I posted this series a 1.5 months ago as an RFC. I'm going to put it in
my tree for merging in v3.17.
This series cleans up the selection of default console devices when
using the device tree. The device tree defines a way of specifying the
console by using a "stdout-path" property in the /chosen node, but very
few drivers actually attempt to use that data, and so for most platforms
there needs to be a "console=" line in the command line if a serial port
is intended to be used as the console.
With this series, if there is a /chosen/stdout-path property, and that
property points to a serial port node, then when the serial driver
registers he port, the core uart_add_one_port() function will notice
and if no console= argument was provided then add it as a preferred
console.
The devicetree has a binding for specifying the console device in the
/chosen node, but the kernel doesn't use it consistently. This change
adds an API for testing if a device node is a console, and adds a
preferred console entry if it is.
At the same time this patch removes the of_device_is_stdout_path() API
since it is unused.
Signed-off-by: Grant Likely <[email protected]>
Tested-by: Sascha Hauer <[email protected]>
---
drivers/of/base.c | 23 +++++++++++++----------
include/linux/of.h | 6 +++---
2 files changed, 16 insertions(+), 13 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 8368d96ae7b4..ed037ae7eefe 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -17,6 +17,7 @@
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/console.h>
#include <linux/ctype.h>
#include <linux/cpu.h>
#include <linux/module.h>
@@ -2179,20 +2180,22 @@ const char *of_prop_next_string(struct property *prop, const char *cur)
EXPORT_SYMBOL_GPL(of_prop_next_string);
/**
- * of_device_is_stdout_path - check if a device node matches the
- * linux,stdout-path property
- *
- * Check if this device node matches the linux,stdout-path property
- * in the chosen node. return true if yes, false otherwise.
+ * of_console_check() - Test and setup console for DT setup
+ * @dn - Pointer to device node
+ * @name - Name to use for preferred console without index. ex. "ttyS"
+ * @index - Index to use for preferred console.
+ *
+ * Check if the given device node matches the stdout-path property in the
+ * /chosen node. If it does then register it as the preferred console and return
+ * TRUE. Otherwise return FALSE.
*/
-int of_device_is_stdout_path(struct device_node *dn)
+bool of_console_check(struct device_node *dn, char *name, int index)
{
- if (!of_stdout)
+ if (!dn || dn != of_stdout || console_set_on_cmdline)
return false;
-
- return of_stdout == dn;
+ return add_preferred_console(name, index, NULL);
}
-EXPORT_SYMBOL_GPL(of_device_is_stdout_path);
+EXPORT_SYMBOL_GPL(of_console_check);
/**
* of_find_next_cache_node - Find a node's subsidiary cache
diff --git a/include/linux/of.h b/include/linux/of.h
index 196b34c1ef4e..9d9734056e39 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -352,7 +352,7 @@ const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
*/
const char *of_prop_next_string(struct property *prop, const char *cur);
-int of_device_is_stdout_path(struct device_node *dn);
+bool of_console_check(struct device_node *dn, char *name, int index);
#else /* CONFIG_OF */
@@ -564,9 +564,9 @@ static inline int of_machine_is_compatible(const char *compat)
return 0;
}
-static inline int of_device_is_stdout_path(struct device_node *dn)
+static inline bool of_console_check(const struct device_node *dn, const char *name, int index)
{
- return 0;
+ return false;
}
static inline const __be32 *of_prop_next_u32(struct property *prop,
--
1.9.1
If the devicetree specifies a serial port as a stdout device, then the
kernel can use it as the default console if nothing else was selected on
the command line. For any serial port that uses the uart_add_one_port()
feature, the uart_add_one_port() has all the information needed to
automatically enable the console device, which is what this patch does.
With this change applied, a device tree platform can be booted without
any console= parameters on the command line and the kernel will still be
able to determine its console.
Tested on QEMU Versatile model and i.MX
Signed-off-by: Grant Likely <[email protected]>
Tested-by: Sascha Hauer <[email protected]>
---
drivers/tty/serial/serial_core.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index fbf6c5ad222f..3ce68f962c92 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -26,6 +26,7 @@
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/console.h>
+#include <linux/of.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/device.h>
@@ -2615,6 +2616,8 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
spin_lock_init(&uport->lock);
lockdep_set_class(&uport->lock, &port_lock_key);
}
+ if (uport->cons && uport->dev)
+ of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
uart_configure_port(drv, state, uport);
--
1.9.1
The evh_bytechan, hvc_opal and hvc_vio drivers all open code the parsing
of the stdout node in the device tree. This patch simplifies the driver
by removing the duplicated functionality.
Signed-off-by: Grant Likely <[email protected]>
---
drivers/of/base.c | 5 ++++-
drivers/tty/ehv_bytechan.c | 43 ++++---------------------------------------
drivers/tty/hvc/hvc_opal.c | 15 +++------------
drivers/tty/hvc/hvc_vio.c | 29 ++++++++++-------------------
include/linux/of.h | 1 +
5 files changed, 22 insertions(+), 71 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ed037ae7eefe..af3d8722064a 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -36,7 +36,7 @@ struct device_node *of_allnodes;
EXPORT_SYMBOL(of_allnodes);
struct device_node *of_chosen;
struct device_node *of_aliases;
-static struct device_node *of_stdout;
+struct device_node *of_stdout;
static struct kset *of_kset;
@@ -2062,9 +2062,12 @@ void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align))
of_chosen = of_find_node_by_path("/chosen@0");
if (of_chosen) {
+ /* linux,stdout-path and /aliases/stdout are for legacy compatibility */
const char *name = of_get_property(of_chosen, "stdout-path", NULL);
if (!name)
name = of_get_property(of_chosen, "linux,stdout-path", NULL);
+ if (IS_ENABLED(CONFIG_PPC) && !name)
+ name = of_get_property(of_aliases, "stdout", NULL);
if (name)
of_stdout = of_find_node_by_path(name);
}
diff --git a/drivers/tty/ehv_bytechan.c b/drivers/tty/ehv_bytechan.c
index 0419b69e270f..4f485e88f60c 100644
--- a/drivers/tty/ehv_bytechan.c
+++ b/drivers/tty/ehv_bytechan.c
@@ -108,55 +108,23 @@ static void disable_tx_interrupt(struct ehv_bc_data *bc)
*
* The byte channel to be used for the console is specified via a "stdout"
* property in the /chosen node.
- *
- * For compatible with legacy device trees, we also look for a "stdout" alias.
*/
static int find_console_handle(void)
{
- struct device_node *np, *np2;
+ struct device_node *np = of_stdout;
const char *sprop = NULL;
const uint32_t *iprop;
- np = of_find_node_by_path("/chosen");
- if (np)
- sprop = of_get_property(np, "stdout-path", NULL);
-
- if (!np || !sprop) {
- of_node_put(np);
- np = of_find_node_by_name(NULL, "aliases");
- if (np)
- sprop = of_get_property(np, "stdout", NULL);
- }
-
- if (!sprop) {
- of_node_put(np);
- return 0;
- }
-
/* We don't care what the aliased node is actually called. We only
* care if it's compatible with "epapr,hv-byte-channel", because that
- * indicates that it's a byte channel node. We use a temporary
- * variable, 'np2', because we can't release 'np' until we're done with
- * 'sprop'.
+ * indicates that it's a byte channel node.
*/
- np2 = of_find_node_by_path(sprop);
- of_node_put(np);
- np = np2;
- if (!np) {
- pr_warning("ehv-bc: stdout node '%s' does not exist\n", sprop);
- return 0;
- }
-
- /* Is it a byte channel? */
- if (!of_device_is_compatible(np, "epapr,hv-byte-channel")) {
- of_node_put(np);
+ if (!np || !of_device_is_compatible(np, "epapr,hv-byte-channel"))
return 0;
- }
stdout_irq = irq_of_parse_and_map(np, 0);
if (stdout_irq == NO_IRQ) {
- pr_err("ehv-bc: no 'interrupts' property in %s node\n", sprop);
- of_node_put(np);
+ pr_err("ehv-bc: no 'interrupts' property in %s node\n", np->full_name);
return 0;
}
@@ -167,12 +135,9 @@ static int find_console_handle(void)
if (!iprop) {
pr_err("ehv-bc: no 'hv-handle' property in %s node\n",
np->name);
- of_node_put(np);
return 0;
}
stdout_bc = be32_to_cpu(*iprop);
-
- of_node_put(np);
return 1;
}
diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
index a585079b4b38..a2cc5f834c63 100644
--- a/drivers/tty/hvc/hvc_opal.c
+++ b/drivers/tty/hvc/hvc_opal.c
@@ -342,22 +342,13 @@ static void udbg_init_opal_common(void)
void __init hvc_opal_init_early(void)
{
- struct device_node *stdout_node = NULL;
+ struct device_node *stdout_node = of_node_get(of_stdout);
const __be32 *termno;
- const char *name = NULL;
const struct hv_ops *ops;
u32 index;
- /* find the boot console from /chosen/stdout */
- if (of_chosen)
- name = of_get_property(of_chosen, "linux,stdout-path", NULL);
- if (name) {
- stdout_node = of_find_node_by_path(name);
- if (!stdout_node) {
- pr_err("hvc_opal: Failed to locate default console!\n");
- return;
- }
- } else {
+ /* If the console wasn't in /chosen, try /ibm,opal */
+ if (!stdout_node) {
struct device_node *opal, *np;
/* Current OPAL takeover doesn't provide the stdout
diff --git a/drivers/tty/hvc/hvc_vio.c b/drivers/tty/hvc/hvc_vio.c
index b594abfbf21e..5618b5fc7500 100644
--- a/drivers/tty/hvc/hvc_vio.c
+++ b/drivers/tty/hvc/hvc_vio.c
@@ -404,42 +404,35 @@ module_exit(hvc_vio_exit);
void __init hvc_vio_init_early(void)
{
- struct device_node *stdout_node;
const __be32 *termno;
const char *name;
const struct hv_ops *ops;
/* find the boot console from /chosen/stdout */
- if (!of_chosen)
+ if (!of_stdout)
return;
- name = of_get_property(of_chosen, "linux,stdout-path", NULL);
- if (name == NULL)
- return;
- stdout_node = of_find_node_by_path(name);
- if (!stdout_node)
- return;
- name = of_get_property(stdout_node, "name", NULL);
+ name = of_get_property(of_stdout, "name", NULL);
if (!name) {
printk(KERN_WARNING "stdout node missing 'name' property!\n");
- goto out;
+ return;
}
/* Check if it's a virtual terminal */
if (strncmp(name, "vty", 3) != 0)
- goto out;
- termno = of_get_property(stdout_node, "reg", NULL);
+ return;
+ termno = of_get_property(of_stdout, "reg", NULL);
if (termno == NULL)
- goto out;
+ return;
hvterm_priv0.termno = of_read_number(termno, 1);
spin_lock_init(&hvterm_priv0.buf_lock);
hvterm_privs[0] = &hvterm_priv0;
/* Check the protocol */
- if (of_device_is_compatible(stdout_node, "hvterm1")) {
+ if (of_device_is_compatible(of_stdout, "hvterm1")) {
hvterm_priv0.proto = HV_PROTOCOL_RAW;
ops = &hvterm_raw_ops;
}
- else if (of_device_is_compatible(stdout_node, "hvterm-protocol")) {
+ else if (of_device_is_compatible(of_stdout, "hvterm-protocol")) {
hvterm_priv0.proto = HV_PROTOCOL_HVSI;
ops = &hvterm_hvsi_ops;
hvsilib_init(&hvterm_priv0.hvsi, hvc_get_chars, hvc_put_chars,
@@ -447,7 +440,7 @@ void __init hvc_vio_init_early(void)
/* HVSI, perform the handshake now */
hvsilib_establish(&hvterm_priv0.hvsi);
} else
- goto out;
+ return;
udbg_putc = udbg_hvc_putc;
udbg_getc = udbg_hvc_getc;
udbg_getc_poll = udbg_hvc_getc_poll;
@@ -456,14 +449,12 @@ void __init hvc_vio_init_early(void)
* backend for HVSI, only do udbg
*/
if (hvterm_priv0.proto == HV_PROTOCOL_HVSI)
- goto out;
+ return;
#endif
/* Check whether the user has requested a different console. */
if (!strstr(cmd_line, "console="))
add_preferred_console("hvc", 0, NULL);
hvc_instantiate(0, 0, ops);
-out:
- of_node_put(stdout_node);
}
/* call this from early_init() for a working debug console on
diff --git a/include/linux/of.h b/include/linux/of.h
index 9d9734056e39..f0d256273c83 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -113,6 +113,7 @@ static inline void of_node_put(struct device_node *node) { }
extern struct device_node *of_allnodes;
extern struct device_node *of_chosen;
extern struct device_node *of_aliases;
+extern struct device_node *of_stdout;
extern raw_spinlock_t devtree_lock;
static inline bool of_have_populated_dt(void)
--
1.9.1
Add a stdout-path property to the Versatile devicetree so that automatic
console selection works without needing a console= line on the kernel
command line.
Signed-off-by: Grant Likely <[email protected]>
---
arch/arm/boot/dts/versatile-ab.dts | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm/boot/dts/versatile-ab.dts b/arch/arm/boot/dts/versatile-ab.dts
index e01e5a081def..88e94c5506a1 100644
--- a/arch/arm/boot/dts/versatile-ab.dts
+++ b/arch/arm/boot/dts/versatile-ab.dts
@@ -15,6 +15,10 @@
i2c0 = &i2c0;
};
+ chosen {
+ stdout-path = &uart0;
+ };
+
memory {
reg = <0x0 0x08000000>;
};
--
1.9.1