gpio: Add Delta TN48M CPLD GPIO driver

Delta TN48M switch has an onboard Lattice CPLD that is used as a GPIO
expander.

The CPLD provides 12 pins in total on the TN48M, but on more advanced
switch models it provides up to 192 pins, so the driver is extendable
to support more switches.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Link: https://lore.kernel.org/r/20220131133049.77780-3-robert.marko@sartura.hr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 100 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-tn48m.c b/drivers/gpio/gpio-tn48m.c
new file mode 100644
index 000000000000..cd4a80b22794
--- /dev/null
+++ b/drivers/gpio/gpio-tn48m.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Delta TN48M CPLD GPIO driver
+ *
+ * Copyright (C) 2021 Sartura Ltd.
+ *
+ * Author: Robert Marko <robert.marko@sartura.hr>
+ */
+
+#include <linux/device.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/regmap.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+enum tn48m_gpio_type {
+	TN48M_GP0 = 1,
+	TN48M_GPI,
+};
+
+struct tn48m_gpio_config {
+	int ngpio;
+	int ngpio_per_reg;
+	enum tn48m_gpio_type type;
+};
+
+static const struct tn48m_gpio_config tn48m_gpo_config = {
+	.ngpio = 4,
+	.ngpio_per_reg = 4,
+	.type = TN48M_GP0,
+};
+
+static const struct tn48m_gpio_config tn48m_gpi_config = {
+	.ngpio = 4,
+	.ngpio_per_reg = 4,
+	.type = TN48M_GPI,
+};
+
+static int tn48m_gpio_probe(struct platform_device *pdev)
+{
+	const struct tn48m_gpio_config *gpio_config;
+	struct gpio_regmap_config config = {};
+	struct regmap *regmap;
+	u32 base;
+	int ret;
+
+	if (!pdev->dev.parent)
+		return -ENODEV;
+
+	gpio_config = device_get_match_data(&pdev->dev);
+	if (!gpio_config)
+		return -ENODEV;
+
+	ret = device_property_read_u32(&pdev->dev, "reg", &base);
+	if (ret)
+		return ret;
+
+	regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!regmap)
+		return -ENODEV;
+
+	config.regmap = regmap;
+	config.parent = &pdev->dev;
+	config.ngpio = gpio_config->ngpio;
+	config.ngpio_per_reg = gpio_config->ngpio_per_reg;
+	switch (gpio_config->type) {
+	case TN48M_GP0:
+		config.reg_set_base = base;
+		break;
+	case TN48M_GPI:
+		config.reg_dat_base = base;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(&pdev->dev, &config));
+}
+
+static const struct of_device_id tn48m_gpio_of_match[] = {
+	{ .compatible = "delta,tn48m-gpo", .data = &tn48m_gpo_config },
+	{ .compatible = "delta,tn48m-gpi", .data = &tn48m_gpi_config },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tn48m_gpio_of_match);
+
+static struct platform_driver tn48m_gpio_driver = {
+	.driver = {
+		.name = "delta-tn48m-gpio",
+		.of_match_table = tn48m_gpio_of_match,
+	},
+	.probe = tn48m_gpio_probe,
+};
+module_platform_driver(tn48m_gpio_driver);
+
+MODULE_AUTHOR("Robert Marko <robert.marko@sartura.hr>");
+MODULE_DESCRIPTION("Delta TN48M CPLD GPIO driver");
+MODULE_LICENSE("GPL");