[PATCH v2] gpio: pca953x: add support for open drain pins on PCAL6524

[Alban Bedel <alban.bedel@xxxxxxxx>]

>From a quick glance at various datasheets the PCAL6524 and the
PCAL6534 seems to be the only chips in this family that support
setting the drive mode of single pins. Other chips either don't
support it at all, or can only set the drive mode of whole banks,
which doesn't map to the GPIO API.

Add a new flag, PCAL65xx_REGS, to mark chips that have the extra
registers needed for this feature. Then mark the needed register banks
as readable and writable, here we don't set OUT_CONF as writable,
although it is, as we only need to read it. Finally add a function
that configures the OUT_INDCONF register when the GPIO API sets the
drive mode of the pins.

Signed-off-by: Alban Bedel <alban.bedel@xxxxxxxx>
---
v2: - Rename the feature flag to PCAL65xx_REGS as there is at least
      the PCAL6534 which also have this feature.
    - Fixed the typos in the log message.
    - Fixed the code style issues.
---
 drivers/gpio/gpio-pca953x.c | 64 +++++++++++++++++++++++++++++++++++--
 1 file changed, 61 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 825b362eb4b7..c5c216ddfe18 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -64,6 +64,7 @@
 #define PCA_INT			BIT(8)
 #define PCA_PCAL		BIT(9)
 #define PCA_LATCH_INT		(PCA_PCAL | PCA_INT)
+#define PCAL65xx_REGS		BIT(10)
 #define PCA953X_TYPE		BIT(12)
 #define PCA957X_TYPE		BIT(13)
 #define PCA_TYPE_MASK		GENMASK(15, 12)
@@ -88,7 +89,7 @@ static const struct i2c_device_id pca953x_id[] = {
 	{ "pca9698", 40 | PCA953X_TYPE, },
 
 	{ "pcal6416", 16 | PCA953X_TYPE | PCA_LATCH_INT, },
-	{ "pcal6524", 24 | PCA953X_TYPE | PCA_LATCH_INT, },
+	{ "pcal6524", 24 | PCA953X_TYPE | PCA_LATCH_INT | PCAL65xx_REGS, },
 	{ "pcal9535", 16 | PCA953X_TYPE | PCA_LATCH_INT, },
 	{ "pcal9554b", 8  | PCA953X_TYPE | PCA_LATCH_INT, },
 	{ "pcal9555a", 16 | PCA953X_TYPE | PCA_LATCH_INT, },
@@ -265,6 +266,9 @@ static int pca953x_bank_shift(struct pca953x_chip *chip)
 #define PCAL9xxx_BANK_PULL_SEL	BIT(8 + 4)
 #define PCAL9xxx_BANK_IRQ_MASK	BIT(8 + 5)
 #define PCAL9xxx_BANK_IRQ_STAT	BIT(8 + 6)
+#define PCAL9xxx_BANK_OUT_CONF	BIT(8 + 7)
+
+#define PCAL65xx_BANK_INDOUT_CONF BIT(8 + 12)
 
 /*
  * We care about the following registers:
@@ -288,6 +292,10 @@ static int pca953x_bank_shift(struct pca953x_chip *chip)
  *     Pull-up/pull-down select reg	0x40 + 4 * bank_size    RW
  *     Interrupt mask register		0x40 + 5 * bank_size	RW
  *     Interrupt status register	0x40 + 6 * bank_size	R
+ *     Output port configuration	0x40 + 7 * bank_size	R
+ *
+ *   - PCAL65xx with individual pin configuration
+ *     Individual pin output config	0x40 + 12 * bank_size	RW
  *
  * - Registers with bit 0x80 set, the AI bit
  *   The bit is cleared and the registers fall into one of the
@@ -336,9 +344,12 @@ static bool pca953x_readable_register(struct device *dev, unsigned int reg)
 	if (chip->driver_data & PCA_PCAL) {
 		bank |= PCAL9xxx_BANK_IN_LATCH | PCAL9xxx_BANK_PULL_EN |
 			PCAL9xxx_BANK_PULL_SEL | PCAL9xxx_BANK_IRQ_MASK |
-			PCAL9xxx_BANK_IRQ_STAT;
+			PCAL9xxx_BANK_IRQ_STAT | PCAL9xxx_BANK_OUT_CONF;
 	}
 
+	if (chip->driver_data & PCAL65xx_REGS)
+		bank |= PCAL65xx_BANK_INDOUT_CONF;
+
 	return pca953x_check_register(chip, reg, bank);
 }
 
@@ -359,6 +370,9 @@ static bool pca953x_writeable_register(struct device *dev, unsigned int reg)
 		bank |= PCAL9xxx_BANK_IN_LATCH | PCAL9xxx_BANK_PULL_EN |
 			PCAL9xxx_BANK_PULL_SEL | PCAL9xxx_BANK_IRQ_MASK;
 
+	if (chip->driver_data & PCAL65xx_REGS)
+		bank |= PCAL65xx_BANK_INDOUT_CONF;
+
 	return pca953x_check_register(chip, reg, bank);
 }
 
@@ -618,6 +632,46 @@ static int pca953x_gpio_set_pull_up_down(struct pca953x_chip *chip,
 	return ret;
 }
 
+static int pcal6524_gpio_set_drive_mode(struct pca953x_chip *chip,
+					unsigned int offset,
+					unsigned long config)
+{
+	u8 out_indconf_reg = pca953x_recalc_addr(chip, PCAL6524_OUT_INDCONF,
+						 offset);
+	u8 out_conf_reg = pca953x_recalc_addr(chip, PCAL953X_OUT_CONF, 0);
+	u8 mask = BIT(offset % BANK_SZ);
+	unsigned int out_conf;
+	int ret;
+	u8 val;
+
+	/* configuration requires the PCAL65xx extended registers */
+	if (!(chip->driver_data & PCAL65xx_REGS))
+		return -ENOTSUPP;
+
+	if (config == PIN_CONFIG_DRIVE_OPEN_DRAIN)
+		val = mask;
+	else if (config == PIN_CONFIG_DRIVE_PUSH_PULL)
+		val = 0;
+	else
+		return -EINVAL;
+
+	mutex_lock(&chip->i2c_lock);
+
+	/* Invert the value if ODENn is set */
+	ret = regmap_read(chip->regmap, out_conf_reg, &out_conf);
+	if (ret)
+		goto exit;
+	if (out_conf & BIT(offset / BANK_SZ))
+		val ^= mask;
+
+	/* Configure the drive mode */
+	ret = regmap_write_bits(chip->regmap, out_indconf_reg, mask, val);
+
+exit:
+	mutex_unlock(&chip->i2c_lock);
+	return ret;
+}
+
 static int pca953x_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 				   unsigned long config)
 {
@@ -627,6 +681,9 @@ static int pca953x_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 	case PIN_CONFIG_BIAS_PULL_UP:
 	case PIN_CONFIG_BIAS_PULL_DOWN:
 		return pca953x_gpio_set_pull_up_down(chip, offset, config);
+	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+	case PIN_CONFIG_DRIVE_PUSH_PULL:
+		return pcal6524_gpio_set_drive_mode(chip, offset, config);
 	default:
 		return -ENOTSUPP;
 	}
@@ -1232,6 +1289,7 @@ static int pca953x_resume(struct device *dev)
 /* convenience to stop overlong match-table lines */
 #define OF_953X(__nrgpio, __int) (void *)(__nrgpio | PCA953X_TYPE | __int)
 #define OF_957X(__nrgpio, __int) (void *)(__nrgpio | PCA957X_TYPE | __int)
+#define OF_L65XX(__nrgpio) OF_953X(__nrgpio, PCA_LATCH_INT | PCAL65xx_REGS)
 
 static const struct of_device_id pca953x_dt_ids[] = {
 	{ .compatible = "nxp,pca6416", .data = OF_953X(16, PCA_INT), },
@@ -1251,7 +1309,7 @@ static const struct of_device_id pca953x_dt_ids[] = {
 	{ .compatible = "nxp,pca9698", .data = OF_953X(40, 0), },
 
 	{ .compatible = "nxp,pcal6416", .data = OF_953X(16, PCA_LATCH_INT), },
-	{ .compatible = "nxp,pcal6524", .data = OF_953X(24, PCA_LATCH_INT), },
+	{ .compatible = "nxp,pcal6524", .data = OF_L65XX(24), },
 	{ .compatible = "nxp,pcal9535", .data = OF_953X(16, PCA_LATCH_INT), },
 	{ .compatible = "nxp,pcal9554b", .data = OF_953X( 8, PCA_LATCH_INT), },
 	{ .compatible = "nxp,pcal9555a", .data = OF_953X(16, PCA_LATCH_INT), },
-- 
2.25.1