From 32614aad30549b0e4caf44c26efe8e2b09d597ce Mon Sep 17 00:00:00 2001 From: Matthew Leach Date: Tue, 28 Aug 2012 16:41:28 +0100 Subject: serial: pl011: honour serial aliases in device tree If the order of UART nodes is changed in the device tree, then tty dev devices are attached to different serial ports causing the console to be directed to a different physical serial port. The "serial" aliases in the device tree should prevent this. This patch ensures that the UART driver creates tty devices that honour these aliases if a device tree is present. Acked-by: Linus Walleij Reviewed-by: Will Deacon Acked-by: Rob Herring Signed-off-by: Matthew Leach Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/amba-pl011.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'drivers/tty/serial') diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 3322023e38aa..05c15ec7bd21 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -52,6 +52,8 @@ #include #include #include +#include +#include #include #include @@ -1862,6 +1864,38 @@ static struct uart_driver amba_reg = { .cons = AMBA_CONSOLE, }; +static int pl011_probe_dt_alias(int index, struct device *dev) +{ + struct device_node *np; + static bool seen_dev_with_alias = false; + static bool seen_dev_without_alias = false; + int ret = index; + + if (!IS_ENABLED(CONFIG_OF)) + return ret; + + np = dev->of_node; + if (!np) + return ret; + + ret = of_alias_get_id(np, "serial"); + if (IS_ERR_VALUE(ret)) { + seen_dev_without_alias = true; + ret = index; + } else { + seen_dev_with_alias = true; + if (ret >= ARRAY_SIZE(amba_ports) || amba_ports[ret] != NULL) { + dev_warn(dev, "requested serial port %d not available.\n", ret); + ret = index; + } + } + + if (seen_dev_with_alias && seen_dev_without_alias) + dev_warn(dev, "aliased and non-aliased serial devices found in device tree. Serial port enumeration may be unpredictable.\n"); + + return ret; +} + static int pl011_probe(struct amba_device *dev, const struct amba_id *id) { struct uart_amba_port *uap; @@ -1884,6 +1918,8 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id) goto out; } + i = pl011_probe_dt_alias(i, &dev->dev); + base = ioremap(dev->res.start, resource_size(&dev->res)); if (!base) { ret = -ENOMEM; -- cgit v1.2.1