tty: Update hypervisor tty drivers to use core stdout parsing code.

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 <grant.likely@linaro.org>

5 files changed, 22 insertions, 71 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index df9b2bb7bb27..e4f95ba0a3eb 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;
 
@@ -2063,9 +2063,12 @@ 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)