Re: [PATCH] serial: pl011: honour serial aliases in device tree
From: Rob Herring <hidden>
Date: 2012-08-21 13:26:15
Also in:
linux-arm-kernel, linux-devicetree
On 08/21/2012 05:18 AM, Matthew Leach wrote:
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. Signed-off-by: Matthew Leach <redacted>
One comment/question below, but otherwise: Acked-by: Rob Herring <redacted>
quoted hunk ↗ jump to hunk
--- drivers/tty/serial/amba-pl011.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 files changed, 39 insertions(+), 0 deletions(-)diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index c17923e..5919599 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c@@ -52,6 +52,7 @@ #include <linux/scatterlist.h> #include <linux/delay.h> #include <linux/types.h> +#include <linux/of_device.h> #include <linux/pinctrl/consumer.h> #include <asm/io.h>@@ -1869,6 +1870,42 @@ static struct uart_driver amba_reg = { .cons = AMBA_CONSOLE, }; +#ifdef CONFIG_OF
Now that we have IS_ENABLED, perhaps we want to put this inside the function instead? if (!IS_ENABLED(CONFIG_OF)) return index;
quoted hunk ↗ jump to hunk
+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; + + 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; +} +#else +static int pl011_probe_dt_alias(int index, struct device *dev) +{ + return index; +} +#endif + static int pl011_probe(struct amba_device *dev, const struct amba_id *id) { struct uart_amba_port *uap;@@ -1891,6 +1928,8 @@ 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;