[PATCH 09/24] gpio: Add ZTE ZX279128S GPIO driver

[Navid Ghahremani]

Expose the six banks using the generic GPIO implementation and enable
the register clock before accessing the bank.

Assisted-by: LLM
Signed-off-by: Navid Ghahremani <ghahramani.navid at gmail.com>
---
 drivers/gpio/Kconfig          | 12 ++++++
 drivers/gpio/Makefile         |  1 +
 drivers/gpio/gpio-zx279128s.c | 78 +++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+)
 create mode 100644 drivers/gpio/gpio-zx279128s.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index a48586bb8e..3ae51a3c10 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -902,6 +902,18 @@ config GPIO_ZEVIO
 	help
 	  Say yes here to support the GPIO controller in LSI ZEVIO SoCs.
 
+config GPIO_ZX279128S
+	tristate "ZTE zx279128s GPIO support"
+	depends on ARCH_ZTE || COMPILE_TEST
+	select GPIO_GENERIC
+	help
+	  Say yes here to support the GPIO controller of the ZTE zx279128s
+	  SoC. It has several banks of 16 lines each, which boards such as
+	  the ZTE ZXHN H3600 use for LEDs, buttons and reset lines.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called gpio-zx279128s.
+
 config GPIO_ZYNQ
 	tristate "Xilinx Zynq GPIO support"
 	depends on ARCH_ZYNQ || ARCH_ZYNQMP || COMPILE_TEST
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index dc9e6d643b..a57ed7ec71 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -223,5 +223,6 @@ obj-$(CONFIG_GPIO_XLP)			+= gpio-xlp.o
 obj-$(CONFIG_GPIO_XRA1403)		+= gpio-xra1403.o
 obj-$(CONFIG_GPIO_XTENSA)		+= gpio-xtensa.o
 obj-$(CONFIG_GPIO_ZEVIO)		+= gpio-zevio.o
+obj-$(CONFIG_GPIO_ZX279128S)		+= gpio-zx279128s.o
 obj-$(CONFIG_GPIO_ZYNQ)			+= gpio-zynq.o
 obj-$(CONFIG_GPIO_ZYNQMP_MODEPIN)	+= gpio-zynqmp-modepin.o
diff --git a/drivers/gpio/gpio-zx279128s.c b/drivers/gpio/gpio-zx279128s.c
new file mode 100644
index 0000000000..8f37b908bb
--- /dev/null
+++ b/drivers/gpio/gpio-zx279128s.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ZTE zx279128s GPIO controller
+ *
+ * Copyright (C) 2026 Navid Ghahremani <ghahramani.navid at gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/generic.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+/*
+ * Each bank has 16 lines, one bit per line in each register. The registers
+ * at 0x04-0x10 and 0x28-0x34 control the interrupts, which are not supported
+ * yet.
+ */
+#define ZX279128S_GPIO_DIR	0x00	/* 1: output */
+#define ZX279128S_GPIO_DATA	0x14	/* line level */
+#define ZX279128S_GPIO_SET	0x18	/* write 1: drive high */
+#define ZX279128S_GPIO_CLEAR	0x1c	/* write 1: drive low */
+
+static int zx279128s_gpio_probe(struct platform_device *pdev)
+{
+	struct gpio_generic_chip_config config = { };
+	struct device *dev = &pdev->dev;
+	struct gpio_generic_chip *chip;
+	void __iomem *base;
+	struct clk *clk;
+	int ret;
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "failed to get the clock\n");
+
+	config.dev = dev;
+	config.sz = 2;
+	config.dat = base + ZX279128S_GPIO_DATA;
+	config.set = base + ZX279128S_GPIO_SET;
+	config.clr = base + ZX279128S_GPIO_CLEAR;
+	config.dirout = base + ZX279128S_GPIO_DIR;
+
+	ret = gpio_generic_chip_init(chip, &config);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to set up the GPIO chip\n");
+
+	return devm_gpiochip_add_data(dev, &chip->gc, NULL);
+}
+
+static const struct of_device_id zx279128s_gpio_of_match[] = {
+	{ .compatible = "zte,zx279128s-gpio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, zx279128s_gpio_of_match);
+
+static struct platform_driver zx279128s_gpio_driver = {
+	.probe = zx279128s_gpio_probe,
+	.driver = {
+		.name = "zx279128s-gpio",
+		.of_match_table = zx279128s_gpio_of_match,
+	},
+};
+module_platform_driver(zx279128s_gpio_driver);
+
+MODULE_AUTHOR("Navid Ghahremani <ghahramani.navid at gmail.com>");
+MODULE_DESCRIPTION("ZTE zx279128s GPIO controller driver");
+MODULE_LICENSE("GPL");
-- 
2.55.0