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Date: Fri, 15 Jun 2018 23:29:57 +0200
From: Karoly Pados <pados@...os.hu>
To: Johan Hovold <johan@...nel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Karoly Pados <pados@...os.hu>
Subject: [PATCH] USB: serial: cp210x: Improve baudrate support for CP2102N
The CP2102N supports more baudrates than earlier chips by SiLabs.
This patch adds support for all rates documented in the datasheet
of this device.
Signed-off-by: Karoly Pados <pados@...os.hu>
---
drivers/usb/serial/cp210x.c | 39 ++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index b1849f657e01..793b86252c46 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -357,6 +357,9 @@ static struct usb_serial_driver * const serial_drivers[] = {
#define CP210X_PARTNUM_CP2104 0x04
#define CP210X_PARTNUM_CP2105 0x05
#define CP210X_PARTNUM_CP2108 0x08
+#define CP210X_PARTNUM_CP2102N_QFN28 0x20
+#define CP210X_PARTNUM_CP2102N_QFN24 0x21
+#define CP210X_PARTNUM_CP2102N_QFN20 0x22
#define CP210X_PARTNUM_UNKNOWN 0xFF
/* CP210X_GET_COMM_STATUS returns these 0x13 bytes */
@@ -758,8 +761,12 @@ static int cp210x_get_line_ctl(struct usb_serial_port *port, u16 *ctl)
/*
* cp210x_quantise_baudrate
* Quantises the baud rate as per AN205 Table 1
+ * The CP2102N is fully (except for baud rate aliasing) software-
+ * compatible, but supports some additional baudrates. However, there is
+ * no quantitisation table available for this model, so in this case we
+ * take the supported baudrate which is closest to the requested one.
*/
-static unsigned int cp210x_quantise_baudrate(unsigned int baud)
+static unsigned int cp210x_quantise_baudrate(unsigned int baud, bool cp2102n)
{
if (baud <= 300)
baud = 300;
@@ -790,10 +797,17 @@ static unsigned int cp210x_quantise_baudrate(unsigned int baud)
else if (baud <= 491520) baud = 460800;
else if (baud <= 567138) baud = 500000;
else if (baud <= 670254) baud = 576000;
- else if (baud < 1000000)
- baud = 921600;
- else if (baud > 2000000)
- baud = 2000000;
+ else if (cp2102n) {
+ if (baud <= 960800) baud = 921600;
+ else if (baud <= 1100000) baud = 1000000;
+ else if (baud <= 1350000) baud = 1200000;
+ else if (baud <= 1750000) baud = 1500000;
+ else if (baud <= 2500000) baud = 2000000;
+ else baud = 3000000;
+ } else {
+ if (baud < 1000000) baud = 921600;
+ else if (baud > 2000000) baud = 2000000;
+ }
return baud;
}
@@ -1045,16 +1059,19 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
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;
+ bool is_cp2102n;
+ u32 baud = tty->termios.c_ospeed;
+ struct cp210x_serial_private *priv = usb_get_serial_data(port->serial);
- /* This maps the requested rate to a rate valid on cp2102 or cp2103,
- * or to an arbitrary rate in [1M,2M].
+ /* This maps the requested rate to a rate valid on cp2102(n) or
+ * cp2103 or to an arbitrary rate in [1M,2M].
*
* NOTE: B0 is not implemented.
*/
- baud = cp210x_quantise_baudrate(baud);
+ is_cp2102n = (priv->partnum == CP210X_PARTNUM_CP2102N_QFN28) ||
+ (priv->partnum == CP210X_PARTNUM_CP2102N_QFN24) ||
+ (priv->partnum == CP210X_PARTNUM_CP2102N_QFN20);
+ baud = cp210x_quantise_baudrate(baud, is_cp2102n);
dev_dbg(&port->dev, "%s - setting baud rate to %u\n", __func__, baud);
if (cp210x_write_u32_reg(port, CP210X_SET_BAUDRATE, baud)) {
--
2.17.1
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