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authorJohan Hovold <jhovold@gmail.com>2012-01-16 00:36:51 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-02-03 09:22:25 -0800
commit4a48179074ac1ee5ed21a6ea0c5416a65a2776f1 (patch)
tree5a024a75c277c1a9a142538c5ed8db1fa03a5704
parent0155ff5bd1c75960263bb4a6fd4b3dedc566a3e1 (diff)
downloadlinux-linaro-stable-4a48179074ac1ee5ed21a6ea0c5416a65a2776f1.tar.gz
USB: cp210x: clean up, refactor and document speed handling
commit e5990874e511d5bbca23b3396419480cb2ca0ee7 upstream. Clean up and refactor speed handling. Document baud rate handling for CP210{1,2,4,5,10}. Signed-off-by: Johan Hovold <jhovold@gmail.com> Cc: Preston Fick <preston.fick@silabs.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/usb/serial/cp210x.c71
1 files changed, 57 insertions, 14 deletions
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 5c3b7d1c25a5..d2c40801ed85 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -39,6 +39,8 @@ static void cp210x_get_termios(struct tty_struct *,
struct usb_serial_port *port);
static void cp210x_get_termios_port(struct usb_serial_port *port,
unsigned int *cflagp, unsigned int *baudp);
+static void cp210x_change_speed(struct tty_struct *, struct usb_serial_port *,
+ struct ktermios *);
static void cp210x_set_termios(struct tty_struct *, struct usb_serial_port *,
struct ktermios*);
static int cp210x_tiocmget(struct tty_struct *);
@@ -572,11 +574,62 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
*cflagp = cflag;
}
+/*
+ * CP2101 supports the following baud rates:
+ *
+ * 300, 600, 1200, 1800, 2400, 4800, 7200, 9600, 14400, 19200, 28800,
+ * 38400, 56000, 57600, 115200, 128000, 230400, 460800, 921600
+ *
+ * CP2102 and CP2103 support the following additional rates:
+ *
+ * 4000, 16000, 51200, 64000, 76800, 153600, 250000, 256000, 500000,
+ * 576000
+ *
+ * The device will map a requested rate to a supported one, but the result
+ * of requests for rates greater than 1053257 is undefined (see AN205).
+ *
+ * CP2104, CP2105 and CP2110 support most rates up to 2M, 921k and 1M baud,
+ * respectively, with an error less than 1%. The actual rates are determined
+ * by
+ *
+ * div = round(freq / (2 x prescale x request))
+ * actual = freq / (2 x prescale x div)
+ *
+ * For CP2104 and CP2105 freq is 48Mhz and prescale is 4 for request <= 365bps
+ * or 1 otherwise.
+ * For CP2110 freq is 24Mhz and prescale is 4 for request <= 300bps or 1
+ * otherwise.
+ */
+static void cp210x_change_speed(struct tty_struct *tty,
+ struct usb_serial_port *port, struct ktermios *old_termios)
+{
+ u32 baud;
+
+ baud = tty->termios->c_ospeed;
+
+ /* This maps the requested rate to a rate valid on cp2102 or cp2103.
+ *
+ * NOTE: B0 is not implemented.
+ */
+ baud = cp210x_quantise_baudrate(baud);
+
+ dbg("%s - setting baud rate to %u", __func__, baud);
+ if (cp210x_set_config(port, CP210X_SET_BAUDRATE, &baud,
+ sizeof(baud))) {
+ dev_warn(&port->dev, "failed to set baud rate to %u\n", baud);
+ if (old_termios)
+ baud = old_termios->c_ospeed;
+ else
+ baud = 9600;
+ }
+
+ tty_encode_baud_rate(tty, baud, baud);
+}
+
static void cp210x_set_termios(struct tty_struct *tty,
struct usb_serial_port *port, struct ktermios *old_termios)
{
unsigned int cflag, old_cflag;
- u32 baud;
unsigned int bits;
unsigned int modem_ctl[4];
@@ -588,19 +641,9 @@ static void cp210x_set_termios(struct tty_struct *tty,
tty->termios->c_cflag &= ~CMSPAR;
cflag = tty->termios->c_cflag;
old_cflag = old_termios->c_cflag;
- baud = cp210x_quantise_baudrate(tty_get_baud_rate(tty));
-
- /* If the baud rate is to be updated*/
- if (baud != tty_termios_baud_rate(old_termios) && baud != 0) {
- dbg("%s - Setting baud rate to %d baud", __func__,
- baud);
- if (cp210x_set_config(port, CP210X_SET_BAUDRATE, &baud, sizeof(baud))) {
- dbg("Baud rate requested not supported by device");
- baud = tty_termios_baud_rate(old_termios);
- }
- }
- /* Report back the resulting baud rate */
- tty_encode_baud_rate(tty, baud, baud);
+
+ if (tty->termios->c_ospeed != old_termios->c_ospeed)
+ cp210x_change_speed(tty, port, old_termios);
/* If the number of data bits is to be updated */
if ((cflag & CSIZE) != (old_cflag & CSIZE)) {