[PATCH v1] drivers/gpio: add support for MAX7320 i2c i/o expander

Hannes Schmelzer
2021-10-01T11:38:19Z

This commit adds support for the MAX7320 (and clones) gpio expander.

Signed-off-by: Hannes Schmelzer <hannes.schmelzer@br-automation.com>

---

doc/device-tree-bindings/gpio/gpio-max7320.txt | 36 ++++++++
drivers/gpio/Kconfig | 8 ++
drivers/gpio/Makefile | 1 +
drivers/gpio/max7320_gpio.c | 113 +++++++++++++++++++++++++
4 files changed, 158 insertions(+)
create mode 100644 doc/device-tree-bindings/gpio/gpio-max7320.txt
create mode 100644 drivers/gpio/max7320_gpio.c

diff --git a/doc/device-tree-bindings/gpio/gpio-max7320.txt b/doc/device-tree-bindings/gpio/gpio-max7320.txt
new file mode 100644
index 0000000..87b703b
--- /dev/null
+++ b/doc/device-tree-bindings/gpio/gpio-max7320.txt
@@ -0,0 +1,36 @@
+* MAX7320 I/O expanders
+
+The original maxim 7320 i/o expander offers 8 bit push/pull outputs.
+There exists some clones which offers 16 bit.
+
+Required Properties:
+
+ - compatible: should be one of the following.
+ - "maxim,max7320"
+
+ - reg: I2C slave address.
+
+ - gpio-controller: Marks the device node as a gpio controller.
+ - #gpio-cells: Should be 2. The first cell is the GPIO number and the second
+ cell specifies GPIO flags, as defined in <dt-bindings/gpio/gpio.h>. Only the
+ GPIO_ACTIVE_HIGH and GPIO_ACTIVE_LOW flags are supported.
+
+Optional Properties:
+
+ - ngpios: tell the driver how many gpios the device offers.
+ if the property is omitted, 8bit (original maxim) is assumed.
+
+Please refer to gpio.txt in this directory for details of the common GPIO
+bindings used by client devices.
+
+Example: MAX7320 I/O expander node
+
+ ledgpio: max7320@5d {
+ status = "okay";
+ compatible = "maxim,max7320";
+ reg = <0x5d>;
+ #gpio-cells = <2>;
+ gpio-controller;
+ ngpios = <16>;
+ };
+
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index e37ac9f..3aafbe3 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -513,4 +513,12 @@ config NOMADIK_GPIO
into a number of banks each with 32 GPIOs. The GPIOs for a device are
defined in the device tree with one node for each bank.

+config MAX7320_GPIO
+ bool "MAX7320 I2C GPIO Expander driver"
+ depends on DM_GPIO && DM_I2C
+ help
+ Support for MAX7320 I2C 8/16-bit GPIO expander.
+ original maxim device has 8 push/pull outputs,
+ some clones offers 16bit.
+
endmenu
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 58f4704..f59ea4a 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -69,3 +69,4 @@ obj-$(CONFIG_MSCC_SGPIO) += mscc_sgpio.o
obj-$(CONFIG_NX_GPIO) += nx_gpio.o
obj-$(CONFIG_SIFIVE_GPIO) += sifive-gpio.o
obj-$(CONFIG_NOMADIK_GPIO) += nmk_gpio.o
+obj-$(CONFIG_MAX7320_GPIO) += max7320_gpio.o
diff --git a/drivers/gpio/max7320_gpio.c b/drivers/gpio/max7320_gpio.c
new file mode 100644
index 0000000..647aed9
--- /dev/null
+++ b/drivers/gpio/max7320_gpio.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * max7320 I2C GPIO EXPANDER DRIVER
+ *
+ * Copyright (C) 2021 Hannes Schmelzer <oe5hpm@oevsv.at>
+ * B&R Industrial Automation GmbH - http://www.br-automation.com
+ *
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <i2c.h>
+#include <asm-generic/gpio.h>
+#include <linux/bitops.h>
+
+struct max7320_chip {
+ u32 outreg;
+};
+
+static int max7320_direction_output(struct udevice *dev,
+ unsigned int offset, int value)
+{
+ struct max7320_chip *plat = dev_get_plat(dev);
+ struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+ struct dm_i2c_chip *chip = dev_get_parent_plat(dev);
+
+ int ret;
+
+ if (value)
+ plat->outreg |= BIT(offset);
+ else
+ plat->outreg &= ~BIT(offset);
+
+ ret = dm_i2c_write(dev,
+ plat->outreg & 0xff,
+ (uint8_t *)&plat->outreg + 1,
+ uc_priv->gpio_count > 8 ? 1 : 0);
+ if (ret)
+ printf("%s i2c write failed to addr %x\n", __func__,
+ chip->chip_addr);
+
+ return ret;
+}
+
+static int max7320_get_value(struct udevice *dev, unsigned int offset)
+{
+ struct max7320_chip *plat = dev_get_plat(dev);
+
+ return (plat->outreg >> offset) & 0x1;
+}
+
+static int max7320_set_value(struct udevice *dev, unsigned int offset,
+ int value)
+{
+ return max7320_direction_output(dev, offset, value);
+}
+
+static int max7320_get_function(struct udevice *dev, unsigned int offset)
+{
+ return GPIOF_OUTPUT;
+}
+
+static int max7320_ofdata_plat(struct udevice *dev)
+{
+ struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+ uc_priv->gpio_count = dev_read_u32_default(dev, "ngpios", 8);
+ if (uc_priv->gpio_count > 16) {
+ printf("%s: max7320 doesn't support more than 16 gpios!",
+ __func__);
+ return -EINVAL;
+ }
+
+ uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev_of_offset(dev),
+ "gpio-bank-name", NULL);
+ if (!uc_priv->bank_name)
+ uc_priv->bank_name = fdt_get_name(gd->fdt_blob,
+ dev_of_offset(dev), NULL);
+
+ return 0;
+}
+
+static int max7320_gpio_probe(struct udevice *dev)
+{
+ struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+ debug("%s GPIO controller with %d gpios probed\n",
+ uc_priv->bank_name, uc_priv->gpio_count);
+
+ return 0;
+}
+
+static const struct dm_gpio_ops max7320_gpio_ops = {
+ .direction_output = max7320_direction_output,
+ .set_value = max7320_set_value,
+ .get_value = max7320_get_value,
+ .get_function = max7320_get_function,
+};
+
+static const struct udevice_id max7320_gpio_ids[] = {
+ { .compatible = "maxim,max7320" },
+ { }
+};
+
+U_BOOT_DRIVER(gpio_max7320) = {
+ .name = "gpio_max7320",
+ .id = UCLASS_GPIO,
+ .ops = &max7320_gpio_ops,
+ .of_match = max7320_gpio_ids,
+ .of_to_plat = max7320_ofdata_plat,
+ .probe = max7320_gpio_probe,
+ .plat_auto = sizeof(struct max7320_chip),
+};
--
2.7.4