[ltsi-3.10,469/595] ARM: shmobile: Add shared SCU CPU Hotplug code

Commit Message

Simon Horman Nov. 20, 2013, 3:19 a.m. UTC

From: Magnus Damm <[e-mail]>

Add CPU Hotplug functions for SCU equipped mach-shmobile SoCs.

The functions shmobile_smp_scu_cpu_die() together with
shmobile_smp_scu_cpu_kill() perform basic shutdown and
allows checking of shutdown status. These are written
to work together with SMP boot code in  headsmp-scu.S.

Signed-off-by: Magnus Damm <[e-mail]>
Signed-off-by: Simon Horman <[e-mail]>
(cherry picked from commit e7b1c96384181d690950530f5a64167965226744)
Signed-off-by: Simon Horman <[e-mail]>
---
 arch/arm/mach-shmobile/include/mach/common.h |  2 ++
 arch/arm/mach-shmobile/platsmp-scu.c         | 45 ++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

Patch

diff --git a/arch/arm/mach-shmobile/include/mach/common.h b/arch/arm/mach-shmobile/include/mach/common.h
index 08d7cac..2731dd7 100644
--- a/arch/arm/mach-shmobile/include/mach/common.h
+++ b/arch/arm/mach-shmobile/include/mach/common.h
@@ -13,6 +13,8 @@  extern void shmobile_boot_scu(void);
 extern void shmobile_smp_scu_prepare_cpus(unsigned int max_cpus);
 extern int shmobile_smp_scu_boot_secondary(unsigned int cpu,
 					   struct task_struct *idle);
+extern void shmobile_smp_scu_cpu_die(unsigned int cpu);
+extern int shmobile_smp_scu_cpu_kill(unsigned int cpu);
 struct clk;
 extern int shmobile_clk_init(void);
 extern void shmobile_handle_irq_intc(struct pt_regs *);
diff --git a/arch/arm/mach-shmobile/platsmp-scu.c b/arch/arm/mach-shmobile/platsmp-scu.c
index 8f478e4..7a0c066 100644
--- a/arch/arm/mach-shmobile/platsmp-scu.c
+++ b/arch/arm/mach-shmobile/platsmp-scu.c
@@ -7,9 +7,11 @@ 
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
+#include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/smp.h>
+#include <asm/cacheflush.h>
 #include <asm/smp_plat.h>
 #include <asm/smp_scu.h>
 #include <mach/common.h>
@@ -29,3 +31,46 @@  int shmobile_smp_scu_boot_secondary(unsigned int cpu, struct task_struct *idle)
 	/* do nothing for now */
 	return 0;
 }
+
+#ifdef CONFIG_HOTPLUG_CPU
+void shmobile_smp_scu_cpu_die(unsigned int cpu)
+{
+	dsb();
+	flush_cache_all();
+
+	/* disable cache coherency */
+	scu_power_mode(shmobile_scu_base, SCU_PM_POWEROFF);
+
+	/* Endless loop until reset */
+	while (1)
+		cpu_do_idle();
+}
+
+static int shmobile_smp_scu_psr_core_disabled(int cpu)
+{
+	unsigned long mask = SCU_PM_POWEROFF << (cpu * 8);
+
+	if ((__raw_readl(shmobile_scu_base + 8) & mask) == mask)
+		return 1;
+
+	return 0;
+}
+
+int shmobile_smp_scu_cpu_kill(unsigned int cpu)
+{
+	int k;
+
+	/* this function is running on another CPU than the offline target,
+	 * here we need wait for shutdown code in platform_cpu_die() to
+	 * finish before asking SoC-specific code to power off the CPU core.
+	 */
+	for (k = 0; k < 1000; k++) {
+		if (shmobile_smp_scu_psr_core_disabled(cpu))
+			return 1;
+
+		mdelay(1);
+	}
+
+	return 0;
+}
+#endif