diff options
| author | Johan Hovold <johan@kernel.org> | 2021-01-25 14:48:16 +0100 |
|---|---|---|
| committer | Johan Hovold <johan@kernel.org> | 2021-02-01 10:03:55 +0100 |
| commit | cf00ead0bde8e47ccd3aa8a4e51cfa59bbf5e055 (patch) | |
| tree | bf35b76a1e8c17d416d06a192b3f6f34a6aad178 /drivers/usb/serial | |
| parent | 6b667274f41a0269a8b493079fcacd4f55183f60 (diff) | |
| download | linux-next-cf00ead0bde8e47ccd3aa8a4e51cfa59bbf5e055.tar.gz | |
USB: serial: cp210x: fix RTS handling
Clearing TIOCM_RTS should always deassert RTS and setting the same bit
should enable auto-RTS if hardware flow control is enabled.
This allows user space to throttle input directly at the source also
when hardware-assisted flow control is enabled and makes dtr_rts()
always deassert both lines during close (when HUPCL is set).
Signed-off-by: Johan Hovold <johan@kernel.org>
Diffstat (limited to 'drivers/usb/serial')
| -rw-r--r-- | drivers/usb/serial/cp210x.c | 47 |
1 files changed, 40 insertions, 7 deletions
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index 4ba3fb096bf1..f00b736f3cd3 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -1166,7 +1166,10 @@ static void cp210x_set_flow_control(struct tty_struct *tty, if (C_CRTSCTS(tty)) { ctl_hs |= CP210X_SERIAL_CTS_HANDSHAKE; flow_repl &= ~CP210X_SERIAL_RTS_MASK; - flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; + if (port_priv->rts) + flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; + else + flow_repl |= CP210X_SERIAL_RTS_INACTIVE; port_priv->crtscts = true; } else { ctl_hs &= ~CP210X_SERIAL_CTS_HANDSHAKE; @@ -1286,6 +1289,8 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, unsigned int set, unsigned int clear) { struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); + struct cp210x_flow_ctl flow_ctl; + u32 ctl_hs, flow_repl; u16 control = 0; int ret; @@ -1313,16 +1318,44 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, } /* - * SET_MHS cannot be used to control RTS when auto-RTS is enabled. - * Note that RTS is still deasserted when disabling the UART on close. + * Use SET_FLOW to set DTR and enable/disable auto-RTS when hardware + * flow control is enabled. */ - if (port_priv->crtscts) - control &= ~CONTROL_WRITE_RTS; + if (port_priv->crtscts && control & CONTROL_WRITE_RTS) { + ret = cp210x_read_reg_block(port, CP210X_GET_FLOW, &flow_ctl, + sizeof(flow_ctl)); + if (ret) + goto out_unlock; - dev_dbg(&port->dev, "%s - control = 0x%04x\n", __func__, control); + ctl_hs = le32_to_cpu(flow_ctl.ulControlHandshake); + flow_repl = le32_to_cpu(flow_ctl.ulFlowReplace); - ret = cp210x_write_u16_reg(port, CP210X_SET_MHS, control); + ctl_hs &= ~CP210X_SERIAL_DTR_MASK; + if (port_priv->dtr) + ctl_hs |= CP210X_SERIAL_DTR_ACTIVE; + else + ctl_hs |= CP210X_SERIAL_DTR_INACTIVE; + flow_repl &= ~CP210X_SERIAL_RTS_MASK; + if (port_priv->rts) + flow_repl |= CP210X_SERIAL_RTS_FLOW_CTL; + else + flow_repl |= CP210X_SERIAL_RTS_INACTIVE; + + flow_ctl.ulControlHandshake = cpu_to_le32(ctl_hs); + flow_ctl.ulFlowReplace = cpu_to_le32(flow_repl); + + dev_dbg(&port->dev, "%s - ctrl = 0x%02x, flow = 0x%02x\n", + __func__, ctl_hs, flow_repl); + + ret = cp210x_write_reg_block(port, CP210X_SET_FLOW, &flow_ctl, + sizeof(flow_ctl)); + } else { + dev_dbg(&port->dev, "%s - control = 0x%04x\n", __func__, control); + + ret = cp210x_write_u16_reg(port, CP210X_SET_MHS, control); + } +out_unlock: mutex_unlock(&port_priv->mutex); return ret; |