st->back, trigger);
+}
+
+/*
+ * The idea is pretty simple. Find the max number of successful points in a row
+ * and get the one in the middle.
+ */
+static unsigned int ad9467_find_optimal_point(const unsigned long *calib_map,
+					      unsigned int start,
+					      unsigned int nbits,
+					      unsigned int *val)
+{
+	unsigned int bit = start, end, start_cnt, cnt = 0;
+
+	for_each_clear_bitrange_from(bit, end, calib_map, nbits + start) {
+		if (end - bit > cnt) {
+			cnt = end - bit;
+			start_cnt = bit;
+		}
+	}
+
+	if (cnt)
+		*val = start_cnt + cnt / 2;
+
+	return cnt;
+}
+
+static int ad9467_calibrate_apply(struct ad9467_state *st, unsigned int val)
+{
+	unsigned int lane;
+	int ret;
+
+	if (st->info->has_dco) {
+		ret = ad9467_spi_write(st, AN877_ADC_REG_OUTPUT_DELAY,
+				       val);
+		if (ret)
+			return ret;
+
+		return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
+					AN877_ADC_TRANSFER_SYNC);
+	}
+
+	for (lane = 0; lane < st->info->num_lanes; lane++) {
+		ret = iio_backend_iodelay_set(st->back, lane, val);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int ad9647_calibrate_stop(struct ad9467_state *st)
+{
+	struct iio_backend_data_fmt data = {
+		.sign_extend = true,
+		.enable = true,
+	};
+	unsigned int c, mode;
+	int ret;
+
+	ret = iio_backend_chan_disable(st->back, 0);
+	if (ret)
+		return ret;
+
+	ret = iio_backend_test_pattern_set(st->back, 0,
+					   IIO_BACKEND_NO_TEST_PATTERN);
+	if (ret)
+		return ret;
+
+	for (c = 0; c < st->info->num_channels; c++) {
+		ret = iio_backend_data_format_set(st->back, c, &data);
+		if (ret)
+			return ret;
+	}
+
+	mode = st->info->default_output_mode | AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
+	ret = ad9467_outputmode_set(st, mode);
+	if (ret)
+		return ret;
+
+	ret = ad9467_spi_write(st, AN877_ADC_REG_TEST_IO,
+			       AN877_ADC_TESTMODE_OFF);
+	if (ret)
+		return ret;
+
+	return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
+			       AN877_ADC_TRANSFER_SYNC);
+}
+
+static int ad9467_calibrate(struct ad9467_state *st)
+{
+	unsigned int point, val, inv_val, cnt, inv_cnt = 0;
+	/*
+	 * Half of the bitmap is for the inverted signal. The number of test
+	 * points is the same though...
+	 */
+	unsigned int test_points = AD9647_MAX_TEST_POINTS;
+	unsigned long sample_rate = clk_get_rate(st->clk);
+	struct device *dev = &st->spi->dev;
+	bool invert = false, stat;
+	int ret;
+
+	/* all points invalid */
+	bitmap_fill(st->calib_map, BITS_PER_TYPE(st->calib_map));
+
+	ret = ad9647_calibrate_prepare(st);
+	if (ret)
+		return ret;
+retune:
+	ret = ad9647_calibrate_polarity_set(st, invert);
+	if (ret)
+		return ret;
+
+	for (point = 0; point < test_points; point++) {
+		ret = ad9467_calibrate_apply(st, point);
+		if (ret)
+			return ret;
+
+		ret = iio_backend_chan_status(st->back, 0, &stat);
+		if (ret)
+			return ret;
+
+		__assign_bit(point + invert * test_points, st->calib_map, stat);
+	}
+
+	if (!invert) {
+		cnt = ad9467_find_optimal_point(st->calib_map, 0, test_points,
+						&val);
+		/*
+		 * We're happy if we find, at least, three good test points in
+		 * a row.
+		 */
+		if (cnt < 3) {
+			invert = true;
+			goto retune;
+		}
+	} else {
+		inv_cnt = ad9467_find_optimal_point(st->calib_map, test_points,
+						    test_points, &inv_val);
+		if (!inv_cnt && !cnt)
+			return -EIO;
+	}
+
+	if (inv_cnt < cnt) {
+		ret = ad9647_calibrate_polarity_set(st, false);
+		if (ret)
+			return ret;
+	} else {
+		/*
+		 * polarity inverted is the last test to run. Hence, there's no
+		 * need to re-do any configuration. We just need to "normalize"
+		 * the selected value.
+		 */
+		val = inv_val - test_points;
+	}
+
+	if (st->info->has_dco)
+		dev_dbg(dev, "%sDCO 0x%X CLK %lu Hz\n", inv_cnt >= cnt ? "INVERT " : "",
+			val, sample_rate);
+	else
+		dev_dbg(dev, "%sIDELAY 0x%x\n", inv_cnt >= cnt ? "INVERT " : "",
+			val);
+
+	ret = ad9467_calibrate_apply(st, val);
+	if (ret)
+		return ret;
+
+	/* finally apply the optimal value */
+	return ad9647_calibrate_stop(st);
+}
+
 static int ad9467_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long m)
@@ -345,7 +603,9 @@ static int ad9467_write_raw(struct iio_dev *indio_dev,
 {
 	struct ad9467_state *st = iio_priv(indio_dev);
 	const struct ad9467_chip_info *info = st->info;
+	unsigned long sample_rate;
 	long r_clk;
+	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_SCALE:
@@ -358,7 +618,23 @@ static int ad9467_write_raw(struct iio_dev *indio_dev,
 			return -EINVAL;
 		}
 
-		return clk_set_rate(st->clk, r_clk);
+		sample_rate = clk_get_rate(st->clk);
+		/*
+		 * clk_set_rate() would also do this but since we would still
+		 * need it for avoiding an unnecessary calibration, do it now.
+		 */
+		if (sample_rate == r_clk)
+			return 0;
+
+		iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
+			ret = clk_set_rate(st->clk, r_clk);
+			if (ret)
+				return ret;
+
+			guard(mutex)(&st->lock);
+			ret = ad9467_calibrate(st);
+		}
+		return ret;
 	default:
 		return -EINVAL;
 	}
@@ -411,18 +687,6 @@ static const struct iio_info ad9467_info = {
 	.read_avail = ad9467_read_avail,
 };
 
-static int ad9467_outputmode_set(struct spi_device *spi, unsigned int mode)
-{
-	int ret;
-
-	ret = ad9467_spi_write(spi, AN877_ADC_REG_OUTPUT_MODE, mode);
-	if (ret < 0)
-		return ret;
-
-	return ad9467_spi_write(spi, AN877_ADC_REG_TRANSFER,
-				AN877_ADC_TRANSFER_SYNC);
-}
-
 static int ad9467_scale_fill(struct ad9467_state *st)
 {
 	const struct ad9467_chip_info *info = st->info;
@@ -442,29 +706,6 @@ static int ad9467_scale_fill(struct ad9467_state *st)
 	return 0;
 }
 
-static int ad9467_setup(struct ad9467_state *st)
-{
-	struct iio_backend_data_fmt data = {
-		.sign_extend = true,
-		.enable = true,
-	};
-	unsigned int c, mode;
-	int ret;
-
-	mode = st->info->default_output_mode | AN877_ADC_OUTPUT_MODE_TWOS_COMPLEMENT;
-	ret = ad9467_outputmode_set(st->spi, mode);
-	if (ret)
-		return ret;
-
-	for (c = 0; c < st->info->num_channels; c++) {
-		ret = iio_backend_data_format_set(st->back, c, &data);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-
 static int ad9467_reset(struct device *dev)
 {
 	struct gpio_desc *gpio;
@@ -521,6 +762,52 @@ static int ad9467_iio_backend_get(struct ad9467_state *st)
 	return -ENODEV;
 }
 
+static ssize_t ad9467_dump_calib_table(struct file *file,
+				       char __user *userbuf,
+				       size_t count, loff_t *ppos)
+{
+	struct ad9467_state *st = file->private_data;
+	unsigned int bit, size = BITS_PER_TYPE(st->calib_map);
+	/* +2 for the newline and +1 for the string termination */
+	unsigned char map[AD9647_MAX_TEST_POINTS * 2 + 3];
+	ssize_t len = 0;
+
+	guard(mutex)(&st->lock);
+	if (*ppos)
+		goto out_read;
+
+	for (bit = 0; bit < size; bit++) {
+		if (bit == size / 2)
+			len += scnprintf(map + len, sizeof(map) - len, "\n");
+
+		len += scnprintf(map + len, sizeof(map) - len, "%c",
+				 test_bit(bit, st->calib_map) ? 'x' : 'o');
+	}
+
+	len += scnprintf(map + len, sizeof(map) - len, "\n");
+out_read:
+	return simple_read_from_buffer(userbuf, count, ppos, map, len);
+}
+
+static const struct file_operations ad9467_calib_table_fops = {
+	.open = simple_open,
+	.read = ad9467_dump_calib_table,
+	.llseek = default_llseek,
+	.owner = THIS_MODULE,
+};
+
+static void ad9467_debugfs_init(struct iio_dev *indio_dev)
+{
+	struct dentry *d = iio_get_debugfs_dentry(indio_dev);
+	struct ad9467_state *st = iio_priv(indio_dev);
+
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return;
+
+	debugfs_create_file("calibration_table_dump", 0400, d, st,
+			    &ad9467_calib_table_fops);
+}
+
 static int ad9467_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
@@ -556,7 +843,7 @@ static int ad9467_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
-	id = ad9467_spi_read(spi, AN877_ADC_REG_CHIP_ID);
+	id = ad9467_spi_read(st, AN877_ADC_REG_CHIP_ID);
 	if (id != st->info->id) {
 		dev_err(&spi->dev, "Mismatch CHIP_ID, got 0x%X, expected 0x%X\n",
 			id, st->info->id);
@@ -580,11 +867,17 @@ static int ad9467_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
-	ret = ad9467_setup(st);
+	ret = ad9467_calibrate(st);
 	if (ret)
 		return ret;
 
-	return devm_iio_device_register(&spi->dev, indio_dev);
+	ret = devm_iio_device_register(&spi->dev, indio_dev);
+	if (ret)
+		return ret;
+
+	ad9467_debugfs_init(indio_dev);
+
+	return 0;
 }
 
 static const struct of_device_id ad9467_of_match[] = {