reset: tps380x: Add TPS380x device driver supprt

The TI TPS380x family [1] is a voltage supervisor with a dedicated
manual reset (mr) line input and a reset output. The chip(s) have a
build in reset delay, depending on the chip partnumber. This simple
driver addresses this so the cosumer don't need to care about it.

[1] https://www.ti.com/product/TPS3801

Signed-off-by: Marco Felsch <[e-mail]>
[[e-mail]: drop Todo comment about min/typ/max reset time]
Signed-off-by: Philipp Zabel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/reset/Kconfig

···
 	  you wish to use the reset framework for such memory-mapped devices,
 	  say Y here. Otherwise, say N.
 
+config RESET_TI_TPS380X
+	tristate "TI TPS380x Reset Driver"
+	select GPIOLIB
+	help
+	  This enables the reset driver support for TI TPS380x devices. If
+	  you wish to use the reset framework for such devices, say Y here.
+	  Otherwise, say N.
+
 config RESET_TN48M_CPLD
 	tristate "Delta Networks TN48M switch CPLD reset controller"
 	depends on MFD_TN48M_CPLD || COMPILE_TEST

drivers/reset/Makefile

···
 obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
 obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
 obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
+obj-$(CONFIG_RESET_TI_TPS380X) += reset-tps380x.o
 obj-$(CONFIG_RESET_TN48M_CPLD) += reset-tn48m.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o

drivers/reset/reset-tps380x.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TI TPS380x Supply Voltage Supervisor and Reset Controller Driver
+ *
+ * Copyright (C) 2022 Pengutronix, Marco Felsch <[e-mail]>
+ *
+ * Based on Simple Reset Controller Driver
+ *
+ * Copyright (C) 2017 Pengutronix, Philipp Zabel <[e-mail]>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/reset-controller.h>
+
+struct tps380x_reset {
+	struct reset_controller_dev	rcdev;
+	struct gpio_desc		*reset_gpio;
+	unsigned int			reset_ms;
+};
+
+struct tps380x_reset_devdata {
+	unsigned int min_reset_ms;
+	unsigned int typ_reset_ms;
+	unsigned int max_reset_ms;
+};
+
+static inline
+struct tps380x_reset *to_tps380x_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct tps380x_reset, rcdev);
+}
+
+static int
+tps380x_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct tps380x_reset *tps380x = to_tps380x_reset(rcdev);
+
+	gpiod_set_value_cansleep(tps380x->reset_gpio, 1);
+
+	return 0;
+}
+
+static int
+tps380x_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct tps380x_reset *tps380x = to_tps380x_reset(rcdev);
+
+	gpiod_set_value_cansleep(tps380x->reset_gpio, 0);
+	msleep(tps380x->reset_ms);
+
+	return 0;
+}
+
+static const struct reset_control_ops reset_tps380x_ops = {
+	.assert		= tps380x_reset_assert,
+	.deassert	= tps380x_reset_deassert,
+};
+
+static int tps380x_reset_of_xlate(struct reset_controller_dev *rcdev,
+				  const struct of_phandle_args *reset_spec)
+{
+	/* No special handling needed, we have only one reset line per device */
+	return 0;
+}
+
+static int tps380x_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct tps380x_reset_devdata *devdata;
+	struct tps380x_reset *tps380x;
+
+	devdata = device_get_match_data(dev);
+	if (!devdata)
+		return -EINVAL;
+
+	tps380x = devm_kzalloc(dev, sizeof(*tps380x), GFP_KERNEL);
+	if (!tps380x)
+		return -ENOMEM;
+
+	tps380x->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(tps380x->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(tps380x->reset_gpio),
+				     "Failed to get GPIO\n");
+
+	tps380x->reset_ms = devdata->max_reset_ms;
+
+	tps380x->rcdev.ops = &reset_tps380x_ops;
+	tps380x->rcdev.owner = THIS_MODULE;
+	tps380x->rcdev.dev = dev;
+	tps380x->rcdev.of_node = dev->of_node;
+	tps380x->rcdev.of_reset_n_cells = 0;
+	tps380x->rcdev.of_xlate = tps380x_reset_of_xlate;
+	tps380x->rcdev.nr_resets = 1;
+
+	return devm_reset_controller_register(dev, &tps380x->rcdev);
+}
+
+static const struct tps380x_reset_devdata tps3801_reset_data = {
+	.min_reset_ms = 120,
+	.typ_reset_ms = 200,
+	.max_reset_ms = 280,
+};
+
+static const struct of_device_id tps380x_reset_dt_ids[] = {
+	{ .compatible = "ti,tps3801", .data = &tps3801_reset_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, tps380x_reset_dt_ids);
+
+static struct platform_driver tps380x_reset_driver = {
+	.probe	= tps380x_reset_probe,
+	.driver = {
+		.name		= "tps380x-reset",
+		.of_match_table	= tps380x_reset_dt_ids,
+	},
+};
+module_platform_driver(tps380x_reset_driver);
+
+MODULE_AUTHOR("Marco Felsch <[e-mail]>");
+MODULE_DESCRIPTION("TI TPS380x Supply Voltags Supervisor and Reset Driver");
+MODULE_LICENSE("GPL v2");