Module Name: src
Committed By: nisimura
Date: Wed Jul 14 07:34:16 UTC 2021
Modified Files:
src/sys/dev/usb: uchcom.c
Log Message:
The second REQ_RESET USB request by reset_chip() makes LCR, PRE and DIV
registers to have default values 8N1 and 19200 just as the first req does.
Nuke reset_chip() and rundandant set_dte_rate() to amend.
While here added some narrative about prescale/divisor calculation.
To generate a diff of this commit:
cvs rdiff -u -r1.37 -r1.38 src/sys/dev/usb/uchcom.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/usb/uchcom.c
diff -u src/sys/dev/usb/uchcom.c:1.37 src/sys/dev/usb/uchcom.c:1.38
--- src/sys/dev/usb/uchcom.c:1.37 Sat Apr 24 23:36:59 2021
+++ src/sys/dev/usb/uchcom.c Wed Jul 14 07:34:16 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: uchcom.c,v 1.37 2021/04/24 23:36:59 thorpej Exp $ */
+/* $NetBSD: uchcom.c,v 1.38 2021/07/14 07:34:16 nisimura Exp $ */
/*
* Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uchcom.c,v 1.37 2021/04/24 23:36:59 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uchcom.c,v 1.38 2021/07/14 07:34:16 nisimura Exp $");
#ifdef _KERNEL_OPT
#include "opt_usb.h"
@@ -118,9 +118,6 @@ int uchcomdebug = 0;
#define UCHCOMIBUFSIZE 256
#define UCHCOMOBUFSIZE 256
-#define UCHCOM_RESET_VALUE 0x501F
-#define UCHCOM_RESET_INDEX 0xD90A
-
struct uchcom_softc
{
device_t sc_dev;
@@ -155,6 +152,7 @@ struct uchcom_divider
uint8_t dv_div;
};
+/* 0,1,2,3,7 are prescale factors for given 4x 12000000 clock formula */
static const uint32_t rates4x[8] = {
[0] = 4 * 12000000 / 1024,
[1] = 4 * 12000000 / 128,
@@ -618,6 +616,24 @@ set_break(struct uchcom_softc *sc, int o
static int
calc_divider_settings(struct uchcom_divider *dp, uint32_t rate)
{
+/*
+ * combined with rates4x[] defined above, this routine generates,
+ * 1200: prescale = 1/0x1, divisor = 178/0xb2
+ * 2400: prescale = 1/0x1, divisor = 217/0xd9
+ * 4800: prescale = 2/0x2, divisor = 100/0x64
+ * 9600: prescale = 2/0x2, divisor = 178/0xb2
+ * 19200: prescale = 2/0x2, divisor = 217/0xd9
+ * 38400: prescale = 3/0x3, divisor = 100/0x64
+ * 57600: prescale = 2/0x2, divisor = 243/0xf3
+ * 115200: prescale = 3/0x3, divisor = 204/0xcc
+ * 921600: prescale = 7/0x7, divisor = 243/0xf3
+ * 500000: prescale = 3/0x3, divisor = 244/0xf4
+ * 1000000: prescale = 3/0x3, divisor = 250/0xfa
+ * 1500000: prescale = 3/0x3, divisor = 252/0xfc
+ * 2000000: prescale = 3/0x3, divisor = 253/0xfd
+ * 2500000: unsupported
+ * 3000000: prescale = 3/0x3, divisor = 254/0xfe
+ */
size_t i;
uint32_t best, div, pre;
const uint32_t rate4x = rate * 4U;
@@ -652,7 +668,7 @@ calc_divider_settings(struct uchcom_divi
return -1;
dp->dv_prescaler = pre;
- dp->dv_div = (uint8_t)-div;
+ dp->dv_div = 256 - div;
return 0;
}
@@ -740,26 +756,12 @@ clear_chip(struct uchcom_softc *sc)
usbd_errstr(err));
return EIO;
}
-
- return 0;
-}
-
-static int
-reset_chip(struct uchcom_softc *sc)
-{
- usbd_status err;
-
- err = generic_control_out(sc, UCHCOM_REQ_RESET,
- UCHCOM_RESET_VALUE, UCHCOM_RESET_INDEX);
- if (err)
- goto failed;
-
+ /*
+ * this REQ_RESET call ends up with
+ * LCR=0xc0 (8N1)
+ * PRE=0x02, DIV=0xb2 (19200)
+ */
return 0;
-
-failed:
- printf("%s: cannot reset: %s\n",
- device_xname(sc->sc_dev), usbd_errstr(err));
- return EIO;
}
static int
@@ -787,14 +789,6 @@ setup_comm(struct uchcom_softc *sc)
if (ret)
return ret;
- ret = reset_chip(sc);
- if (ret)
- return ret;
-
- ret = set_dte_rate(sc, TTYDEF_SPEED); /* XXX */
- if (ret)
- return ret;
-
sc->sc_dtr = sc->sc_rts = 1;
ret = set_dtrrts(sc, sc->sc_dtr, sc->sc_rts);
if (ret)
