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Date: Wed, 4 Feb 2015 16:29:29 +0100
From: Johan Hovold <johan@...nel.org>
To: Peter Hung <hpeter@...il.com>
Cc: johan@...nel.org, gregkh@...uxfoundation.org,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
tom_tsai@...tek.com.tw, peter_hong@...tek.com.tw,
Peter Hung <hpeter+linux_kernel@...il.com>
Subject: Re: [PATCH v4 5/7] usb: serial: implement set_termios for F81232
On Fri, Jan 30, 2015 at 02:13:39PM +0800, Peter Hung wrote:
> The original driver had do not any h/w change in driver.
> This patch implements with configure H/W for
> baud/parity/word length/stop bits functional.
>
> Signed-off-by: Peter Hung <hpeter+linux_kernel@...il.com>
> ---
> drivers/usb/serial/f81232.c | 144 +++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 137 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
> index 12e1ae4..248f40d 100644
> --- a/drivers/usb/serial/f81232.c
> +++ b/drivers/usb/serial/f81232.c
> @@ -51,6 +51,10 @@ MODULE_DEVICE_TABLE(usb, id_table);
> #define F81232_USB_TIMEOUT 3000
>
> #define SERIAL_BASE_ADDRESS (0x0120)
> +#define RECEIVE_BUFFER_REGISTER (0x00 + SERIAL_BASE_ADDRESS)
> +#define INTERRUPT_ENABLE_REGISTER (0x01 + SERIAL_BASE_ADDRESS)
> +#define FIFO_CONTROL_REGISTER (0x02 + SERIAL_BASE_ADDRESS)
> +#define LINE_CONTROL_REGISTER (0x03 + SERIAL_BASE_ADDRESS)
> #define MODEM_STATUS_REGISTER (0x06 + SERIAL_BASE_ADDRESS)
> struct f81232_private {
> spinlock_t lock;
> @@ -61,6 +65,20 @@ struct f81232_private {
> struct usb_serial_port *port;
> };
>
> +static inline int calc_baud_divisor(u32 baudrate)
No need for inline.
> +{
> + u32 divisor, rem;
> +
> + divisor = 115200L / baudrate;
> + rem = 115200L % baudrate;
Use a define for the base baud rate. Is 115200 really the maximum baud
rate?
> +
> + /* Round to nearest divisor */
> + if (((rem * 2) >= baudrate) && (baudrate != 110))
> + divisor++;
Can't you use DIV_ROUND_CLOSEST here as serial core does?
> +
> + return divisor;
> +}
> +
> static inline int f81232_get_register(struct usb_device *dev,
> u16 reg, u8 *data)
No inline.
> {
> @@ -84,6 +102,29 @@ static inline int f81232_get_register(struct usb_device *dev,
> return status;
> }
>
> +static inline int f81232_set_register(struct usb_device *dev,
> + u16 reg, u8 data)
Pass the usb-serial port instead of usb device here as well.
> +{
> + int status;
> +
> + status = usb_control_msg(dev,
> + usb_sndctrlpipe(dev, 0),
> + REGISTER_REQUEST,
> + SET_REGISTER,
> + reg,
> + 0,
> + &data,
> + 1,
sizeof(data) for clarity?
> + F81232_USB_TIMEOUT);
> +
> + if (status < 0) {
> + dev_dbg(&dev->dev,
> + "%s status: %d\n", __func__, status);
dev_err, no line break
> + }
> +
> + return status;
> +}
> +
> static void f81232_read_msr(struct f81232_private *priv)
> {
> int status;
> @@ -240,15 +281,104 @@ static void f81232_break_ctl(struct tty_struct *tty, int break_state)
> static void f81232_set_termios(struct tty_struct *tty,
> struct usb_serial_port *port, struct ktermios *old_termios)
> {
> - /* FIXME - Stubbed out for now */
> + u16 divisor;
> + u16 new_lcr = 0;
Why u16 for an 8-bit register?
> + u8 data;
> + int status;
> + struct ktermios *termios = &tty->termios;
> + struct usb_device *dev = port->serial->dev;
> + unsigned int cflag = termios->c_cflag;
Use the cflag macros directly below (e.g. C_PARENB(tty)) and you won't
need this (or termios above).
>
> - /* Don't change anything if nothing has changed */
> - if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
> - return;
> + divisor = calc_baud_divisor(tty_get_baud_rate(tty));
You get a division by zero here of the baud rate is 0 (B0 is used to
drop DTR/RTS).
> +
> + status = f81232_set_register(dev, LINE_CONTROL_REGISTER,
> + UART_LCR_DLAB); /* DLAB */
> +
No newline before testing return values (again, applies to whole
series).
> + if (status < 0) {
> + dev_dbg(&dev->dev,
> + "%s status: %d line:%d\n", __func__, status, __LINE__);
> + }
Use dev_err for errors throughout, but remember that you already log
errors in the accessor function.
> +
> + status = f81232_set_register(dev, RECEIVE_BUFFER_REGISTER,
> + divisor & 0x00ff); /* low */
> +
> + if (status < 0) {
> + dev_dbg(&dev->dev,
> + "%s status: %d line:%d\n", __func__, status, __LINE__);
> + }
> +
> + status = f81232_set_register(dev, INTERRUPT_ENABLE_REGISTER,
> + (divisor & 0xff00) >> 8); /* high */
> +
> + if (status < 0) {
> + dev_dbg(&dev->dev,
> + "%s status: %d line:%d\n", __func__, status, __LINE__);
> + }
> +
> + status = f81232_set_register(dev, LINE_CONTROL_REGISTER, 0x00);
> +
> + if (status < 0) {
> + dev_dbg(&dev->dev,
> + "%s status: %d line:%d\n", __func__, status, __LINE__);
> + }
Perhaps factor the above out in a f81232_set_baudrate helper?
> +
> + if (cflag & PARENB) {
> + new_lcr |= UART_LCR_PARITY; /* default parity on/odd */
> +
> + if (cflag & CMSPAR) {
> + if (cflag & PARODD) {
> + /* stick mark */
> + new_lcr |= UART_LCR_SPAR;
> + } else {
> + /* stick space */
> + new_lcr |= (UART_LCR_EPAR | UART_LCR_SPAR);
> + }
> + } else {
> + if (!(cflag & PARODD)) {
> + /* even */
> + new_lcr |= UART_LCR_EPAR;
> + }
> + }
> + }
Looks like you could simplify the above to something like
if (C_PARENB(tty) {
lcr |= UART_LCR_PARITY;
if (!C_PARODD(tty))
lcr |= UART_LCR_EPAR
if (C_CMSPAR(tty))
lcr |= UART_LCR_SPAR;
}
> +
> + if (cflag & CSTOPB)
> + new_lcr |= UART_LCR_STOP;
> + else
> + new_lcr &= ~UART_LCR_STOP;
No need to clear bits since you initialise to 0.
> +
> + switch (cflag & CSIZE) {
> + case CS5:
> + new_lcr |= UART_LCR_WLEN5;
> + break;
> + case CS6:
> + new_lcr |= UART_LCR_WLEN6;
> + break;
> + case CS7:
> + new_lcr |= UART_LCR_WLEN7;
> + break;
> + default:
> + case CS8:
> + new_lcr |= UART_LCR_WLEN8;
> + break;
> + }
> +
> + status |= f81232_set_register(dev, LINE_CONTROL_REGISTER, new_lcr);
> +
> + /* fifo on, trigger8, clear TX/RX*/
> + data = UART_FCR_TRIGGER_8 | UART_FCR_ENABLE_FIFO | UART_FCR_CLEAR_RCVR
> + | UART_FCR_CLEAR_XMIT;
> +
> + status |= f81232_set_register(dev, FIFO_CONTROL_REGISTER, data);
> +
> + data = UART_IER_MSI | UART_IER_RLSI | UART_IER_THRI | UART_IER_RDI;
> +
> + status |= f81232_set_register(dev,
> + INTERRUPT_ENABLE_REGISTER, 0xf); /* IER */
> +
> + if (status < 0)
> + dev_err(&port->dev, "LINE_CONTROL_REGISTER set error: %d\n",
> + status);
Some of the above should only be needed when initialising (or opening)
the port and not on every set_termios, right?
>
> - /* Do the real work here... */
> - if (old_termios)
> - tty_termios_copy_hw(&tty->termios, old_termios);
> }
>
> static int f81232_tiocmget(struct tty_struct *tty)
Johan
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