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    Subject[RESEND PATCH v4 2/3] usb: serial: xr_serial: Add gpiochip support
    Date
    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@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 | 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@kernel.org>
    */

    +#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
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      Last update: 2020-06-07 18:25    [W:2.177 / U:0.004 seconds]
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