TTY/Serial fixes for 4.17-rc3

Here are some tty and serial driver fixes for reported issues for
 4.17-rc3.
 
 Nothing major, but a number of small things:
 	- device tree fixes/updates for serial ports
 	- earlycon fixes
 	- n_gsm fixes
 	- tty core change reverted to help resolve syszkaller reports
 	- other serial driver small fixes
 
 All of these have been in linux-next with no reported issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-4.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some tty and serial driver fixes for reported issues for
  4.17-rc3.

  Nothing major, but a number of small things:

   - device tree fixes/updates for serial ports

   - earlycon fixes

   - n_gsm fixes

   - tty core change reverted to help resolve syszkaller reports

   - other serial driver small fixes

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

* tag 'tty-4.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: Use __GFP_NOFAIL for tty_ldisc_get()
  tty: serial: xuartps: Setup early console when uartclk is also passed
  tty: Don't call panic() at tty_ldisc_init()
  tty: Avoid possible error pointer dereference at tty_ldisc_restore().
  dt-bindings: mvebu-uart: DT fix s/interrupts-names/interrupt-names/
  tty: serial: qcom_geni_serial: Use signed variable to get IRQ
  earlycon: Use a pointer table to fix __earlycon_table stride
  serial: sh-sci: Document r8a77470 bindings
  dt-bindings: meson-uart: DT fix s/clocks-names/clock-names/
  serial: imx: fix cached UCR2 read on software reset
  serial: imx: warn user when using unsupported configuration
  serial: mvebu-uart: Fix local flags handling on termios update
  tty: n_gsm: Fix DLCI handling for ADM mode if debug & 2 is not set
  tty: n_gsm: Fix long delays with control frame timeouts in ADM mode

Documentation/devicetree/bindings/serial/amlogic,meson-uart.txt

@@ -21,7 +21,7 @@ Required properties:
 - interrupts : identifier to the device interrupt
 - clocks : a list of phandle + clock-specifier pairs, one for each
 	   entry in clock names.
-- clocks-names :
+- clock-names :
    * "xtal" for external xtal clock identifier
    * "pclk" for the bus core clock, either the clk81 clock or the gate clock
    * "baud" for the source of the baudrate generator, can be either the xtal

Documentation/devicetree/bindings/serial/mvebu-uart.txt

@@ -24,7 +24,7 @@ Required properties:
     - Must contain two elements for the extended variant of the IP
       (marvell,armada-3700-uart-ext): "uart-tx" and "uart-rx",
       respectively the UART TX interrupt and the UART RX interrupt. A
-      corresponding interrupts-names property must be defined.
+      corresponding interrupt-names property must be defined.
     - For backward compatibility reasons, a single element interrupts
       property is also supported for the standard variant of the IP,
       containing only the UART sum interrupt. This form is deprecated

Documentation/devicetree/bindings/serial/renesas,sci-serial.txt

@@ -17,6 +17,8 @@ Required properties:
     - "renesas,scifa-r8a7745" for R8A7745 (RZ/G1E) SCIFA compatible UART.
     - "renesas,scifb-r8a7745" for R8A7745 (RZ/G1E) SCIFB compatible UART.
     - "renesas,hscif-r8a7745" for R8A7745 (RZ/G1E) HSCIF compatible UART.
+    - "renesas,scif-r8a77470" for R8A77470 (RZ/G1C) SCIF compatible UART.
+    - "renesas,hscif-r8a77470" for R8A77470 (RZ/G1C) HSCIF compatible UART.
     - "renesas,scif-r8a7778" for R8A7778 (R-Car M1) SCIF compatible UART.
     - "renesas,scif-r8a7779" for R8A7779 (R-Car H1) SCIF compatible UART.
     - "renesas,scif-r8a7790" for R8A7790 (R-Car H2) SCIF compatible UART.

drivers/of/fdt.c

@@ -942,7 +942,7 @@ int __init early_init_dt_scan_chosen_stdout(void)
 	int offset;
 	const char *p, *q, *options = NULL;
 	int l;
-	const struct earlycon_id *match;
+	const struct earlycon_id **p_match;
 	const void *fdt = initial_boot_params;
 
 	offset = fdt_path_offset(fdt, "/chosen");
@@ -969,7 +969,10 @@ int __init early_init_dt_scan_chosen_stdout(void)
 		return 0;
 	}
 
-	for (match = __earlycon_table; match < __earlycon_table_end; match++) {
+	for (p_match = __earlycon_table; p_match < __earlycon_table_end;
+	     p_match++) {
+		const struct earlycon_id *match = *p_match;
+
 		if (!match->compatible[0])
 			continue;
 

drivers/tty/n_gsm.c

@@ -121,6 +121,9 @@ struct gsm_dlci {
 	struct mutex mutex;
 
 	/* Link layer */
+	int mode;
+#define DLCI_MODE_ABM		0	/* Normal Asynchronous Balanced Mode */
+#define DLCI_MODE_ADM		1	/* Asynchronous Disconnected Mode */
 	spinlock_t lock;	/* Protects the internal state */
 	struct timer_list t1;	/* Retransmit timer for SABM and UA */
 	int retries;
@@ -1364,7 +1367,13 @@ retry:
 	ctrl->data = data;
 	ctrl->len = clen;
 	gsm->pending_cmd = ctrl;
-	gsm->cretries = gsm->n2;
+
+	/* If DLCI0 is in ADM mode skip retries, it won't respond */
+	if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
+		gsm->cretries = 1;
+	else
+		gsm->cretries = gsm->n2;
+
 	mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
 	gsm_control_transmit(gsm, ctrl);
 	spin_unlock_irqrestore(&gsm->control_lock, flags);
@@ -1472,6 +1481,7 @@ static void gsm_dlci_t1(struct timer_list *t)
 			if (debug & 8)
 				pr_info("DLCI %d opening in ADM mode.\n",
 					dlci->addr);
+			dlci->mode = DLCI_MODE_ADM;
 			gsm_dlci_open(dlci);
 		} else {
 			gsm_dlci_close(dlci);
@@ -2861,11 +2871,22 @@ static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
 static int gsm_carrier_raised(struct tty_port *port)
 {
 	struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
+	struct gsm_mux *gsm = dlci->gsm;
+
 	/* Not yet open so no carrier info */
 	if (dlci->state != DLCI_OPEN)
 		return 0;
 	if (debug & 2)
 		return 1;
+
+	/*
+	 * Basic mode with control channel in ADM mode may not respond
+	 * to CMD_MSC at all and modem_rx is empty.
+	 */
+	if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
+	    !dlci->modem_rx)
+		return 1;
+
 	return dlci->modem_rx & TIOCM_CD;
 }
 

drivers/tty/serial/earlycon.c

@@ -169,7 +169,7 @@ static int __init register_earlycon(char *buf, const struct earlycon_id *match)
  */
 int __init setup_earlycon(char *buf)
 {
-	const struct earlycon_id *match;
+	const struct earlycon_id **p_match;
 
 	if (!buf || !buf[0])
 		return -EINVAL;
@@ -177,7 +177,9 @@ int __init setup_earlycon(char *buf)
 	if (early_con.flags & CON_ENABLED)
 		return -EALREADY;
 
-	for (match = __earlycon_table; match < __earlycon_table_end; match++) {
+	for (p_match = __earlycon_table; p_match < __earlycon_table_end;
+	     p_match++) {
+		const struct earlycon_id *match = *p_match;
 		size_t len = strlen(match->name);
 
 		if (strncmp(buf, match->name, len))

drivers/tty/serial/imx.c

@@ -316,7 +316,7 @@ static u32 imx_uart_readl(struct imx_port *sport, u32 offset)
 		 * differ from the value that was last written. As it only
 		 * clears after being set, reread conditionally.
 		 */
-		if (sport->ucr2 & UCR2_SRST)
+		if (!(sport->ucr2 & UCR2_SRST))
 			sport->ucr2 = readl(sport->port.membase + offset);
 		return sport->ucr2;
 		break;
@@ -1833,6 +1833,11 @@ static int imx_uart_rs485_config(struct uart_port *port,
 		rs485conf->flags &= ~SER_RS485_ENABLED;
 
 	if (rs485conf->flags & SER_RS485_ENABLED) {
+		/* Enable receiver if low-active RTS signal is requested */
+		if (sport->have_rtscts &&  !sport->have_rtsgpio &&
+		    !(rs485conf->flags & SER_RS485_RTS_ON_SEND))
+			rs485conf->flags |= SER_RS485_RX_DURING_TX;
+
 		/* disable transmitter */
 		ucr2 = imx_uart_readl(sport, UCR2);
 		if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)
@@ -2265,6 +2270,18 @@ static int imx_uart_probe(struct platform_device *pdev)
 	    (!sport->have_rtscts && !sport->have_rtsgpio))
 		dev_err(&pdev->dev, "no RTS control, disabling rs485\n");
 
+	/*
+	 * If using the i.MX UART RTS/CTS control then the RTS (CTS_B)
+	 * signal cannot be set low during transmission in case the
+	 * receiver is off (limitation of the i.MX UART IP).
+	 */
+	if (sport->port.rs485.flags & SER_RS485_ENABLED &&
+	    sport->have_rtscts && !sport->have_rtsgpio &&
+	    (!(sport->port.rs485.flags & SER_RS485_RTS_ON_SEND) &&
+	     !(sport->port.rs485.flags & SER_RS485_RX_DURING_TX)))
+		dev_err(&pdev->dev,
+			"low-active RTS not possible when receiver is off, enabling receiver\n");
+
 	imx_uart_rs485_config(&sport->port, &sport->port.rs485);
 
 	/* Disable interrupts before requesting them */

drivers/tty/serial/mvebu-uart.c

@@ -495,7 +495,6 @@ static void mvebu_uart_set_termios(struct uart_port *port,
 		termios->c_iflag |= old->c_iflag & ~(INPCK | IGNPAR);
 		termios->c_cflag &= CREAD | CBAUD;
 		termios->c_cflag |= old->c_cflag & ~(CREAD | CBAUD);
-		termios->c_lflag = old->c_lflag;
 	}
 
 	spin_unlock_irqrestore(&port->lock, flags);

drivers/tty/serial/qcom_geni_serial.c

@@ -1022,6 +1022,7 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 	struct qcom_geni_serial_port *port;
 	struct uart_port *uport;
 	struct resource *res;
+	int irq;
 
 	if (pdev->dev.of_node)
 		line = of_alias_get_id(pdev->dev.of_node, "serial");
@@ -1061,11 +1062,12 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 	port->rx_fifo_depth = DEF_FIFO_DEPTH_WORDS;
 	port->tx_fifo_width = DEF_FIFO_WIDTH_BITS;
 
-	uport->irq = platform_get_irq(pdev, 0);
-	if (uport->irq < 0) {
-		dev_err(&pdev->dev, "Failed to get IRQ %d\n", uport->irq);
-		return uport->irq;
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to get IRQ %d\n", irq);
+		return irq;
 	}
+	uport->irq = irq;
 
 	uport->private_data = &qcom_geni_console_driver;
 	platform_set_drvdata(pdev, port);

drivers/tty/serial/xilinx_uartps.c

@@ -1181,7 +1181,7 @@ static int __init cdns_early_console_setup(struct earlycon_device *device,
 	/* only set baud if specified on command line - otherwise
 	 * assume it has been initialized by a boot loader.
 	 */
-	if (device->baud) {
+	if (port->uartclk && device->baud) {
 		u32 cd = 0, bdiv = 0;
 		u32 mr;
 		int div8;

drivers/tty/tty_io.c

@@ -2816,7 +2816,10 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
 
 	kref_init(&tty->kref);
 	tty->magic = TTY_MAGIC;
-	tty_ldisc_init(tty);
+	if (tty_ldisc_init(tty)) {
+		kfree(tty);
+		return NULL;
+	}
 	tty->session = NULL;
 	tty->pgrp = NULL;
 	mutex_init(&tty->legacy_mutex);

drivers/tty/tty_ldisc.c

@@ -176,12 +176,11 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
 			return ERR_CAST(ldops);
 	}
 
-	ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL);
-	if (ld == NULL) {
-		put_ldops(ldops);
-		return ERR_PTR(-ENOMEM);
-	}
-
+	/*
+	 * There is no way to handle allocation failure of only 16 bytes.
+	 * Let's simplify error handling and save more memory.
+	 */
+	ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL);
 	ld->ops = ldops;
 	ld->tty = tty;
 
@@ -527,19 +526,16 @@ static int tty_ldisc_failto(struct tty_struct *tty, int ld)
 static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
 {
 	/* There is an outstanding reference here so this is safe */
-	old = tty_ldisc_get(tty, old->ops->num);
-	WARN_ON(IS_ERR(old));
-	tty->ldisc = old;
-	tty_set_termios_ldisc(tty, old->ops->num);
-	if (tty_ldisc_open(tty, old) < 0) {
-		tty_ldisc_put(old);
+	if (tty_ldisc_failto(tty, old->ops->num) < 0) {
+		const char *name = tty_name(tty);
+
+		pr_warn("Falling back ldisc for %s.\n", name);
 		/* The traditional behaviour is to fall back to N_TTY, we
 		   want to avoid falling back to N_NULL unless we have no
 		   choice to avoid the risk of breaking anything */
 		if (tty_ldisc_failto(tty, N_TTY) < 0 &&
 		    tty_ldisc_failto(tty, N_NULL) < 0)
-			panic("Couldn't open N_NULL ldisc for %s.",
-			      tty_name(tty));
+			panic("Couldn't open N_NULL ldisc for %s.", name);
 	}
 }
 
@@ -824,12 +820,13 @@ EXPORT_SYMBOL_GPL(tty_ldisc_release);
  *	the tty structure is not completely set up when this call is made.
  */
 
-void tty_ldisc_init(struct tty_struct *tty)
+int tty_ldisc_init(struct tty_struct *tty)
 {
 	struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY);
 	if (IS_ERR(ld))
-		panic("n_tty: init_tty");
+		return PTR_ERR(ld);
 	tty->ldisc = ld;
+	return 0;
 }
 
 /**

include/asm-generic/vmlinux.lds.h

@@ -188,7 +188,7 @@
 #endif
 
 #ifdef CONFIG_SERIAL_EARLYCON
-#define EARLYCON_TABLE() STRUCT_ALIGN();			\
+#define EARLYCON_TABLE() . = ALIGN(8);				\
 			 VMLINUX_SYMBOL(__earlycon_table) = .;	\
 			 KEEP(*(__earlycon_table))		\
 			 VMLINUX_SYMBOL(__earlycon_table_end) = .;

include/linux/serial_core.h

@@ -351,10 +351,10 @@ struct earlycon_id {
 	char	name[16];
 	char	compatible[128];
 	int	(*setup)(struct earlycon_device *, const char *options);
-} __aligned(32);
+};
 
-extern const struct earlycon_id __earlycon_table[];
-extern const struct earlycon_id __earlycon_table_end[];
+extern const struct earlycon_id *__earlycon_table[];
+extern const struct earlycon_id *__earlycon_table_end[];
 
 #if defined(CONFIG_SERIAL_EARLYCON) && !defined(MODULE)
 #define EARLYCON_USED_OR_UNUSED	__used
@@ -362,12 +362,19 @@ extern const struct earlycon_id __earlycon_table_end[];
 #define EARLYCON_USED_OR_UNUSED	__maybe_unused
 #endif
 
-#define OF_EARLYCON_DECLARE(_name, compat, fn)				\
-	static const struct earlycon_id __UNIQUE_ID(__earlycon_##_name)	\
-	     EARLYCON_USED_OR_UNUSED __section(__earlycon_table)	\
+#define _OF_EARLYCON_DECLARE(_name, compat, fn, unique_id)		\
+	static const struct earlycon_id unique_id			\
+	     EARLYCON_USED_OR_UNUSED __initconst			\
 		= { .name = __stringify(_name),				\
 		    .compatible = compat,				\
-		    .setup = fn  }
+		    .setup = fn  };					\
+	static const struct earlycon_id EARLYCON_USED_OR_UNUSED		\
+		__section(__earlycon_table)				\
+		* const __PASTE(__p, unique_id) = &unique_id
+
+#define OF_EARLYCON_DECLARE(_name, compat, fn)				\
+	_OF_EARLYCON_DECLARE(_name, compat, fn,				\
+			     __UNIQUE_ID(__earlycon_##_name))
 
 #define EARLYCON_DECLARE(_name, fn)	OF_EARLYCON_DECLARE(_name, "", fn)
 

include/linux/tty.h

@@ -701,7 +701,7 @@ extern int tty_unregister_ldisc(int disc);
 extern int tty_set_ldisc(struct tty_struct *tty, int disc);
 extern int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty);
 extern void tty_ldisc_release(struct tty_struct *tty);
-extern void tty_ldisc_init(struct tty_struct *tty);
+extern int __must_check tty_ldisc_init(struct tty_struct *tty);
 extern void tty_ldisc_deinit(struct tty_struct *tty);
 extern int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
 				 char *f, int count);