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Message-Id: <20220703111057.23246-2-aidanmacdonald.0x0@gmail.com>
Date: Sun, 3 Jul 2022 12:10:55 +0100
From: Aidan MacDonald <aidanmacdonald.0x0@...il.com>
To: michael@...le.cc, linus.walleij@...aro.org, brgl@...ev.pl
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] gpio: regmap: Support registers with more than one bit per GPIO
Some devices use a multi-bit register field to change the GPIO
input/output direction. Add the ->reg_field_xlate() callback to
support such devices in gpio-regmap.
->reg_field_xlate() builds on ->reg_mask_xlate() by allowing the
driver to return a mask and values to describe a register field.
gpio-regmap will use the mask to isolate the field and compare or
update it using the values to implement GPIO level and direction
get and set ops.
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@...il.com>
---
drivers/gpio/gpio-regmap.c | 73 +++++++++++++++++++++----------------
include/linux/gpio/regmap.h | 14 +++++++
2 files changed, 56 insertions(+), 31 deletions(-)
diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 6383136cbe59..9256b922c654 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -27,6 +27,10 @@ struct gpio_regmap {
int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
unsigned int offset, unsigned int *reg,
unsigned int *mask);
+ void (*reg_field_xlate)(struct gpio_regmap *gpio,
+ unsigned int base, unsigned int offset,
+ unsigned int *reg, unsigned int *mask,
+ unsigned int *values);
void *driver_data;
};
@@ -52,10 +56,22 @@ static int gpio_regmap_simple_xlate(struct gpio_regmap *gpio,
return 0;
}
+static void
+gpio_regmap_simple_field_xlate(struct gpio_regmap *gpio,
+ unsigned int base, unsigned int offset,
+ unsigned int *reg, unsigned int *mask,
+ unsigned int *values)
+{
+ gpio->reg_mask_xlate(gpio, base, offset, reg, mask);
+ values[0] = 0;
+ values[1] = *mask;
+}
+
static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
{
struct gpio_regmap *gpio = gpiochip_get_data(chip);
unsigned int base, val, reg, mask;
+ unsigned int values[2];
int ret;
/* we might not have an output register if we are input only */
@@ -64,15 +80,13 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
else
base = gpio_regmap_addr(gpio->reg_set_base);
- ret = gpio->reg_mask_xlate(gpio, base, offset, ®, &mask);
- if (ret)
- return ret;
+ gpio->reg_field_xlate(gpio, base, offset, ®, &mask, values);
ret = regmap_read(gpio->regmap, reg, &val);
if (ret)
return ret;
- return !!(val & mask);
+ return (val & mask) == values[1];
}
static void gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
@@ -81,12 +95,10 @@ static void gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
struct gpio_regmap *gpio = gpiochip_get_data(chip);
unsigned int base = gpio_regmap_addr(gpio->reg_set_base);
unsigned int reg, mask;
+ unsigned int values[2];
- gpio->reg_mask_xlate(gpio, base, offset, ®, &mask);
- if (val)
- regmap_update_bits(gpio->regmap, reg, mask, mask);
- else
- regmap_update_bits(gpio->regmap, reg, mask, 0);
+ gpio->reg_field_xlate(gpio, base, offset, ®, &mask, values);
+ regmap_update_bits(gpio->regmap, reg, mask, values[!!val]);
}
static void gpio_regmap_set_with_clear(struct gpio_chip *chip,
@@ -94,14 +106,15 @@ static void gpio_regmap_set_with_clear(struct gpio_chip *chip,
{
struct gpio_regmap *gpio = gpiochip_get_data(chip);
unsigned int base, reg, mask;
+ unsigned int values[2];
if (val)
base = gpio_regmap_addr(gpio->reg_set_base);
else
base = gpio_regmap_addr(gpio->reg_clr_base);
- gpio->reg_mask_xlate(gpio, base, offset, ®, &mask);
- regmap_write(gpio->regmap, reg, mask);
+ gpio->reg_field_xlate(gpio, base, offset, ®, &mask, values);
+ regmap_update_bits(gpio->regmap, reg, mask, values[1]);
}
static int gpio_regmap_get_direction(struct gpio_chip *chip,
@@ -109,6 +122,7 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
{
struct gpio_regmap *gpio = gpiochip_get_data(chip);
unsigned int base, val, reg, mask;
+ unsigned int values[2];
int invert, ret;
if (gpio->reg_dir_out_base) {
@@ -121,47 +135,36 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
return -EOPNOTSUPP;
}
- ret = gpio->reg_mask_xlate(gpio, base, offset, ®, &mask);
- if (ret)
- return ret;
+ gpio->reg_field_xlate(gpio, base, offset, ®, &mask, values);
ret = regmap_read(gpio->regmap, reg, &val);
if (ret)
return ret;
- if (!!(val & mask) ^ invert)
- return GPIO_LINE_DIRECTION_OUT;
- else
+ if ((val & mask) == values[invert])
return GPIO_LINE_DIRECTION_IN;
+ else
+ return GPIO_LINE_DIRECTION_OUT;
}
static int gpio_regmap_set_direction(struct gpio_chip *chip,
unsigned int offset, bool output)
{
struct gpio_regmap *gpio = gpiochip_get_data(chip);
- unsigned int base, val, reg, mask;
- int invert, ret;
+ unsigned int base, reg, mask;
+ unsigned int values[2];
if (gpio->reg_dir_out_base) {
base = gpio_regmap_addr(gpio->reg_dir_out_base);
- invert = 0;
} else if (gpio->reg_dir_in_base) {
base = gpio_regmap_addr(gpio->reg_dir_in_base);
- invert = 1;
+ output = !output;
} else {
return -EOPNOTSUPP;
}
- ret = gpio->reg_mask_xlate(gpio, base, offset, ®, &mask);
- if (ret)
- return ret;
-
- if (invert)
- val = output ? 0 : mask;
- else
- val = output ? mask : 0;
-
- return regmap_update_bits(gpio->regmap, reg, mask, val);
+ gpio->reg_field_xlate(gpio, base, offset, ®, &mask, values);
+ return regmap_update_bits(gpio->regmap, reg, mask, values[output]);
}
static int gpio_regmap_direction_input(struct gpio_chip *chip,
@@ -215,6 +218,10 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
if (config->reg_dir_out_base && config->reg_dir_in_base)
return ERR_PTR(-EINVAL);
+ /* only one of these should be provided */
+ if (config->reg_field_xlate && config->reg_mask_xlate)
+ return ERR_PTR(-EINVAL);
+
gpio = kzalloc(sizeof(*gpio), GFP_KERNEL);
if (!gpio)
return ERR_PTR(-ENOMEM);
@@ -225,6 +232,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
gpio->ngpio_per_reg = config->ngpio_per_reg;
gpio->reg_stride = config->reg_stride;
gpio->reg_mask_xlate = config->reg_mask_xlate;
+ gpio->reg_field_xlate = config->reg_field_xlate;
gpio->reg_dat_base = config->reg_dat_base;
gpio->reg_set_base = config->reg_set_base;
gpio->reg_clr_base = config->reg_clr_base;
@@ -242,6 +250,9 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
if (!gpio->reg_mask_xlate)
gpio->reg_mask_xlate = gpio_regmap_simple_xlate;
+ if (!gpio->reg_field_xlate)
+ gpio->reg_field_xlate = gpio_regmap_simple_field_xlate;
+
chip = &gpio->gpio_chip;
chip->parent = config->parent;
chip->fwnode = config->fwnode;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index a9f7b7faf57b..a673dbfe88a3 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -37,6 +37,10 @@ struct regmap;
* offset to a register/bitmask pair. If not
* given the default gpio_regmap_simple_xlate()
* is used.
+ * @reg_field_xlate: (Optional) Translates base address and GPIO offset
+ * to register, mask, and field values. If not given
+ * the default gpio_regmap_field_xlate() is used, which
+ * is implemented in terms of ->reg_mask_xlate.
* @drvdata: (Optional) Pointer to driver specific data which is
* not used by gpio-remap but is provided "as is" to the
* driver callback(s).
@@ -45,6 +49,12 @@ struct regmap;
* register and mask pair. The base address is one of the given register
* base addresses in this structure.
*
+ * ->reg_field_xlate supports chips that have more than one bit per GPIO for
+ * controlling the output level or direction. In addition to the register and
+ * mask it should output field values for low/high level or in/out direction
+ * in ``values[0]`` and ``values[1]``. If ->reg_field_xlate is provided then
+ * it overrides any ->reg_mask_xlate callback.
+ *
* Although all register base addresses are marked as optional, there are
* several rules:
* 1. if you only have @reg_dat_base set, then it is input-only
@@ -81,6 +91,10 @@ struct gpio_regmap_config {
int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int base,
unsigned int offset, unsigned int *reg,
unsigned int *mask);
+ void (*reg_field_xlate)(struct gpio_regmap *gpio,
+ unsigned int base, unsigned int offset,
+ unsigned int *reg, unsigned int *mask,
+ unsigned int *values);
void *drvdata;
};
--
2.35.1
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