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Subject[PATCH v5 2/3] USB: serial: cp210x: Got rid of magic numbers in CRTSCTS flag code.
Date
Replaced magic numbers used in the CRTSCTS flag code with symbolic names
from the chip specification.

Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@gmail.com>
---
drivers/usb/serial/cp210x.c | 109 ++++++++++++++++++++++++++++++++++----------
1 file changed, 84 insertions(+), 25 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index fef7a51..ba14dd4 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -327,6 +327,42 @@ struct cp210x_comm_status {
*/
#define PURGE_ALL 0x000f

+/* CP210X_GET_FLOW/CP210X_SET_FLOW read/write these 0x10 bytes */
+struct cp210x_flow_ctl {
+ __le32 ulControlHandshake;
+ __le32 ulFlowReplace;
+ __le32 ulXonLimit;
+ __le32 ulXoffLimit;
+} __packed;
+
+/* cp210x_flow_ctl::ulControlHandshake */
+#define CP210X_SERIAL_DTR_MASK GENMASK(1, 0)
+#define CP210X_SERIAL_DTR_SHIFT(_mode) (_mode)
+#define CP210X_SERIAL_CTS_HANDSHAKE BIT(3)
+#define CP210X_SERIAL_DSR_HANDSHAKE BIT(4)
+#define CP210X_SERIAL_DCD_HANDSHAKE BIT(5)
+#define CP210X_SERIAL_DSR_SENSITIVITY BIT(6)
+
+/* values for cp210x_flow_ctl::ulControlHandshake::CP210X_SERIAL_DTR_MASK */
+#define CP210X_SERIAL_DTR_INACTIVE 0
+#define CP210X_SERIAL_DTR_ACTIVE 1
+#define CP210X_SERIAL_DTR_FLOW_CTL 2
+
+/* cp210x_flow_ctl::ulFlowReplace */
+#define CP210X_SERIAL_AUTO_TRANSMIT BIT(0)
+#define CP210X_SERIAL_AUTO_RECEIVE BIT(1)
+#define CP210X_SERIAL_ERROR_CHAR BIT(2)
+#define CP210X_SERIAL_NULL_STRIPPING BIT(3)
+#define CP210X_SERIAL_BREAK_CHAR BIT(4)
+#define CP210X_SERIAL_RTS_MASK GENMASK(7, 6)
+#define CP210X_SERIAL_RTS_SHIFT(_mode) (_mode << 6)
+#define CP210X_SERIAL_XOFF_CONTINUE BIT(31)
+
+/* values for cp210x_flow_ctl::ulFlowReplace::CP210X_SERIAL_RTS_MASK */
+#define CP210X_SERIAL_RTS_INACTIVE 0
+#define CP210X_SERIAL_RTS_ACTIVE 1
+#define CP210X_SERIAL_RTS_FLOW_CTL 2
+
/*
* Reads a variable-sized block of CP210X_ registers, identified by req.
* Returns data into buf in native USB byte order.
@@ -694,9 +730,10 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
{
struct device *dev = &port->dev;
unsigned int cflag;
- u8 modem_ctl[16];
+ struct cp210x_flow_ctl flow_ctl;
u32 baud;
u16 bits;
+ u32 ctl_hs;

cp210x_read_u32_reg(port, CP210X_GET_BAUDRATE, &baud);

@@ -792,9 +829,10 @@ static void cp210x_get_termios_port(struct usb_serial_port *port,
break;
}

- cp210x_read_reg_block(port, CP210X_GET_FLOW, modem_ctl,
- sizeof(modem_ctl));
- if (modem_ctl[0] & 0x08) {
+ cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl,
+ sizeof(flow_ctl));
+ ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
+ if (ctl_hs & CP210X_SERIAL_CTS_HANDSHAKE) {
dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__);
cflag |= CRTSCTS;
} else {
@@ -863,7 +901,6 @@ static void cp210x_set_termios(struct tty_struct *tty,
struct device *dev = &port->dev;
unsigned int cflag, old_cflag;
u16 bits;
- u8 modem_ctl[16];

cflag = tty->termios.c_cflag;
old_cflag = old_termios->c_cflag;
@@ -947,34 +984,56 @@ static void cp210x_set_termios(struct tty_struct *tty,
}

if ((cflag & CRTSCTS) != (old_cflag & CRTSCTS)) {
+ struct cp210x_flow_ctl flow_ctl;
+ u32 ctl_hs;
+ u32 flow_repl;

- /* Only bytes 0, 4 and 7 out of first 8 have functional bits */
-
- cp210x_read_reg_block(port, CP210X_GET_FLOW, modem_ctl,
- sizeof(modem_ctl));
- dev_dbg(dev, "%s - read modem controls = %02x .. .. .. %02x .. .. %02x\n",
- __func__, modem_ctl[0], modem_ctl[4], modem_ctl[7]);
+ cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl,
+ sizeof(flow_ctl));
+ ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake);
+ flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace);
+ dev_dbg(dev, "%s - read ulControlHandshake=0x%08x, ulFlowReplace=0x%08x\n",
+ __func__, ctl_hs, flow_repl);

if (cflag & CRTSCTS) {
- modem_ctl[0] &= ~0x7B;
- modem_ctl[0] |= 0x09;
- modem_ctl[4] = 0x80;
- /* FIXME - why clear reserved bits just read? */
- modem_ctl[5] = 0;
- modem_ctl[6] = 0;
- modem_ctl[7] = 0;
+ ctl_hs &= ~(CP210X_SERIAL_DTR_MASK |
+ CP210X_SERIAL_CTS_HANDSHAKE |
+ CP210X_SERIAL_DSR_HANDSHAKE |
+ CP210X_SERIAL_DCD_HANDSHAKE |
+ CP210X_SERIAL_DSR_SENSITIVITY);
+ ctl_hs |= CP210X_SERIAL_DTR_SHIFT(
+ CP210X_SERIAL_DTR_ACTIVE);
+ ctl_hs |= CP210X_SERIAL_CTS_HANDSHAKE;
+ /*
+ * FIXME: Why clear bits unrelated to flow control.
+ * Why clear CP210X_SERIAL_XOFF_CONTINUE which is
+ * never set
+ */
+ flow_repl = 0;
+ flow_repl |= CP210X_SERIAL_RTS_SHIFT(
+ CP210X_SERIAL_RTS_FLOW_CTL);
dev_dbg(dev, "%s - flow control = CRTSCTS\n", __func__);
} else {
- modem_ctl[0] &= ~0x7B;
- modem_ctl[0] |= 0x01;
- modem_ctl[4] = 0x40;
+ ctl_hs &= ~(CP210X_SERIAL_DTR_MASK |
+ CP210X_SERIAL_CTS_HANDSHAKE |
+ CP210X_SERIAL_DSR_HANDSHAKE |
+ CP210X_SERIAL_DCD_HANDSHAKE |
+ CP210X_SERIAL_DSR_SENSITIVITY);
+ ctl_hs |= CP210X_SERIAL_DTR_SHIFT(
+ CP210X_SERIAL_DTR_ACTIVE);
+ /* FIXME: Why clear bits unrelated to flow control */
+ flow_repl &= 0xffffff00;
+ flow_repl |= CP210X_SERIAL_RTS_SHIFT(
+ CP210X_SERIAL_RTS_ACTIVE);
dev_dbg(dev, "%s - flow control = NONE\n", __func__);
}

- dev_dbg(dev, "%s - write modem controls = %02x .. .. .. %02x .. .. %02x\n",
- __func__, modem_ctl[0], modem_ctl[4], modem_ctl[7]);
- cp210x_write_reg_block(port, CP210X_SET_FLOW, modem_ctl,
- sizeof(modem_ctl));
+ dev_dbg(dev, "%s - write ulControlHandshake=0x%08x, ulFlowReplace=0x%08x\n",
+ __func__, ctl_hs, flow_repl);
+ flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs);
+ flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl);
+ cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl,
+ sizeof(flow_ctl));
}

}
--
1.8.4.5
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