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Message-Id: <20231005025843.508689-5-takahiro.akashi@linaro.org>
Date: Thu, 5 Oct 2023 11:58:42 +0900
From: AKASHI Takahiro <takahiro.akashi@...aro.org>
To: sudeep.holla@....com, cristian.marussi@....com, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
linus.walleij@...aro.org
Cc: Oleksii_Moisieiev@...m.com, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-gpio@...r.kernel.org,
AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [RFC v2 4/5] gpio: add pinctrl based generic gpio driver
Some pin controllers provide not only a method to set up lines but
also gpio function. With this commit, a new generic gpio driver will
be provided. It is implemented purely by using pinctrl interfaces.
One of such pin controllers is Arm's SCMI.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
---
RFC v2 (Oct 5, 2023)
* rename the driver to pin-control-gpio (CONFIG_GPIO_BY_PINCTRL)
* return meaningful error codes instead of -1
* remove the masking at PIN_CONFIG_PACKED
* handle emulated OPEN_DRAIN configuration at get_direction()
* define config_set in gpio_chip
* drop remove hook
RFC (Oct 2, 2023)
---
drivers/gpio/Kconfig | 7 ++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-by-pinctrl.c | 165 +++++++++++++++++++++++++++++++++
3 files changed, 173 insertions(+)
create mode 100644 drivers/gpio/gpio-by-pinctrl.c
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 673bafb8be58..a60972be114c 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -216,6 +216,13 @@ config GPIO_BRCMSTB
help
Say yes here to enable GPIO support for Broadcom STB (BCM7XXX) SoCs.
+config GPIO_BY_PINCTRL
+ tristate "GPIO support based on a pure pin control backend"
+ depends on GPIOLIB
+ help
+ Select this option to support GPIO devices based solely on pin
+ control, specifically pin configuration, such as SCMI.
+
config GPIO_CADENCE
tristate "Cadence GPIO support"
depends on OF_GPIO
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index eb73b5d633eb..71458d81e16a 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -43,6 +43,7 @@ obj-$(CONFIG_GPIO_BD71828) += gpio-bd71828.o
obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd9571mwv.o
obj-$(CONFIG_GPIO_BRCMSTB) += gpio-brcmstb.o
obj-$(CONFIG_GPIO_BT8XX) += gpio-bt8xx.o
+obj-$(CONFIG_GPIO_BY_PINCTRL) += gpio-by-pinctrl.o
obj-$(CONFIG_GPIO_CADENCE) += gpio-cadence.o
obj-$(CONFIG_GPIO_CLPS711X) += gpio-clps711x.o
obj-$(CONFIG_GPIO_SNPS_CREG) += gpio-creg-snps.o
diff --git a/drivers/gpio/gpio-by-pinctrl.c b/drivers/gpio/gpio-by-pinctrl.c
new file mode 100644
index 000000000000..c297a9633e03
--- /dev/null
+++ b/drivers/gpio/gpio-by-pinctrl.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2023 Linaro Inc.
+// Author: AKASHI takahiro <takahiro.akashi@...aro.org>
+
+#include <linux/gpio/driver.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include "gpiolib.h"
+
+struct pin_control_gpio_priv {
+ struct gpio_chip chip;
+};
+
+static int pin_control_gpio_get_direction(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ unsigned long config;
+ bool out_en, in_en;
+ int ret;
+
+ config = PIN_CONFIG_OUTPUT_ENABLE;
+ ret = pinctrl_gpio_get_config(chip->gpiodev->base + offset, &config);
+ if (!ret)
+ out_en = !!config;
+ else if (ret == -EINVAL)
+ out_en = false;
+ else
+ return ret;
+
+ config = PIN_CONFIG_INPUT_ENABLE;
+ ret = pinctrl_gpio_get_config(chip->gpiodev->base + offset, &config);
+ if (!ret)
+ in_en = !!config;
+ else if (ret == -EINVAL)
+ in_en = false;
+ else
+ return ret;
+
+ if (in_en && !out_en)
+ return GPIO_LINE_DIRECTION_IN;
+
+ if (!in_en && out_en)
+ return GPIO_LINE_DIRECTION_OUT;
+
+ if (in_en && out_en) {
+ /* This may be an emulation for output with open drain */
+ config = PIN_CONFIG_DRIVE_OPEN_DRAIN;
+ ret = pinctrl_gpio_get_config(chip->gpiodev->base + offset,
+ &config);
+ if (!ret && config)
+ return GPIO_LINE_DIRECTION_OUT;
+ }
+
+ return -EINVAL;
+}
+
+static int pin_control_gpio_direction_input(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ return pinctrl_gpio_direction_input(chip->gpiodev->base + offset);
+}
+
+static int pin_control_gpio_direction_output(struct gpio_chip *chip,
+ unsigned int offset, int val)
+{
+ return pinctrl_gpio_direction_output(chip->gpiodev->base + offset);
+}
+
+static int pin_control_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ unsigned long config;
+ int ret;
+
+ config = PIN_CONFIG_INPUT;
+ ret = pinctrl_gpio_get_config(chip->gpiodev->base + offset, &config);
+ if (ret)
+ return ret;
+
+ if (config >> 8)
+ return 1;
+
+ return 0;
+}
+
+static void pin_control_gpio_set(struct gpio_chip *chip, unsigned int offset,
+ int val)
+{
+ unsigned long config;
+
+ config = PIN_CONF_PACKED(PIN_CONFIG_OUTPUT, val);
+
+ pinctrl_gpio_set_config(chip->gpiodev->base + offset, config);
+}
+
+static u16 sum_up_ngpios(struct gpio_chip *chip)
+{
+ struct gpio_pin_range *range;
+ struct gpio_device *gdev = chip->gpiodev;
+ u16 ngpios = 0;
+
+ list_for_each_entry(range, &gdev->pin_ranges, node) {
+ ngpios += range->range.npins;
+ }
+
+ return ngpios;
+}
+
+static int pin_control_gpio_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct pin_control_gpio_priv *priv;
+ struct gpio_chip *chip;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ chip = &priv->chip;
+ chip->label = dev_name(dev);
+ chip->parent = dev;
+ chip->base = -1;
+
+ chip->request = gpiochip_generic_request;
+ chip->free = gpiochip_generic_free;
+ chip->get_direction = pin_control_gpio_get_direction;
+ chip->direction_input = pin_control_gpio_direction_input;
+ chip->direction_output = pin_control_gpio_direction_output;
+ chip->get = pin_control_gpio_get;
+ chip->set = pin_control_gpio_set;
+ chip->set_config = gpiochip_generic_config;
+
+ ret = devm_gpiochip_add_data(dev, chip, priv);
+ if (ret)
+ return ret;
+
+ chip->ngpio = sum_up_ngpios(chip);
+
+ platform_set_drvdata(pdev, priv);
+
+ return 0;
+}
+
+static const struct of_device_id pin_control_gpio_match[] = {
+ { .compatible = "pin-control-gpio" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pin_control_gpio_match);
+
+static struct platform_driver pin_control_gpio_driver = {
+ .probe = pin_control_gpio_probe,
+ .driver = {
+ .name = "pin-control-gpio",
+ .of_match_table = pin_control_gpio_match,
+ },
+};
+module_platform_driver(pin_control_gpio_driver);
+
+MODULE_AUTHOR("AKASHI Takahiro <takahiro.akashi@...aro.org>");
+MODULE_DESCRIPTION("Pinctrl based GPIO driver");
+MODULE_LICENSE("GPL");
--
2.34.1
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