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Calculate baud rate divisor instead of allowing only a fixed set of
standard rates. Obtained from OpenBSD src/sys/dev/usb/uftdi.c 1.29 src/sys/dev/usb/uftdireg.h 1.11 OpenBSD revisions noted by: ticso, on hackers
This commit is contained in:
Ed Maste
parent
515594a06f
commit
27e05557a5
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=175655
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@ -121,6 +121,7 @@ static void uftdi_read(void *sc, int portno, u_char **ptr,u_int32_t *count);
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static void uftdi_write(void *sc, int portno, u_char *to, u_char *from,
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u_int32_t *count);
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static void uftdi_break(void *sc, int portno, int onoff);
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static int uftdi_8u232am_getrate(speed_t speed, int *rate);
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struct ucom_callback uftdi_callback = {
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uftdi_get_status,
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@ -569,25 +570,8 @@ uftdi_param(void *vsc, int portno, struct termios *t)
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break;
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case UFTDI_TYPE_8U232AM:
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switch(t->c_ospeed) {
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case 300: rate = ftdi_8u232am_b300; break;
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case 600: rate = ftdi_8u232am_b600; break;
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case 1200: rate = ftdi_8u232am_b1200; break;
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case 2400: rate = ftdi_8u232am_b2400; break;
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case 4800: rate = ftdi_8u232am_b4800; break;
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case 9600: rate = ftdi_8u232am_b9600; break;
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case 19200: rate = ftdi_8u232am_b19200; break;
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case 38400: rate = ftdi_8u232am_b38400; break;
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case 57600: rate = ftdi_8u232am_b57600; break;
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case 115200: rate = ftdi_8u232am_b115200; break;
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case 230400: rate = ftdi_8u232am_b230400; break;
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case 460800: rate = ftdi_8u232am_b460800; break;
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case 921600: rate = ftdi_8u232am_b921600; break;
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case 2000000: rate = ftdi_8u232am_b2000000; break;
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case 3000000: rate = ftdi_8u232am_b3000000; break;
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default:
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if (uftdi_8u232am_getrate(t->c_ospeed, &rate) == -1)
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return (EINVAL);
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}
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break;
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}
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req.bmRequestType = UT_WRITE_VENDOR_DEVICE;
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@ -702,6 +686,70 @@ uftdi_break(void *vsc, int portno, int onoff)
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(void)usbd_do_request(ucom->sc_udev, &req, NULL);
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}
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static int
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uftdi_8u232am_getrate(speed_t speed, int *rate)
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{
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/* Table of the nearest even powers-of-2 for values 0..15. */
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static const unsigned char roundoff[16] = {
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0, 2, 2, 4, 4, 4, 8, 8,
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8, 8, 8, 8, 16, 16, 16, 16,
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};
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unsigned int d, freq;
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int result;
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if (speed <= 0)
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return (-1);
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/* Special cases for 2M and 3M. */
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if (speed >= 3000000 * 100 / 103 &&
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speed <= 3000000 * 100 / 97) {
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result = 0;
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goto done;
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}
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if (speed >= 2000000 * 100 / 103 &&
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speed <= 2000000 * 100 / 97) {
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result = 1;
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goto done;
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}
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d = (FTDI_8U232AM_FREQ << 4) / speed;
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d = (d & ~15) + roundoff[d & 15];
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if (d < FTDI_8U232AM_MIN_DIV)
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d = FTDI_8U232AM_MIN_DIV;
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else if (d > FTDI_8U232AM_MAX_DIV)
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d = FTDI_8U232AM_MAX_DIV;
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/*
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* Calculate the frequency needed for d to exactly divide down
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* to our target speed, and check that the actual frequency is
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* within 3% of this.
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*/
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freq = speed * d;
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if (freq < (quad_t)(FTDI_8U232AM_FREQ << 4) * 100 / 103 ||
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freq > (quad_t)(FTDI_8U232AM_FREQ << 4) * 100 / 97)
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return (-1);
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/*
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* Pack the divisor into the resultant value. The lower
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* 14-bits hold the integral part, while the upper 2 bits
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* encode the fractional component: either 0, 0.5, 0.25, or
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* 0.125.
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*/
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result = d >> 4;
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if (d & 8)
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result |= 0x4000;
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else if (d & 4)
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result |= 0x8000;
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else if (d & 2)
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result |= 0xc000;
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done:
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*rate = result;
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return (0);
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}
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static device_method_t uftdi_methods[] = {
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/* Device interface */
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DEVMETHOD(device_probe, uftdi_match),
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@ -91,23 +91,11 @@ enum {
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ftdi_sio_b115200 = 9
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};
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enum {
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ftdi_8u232am_b300 = 0x2710,
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ftdi_8u232am_b600 = 0x1388,
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ftdi_8u232am_b1200 = 0x09c4,
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ftdi_8u232am_b2400 = 0x04e2,
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ftdi_8u232am_b4800 = 0x0271,
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ftdi_8u232am_b9600 = 0x4138,
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ftdi_8u232am_b19200 = 0x809c,
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ftdi_8u232am_b38400 = 0xc04e,
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ftdi_8u232am_b57600 = 0x0034,
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ftdi_8u232am_b115200 = 0x001a,
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ftdi_8u232am_b230400 = 0x000d,
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ftdi_8u232am_b460800 = 0x4006,
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ftdi_8u232am_b921600 = 0x8003,
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ftdi_8u232am_b2000000 = 0x0001, /* special case for 2M baud */
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ftdi_8u232am_b3000000 = 0x0000, /* special case for 3M baud */
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};
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#define FTDI_8U232AM_FREQ 3000000
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/* Bounds for normal divisors as 4-bit fixed precision ints. */
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#define FTDI_8U232AM_MIN_DIV 0x20
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#define FTDI_8U232AM_MAX_DIV 0x3fff8
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/*
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* BmRequestType: 0100 0000B
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