From dfd1cc0d1f8680ba3c405fb479f4e65aba2c679c Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Mon, 5 Mar 2018 18:17:40 +0100
Subject: [PATCH 1262/1795] serial: sh-sci: Add support for dynamic instances

On DT platforms, the sh-sci driver requires the presence of "serialN"
aliases in DT, from which instance IDs are derived.  If a DT alias is
missing, the drivers fails to probe the corresponding serial port.

This becomes cumbersome when considering DT overlays, as currently
there is no upstream support for dynamically updating the /aliases node
in DT.  Furthermore, even in the presence of such support, hardcoded
instance IDs in independent overlays are prone to conflicts.

Hence add support for dynamic instance IDs, to be used in the absence of
a DT alias.  This makes serial ports behave similar to I2C and SPI
buses, which already support dynamic instances.

Ports in use are tracked using a simple bitmask of type unsigned long,
which is sufficient to handle all current hardware (max. 18 ports).
The maximum number of serial ports is still fixed, and configurable
through Kconfig.  Range validation is done through both Kconfig and a
compile-time check.

Due to the fixed maximum number of serial ports, dynamic and static
instances share the same ID space.  Static instances added later are
rejected when conflicting with dynamic instances registered earlier.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 7678f4c20fa7670fcc23e2537a26543c5c6a7772)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/tty/serial/Kconfig  | 2 ++
 drivers/tty/serial/sh-sci.c | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 3682fd3e960c..76005dc5f624 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -762,6 +762,8 @@ config SERIAL_SH_SCI
 
 config SERIAL_SH_SCI_NR_UARTS
 	int "Maximum number of SCI(F) serial ports" if EXPERT
+	range 1 64 if 64BIT
+	range 1 32 if !64BIT
 	depends on SERIAL_SH_SCI
 	default "3" if H8300
 	default "10" if SUPERH
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 2051a5309851..59fac9761e9c 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -160,6 +160,7 @@ struct sci_port {
 #define SCI_NPORTS CONFIG_SERIAL_SH_SCI_NR_UARTS
 
 static struct sci_port sci_ports[SCI_NPORTS];
+static unsigned long sci_ports_in_use;
 static struct uart_driver sci_uart_driver;
 
 static inline struct sci_port *
@@ -3024,6 +3025,7 @@ static int sci_remove(struct platform_device *dev)
 {
 	struct sci_port *port = platform_get_drvdata(dev);
 
+	sci_ports_in_use &= ~BIT(port->port.line);
 	uart_remove_one_port(&sci_uart_driver, &port->port);
 
 	sci_cleanup_single(port);
@@ -3105,6 +3107,8 @@ static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
 
 	/* Get the line number from the aliases node. */
 	id = of_alias_get_id(np, "serial");
+	if (id < 0 && ~sci_ports_in_use)
+		id = ffz(sci_ports_in_use);
 	if (id < 0) {
 		dev_err(&pdev->dev, "failed to get alias id (%d)\n", id);
 		return NULL;
@@ -3139,6 +3143,9 @@ static int sci_probe_single(struct platform_device *dev,
 		dev_notice(&dev->dev, "Consider bumping CONFIG_SERIAL_SH_SCI_NR_UARTS!\n");
 		return -EINVAL;
 	}
+	BUILD_BUG_ON(SCI_NPORTS > sizeof(sci_ports_in_use) * 8);
+	if (sci_ports_in_use & BIT(index))
+		return -EBUSY;
 
 	mutex_lock(&sci_uart_registration_lock);
 	if (!sci_uart_driver.state) {
@@ -3237,6 +3244,7 @@ static int sci_probe(struct platform_device *dev)
 	sh_bios_gdb_detach();
 #endif
 
+	sci_ports_in_use |= BIT(dev_id);
 	return 0;
 }
 
-- 
2.19.0