On Sat, Sep 24, 2022 at 12:27:18PM +0200, Pali Rohár wrote:
> Calculate baud rate value in c_*speed fields to the real values which were
> set on hardware. For this operation, add a new set of methods
> *_divisor_to_baud() for each chip and use them for calculating the real
> baud rate values.
>
> Each *_divisor_to_baud() method is constructed as an inverse function of
> its corresponding *_baud_to_divisor() method.
>
> Signed-off-by: Pali Rohár <pali@xxxxxxxxxx>
> Tested-by: Marek Behún <kabel@xxxxxxxxxx>
> Signed-off-by: Marek Behún <kabel@xxxxxxxxxx>
> ---
> drivers/usb/serial/ftdi_sio.c | 93 +++++++++++++++++++++++++++++++++++
> 1 file changed, 93 insertions(+)
>
> diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
> index 79b00912c81c..350ed14b014c 100644
> --- a/drivers/usb/serial/ftdi_sio.c
> +++ b/drivers/usb/serial/ftdi_sio.c
> @@ -1183,6 +1183,34 @@ static u32 ftdi_sio_baud_to_divisor(int baud)
> }
> }
>
> +static int ftdi_sdio_divisor_to_baud(u32 divisor)
> +{
> + switch (divisor) {
> + case ftdi_sio_b300:
> + return 300;
> + case ftdi_sio_b600:
> + return 600;
> + case ftdi_sio_b1200:
> + return 1200;
> + case ftdi_sio_b2400:
> + return 2400;
> + case ftdi_sio_b4800:
> + return 4800;
> + case ftdi_sio_b9600:
> + return 9600;
> + case ftdi_sio_b19200:
> + return 19200;
> + case ftdi_sio_b38400:
> + return 38400;
> + case ftdi_sio_b57600:
> + return 57600;
> + case ftdi_sio_b115200:
> + return 115200;
> + default:
> + return 9600;
> + }
> +}
As I mentioned before, this one should no be needed as the SIO only
supports this discrete set of values (or errors out).
> +
> static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> {
> unsigned short int divisor;
> @@ -1205,11 +1233,28 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> return divisor;
> }
>
> +static int ftdi_232am_divisor_base_to_baud(unsigned short int divisor, int base)
> +{
> + static const unsigned char divfrac_inv[4] = { 0, 4, 2, 1 };
> + unsigned int divisor3;
> +
> + if (divisor == 0)
> + divisor = 1;
> + divisor3 = (GENMASK(13, 0) & divisor) << 3;
> + divisor3 |= divfrac_inv[(divisor >> 14) & 0x3];
> + return DIV_ROUND_CLOSEST(base, 2 * divisor3);
> +}
Still no motivation to review these.
[...]
> @@ -1358,6 +1444,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
> }
> div_okay = 0;
> }
> + baud = ftdi_sdio_divisor_to_baud(div_value);
> break;
> case FT8U232AM: /* 8U232AM chip */
> if (baud >= 183 && baud <= 3000000) {
> @@ -1371,6 +1458,7 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
> div_value = ftdi_232am_baud_to_divisor(baud);
> div_okay = 0;
> }
> + baud = ftdi_232am_divisor_to_baud(div_value);
> break;
> case FT232BM: /* FT232BM chip */
> case FT2232C: /* FT2232C chip */
> @@ -1397,25 +1485,30 @@ static u32 get_ftdi_divisor(struct tty_struct *tty,
> div_value = ftdi_232bm_baud_to_divisor(baud);
> div_okay = 0;
> }
> + baud = ftdi_232bm_divisor_to_baud(div_value);
> break;
> case FT2232H: /* FT2232H chip */
> case FT4232H: /* FT4232H chip */
> case FT232H: /* FT232H chip */
> if ((baud <= 12000000) && (baud >= 1200)) {
> div_value = ftdi_2232h_baud_to_divisor(baud);
> + baud = ftdi_2232h_divisor_to_baud(div_value);
> } else if (baud >= 183 && baud < 1200) {
> div_value = ftdi_232bm_baud_to_divisor(baud);
> + baud = ftdi_232bm_divisor_to_baud(div_value);
> } else {
> dev_dbg(dev, "%s - Baud rate too high!\n", __func__);
> if (old_baud >= 183 && old_baud < 1200) {
> baud = old_baud;
> div_value = ftdi_232bm_baud_to_divisor(baud);
> + baud = ftdi_232bm_divisor_to_baud(div_value);
> } else {
> if (old_baud >= 1200 && old_baud <= 12000000)
> baud = old_baud;
> else
> baud = 9600;
> div_value = ftdi_2232h_baud_to_divisor(baud);
> + baud = ftdi_2232h_divisor_to_baud(div_value);
But this must be cleaned up as mentioned earlier in this thread.
> }
> div_okay = 0;
> }
Johan
