gpio: regmap: add the .fixed_direction_output configuration parameter

There are GPIO controllers such as the one present in the LX2160ARDB
QIXIS FPGA which have fixed-direction input and output GPIO lines mixed
together in a single register. This cannot be modeled using the
gpio-regmap as-is since there is no way to present the true direction of
a GPIO line.

In order to make this use case possible, add a new configuration
parameter - fixed_direction_output - into the gpio_regmap_config
structure. This will enable user drivers to provide a bitmap that
represents the fixed direction of the GPIO lines.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index ab9e4077fa608c9a76eaa8aa3680b0af3408e4ef..f4267af00027e23f55388d0e2ca6cedd091ce67a 100644 (file)
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -31,6 +31,7 @@ struct gpio_regmap {
        unsigned int reg_clr_base;
        unsigned int reg_dir_in_base;
        unsigned int reg_dir_out_base;
+       unsigned long *fixed_direction_output;
 
 #ifdef CONFIG_REGMAP_IRQ
        int regmap_irq_line;
@@ -134,6 +135,13 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
        unsigned int base, val, reg, mask;
        int invert, ret;
 
+       if (gpio->fixed_direction_output) {
+               if (test_bit(offset, gpio->fixed_direction_output))
+                       return GPIO_LINE_DIRECTION_OUT;
+               else
+                       return GPIO_LINE_DIRECTION_IN;
+       }
+
        if (gpio->reg_dat_base && !gpio->reg_set_base)
                return GPIO_LINE_DIRECTION_IN;
        if (gpio->reg_set_base && !gpio->reg_dat_base)
@@ -284,6 +292,17 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
                        goto err_free_gpio;
        }
 
+       if (config->fixed_direction_output) {
+               gpio->fixed_direction_output = bitmap_alloc(chip->ngpio,
+                                                           GFP_KERNEL);
+               if (!gpio->fixed_direction_output) {
+                       ret = -ENOMEM;
+                       goto err_free_gpio;
+               }
+               bitmap_copy(gpio->fixed_direction_output,
+                           config->fixed_direction_output, chip->ngpio);
+       }
+
        /* if not set, assume there is only one register */
        gpio->ngpio_per_reg = config->ngpio_per_reg;
        if (!gpio->ngpio_per_reg)
@@ -300,7 +319,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 
        ret = gpiochip_add_data(chip, gpio);
        if (ret < 0)
-               goto err_free_gpio;
+               goto err_free_bitmap;
 
 #ifdef CONFIG_REGMAP_IRQ
        if (config->regmap_irq_chip) {
@@ -309,7 +328,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
                                                 config->regmap_irq_line, config->regmap_irq_flags,
                                                 0, config->regmap_irq_chip, &gpio->irq_chip_data);
                if (ret)
-                       goto err_free_gpio;
+                       goto err_free_bitmap;
 
                irq_domain = regmap_irq_get_domain(gpio->irq_chip_data);
        } else
@@ -326,6 +345,8 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 
 err_remove_gpiochip:
        gpiochip_remove(chip);
+err_free_bitmap:
+       bitmap_free(gpio->fixed_direction_output);
 err_free_gpio:
        kfree(gpio);
        return ERR_PTR(ret);
@@ -344,6 +365,7 @@ void gpio_regmap_unregister(struct gpio_regmap *gpio)
 #endif
 
        gpiochip_remove(&gpio->gpio_chip);
+       bitmap_free(gpio->fixed_direction_output);
        kfree(gpio);
 }
 EXPORT_SYMBOL_GPL(gpio_regmap_unregister);

diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index 622a2939ebe0fd6b5f93dfa371331b2f4e674059..87983a5f3681e55a3ec47e211aa9f3d9d2e66d19 100644 (file)
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -38,6 +38,10 @@ struct regmap;
  *                     offset to a register/bitmask pair. If not
  *                     given the default gpio_regmap_simple_xlate()
  *                     is used.
+ * @fixed_direction_output:
+ *                     (Optional) Bitmap representing the fixed direction of
+ *                     the GPIO lines. Useful when there are GPIO lines with a
+ *                     fixed direction mixed together in the same register.
  * @drvdata:           (Optional) Pointer to driver specific data which is
  *                     not used by gpio-remap but is provided "as is" to the
  *                     driver callback(s).
@@ -85,6 +89,7 @@ struct gpio_regmap_config {
        int reg_stride;
        int ngpio_per_reg;
        struct irq_domain *irq_domain;
+       unsigned long *fixed_direction_output;
 
 #ifdef CONFIG_REGMAP_IRQ
        struct regmap_irq_chip *regmap_irq_chip;