From 7678f4c20fa7670fcc23e2537a26543c5c6a7772 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] 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>
---
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 0f058df0b0701..3c5dd209c1d15 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -676,6 +676,8 @@ 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 fdbbff547106e..919706988c72a 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 *
@@ -3026,6 +3027,7 @@ 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);
@@ -3107,6 +3109,8 @@ 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;
@@ -3141,6 +3145,9 @@ 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) {
@@ -3239,6 +3246,7 @@ static int sci_probe(struct platform_device *dev)
sh_bios_gdb_detach();
#endif
+ sci_ports_in_use |= BIT(dev_id);
return 0;
}