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Subject[PATCH v3 2/2] usb: serial: xr_serial: Add gpiochip support
Date
From: Manivannan Sadhasivam <mani@kernel.org>

Add gpiochip support for Maxlinear/Exar USB to serial converter
for controlling the available gpios.

Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
---
drivers/usb/serial/xr_serial.c | 199 ++++++++++++++++++++++++++++++++-
1 file changed, 198 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c
index fdb9ddf8bd95..255a30540b52 100644
--- a/drivers/usb/serial/xr_serial.c
+++ b/drivers/usb/serial/xr_serial.c
@@ -7,6 +7,7 @@
* Copyright (c) 2020 Manivannan Sadhasivam <mani@kernel.org>
*/

+#include <linux/gpio/driver.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
@@ -32,6 +33,11 @@ struct xr_uart_regs {
};

struct xr_port_private {
+#ifdef CONFIG_GPIOLIB
+ struct gpio_chip gc;
+ bool gpio_registered;
+ u8 gpio_altfunc;
+#endif
const struct xr_uart_regs *regs;
};

@@ -562,6 +568,196 @@ static void xr_break_ctl(struct tty_struct *tty, int break_state)
state);
}

+#ifdef CONFIG_GPIOLIB
+
+static int xr_gpio_request(struct gpio_chip *gc, unsigned int offset)
+{
+ struct usb_serial_port *port = gpiochip_get_data(gc);
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+
+ /* Check if the requested GPIO is occupied */
+ if (port_priv->gpio_altfunc & BIT(offset))
+ return -ENODEV;
+
+ return 0;
+}
+
+static int xr_gpio_get(struct gpio_chip *gc, unsigned int gpio)
+{
+ struct usb_serial_port *port = gpiochip_get_data(gc);
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ int ret;
+ u8 gpio_status;
+
+ ret = xr_get_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_status, &gpio_status);
+ if (ret)
+ return ret;
+
+ return !!(gpio_status & BIT(gpio));
+}
+
+static void xr_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
+{
+ struct usb_serial_port *port = gpiochip_get_data(gc);
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+
+ if (val)
+ xr_set_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_set, BIT(gpio));
+ else
+ xr_set_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_clr, BIT(gpio));
+}
+
+static int xr_gpio_direction_get(struct gpio_chip *gc, unsigned int gpio)
+{
+ struct usb_serial_port *port = gpiochip_get_data(gc);
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ int ret;
+ u8 gpio_dir;
+
+ ret = xr_get_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_dir, &gpio_dir);
+ if (ret)
+ return ret;
+
+ /* Logic 0 = input and Logic 1 = output */
+ return !(gpio_dir & BIT(gpio));
+}
+
+static int xr_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio)
+{
+ struct usb_serial_port *port = gpiochip_get_data(gc);
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ int ret;
+ u8 gpio_dir;
+
+ ret = xr_get_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_dir, &gpio_dir);
+ if (ret)
+ return ret;
+
+ gpio_dir &= ~BIT(gpio);
+
+ return xr_set_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_dir, gpio_dir);
+}
+
+static int xr_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio,
+ int val)
+{
+ struct usb_serial_port *port = gpiochip_get_data(gc);
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ int ret;
+ u8 gpio_dir;
+
+ ret = xr_get_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_dir, &gpio_dir);
+ if (ret)
+ return ret;
+
+ gpio_dir |= BIT(gpio);
+
+ ret = xr_set_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_dir, gpio_dir);
+ if (ret)
+ return ret;
+
+ xr_gpio_set(gc, gpio, val);
+
+ return 0;
+}
+
+static int xr21v141x_gpio_init(struct usb_serial_port *port)
+{
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ int ret;
+ u8 gpio_mode;
+
+ port_priv->gc.ngpio = 6;
+
+ ret = xr_get_reg(port, XR21V141X_UART_REG_BLOCK,
+ port_priv->regs->gpio_mode, &gpio_mode);
+ if (ret)
+ return ret;
+
+ /* Mark all pins which are not in GPIO mode */
+ if (gpio_mode & UART_MODE_RTS_CTS)
+ port_priv->gpio_altfunc |= (BIT(4) | BIT(5));
+ else if (gpio_mode & UART_MODE_DTR_DSR)
+ port_priv->gpio_altfunc |= (BIT(2) | BIT(3));
+ else if (gpio_mode & UART_MODE_RS485)
+ port_priv->gpio_altfunc |= BIT(5);
+ else if (gpio_mode & UART_MODE_RS485_ADDR)
+ port_priv->gpio_altfunc |= BIT(5);
+ else
+ port_priv->gpio_altfunc = 0; /* All GPIOs are available */
+
+ return ret;
+}
+
+static int xr_gpio_init(struct usb_serial_port *port)
+{
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ struct usb_serial *serial = port->serial;
+ int ret = 0;
+ u16 pid;
+
+ /* Don't register gpiochip for interface 0 */
+ if (port->minor == 0)
+ return ret;
+
+ pid = le16_to_cpu(serial->dev->descriptor.idProduct);
+
+ ret = xr21v141x_gpio_init(port);
+ if (ret < 0)
+ return ret;
+
+ port_priv->gc.label = devm_kasprintf(&port->dev, GFP_KERNEL, "XR%04x",
+ pid);
+ port_priv->gc.request = xr_gpio_request;
+ port_priv->gc.get_direction = xr_gpio_direction_get;
+ port_priv->gc.direction_input = xr_gpio_direction_input;
+ port_priv->gc.direction_output = xr_gpio_direction_output;
+ port_priv->gc.get = xr_gpio_get;
+ port_priv->gc.set = xr_gpio_set;
+ port_priv->gc.owner = THIS_MODULE;
+ port_priv->gc.parent = &port->dev;
+ port_priv->gc.base = -1;
+ port_priv->gc.can_sleep = true;
+
+ ret = gpiochip_add_data(&port_priv->gc, port);
+ if (!ret)
+ port_priv->gpio_registered = true;
+
+ return ret;
+}
+
+static void xr_gpio_remove(struct usb_serial_port *port)
+{
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+
+ if (port_priv->gpio_registered) {
+ gpiochip_remove(&port_priv->gc);
+ port_priv->gpio_registered = false;
+ }
+}
+
+#else
+
+static int xr_gpio_init(struct usb_serial_port *port)
+{
+ return 0;
+}
+
+static void xr_gpio_remove(struct usb_serial_port *port)
+{
+ /* Nothing to do */
+}
+
+#endif
+
static int xr_port_probe(struct usb_serial_port *port)
{
struct xr_port_private *port_priv;
@@ -575,13 +771,14 @@ static int xr_port_probe(struct usb_serial_port *port)

usb_set_serial_port_data(port, port_priv);

- return 0;
+ return xr_gpio_init(port);
}

static int xr_port_remove(struct usb_serial_port *port)
{
struct xr_port_private *port_priv = usb_get_serial_port_data(port);

+ xr_gpio_remove(port);
kfree(port_priv);

return 0;
--
2.17.1
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