Add gpiochip support for Maxlinear/Exar USB to serial converter
for controlling the available gpios.
Inspired from cp210x usb to serial converter driver.
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: linux-gpio@xxxxxxxxxxxxxxx
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Manivannan Sadhasivam <mani@xxxxxxxxxx>
---
drivers/usb/serial/xr_serial.c | 209 ++++++++++++++++++++++++++++++++-
1 file changed, 208 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c
index bb7df79cc129..2240fbc9ea7f 100644
--- a/drivers/usb/serial/xr_serial.c
+++ b/drivers/usb/serial/xr_serial.c
@@ -10,6 +10,7 @@
* Copyright (c) 2020 Manivannan Sadhasivam <mani@xxxxxxxxxx>
*/
+#include <linux/gpio/driver.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
@@ -17,6 +18,18 @@
#include <linux/usb.h>
#include <linux/usb/serial.h>
+#ifdef CONFIG_GPIOLIB
+enum gpio_pins {
+ GPIO_RI = 0,
+ GPIO_CD,
+ GPIO_DSR,
+ GPIO_DTR,
+ GPIO_CTS,
+ GPIO_RTS,
+ GPIO_MAX,
+};
+#endif
+
static void xr_set_termios(struct tty_struct *tty,
struct usb_serial_port *port,
struct ktermios *old_termios);
@@ -39,6 +52,11 @@ struct xr_uart_regs {
};
struct xr_port_private {
+#ifdef CONFIG_GPIOLIB
+ struct gpio_chip gc;
+ bool gpio_registered;
+ enum gpio_pins pin_status[GPIO_MAX];
+#endif
const struct xr_uart_regs *regs;
bool port_open;
};
@@ -390,6 +408,13 @@ static void xr_set_flow_mode(struct tty_struct *tty,
*/
gpio_mode &= ~UART_MODE_GPIO_MASK;
if (cflag & CRTSCTS) {
+#ifdef CONFIG_GPIOLIB
+ /* Check if the CTS/RTS pins are occupied */
+ if (port_priv->pin_status[GPIO_RTS] ||
+ port_priv->pin_status[GPIO_CTS])
+ return;
+#endif
+
dev_dbg(&port->dev, "Enabling hardware flow ctrl\n");
flow = UART_FLOW_MODE_HW;
gpio_mode |= UART_MODE_RTS_CTS;
@@ -497,6 +522,17 @@ static int xr_tiocmset_port(struct usb_serial_port *port,
u8 gpio_set = 0;
u8 gpio_clr = 0;
+#ifdef CONFIG_GPIOLIB
+ /* Check if the RTS/DTR pins are occupied */
+ if (set & TIOCM_RTS || clear & TIOCM_RTS)
+ if (port_priv->pin_status[GPIO_RTS])
+ return -EBUSY;
+
+ if (set & TIOCM_DTR || clear & TIOCM_DTR)
+ if (port_priv->pin_status[GPIO_DTR])
+ return -EBUSY;
+#endif
+
/* Modem control pins are active low, so set & clr are swapped */
if (set & TIOCM_RTS)
gpio_clr |= UART_MODE_RTS;
@@ -589,9 +625,175 @@ 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);
+
+ /*
+ * Do not proceed if the port is open. This is done to avoid changing
+ * the GPIO configuration used by the serial driver.
+ */
+ if (port_priv->port_open)
+ return -EBUSY;
+
+ /* Mark the GPIO pin as busy */
+ port_priv->pin_status[offset] = true;
+
+ return 0;
+}
+
+static void xr_gpio_free(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);
+
+ /* Mark the GPIO pin as free */
+ port_priv->pin_status[offset] = false;
+}
+
+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;
+
+ xr_gpio_set(gc, gpio, val);
+
+ 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;
+
+ return 0;
+}
+
+static int xr_gpio_init(struct usb_serial_port *port)
+{
+ struct xr_port_private *port_priv = usb_get_serial_port_data(port);
+ int ret = 0;
+
+ port_priv->gc.ngpio = 6;
+ port_priv->gc.label = "xr_gpios";
+ port_priv->gc.request = xr_gpio_request;
+ port_priv->gc.free = xr_gpio_free;
+ 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)
+{
+}
+
+#endif
+
static int xr_port_probe(struct usb_serial_port *port)
{
struct xr_port_private *port_priv;
+ int ret;
port_priv = kzalloc(sizeof(*port_priv), GFP_KERNEL);
if (!port_priv)
@@ -602,13 +804,18 @@ static int xr_port_probe(struct usb_serial_port *port)
usb_set_serial_port_data(port, port_priv);
- return 0;
+ ret = xr_gpio_init(port);
+ if (ret)
+ kfree(port_priv);
+
+ return ret;
}
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
