Merge tag 'tty-4.15-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver fixes from Greg KH:
 "Here are some small serdev and serial fixes for 4.15-rc3. They resolve
  some reported problems:

   - a number of serdev fixes to resolve crashes

   - MIPS build fixes for their serial port

   - a new 8250 device id

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-4.15-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  MIPS: Add custom serial.h with BASE_BAUD override for generic kernel
  serdev: ttyport: fix tty locking in close
  serdev: ttyport: fix NULL-deref on hangup
  serdev: fix receive_buf return value when no callback
  serdev: ttyport: add missing receive_buf sanity checks
  serial: 8250_early: Only set divisor if valid clk & baud
  serial: 8250_pci: Add Amazon PCI serial device ID

6 files changed, 57 insertions, 11 deletions

diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index 7c8aab23bce8..b1f66699677d 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -16,7 +16,6 @@ generic-y += qrwlock.h
 generic-y += qspinlock.h
 generic-y += sections.h
 generic-y += segment.h
-generic-y += serial.h
 generic-y += trace_clock.h
 generic-y += unaligned.h
 generic-y += user.h
diff --git a/arch/mips/include/asm/serial.h b/arch/mips/include/asm/serial.h
new file mode 100644
index 000000000000..1d830c6666c2
--- /dev/null
+++ b/arch/mips/include/asm/serial.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2017 MIPS Tech, LLC
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+#ifndef __ASM__SERIAL_H
+#define __ASM__SERIAL_H
+
+#ifdef CONFIG_MIPS_GENERIC
+/*
+ * Generic kernels cannot know a correct value for all platforms at
+ * compile time. Set it to 0 to prevent 8250_early using it
+ */
+#define BASE_BAUD 0
+#else
+#include <asm-generic/serial.h>
+#endif
+
+#endif /* __ASM__SERIAL_H */
diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
index ce7ad0acee7a..247788a16f0b 100644
--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -27,23 +27,41 @@ static int ttyport_receive_buf(struct tty_port *port, const unsigned char *cp,
 {
         struct serdev_controller *ctrl = port->client_data;
         struct serport *serport = serdev_controller_get_drvdata(ctrl);
+        int ret;
 
         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
                 return 0;
 
-        return serdev_controller_receive_buf(ctrl, cp, count);
+        ret = serdev_controller_receive_buf(ctrl, cp, count);
+
+        dev_WARN_ONCE(&ctrl->dev, ret < 0 || ret > count,
+                                "receive_buf returns %d (count = %zu)\n",
+                                ret, count);
+        if (ret < 0)
+                return 0;
+        else if (ret > count)
+                return count;
+
+        return ret;
 }
 
 static void ttyport_write_wakeup(struct tty_port *port)
 {
         struct serdev_controller *ctrl = port->client_data;
         struct serport *serport = serdev_controller_get_drvdata(ctrl);
+        struct tty_struct *tty;
+
+        tty = tty_port_tty_get(port);
+        if (!tty)
+                return;
 
-        if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags) &&
+        if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
             test_bit(SERPORT_ACTIVE, &serport->flags))
                 serdev_controller_write_wakeup(ctrl);
 
-        wake_up_interruptible_poll(&port->tty->write_wait, POLLOUT);
+        wake_up_interruptible_poll(&tty->write_wait, POLLOUT);
+
+        tty_kref_put(tty);
 }
 
 static const struct tty_port_client_operations client_ops = {
@@ -136,8 +154,10 @@ static void ttyport_close(struct serdev_controller *ctrl)
 
         clear_bit(SERPORT_ACTIVE, &serport->flags);
 
+        tty_lock(tty);
         if (tty->ops->close)
                 tty->ops->close(tty, NULL);
+        tty_unlock(tty);
 
         tty_release_struct(tty, serport->tty_idx);
 }
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 362c25ff188a..ae6a256524d8 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -122,12 +122,14 @@ static void __init init_port(struct earlycon_device *device)
         serial8250_early_out(port, UART_FCR, 0);        /* no fifo */
         serial8250_early_out(port, UART_MCR, 0x3);      /* DTR + RTS */
 
-        divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
-        c = serial8250_early_in(port, UART_LCR);
-        serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB);
-        serial8250_early_out(port, UART_DLL, divisor & 0xff);
-        serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
-        serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB);
+        if (port->uartclk && device->baud) {
+                divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
+                c = serial8250_early_in(port, UART_LCR);
+                serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB);
+                serial8250_early_out(port, UART_DLL, divisor & 0xff);
+                serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
+                serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB);
+        }
 }
 
 int __init early_serial8250_setup(struct earlycon_device *device,
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index b7e0e3416641..54adf8d56350 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -5135,6 +5135,9 @@ static const struct pci_device_id serial_pci_tbl[] = {
         { PCI_DEVICE(0x1601, 0x0800), .driver_data = pbn_b0_4_1250000 },
         { PCI_DEVICE(0x1601, 0xa801), .driver_data = pbn_b0_4_1250000 },
 
+        /* Amazon PCI serial device */
+        { PCI_DEVICE(0x1d0f, 0x8250), .driver_data = pbn_b0_1_115200 },
+
         /*
          * These entries match devices with class COMMUNICATION_SERIAL,
          * COMMUNICATION_MODEM or COMMUNICATION_MULTISERIAL
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index e69402d4a8ae..d609e6dc5bad 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -184,7 +184,7 @@ static inline int serdev_controller_receive_buf(struct serdev_controller *ctrl,
         struct serdev_device *serdev = ctrl->serdev;
 
         if (!serdev || !serdev->ops->receive_buf)
-                return -EINVAL;
+                return 0;
 
         return serdev->ops->receive_buf(serdev, data, count);
 }