[PATCH v3 2/2] gpio: pca953x: Add support for TI TCA6418
From: Maria Garcia
Date: Tue Jul 01 2025 - 12:19:42 EST
The TI TCA6418 is a 18-channel I2C I/O expander. It is slightly
different to other models from the same family, such as TCA6416,
but has enough in common with them to make it work with just a
few tweaks, which are explained in the code's documentation.
Signed-off-by: Maria Garcia <mariagarcia7293@xxxxxxxxx>
---
drivers/gpio/gpio-pca953x.c | 139 +++++++++++++++++++++++++++++++-----
1 file changed, 120 insertions(+), 19 deletions(-)
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index e80a96f39788..7d77d43ef314 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -38,6 +38,10 @@
#define PCA953X_INVERT 0x02
#define PCA953X_DIRECTION 0x03
+#define TCA6418_INPUT 0x14
+#define TCA6418_OUTPUT 0x17
+#define TCA6418_DIRECTION 0x23
+
#define REG_ADDR_MASK GENMASK(5, 0)
#define REG_ADDR_EXT BIT(6)
#define REG_ADDR_AI BIT(7)
@@ -76,7 +80,8 @@
#define PCA953X_TYPE BIT(12)
#define PCA957X_TYPE BIT(13)
#define PCAL653X_TYPE BIT(14)
-#define PCA_TYPE_MASK GENMASK(15, 12)
+#define TCA6418_TYPE BIT(16)
+#define PCA_TYPE_MASK GENMASK(16, 12)
#define PCA_CHIP_TYPE(x) ((x) & PCA_TYPE_MASK)
@@ -115,6 +120,7 @@ static const struct i2c_device_id pca953x_id[] = {
{ "pca6107", 8 | PCA953X_TYPE | PCA_INT, },
{ "tca6408", 8 | PCA953X_TYPE | PCA_INT, },
{ "tca6416", 16 | PCA953X_TYPE | PCA_INT, },
+ { "tca6418", 18 | TCA6418_TYPE | PCA_INT, },
{ "tca6424", 24 | PCA953X_TYPE | PCA_INT, },
{ "tca9538", 8 | PCA953X_TYPE | PCA_INT, },
{ "tca9539", 16 | PCA953X_TYPE | PCA_INT, },
@@ -204,6 +210,13 @@ static const struct pca953x_reg_config pca957x_regs = {
.invert = PCA957X_INVRT,
};
+static const struct pca953x_reg_config tca6418_regs = {
+ .direction = TCA6418_DIRECTION,
+ .output = TCA6418_OUTPUT,
+ .input = TCA6418_INPUT,
+ .invert = 0xFF, /* Does not apply */
+};
+
struct pca953x_chip {
unsigned gpio_start;
struct mutex i2c_lock;
@@ -237,6 +250,20 @@ static int pca953x_bank_shift(struct pca953x_chip *chip)
return fls((chip->gpio_chip.ngpio - 1) / BANK_SZ);
}
+/* Helper function to get the correct bit mask for a given offset and chip type.
+ * The TCA6418's input, output, and direction banks have a peculiar bit order:
+ * the first byte uses reversed bit order, while the second byte uses standard order.
+ */
+static inline u8 pca953x_get_bit_mask(struct pca953x_chip *chip, unsigned int offset)
+{
+ unsigned int bit_pos_in_bank = offset % BANK_SZ;
+ int msb = BANK_SZ - 1;
+
+ if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE && offset <= msb)
+ return BIT(msb - bit_pos_in_bank);
+ return BIT(bit_pos_in_bank);
+}
+
#define PCA953x_BANK_INPUT BIT(0)
#define PCA953x_BANK_OUTPUT BIT(1)
#define PCA953x_BANK_POLARITY BIT(2)
@@ -353,18 +380,41 @@ static bool pcal6534_check_register(struct pca953x_chip *chip, unsigned int reg,
return true;
}
+/* TCA6418 breaks the PCA953x register order rule */
+static bool tca6418_check_register(struct pca953x_chip *chip, unsigned int reg,
+ u32 access_type_mask)
+{
+ /* Valid Input Registers - BIT(0) for readable access */
+ if (reg >= TCA6418_INPUT && reg < (TCA6418_INPUT + NBANK(chip)))
+ return (access_type_mask & BIT(0));
+ /* Valid Output Registers - BIT(1) for writeable access */
+ if (reg >= TCA6418_OUTPUT && reg < (TCA6418_OUTPUT + NBANK(chip)))
+ return (access_type_mask & (BIT(0) | BIT(1)));
+ /* Valid Direction Registers - BIT(2) for volatile access */
+ if (reg >= TCA6418_DIRECTION && reg < (TCA6418_DIRECTION + NBANK(chip)))
+ return (access_type_mask & (BIT(0) | BIT(1)));
+
+ return false;
+}
+
static bool pca953x_readable_register(struct device *dev, unsigned int reg)
{
struct pca953x_chip *chip = dev_get_drvdata(dev);
u32 bank;
- if (PCA_CHIP_TYPE(chip->driver_data) == PCA957X_TYPE) {
+ switch (PCA_CHIP_TYPE(chip->driver_data)) {
+ case PCA957X_TYPE:
bank = PCA957x_BANK_INPUT | PCA957x_BANK_OUTPUT |
PCA957x_BANK_POLARITY | PCA957x_BANK_CONFIG |
PCA957x_BANK_BUSHOLD;
- } else {
+ break;
+ case TCA6418_TYPE:
+ /* BIT(0) to indicate read access */
+ return tca6418_check_register(chip, reg, BIT(0));
+ default:
bank = PCA953x_BANK_INPUT | PCA953x_BANK_OUTPUT |
PCA953x_BANK_POLARITY | PCA953x_BANK_CONFIG;
+ break;
}
if (chip->driver_data & PCA_PCAL) {
@@ -381,12 +431,18 @@ static bool pca953x_writeable_register(struct device *dev, unsigned int reg)
struct pca953x_chip *chip = dev_get_drvdata(dev);
u32 bank;
- if (PCA_CHIP_TYPE(chip->driver_data) == PCA957X_TYPE) {
+ switch (PCA_CHIP_TYPE(chip->driver_data)) {
+ case PCA957X_TYPE:
bank = PCA957x_BANK_OUTPUT | PCA957x_BANK_POLARITY |
PCA957x_BANK_CONFIG | PCA957x_BANK_BUSHOLD;
- } else {
+ break;
+ case TCA6418_TYPE:
+ /* BIT(1) for write access */
+ return tca6418_check_register(chip, reg, BIT(1));
+ default:
bank = PCA953x_BANK_OUTPUT | PCA953x_BANK_POLARITY |
PCA953x_BANK_CONFIG;
+ break;
}
if (chip->driver_data & PCA_PCAL)
@@ -401,10 +457,17 @@ static bool pca953x_volatile_register(struct device *dev, unsigned int reg)
struct pca953x_chip *chip = dev_get_drvdata(dev);
u32 bank;
- if (PCA_CHIP_TYPE(chip->driver_data) == PCA957X_TYPE)
+ switch (PCA_CHIP_TYPE(chip->driver_data)) {
+ case PCA957X_TYPE:
bank = PCA957x_BANK_INPUT;
- else
+ break;
+ case TCA6418_TYPE:
+ /* BIT(2) for volatile access */
+ return tca6418_check_register(chip, reg, BIT(2));
+ default:
bank = PCA953x_BANK_INPUT;
+ break;
+ }
if (chip->driver_data & PCA_PCAL)
bank |= PCAL9xxx_BANK_IRQ_STAT;
@@ -489,6 +552,16 @@ static u8 pcal6534_recalc_addr(struct pca953x_chip *chip, int reg, int off)
return pinctrl + addr + (off / BANK_SZ);
}
+static u8 tca6418_recalc_addr(struct pca953x_chip *chip, int reg_base, int offset)
+{
+ /*
+ * reg_base will be TCA6418_INPUT, TCA6418_OUTPUT, or TCA6418_DIRECTION
+ * offset is the global GPIO line offset (0-17)
+ * BANK_SZ is 8 for TCA6418 (8 bits per register bank)
+ */
+ return reg_base + (offset / BANK_SZ);
+}
+
static int pca953x_write_regs(struct pca953x_chip *chip, int reg, unsigned long *val)
{
u8 regaddr = chip->recalc_addr(chip, reg, 0);
@@ -529,10 +602,12 @@ static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
{
struct pca953x_chip *chip = gpiochip_get_data(gc);
u8 dirreg = chip->recalc_addr(chip, chip->regs->direction, off);
- u8 bit = BIT(off % BANK_SZ);
+ u8 bit = pca953x_get_bit_mask(chip, off);
guard(mutex)(&chip->i2c_lock);
+ if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)
+ return regmap_write_bits(chip->regmap, dirreg, bit, 0);
return regmap_write_bits(chip->regmap, dirreg, bit, bit);
}
@@ -542,7 +617,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc,
struct pca953x_chip *chip = gpiochip_get_data(gc);
u8 dirreg = chip->recalc_addr(chip, chip->regs->direction, off);
u8 outreg = chip->recalc_addr(chip, chip->regs->output, off);
- u8 bit = BIT(off % BANK_SZ);
+ u8 bit = pca953x_get_bit_mask(chip, off);
int ret;
guard(mutex)(&chip->i2c_lock);
@@ -552,7 +627,11 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc,
if (ret)
return ret;
- /* then direction */
+ /* then direction
+ * (in/out logic is inverted on TCA6418)
+ */
+ if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)
+ return regmap_write_bits(chip->regmap, dirreg, bit, bit);
return regmap_write_bits(chip->regmap, dirreg, bit, 0);
}
@@ -560,7 +639,7 @@ static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
{
struct pca953x_chip *chip = gpiochip_get_data(gc);
u8 inreg = chip->recalc_addr(chip, chip->regs->input, off);
- u8 bit = BIT(off % BANK_SZ);
+ u8 bit = pca953x_get_bit_mask(chip, off);
u32 reg_val;
int ret;
@@ -577,7 +656,7 @@ static int pca953x_gpio_set_value(struct gpio_chip *gc, unsigned int off,
{
struct pca953x_chip *chip = gpiochip_get_data(gc);
u8 outreg = chip->recalc_addr(chip, chip->regs->output, off);
- u8 bit = BIT(off % BANK_SZ);
+ u8 bit = pca953x_get_bit_mask(chip, off);
guard(mutex)(&chip->i2c_lock);
@@ -588,7 +667,7 @@ static int pca953x_gpio_get_direction(struct gpio_chip *gc, unsigned off)
{
struct pca953x_chip *chip = gpiochip_get_data(gc);
u8 dirreg = chip->recalc_addr(chip, chip->regs->direction, off);
- u8 bit = BIT(off % BANK_SZ);
+ u8 bit = pca953x_get_bit_mask(chip, off);
u32 reg_val;
int ret;
@@ -597,9 +676,14 @@ static int pca953x_gpio_get_direction(struct gpio_chip *gc, unsigned off)
if (ret < 0)
return ret;
- if (reg_val & bit)
+ /* (in/out logic is inverted on TCA6418) */
+ if (reg_val & bit) {
+ if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)
+ return GPIO_LINE_DIRECTION_OUT;
+ return GPIO_LINE_DIRECTION_IN;
+ }
+ if (PCA_CHIP_TYPE(chip->driver_data) == TCA6418_TYPE)
return GPIO_LINE_DIRECTION_IN;
-
return GPIO_LINE_DIRECTION_OUT;
}
@@ -1117,12 +1201,22 @@ static int pca953x_probe(struct i2c_client *client)
regmap_config = &pca953x_i2c_regmap;
}
- if (PCA_CHIP_TYPE(chip->driver_data) == PCAL653X_TYPE) {
+ switch (PCA_CHIP_TYPE(chip->driver_data)) {
+ case PCAL653X_TYPE:
chip->recalc_addr = pcal6534_recalc_addr;
chip->check_reg = pcal6534_check_register;
- } else {
+ break;
+ case TCA6418_TYPE:
+ chip->recalc_addr = tca6418_recalc_addr;
+ /*
+ * We don't assign chip->check_reg = tca6418_check_register directly here.
+ * Instead, the wrappers handle the dispatch based on PCA_CHIP_TYPE.
+ */
+ break;
+ default:
chip->recalc_addr = pca953x_recalc_addr;
chip->check_reg = pca953x_check_register;
+ break;
}
chip->regmap = devm_regmap_init_i2c(client, regmap_config);
@@ -1154,12 +1248,18 @@ static int pca953x_probe(struct i2c_client *client)
/* initialize cached registers from their original values.
* we can't share this chip with another i2c master.
*/
- if (PCA_CHIP_TYPE(chip->driver_data) == PCA957X_TYPE) {
+ switch (PCA_CHIP_TYPE(chip->driver_data)) {
+ case PCA957X_TYPE:
chip->regs = &pca957x_regs;
ret = device_pca957x_init(chip);
- } else {
+ break;
+ case TCA6418_TYPE:
+ chip->regs = &tca6418_regs;
+ break;
+ default:
chip->regs = &pca953x_regs;
ret = device_pca95xx_init(chip);
+ break;
}
if (ret)
return ret;
@@ -1325,6 +1425,7 @@ static const struct of_device_id pca953x_dt_ids[] = {
{ .compatible = "ti,pca9536", .data = OF_953X( 4, 0), },
{ .compatible = "ti,tca6408", .data = OF_953X( 8, PCA_INT), },
{ .compatible = "ti,tca6416", .data = OF_953X(16, PCA_INT), },
+ { .compatible = "ti,tca6418", .data = (void *)(18 | TCA6418_TYPE | PCA_INT), },
{ .compatible = "ti,tca6424", .data = OF_953X(24, PCA_INT), },
{ .compatible = "ti,tca9535", .data = OF_953X(16, PCA_INT), },
{ .compatible = "ti,tca9538", .data = OF_953X( 8, PCA_INT), },
--
2.43.0