Merge branch 'sparc64-jump-to-boot-prom'

Vijay Kumar says:

====================
sparc64: Jump to boot prom from console on panic

V3 changes:
  - patch 02/04: Added SERIAL_SUNHV conditional group for
    sunhv_migrate_hvcons_irq in smp_send_stop().
V2 changes:
 -  Added cover letter patch

Currently Stop-A (L1A) does not make the kernel switch to OBP on panic. This
patchset addresses this issue. Also, now we can cause a jump to OBP by sending
'break' twice from sunhv console. On bare metal, one can send a break by
typing Esc + 'B' + Sysrq (or whatever). On LDOM, press Ctrl + ] in telnet,
and then "send break" at the telnet prompt.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 34 insertions, 4 deletions

diff --git a/Documentation/sparc/console.txt b/Documentation/sparc/console.txt
new file mode 100644
index 000000000000..5aa735a44e02
--- /dev/null
+++ b/Documentation/sparc/console.txt
@@ -0,0 +1,9 @@
+Steps for sending 'break' on sunhv console:
+===========================================
+
+On Baremetal:
+   1. press   Esc + 'B'
+
+On LDOM:
+   1. press    Ctrl + ']'
+   2. telnet> send  break
diff --git a/arch/sparc/include/asm/setup.h b/arch/sparc/include/asm/setup.h
index 29d64b1758ed..478bf6bb4598 100644
--- a/arch/sparc/include/asm/setup.h
+++ b/arch/sparc/include/asm/setup.h
@@ -59,8 +59,11 @@ extern atomic_t dcpage_flushes;
 extern atomic_t dcpage_flushes_xcall;
 
 extern int sysctl_tsb_ratio;
-#endif
 
+#ifdef CONFIG_SERIAL_SUNHV
+void sunhv_migrate_hvcons_irq(int cpu);
+#endif
+#endif
 void sun_do_break(void);
 extern int stop_a_enabled;
 extern int scons_pwroff;
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 0ce347f8e4cc..90a02cb64e20 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1443,6 +1443,7 @@ void __irq_entry smp_receive_signal_client(int irq, struct pt_regs *regs)
 
 static void stop_this_cpu(void *dummy)
 {
+        set_cpu_online(smp_processor_id(), false);
         prom_stopself();
 }
 
@@ -1451,9 +1452,15 @@ void smp_send_stop(void)
         int cpu;
 
         if (tlb_type == hypervisor) {
+                int this_cpu = smp_processor_id();
+#ifdef CONFIG_SERIAL_SUNHV
+                sunhv_migrate_hvcons_irq(this_cpu);
+#endif
                 for_each_online_cpu(cpu) {
-                        if (cpu == smp_processor_id())
+                        if (cpu == this_cpu)
                                 continue;
+
+                        set_cpu_online(cpu, false);
 #ifdef CONFIG_SUN_LDOMS
                         if (ldom_domaining_enabled) {
                                 unsigned long hv_err;
diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 73abd89c0108..46e46894e918 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -116,7 +116,7 @@ static int receive_chars_getchar(struct uart_port *port)
 
 static int receive_chars_read(struct uart_port *port)
 {
-        int saw_console_brk = 0;
+        static int saw_console_brk;
         int limit = 10000;
 
         while (limit-- > 0) {
@@ -128,6 +128,9 @@ static int receive_chars_read(struct uart_port *port)
                         bytes_read = 0;
 
                         if (stat == CON_BREAK) {
+                                if (saw_console_brk)
+                                        sun_do_break();
+
                                 if (uart_handle_break(port))
                                         continue;
                                 saw_console_brk = 1;
@@ -151,6 +154,7 @@ static int receive_chars_read(struct uart_port *port)
                 if (port->sysrq != 0 &&  *con_read_page) {
                         for (i = 0; i < bytes_read; i++)
                                 uart_handle_sysrq_char(port, con_read_page[i]);
+                        saw_console_brk = 0;
                 }
 
                 if (port->state == NULL)
@@ -398,6 +402,12 @@ static struct uart_driver sunhv_reg = {
 
 static struct uart_port *sunhv_port;
 
+void sunhv_migrate_hvcons_irq(int cpu)
+{
+        /* Migrate hvcons irq to param cpu */
+        irq_force_affinity(sunhv_port->irq, cpumask_of(cpu));
+}
+
 /* Copy 's' into the con_write_page, decoding "\n" into
  * "\r\n" along the way.  We have to return two lengths
  * because the caller needs to know how much to advance
diff --git a/kernel/panic.c b/kernel/panic.c
index b95959733ce0..3ec16e603e88 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -273,7 +273,8 @@ void panic(const char *fmt, ...)
                 extern int stop_a_enabled;
                 /* Make sure the user can actually press Stop-A (L1-A) */
                 stop_a_enabled = 1;
-                pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
+                pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n"
+                         "twice on console to return to the boot prom\n");
         }
 #endif
 #if defined(CONFIG_S390)