[RFC 3/4] gpio: scmi: add SCMI pinctrl based gpio driver

AKASHI Takahiro
2023-10-02T02:17:33Z

SCMI pin control protocol supports not only pin controllers, but also
gpio controllers by design. This patch includes a generic gpio driver
which allows consumer drivers to access gpio pins that are handled
through SCMI interfaces.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
drivers/gpio/Kconfig | 8 ++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-scmi.c | 154 +++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+)
create mode 100644 drivers/gpio/gpio-scmi.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 673bafb8be58..1a968b950f3a 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -566,6 +566,14 @@ config GPIO_SAMA5D2_PIOBU
The difference from regular GPIOs is that they
maintain their value during backup/self-refresh.

+config GPIO_SCMI
+ tristate "GPIO support based on SCMI pinctrl"
+ depends on OF_GPIO
+ depends on PINCTRL_SCMI
+ help
+ Select this option to support GPIO devices based on SCMI pin
+ control protocol.
+
config GPIO_SIFIVE
tristate "SiFive GPIO support"
depends on OF_GPIO
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index eb73b5d633eb..2abe1e9d5e77 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -141,6 +141,7 @@ obj-$(CONFIG_ARCH_SA1100) += gpio-sa1100.o
obj-$(CONFIG_GPIO_SAMA5D2_PIOBU) += gpio-sama5d2-piobu.o
obj-$(CONFIG_GPIO_SCH311X) += gpio-sch311x.o
obj-$(CONFIG_GPIO_SCH) += gpio-sch.o
+obj-$(CONFIG_GPIO_SCMI) += gpio-scmi.o
obj-$(CONFIG_GPIO_SIFIVE) += gpio-sifive.o
obj-$(CONFIG_GPIO_SIM) += gpio-sim.o
obj-$(CONFIG_GPIO_SIOX) += gpio-siox.o
diff --git a/drivers/gpio/gpio-scmi.c b/drivers/gpio/gpio-scmi.c
new file mode 100644
index 000000000000..ece63ea62b70
--- /dev/null
+++ b/drivers/gpio/gpio-scmi.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2023 Linaro Inc.
+// Author: AKASHI takahiro <takahiro.akashi@linaro.org>
+
+#include <linux/gpio/driver.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include "gpiolib.h"
+
+struct scmi_gpio_priv {
+ struct gpio_chip chip;
+};
+
+static int scmi_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
+{
+ unsigned long config;
+
+ config = PIN_CONFIG_OUTPUT_ENABLE;
+ if (pinctrl_gpio_get_config(chip->gpiodev->base + offset, &config))
+ return -1;
+ if (config)
+ return GPIO_LINE_DIRECTION_OUT;
+
+ config = PIN_CONFIG_INPUT_ENABLE;
+ if (pinctrl_gpio_get_config(chip->gpiodev->base + offset, &config))
+ return -1;
+ if (config)
+ return GPIO_LINE_DIRECTION_IN;
+
+ return -1;
+}
+
+static int scmi_gpio_direction_input(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ return pinctrl_gpio_direction_input(chip->gpiodev->base + offset);
+}
+
+static int scmi_gpio_direction_output(struct gpio_chip *chip,
+ unsigned int offset, int val)
+{
+ return pinctrl_gpio_direction_output(chip->gpiodev->base + offset);
+}
+
+static int scmi_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ unsigned long config;
+
+ /* FIXME: currently, PIN_CONFIG_INPUT not defined */
+ config = PIN_CONFIG_INPUT;
+ if (pinctrl_gpio_get_config(chip->gpiodev->base + offset, &config))
+ return -1;
+
+ /* FIXME: the packed format not defined */
+ if (config >> 8)
+ return 1;
+
+ return 0;
+}
+
+static void scmi_gpio_set(struct gpio_chip *chip, unsigned int offset, int val)
+{
+ unsigned long config;
+
+ config = PIN_CONF_PACKED(PIN_CONFIG_OUTPUT, val & 0x1);
+;
+ 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 scmi_gpio_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *parent_np;
+ struct scmi_gpio_priv *priv;
+ struct gpio_chip *chip;
+ int ret;
+
+ /* FIXME: who should be the parent */
+ parent_np = NULL;
+
+ 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 = scmi_gpio_get_direction;
+ chip->direction_input = scmi_gpio_direction_input;
+ chip->direction_output = scmi_gpio_direction_output;
+ chip->get = scmi_gpio_get;
+ chip->set = scmi_gpio_set;
+
+ 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 int scmi_gpio_remove(struct platform_device *pdev)
+{
+ struct scmi_gpio_priv *priv = platform_get_drvdata(pdev);
+
+ gpiochip_remove(&priv->chip);
+
+ return 0;
+}
+
+static const struct of_device_id scmi_gpio_match[] = {
+ { .compatible = "arm,scmi-gpio-generic" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, scmi_gpio_match);
+
+static struct platform_driver scmi_gpio_driver = {
+ .probe = scmi_gpio_probe,
+ .remove = scmi_gpio_remove,
+ .driver = {
+ .name = "scmi-gpio",
+ .of_match_table = scmi_gpio_match,
+ },
+};
+module_platform_driver(scmi_gpio_driver);
+
+MODULE_AUTHOR("AKASHI Takahiro <takahiro.akashi@linaro.org>");
+MODULE_DESCRIPTION("SCMI Pinctrl based GPIO driver");
+MODULE_LICENSE("GPL");
--
2.34.1