linux-kernel - [PATCH v5 1/1] phy: tusb1210: use bitmasks to set VENDOR

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Date:   Fri, 11 Dec 2020 14:12:41 -0500
From:   Liam Beguin <liambeguin@...il.com>
To:     liambeguin@...il.com, geert@...ux-m68k.org, kishon@...com,
        vkoul@...nel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v5 1/1] phy: tusb1210: use bitmasks to set VENDOR_SPECIFIC2

From: Liam Beguin <lvb@...hos.com>

Start by reading the content of the VENDOR_SPECIFIC2 register and update
each bit field based on device properties when defined.

The use of bit masks prevents fields from overriding each other and
enables users to clear bits which are set by default, like datapolarity
in this instance.

Signed-off-by: Liam Beguin <lvb@...hos.com>
---
Changes since v1:
- use set_mask_bits

Changes since v2:
- fix missing bit shift dropped in v2
- rebase on 5.9-rc1

Changes since v3:
- switch to u8p_replace_bits() since there's little reason to protect
  against concurrent access

Changes since v4:
- rebase on latest master

 drivers/phy/ti/phy-tusb1210.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/phy/ti/phy-tusb1210.c b/drivers/phy/ti/phy-tusb1210.c
index d8d0cc11d187..a63213f5972a 100644
--- a/drivers/phy/ti/phy-tusb1210.c
+++ b/drivers/phy/ti/phy-tusb1210.c
@@ -7,15 +7,16 @@
  * Author: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
  */
 #include <linux/module.h>
+#include <linux/bitfield.h>
 #include <linux/ulpi/driver.h>
 #include <linux/ulpi/regs.h>
 #include <linux/gpio/consumer.h>
 #include <linux/phy/ulpi_phy.h>
 
 #define TUSB1210_VENDOR_SPECIFIC2		0x80
-#define TUSB1210_VENDOR_SPECIFIC2_IHSTX_SHIFT	0
-#define TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_SHIFT	4
-#define TUSB1210_VENDOR_SPECIFIC2_DP_SHIFT	6
+#define TUSB1210_VENDOR_SPECIFIC2_IHSTX_MASK	GENMASK(3, 0)
+#define TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_MASK	GENMASK(5, 4)
+#define TUSB1210_VENDOR_SPECIFIC2_DP_MASK	BIT(6)
 
 struct tusb1210 {
 	struct ulpi *ulpi;
@@ -118,22 +119,22 @@ static int tusb1210_probe(struct ulpi *ulpi)
 	 * diagram optimization and DP/DM swap.
 	 */
 
+	reg = ulpi_read(ulpi, TUSB1210_VENDOR_SPECIFIC2);
+
 	/* High speed output drive strength configuration */
-	device_property_read_u8(&ulpi->dev, "ihstx", &val);
-	reg = val << TUSB1210_VENDOR_SPECIFIC2_IHSTX_SHIFT;
+	if (!device_property_read_u8(&ulpi->dev, "ihstx", &val))
+		u8p_replace_bits(&reg, val, (u8)TUSB1210_VENDOR_SPECIFIC2_IHSTX_MASK);
 
 	/* High speed output impedance configuration */
-	device_property_read_u8(&ulpi->dev, "zhsdrv", &val);
-	reg |= val << TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_SHIFT;
+	if (!device_property_read_u8(&ulpi->dev, "zhsdrv", &val))
+		u8p_replace_bits(&reg, val, (u8)TUSB1210_VENDOR_SPECIFIC2_ZHSDRV_MASK);
 
 	/* DP/DM swap control */
-	device_property_read_u8(&ulpi->dev, "datapolarity", &val);
-	reg |= val << TUSB1210_VENDOR_SPECIFIC2_DP_SHIFT;
+	if (!device_property_read_u8(&ulpi->dev, "datapolarity", &val))
+		u8p_replace_bits(&reg, val, (u8)TUSB1210_VENDOR_SPECIFIC2_DP_MASK);
 
-	if (reg) {
-		ulpi_write(ulpi, TUSB1210_VENDOR_SPECIFIC2, reg);
-		tusb->vendor_specific2 = reg;
-	}
+	ulpi_write(ulpi, TUSB1210_VENDOR_SPECIFIC2, reg);
+	tusb->vendor_specific2 = reg;
 
 	tusb->phy = ulpi_phy_create(ulpi, &phy_ops);
 	if (IS_ERR(tusb->phy))

base-commit: 33dc9614dc208291d0c4bcdeb5d30d481dcd2c4c
-- 
2.27.0