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Message-Id: <20250709-pinctrl-gpio-pinfuncs-v2-9-b6135149c0d9@linaro.org>
Date: Wed, 09 Jul 2025 16:39:05 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konradybcio@...nel.org>,
Alexey Klimov <alexey.klimov@...aro.org>,
Lorenzo Bianconi <lorenzo@...nel.org>, Sean Wang <sean.wang@...nel.org>,
Matthias Brugger <matthias.bgg@...il.com>,
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
Paul Cercueil <paul@...pouillou.net>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH v2 09/12] pinctrl: allow to mark pin functions as
requestable GPIOs
From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
The name of the pin function has no real meaning to pinctrl core and is
there only for human readability of device properties. Some pins are
muxed as GPIOs but for "strict" pinmuxers it's impossible to request
them as GPIOs if they're bound to a devide - even if their function name
explicitly says "gpio". Add a new field to struct pinfunction that
allows to pass additional flags to pinctrl core. While we could go with
a boolean "is_gpio" field, a flags field is more future-proof.
If the PINFUNCTION_FLAG_GPIO is set for a given function, the pin muxed
to it can be requested as GPIO even on strict pin controllers. Add a new
callback to struct pinmux_ops - function_is_gpio() - that allows pinmux
core to inspect a function and see if it's a GPIO one. Provide a generic
implementation of this callback.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
drivers/pinctrl/pinmux.c | 37 +++++++++++++++++++++++++++++++++++--
drivers/pinctrl/pinmux.h | 3 +++
include/linux/pinctrl/pinctrl.h | 14 ++++++++++++++
include/linux/pinctrl/pinmux.h | 2 ++
4 files changed, 54 insertions(+), 2 deletions(-)
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 8f2fe7ffc4f682cd966728f3c77c504489f7f8a0..c0d15817275c6c4638c789b7e91e510b35e6117b 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -89,13 +89,19 @@ bool pinmux_can_be_used_for_gpio(struct pinctrl_dev *pctldev, unsigned int pin)
{
struct pin_desc *desc = pin_desc_get(pctldev, pin);
const struct pinmux_ops *ops = pctldev->desc->pmxops;
+ const struct pinctrl_setting_mux *mux_setting = desc->mux_setting;
+ bool func_is_gpio = false;
/* Can't inspect pin, assume it can be used */
if (!desc || !ops)
return true;
guard(mutex)(&desc->mux_lock);
- if (ops->strict && desc->mux_usecount)
+ if (ops->function_is_gpio && mux_setting)
+ func_is_gpio = ops->function_is_gpio(pctldev,
+ mux_setting->func);
+
+ if (ops->strict && desc->mux_usecount && !func_is_gpio)
return false;
return !(ops->strict && !!desc->gpio_owner);
@@ -116,7 +122,9 @@ static int pin_request(struct pinctrl_dev *pctldev,
{
struct pin_desc *desc;
const struct pinmux_ops *ops = pctldev->desc->pmxops;
+ const struct pinctrl_setting_mux *mux_setting;
int status = -EINVAL;
+ bool func_is_gpio = false;
desc = pin_desc_get(pctldev, pin);
if (desc == NULL) {
@@ -126,11 +134,16 @@ static int pin_request(struct pinctrl_dev *pctldev,
goto out;
}
+ mux_setting = desc->mux_setting;
+
dev_dbg(pctldev->dev, "request pin %d (%s) for %s\n",
pin, desc->name, owner);
scoped_guard(mutex, &desc->mux_lock) {
- if ((!gpio_range || ops->strict) &&
+ if (ops->function_is_gpio && mux_setting)
+ func_is_gpio = ops->function_is_gpio(pctldev,
+ mux_setting->func);
+ if ((!gpio_range || ops->strict) && !func_is_gpio &&
desc->mux_usecount && strcmp(desc->mux_owner, owner)) {
dev_err(pctldev->dev,
"pin %s already requested by %s; cannot claim for %s\n",
@@ -863,6 +876,26 @@ struct function_desc *pinmux_generic_get_function(struct pinctrl_dev *pctldev,
}
EXPORT_SYMBOL_GPL(pinmux_generic_get_function);
+/**
+ * pinmux_generic_function_is_gpio() - returns true if given function is a GPIO
+ * @pctldev: pin controller device
+ * @selector: function number
+ */
+bool pinmux_generic_function_is_gpio(struct pinctrl_dev *pctldev,
+ unsigned int selector)
+{
+ struct function_desc *function;
+
+ function = radix_tree_lookup(&pctldev->pin_function_tree,
+ selector);
+ if (!function)
+ return false;
+
+ return function->func.flags & PINFUNCTION_FLAG_GPIO;
+
+}
+EXPORT_SYMBOL_GPL(pinmux_generic_function_is_gpio);
+
/**
* pinmux_generic_add_function() - adds a function group
* @pctldev: pin controller device
diff --git a/drivers/pinctrl/pinmux.h b/drivers/pinctrl/pinmux.h
index bdb5be1a636ead9695410824b5557937c5baa89a..ae6da930de1b6bf2afab24599b32114584e11198 100644
--- a/drivers/pinctrl/pinmux.h
+++ b/drivers/pinctrl/pinmux.h
@@ -169,6 +169,9 @@ int pinmux_generic_remove_function(struct pinctrl_dev *pctldev,
void pinmux_generic_free_functions(struct pinctrl_dev *pctldev);
+bool pinmux_generic_function_is_gpio(struct pinctrl_dev *pctldev,
+ unsigned int selector);
+
#else
static inline void pinmux_generic_free_functions(struct pinctrl_dev *pctldev)
diff --git a/include/linux/pinctrl/pinctrl.h b/include/linux/pinctrl/pinctrl.h
index d138e18156452e008f24ca06358fcab45135632f..1a8084e2940537f8f0862761d3e47c56c8783193 100644
--- a/include/linux/pinctrl/pinctrl.h
+++ b/include/linux/pinctrl/pinctrl.h
@@ -11,6 +11,7 @@
#ifndef __LINUX_PINCTRL_PINCTRL_H
#define __LINUX_PINCTRL_PINCTRL_H
+#include <linux/bits.h>
#include <linux/types.h>
struct device;
@@ -206,16 +207,20 @@ extern int pinctrl_get_group_pins(struct pinctrl_dev *pctldev,
const char *pin_group, const unsigned int **pins,
unsigned int *num_pins);
+#define PINFUNCTION_FLAG_GPIO BIT(0)
+
/**
* struct pinfunction - Description about a function
* @name: Name of the function
* @groups: An array of groups for this function
* @ngroups: Number of groups in @groups
+ * @flags: Additional pin function flags
*/
struct pinfunction {
const char *name;
const char * const *groups;
size_t ngroups;
+ unsigned long flags;
};
/* Convenience macro to define a single named pinfunction */
@@ -226,6 +231,15 @@ struct pinfunction {
.ngroups = (_ngroups), \
}
+/* Same as PINCTRL_PINFUNCTION() but for the GPIO category of functions */
+#define PINCTRL_GPIO_PINFUNCTION(_name, _groups, _ngroups) \
+(struct pinfunction) { \
+ .name = (_name), \
+ .groups = (_groups), \
+ .ngroups = (_ngroups), \
+ .flags = PINFUNCTION_FLAG_GPIO, \
+ }
+
#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_PINCTRL)
extern struct pinctrl_dev *of_pinctrl_get(struct device_node *np);
#else
diff --git a/include/linux/pinctrl/pinmux.h b/include/linux/pinctrl/pinmux.h
index d6f7b58d6ad0cce421aad80463529c9ccc65d68e..6db6c3e1ccc2249d4b4204e6fc19bf7b4397cc81 100644
--- a/include/linux/pinctrl/pinmux.h
+++ b/include/linux/pinctrl/pinmux.h
@@ -66,6 +66,8 @@ struct pinmux_ops {
unsigned int selector,
const char * const **groups,
unsigned int *num_groups);
+ bool (*function_is_gpio) (struct pinctrl_dev *pctldev,
+ unsigned int selector);
int (*set_mux) (struct pinctrl_dev *pctldev, unsigned int func_selector,
unsigned int group_selector);
int (*gpio_request_enable) (struct pinctrl_dev *pctldev,
--
2.48.1
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