[PATCH v5] iio: frequency: ad9832: Use FIELD_PREP macro to set bit fields

[Siddharth Menon <simeddon@gmail.com>]

Use bitfield and bitmask macros to clearly specify AD9832 SPI
command fields to make register write code more readable.

Suggested-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Signed-off-by: Siddharth Menon <simeddon@gmail.com>
---
 v1->v2:
 - remove CMD_SHIFT and ADD_SHIFT
 - use GENMASK
 - store regval in an array and iterate through it
 v2->v3:
 - add missing header
 - refactor code in the previously introduced loops
 v3->v4:
 - update commit message with a better one
 - convert AD9832_PHASE and RES_MASK to masks
 - cleanup a few if else blocks
 v4->v5
 - remove unnecessary inversion (val ? 0 : 1) used
   with AD9832_PHASE_MASK introduced in v4
 - use ARRAY_SIZE instead of fixed integers
 - use reverse xmas tree order
 - align mask macros
 drivers/staging/iio/frequency/ad9832.c | 85 +++++++++++++-------------
 1 file changed, 44 insertions(+), 41 deletions(-)

diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
index 140ee4f9c137..e74d085fb4f2 100644
--- a/drivers/staging/iio/frequency/ad9832.c
+++ b/drivers/staging/iio/frequency/ad9832.c
@@ -16,6 +16,9 @@
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/sysfs.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/unaligned.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -59,17 +62,18 @@
 #define AD9832_CMD_SLEEPRESCLR	0xC
 
 #define AD9832_FREQ		BIT(11)
-#define AD9832_PHASE(x)		(((x) & 3) << 9)
+#define AD9832_PHASE_MASK	GENMASK(10, 9)
 #define AD9832_SYNC		BIT(13)
 #define AD9832_SELSRC		BIT(12)
 #define AD9832_SLEEP		BIT(13)
 #define AD9832_RESET		BIT(12)
 #define AD9832_CLR		BIT(11)
-#define CMD_SHIFT		12
-#define ADD_SHIFT		8
 #define AD9832_FREQ_BITS	32
 #define AD9832_PHASE_BITS	12
-#define RES_MASK(bits)		((1 << (bits)) - 1)
+#define RES_MASK(bits)		GENMASK((bits) - 1, 0)
+#define AD9832_CMD_MSK		GENMASK(15, 12)
+#define AD9832_ADD_MSK		GENMASK(11, 8)
+#define AD9832_DAT_MSK		GENMASK(7, 0)
 
 /**
  * struct ad9832_state - driver instance specific data
@@ -131,6 +135,8 @@ static int ad9832_write_frequency(struct ad9832_state *st,
 {
 	unsigned long clk_freq;
 	unsigned long regval;
+	u8 regval_bytes[4];
+	u16 freq_cmd;
 
 	clk_freq = clk_get_rate(st->mclk);
 
@@ -138,19 +144,15 @@ static int ad9832_write_frequency(struct ad9832_state *st,
 		return -EINVAL;
 
 	regval = ad9832_calc_freqreg(clk_freq, fout);
+	put_unaligned_be32(regval, regval_bytes);
 
-	st->freq_data[0] = cpu_to_be16((AD9832_CMD_FRE8BITSW << CMD_SHIFT) |
-					(addr << ADD_SHIFT) |
-					((regval >> 24) & 0xFF));
-	st->freq_data[1] = cpu_to_be16((AD9832_CMD_FRE16BITSW << CMD_SHIFT) |
-					((addr - 1) << ADD_SHIFT) |
-					((regval >> 16) & 0xFF));
-	st->freq_data[2] = cpu_to_be16((AD9832_CMD_FRE8BITSW << CMD_SHIFT) |
-					((addr - 2) << ADD_SHIFT) |
-					((regval >> 8) & 0xFF));
-	st->freq_data[3] = cpu_to_be16((AD9832_CMD_FRE16BITSW << CMD_SHIFT) |
-					((addr - 3) << ADD_SHIFT) |
-					((regval >> 0) & 0xFF));
+	for (int i = 0; i < ARRAY_SIZE(regval_bytes); i++) {
+		freq_cmd = (i % 2 == 0) ? AD9832_CMD_FRE8BITSW : AD9832_CMD_FRE16BITSW;
+
+		st->freq_data[i] = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, freq_cmd) |
+			FIELD_PREP(AD9832_ADD_MSK, addr - i) |
+			FIELD_PREP(AD9832_DAT_MSK, regval_bytes[i]));
+	}
 
 	return spi_sync(st->spi, &st->freq_msg);
 }
@@ -158,15 +160,21 @@ static int ad9832_write_frequency(struct ad9832_state *st,
 static int ad9832_write_phase(struct ad9832_state *st,
 			      unsigned long addr, unsigned long phase)
 {
+	u8 phase_bytes[2];
+	u16 phase_cmd;
+
 	if (phase >= BIT(AD9832_PHASE_BITS))
 		return -EINVAL;
 
-	st->phase_data[0] = cpu_to_be16((AD9832_CMD_PHA8BITSW << CMD_SHIFT) |
-					(addr << ADD_SHIFT) |
-					((phase >> 8) & 0xFF));
-	st->phase_data[1] = cpu_to_be16((AD9832_CMD_PHA16BITSW << CMD_SHIFT) |
-					((addr - 1) << ADD_SHIFT) |
-					(phase & 0xFF));
+	put_unaligned_be16(phase, phase_bytes);
+
+	for (int i = 0; i < ARRAY_SIZE(phase_bytes); i++) {
+		phase_cmd = (i % 2 == 0) ? AD9832_CMD_PHA8BITSW : AD9832_CMD_PHA16BITSW;
+
+		st->phase_data[i] = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, phase_cmd) |
+			FIELD_PREP(AD9832_ADD_MSK, addr - i) |
+			FIELD_PREP(AD9832_DAT_MSK, phase_bytes[i]));
+	}
 
 	return spi_sync(st->spi, &st->phase_msg);
 }
@@ -197,24 +205,22 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
 		ret = ad9832_write_phase(st, this_attr->address, val);
 		break;
 	case AD9832_PINCTRL_EN:
-		if (val)
-			st->ctrl_ss &= ~AD9832_SELSRC;
-		else
-			st->ctrl_ss |= AD9832_SELSRC;
-		st->data = cpu_to_be16((AD9832_CMD_SYNCSELSRC << CMD_SHIFT) |
+		st->ctrl_ss &= ~AD9832_SELSRC;
+		st->ctrl_ss |= FIELD_PREP(AD9832_SELSRC, val ? 0 : 1);
+
+		st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_SYNCSELSRC) |
 					st->ctrl_ss);
 		ret = spi_sync(st->spi, &st->msg);
 		break;
 	case AD9832_FREQ_SYM:
-		if (val == 1) {
-			st->ctrl_fp |= AD9832_FREQ;
-		} else if (val == 0) {
+		if (val == 1 || val == 0) {
 			st->ctrl_fp &= ~AD9832_FREQ;
+			st->ctrl_fp |= FIELD_PREP(AD9832_FREQ, val ? 0 : 1);
 		} else {
 			ret = -EINVAL;
 			break;
 		}
-		st->data = cpu_to_be16((AD9832_CMD_FPSELECT << CMD_SHIFT) |
+		st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_FPSELECT) |
 					st->ctrl_fp);
 		ret = spi_sync(st->spi, &st->msg);
 		break;
@@ -224,21 +230,18 @@ static ssize_t ad9832_write(struct device *dev, struct device_attribute *attr,
 			break;
 		}
 
-		st->ctrl_fp &= ~AD9832_PHASE(3);
-		st->ctrl_fp |= AD9832_PHASE(val);
+		st->ctrl_fp &= ~FIELD_PREP(AD9832_PHASE_MASK, 3);
+		st->ctrl_fp |= FIELD_PREP(AD9832_PHASE_MASK, val);
 
-		st->data = cpu_to_be16((AD9832_CMD_FPSELECT << CMD_SHIFT) |
+		st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_FPSELECT) |
 					st->ctrl_fp);
 		ret = spi_sync(st->spi, &st->msg);
 		break;
 	case AD9832_OUTPUT_EN:
-		if (val)
-			st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP |
-					AD9832_CLR);
-		else
-			st->ctrl_src |= AD9832_RESET;
+		st->ctrl_src &= ~(AD9832_RESET | AD9832_SLEEP | AD9832_CLR);
+		st->ctrl_src |= FIELD_PREP(AD9832_RESET, val ? 0 : 1);
 
-		st->data = cpu_to_be16((AD9832_CMD_SLEEPRESCLR << CMD_SHIFT) |
+		st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_SLEEPRESCLR) |
 					st->ctrl_src);
 		ret = spi_sync(st->spi, &st->msg);
 		break;
@@ -396,7 +399,7 @@ static int ad9832_probe(struct spi_device *spi)
 	spi_message_add_tail(&st->phase_xfer[1], &st->phase_msg);
 
 	st->ctrl_src = AD9832_SLEEP | AD9832_RESET | AD9832_CLR;
-	st->data = cpu_to_be16((AD9832_CMD_SLEEPRESCLR << CMD_SHIFT) |
+	st->data = cpu_to_be16(FIELD_PREP(AD9832_CMD_MSK, AD9832_CMD_SLEEPRESCLR) |
 					st->ctrl_src);
 	ret = spi_sync(st->spi, &st->msg);
 	if (ret) {
-- 
2.49.0