[PATCH 2/2] gpio: gpio-ftdi-cbus: add driver for FTDI CBUS GPIOs

Stefan Agner
2015-06-20T22:13:34Z

This driver allows to use the CBUS pins, e.g. CBUS 0-3 on FT232R
type of devices. Note that the pins need to be configured first
by using I/O mode signal option in the EEPROM. This is _not_ the
factory default configuration of any of the four pins.

See also FTDI's Application Note AN_232R-01.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
drivers/gpio/Kconfig | 10 +++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-ftdi-cbus.c | 167 ++++++++++++++++++++++++++++++++++++++++++
drivers/usb/serial/ftdi_sio.c | 16 ++++
4 files changed, 194 insertions(+)
create mode 100644 drivers/gpio/gpio-ftdi-cbus.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index caefe80..450ba9f 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -975,6 +975,16 @@ endmenu
menu "USB GPIO expanders"
depends on USB

+config GPIO_FTDI_CBUS
+ tristate "FTDI FT232R CBUS bitmode GPIO support"
+ depends on USB_SERIAL_FTDI_SIO
+ help
+ Say yes to use up to four CBUS pins on FT232R type of devices
+ Note that the pins need to be configured in EEPROM using to
+ "I/O mode" signal option first. The factory configuration
+ does not ship with this signal option set for any of the four
+ supported CBUS pins.
+
config GPIO_VIPERBOARD
tristate "Viperboard GPIO a & b support"
depends on MFD_VIPERBOARD && USB
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index f71bb97..a5d661b4 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_GPIO_DWAPB) += gpio-dwapb.o
obj-$(CONFIG_GPIO_EM) += gpio-em.o
obj-$(CONFIG_GPIO_EP93XX) += gpio-ep93xx.o
obj-$(CONFIG_GPIO_F7188X) += gpio-f7188x.o
+obj-$(CONFIG_GPIO_FTDI_CBUS) += gpio-ftdi-cbus.o
obj-$(CONFIG_GPIO_GE_FPGA) += gpio-ge.o
obj-$(CONFIG_GPIO_GRGPIO) += gpio-grgpio.o
obj-$(CONFIG_GPIO_ICH) += gpio-ich.o
diff --git a/drivers/gpio/gpio-ftdi-cbus.c b/drivers/gpio/gpio-ftdi-cbus.c
new file mode 100644
index 0000000..3a4dc46
--- /dev/null
+++ b/drivers/gpio/gpio-ftdi-cbus.c
@@ -0,0 +1,167 @@
+/*
+ * gpiolib support for FTDI SIO chips supporting CBUS GPIO's (FT232R class)
+ *
+ * Copyright 2015 Stefan Agner
+ *
+ * Author: Stefan Agner <stefan@agner.ch>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * Note: To use the GPIOs on CBUS the signal option need to be set to
+ * I/O mode in EEPROM!
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/gpio.h>
+#include <linux/platform_device.h>
+#include <linux/seq_file.h>
+#include <linux/regmap.h>
+
+#include <linux/usb/ftdi_sio.h>
+
+struct ftdi_cbus_gpio {
+ struct usb_serial_port *port;
+ struct gpio_chip gpio_chip;
+ u8 cbus_mask;
+};
+
+static inline struct ftdi_cbus_gpio *to_ftdi_cbus_gpio(struct gpio_chip *chip)
+{
+ return container_of(chip, struct ftdi_cbus_gpio, gpio_chip);
+}
+
+static int ftdi_cbus_gpio_direction_input(struct gpio_chip *chip,
+ unsigned offset)
+{
+ struct ftdi_cbus_gpio *fcg = to_ftdi_cbus_gpio(chip);
+
+ fcg->cbus_mask &= ~((1 << offset) << 4);
+
+ return ftdi_sio_set_bitmode(fcg->port, fcg->cbus_mask, BITMODE_CBUS);
+}
+
+static int ftdi_cbus_gpio_direction_output(struct gpio_chip *chip,
+ unsigned offset, int value)
+{
+ struct ftdi_cbus_gpio *fcg = to_ftdi_cbus_gpio(chip);
+
+ fcg->cbus_mask |= ((1 << offset) << 4);
+ if (value)
+ fcg->cbus_mask |= (1 << offset);
+ else
+ fcg->cbus_mask &= ~(1 << offset);
+
+ return ftdi_sio_set_bitmode(fcg->port, fcg->cbus_mask, BITMODE_CBUS);
+}
+
+static void ftdi_cbus_gpio_set(struct gpio_chip *chip, unsigned offset,
+ int value)
+{
+ struct ftdi_cbus_gpio *fcg = to_ftdi_cbus_gpio(chip);
+ int ret;
+
+ if (value)
+ fcg->cbus_mask |= (1 << offset);
+ else
+ fcg->cbus_mask &= ~(1 << offset);
+
+ ret = ftdi_sio_set_bitmode(fcg->port, fcg->cbus_mask, 0x20);
+ if (ret < 0)
+ dev_warn(chip->dev, "error setting pin value, %d\n", ret);
+}
+
+static int ftdi_cbus_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+ struct ftdi_cbus_gpio *fcg = to_ftdi_cbus_gpio(chip);
+ u8 val;
+ int ret;
+
+ ret = ftdi_sio_read_pins(fcg->port, &val);
+
+ if (ret < 0) {
+ dev_warn(chip->dev, "error getting pin value, %d\n", ret);
+ return 0;
+ }
+
+ if (val & (1 << offset))
+ return 1;
+ else
+ return 0;
+}
+
+static struct gpio_chip ftdi_cbus_gpio_chip = {
+ .label = "ftdi-cbus-gpio",
+ .owner = THIS_MODULE,
+ .direction_input = ftdi_cbus_gpio_direction_input,
+ .direction_output = ftdi_cbus_gpio_direction_output,
+ .get = ftdi_cbus_gpio_get,
+ .set = ftdi_cbus_gpio_set,
+ .can_sleep = true,
+};
+
+static int ftdi_cbus_gpio_probe(struct platform_device *pdev)
+{
+ struct ftdi_cbus_gpio *ftdi_cbus_gpio;
+ int ret = 0;
+
+ ftdi_cbus_gpio = devm_kzalloc(&pdev->dev, sizeof(*ftdi_cbus_gpio),
+ GFP_KERNEL);
+ if (ftdi_cbus_gpio == NULL)
+ return -ENOMEM;
+
+ ftdi_cbus_gpio->port = to_usb_serial_port(pdev->dev.parent);
+ ftdi_cbus_gpio->gpio_chip = ftdi_cbus_gpio_chip;
+ ftdi_cbus_gpio->gpio_chip.base = -1;
+ ftdi_cbus_gpio->gpio_chip.ngpio = 4;
+ ftdi_cbus_gpio->gpio_chip.dev = &pdev->dev;
+
+ ret = gpiochip_add(&ftdi_cbus_gpio->gpio_chip);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "Could not register gpiochip, %d\n",
+ ret);
+ goto err;
+ }
+
+ platform_set_drvdata(pdev, ftdi_cbus_gpio);
+
+err:
+ return ret;
+}
+
+static int ftdi_cbus_gpio_remove(struct platform_device *pdev)
+{
+ struct ftdi_cbus_gpio *fcg = platform_get_drvdata(pdev);
+
+ gpiochip_remove(&fcg->gpio_chip);
+
+ return 0;
+}
+
+static struct platform_driver ftdi_cbus_gpio_driver = {
+ .driver.name = "ftdi-cbus-gpio",
+ .driver.owner = THIS_MODULE,
+ .probe = ftdi_cbus_gpio_probe,
+ .remove = ftdi_cbus_gpio_remove,
+};
+
+static int __init ftdi_cbus_gpio_init(void)
+{
+ return platform_driver_register(&ftdi_cbus_gpio_driver);
+}
+subsys_initcall(ftdi_cbus_gpio_init);
+
+static void __exit ftdi_cbus_gpio_exit(void)
+{
+ platform_driver_unregister(&ftdi_cbus_gpio_driver);
+}
+module_exit(ftdi_cbus_gpio_exit);
+
+MODULE_AUTHOR("Stefan Agner <stefan@agner.ch>");
+MODULE_DESCRIPTION("GPIO interface for FTDI SIO chips using CBUS bitmode");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ftdi-cbus-gpio");
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 23a3280..2711d24 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -33,6 +33,7 @@

#include <linux/kernel.h>
#include <linux/errno.h>
+#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
@@ -1846,6 +1847,21 @@ static int ftdi_sio_port_probe(struct usb_serial_port *port)
priv->latency = 16;
write_latency_timer(port);
create_sysfs_attrs(port);
+
+ if (priv->chip_type == FT232RL) {
+ struct platform_device *pdev;
+ int ret;
+
+ pdev = platform_device_alloc("ftdi-cbus-gpio", priv->interface);
+ if (!pdev)
+ return -ENOMEM;
+ pdev->dev.parent = &port->dev;
+
+ ret = platform_device_add(pdev);
+ if (ret)
+ return ret;
+ }
+
return 0;
}

--
2.4.4