USB: serial: cp210x: get rid of magic numbers in CRTSCTS flag code

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>
Signed-off-by: Johan Hovold <johan@kernel.org>

1 files changed, 84 insertions, 25 deletions

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index fef7a512bff4..a33a4265125d 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));
         }
 
 }