Re: [PATCH] arm: exynos: generalize power register address calculation

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Hi Chander,

Few more comments inline.

On 09.04.2014 13:09, Chander Kashyap wrote:
Currently status/configuration power register values are hard-coded for cpu1.

Make it generic so that it is useful for SoC's with more than two cpus.

Signed-off-by: Chander Kashyap <chander.kashyap@xxxxxxxxxx>
---
changes in v2 : Used existing macros for clusterid and cpuid calculation

  arch/arm/mach-exynos/hotplug.c  |   15 ++++++++++++---
  arch/arm/mach-exynos/platsmp.c  |   20 +++++++++++++++-----
  arch/arm/mach-exynos/regs-pmu.h |    9 +++++++--
  3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/arch/arm/mach-exynos/hotplug.c b/arch/arm/mach-exynos/hotplug.c
index 5eead53..eab6121 100644
--- a/arch/arm/mach-exynos/hotplug.c
+++ b/arch/arm/mach-exynos/hotplug.c
@@ -17,6 +17,7 @@

  #include <asm/cacheflush.h>
  #include <asm/cp15.h>
+#include <asm/cputype.h>
  #include <asm/smp_plat.h>

  #include <plat/cpu.h>
@@ -92,11 +93,19 @@ static inline void cpu_leave_lowpower(void)

  static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  {
+	unsigned int mpidr, cpunr, cluster;
+
+	mpidr = cpu_logical_map(cpu);
+	cpunr = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+	cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+
+	/* Maximum possible cpus in a cluster can be 4 */
+	cpunr += cluster * 4;

This could be put in a helper, as it seems to be used both by hotplug and platsmp code. Also 4 could be defined as a preprocessor macro.

  	for (;;) {

-		/* make cpu1 to be turned off at next WFI command */
-		if (cpu == 1)
-			__raw_writel(0, S5P_ARM_CORE1_CONFIGURATION);
+		/* make cpu to be turned off at next WFI command */
+		if (cpu)

Do you need this if here at all? I don't think there would be any problem with this function called for CPU 0 (which shouldn't happen anyway, without CPU 0 hotplug support enabled).

+			__raw_writel(0, S5P_ARM_CORE_CONFIGURATION(cpunr));

  		/*
  		 * here's the WFI
diff --git a/arch/arm/mach-exynos/platsmp.c b/arch/arm/mach-exynos/platsmp.c
index 8ea02f6..8d06b2c 100644
--- a/arch/arm/mach-exynos/platsmp.c
+++ b/arch/arm/mach-exynos/platsmp.c
@@ -22,6 +22,7 @@
  #include <linux/io.h>

  #include <asm/cacheflush.h>
+#include <asm/cputype.h>
  #include <asm/smp_plat.h>
  #include <asm/smp_scu.h>
  #include <asm/firmware.h>
@@ -92,6 +93,14 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
  {
  	unsigned long timeout;
  	unsigned long phys_cpu = cpu_logical_map(cpu);
+	unsigned int mpidr, cpunr, cluster;
+
+	mpidr = cpu_logical_map(cpu);
+	cpunr = MPIDR_AFFINITY_LEVEL(mpidr, 0);
+	cluster = MPIDR_AFFINITY_LEVEL(mpidr, 1);
+
+	/* Maximum possible cpus in a cluster can be 4 */
+	cpunr += cluster * 4;

Here basically the same code is used as in hotplug.c, so a helper would be nice. (e.g. cpunr = exynos_pmu_cpunr(mpidr)).


  	/*
  	 * Set synchronisation state between this boot processor
@@ -109,14 +118,15 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
  	 */
  	write_pen_release(phys_cpu);

-	if (!(__raw_readl(S5P_ARM_CORE1_STATUS) & S5P_CORE_LOCAL_PWR_EN)) {
+	if (!(__raw_readl(S5P_ARM_CORE_STATUS(cpunr))
+		& S5P_CORE_LOCAL_PWR_EN)) {
  		__raw_writel(S5P_CORE_LOCAL_PWR_EN,
-			     S5P_ARM_CORE1_CONFIGURATION);
+			     S5P_ARM_CORE_CONFIGURATION(cpunr));

  		timeout = 10;

-		/* wait max 10 ms until cpu1 is on */
-		while ((__raw_readl(S5P_ARM_CORE1_STATUS)
+		/* wait max 10 ms until secondary cpu is on */
+		while ((__raw_readl(S5P_ARM_CORE_STATUS(cpunr))
  			& S5P_CORE_LOCAL_PWR_EN) != S5P_CORE_LOCAL_PWR_EN) {
  			if (timeout-- == 0)
  				break;
@@ -125,7 +135,7 @@ static int exynos_boot_secondary(unsigned int cpu, struct task_struct *idle)
  		}

  		if (timeout == 0) {
-			printk(KERN_ERR "cpu1 power enable failed");
+			pr_err("cpu%x power enable failed", cpu);

Shouldn't %d be used instead? "cpu a" on a 10-core machine would sound weird.

  			spin_unlock(&boot_lock);
  			return -ETIMEDOUT;
  		}
diff --git a/arch/arm/mach-exynos/regs-pmu.h b/arch/arm/mach-exynos/regs-pmu.h
index 7c029ce..16e17e4 100644
--- a/arch/arm/mach-exynos/regs-pmu.h
+++ b/arch/arm/mach-exynos/regs-pmu.h
@@ -104,8 +104,13 @@
  #define S5P_GPS_LOWPWR				S5P_PMUREG(0x139C)
  #define S5P_GPS_ALIVE_LOWPWR			S5P_PMUREG(0x13A0)

-#define S5P_ARM_CORE1_CONFIGURATION		S5P_PMUREG(0x2080)
-#define S5P_ARM_CORE1_STATUS			S5P_PMUREG(0x2084)
+#define S5P_ARM_CORE0_CONFIGURATION		S5P_PMUREG(0x2000)
+#define S5P_ARM_CORE0_STATUS			S5P_PMUREG(0x2004)
+
+#define S5P_ARM_CORE_CONFIGURATION(_cpunr)	\
+		(S5P_ARM_CORE0_CONFIGURATION + 0x80 * _cpunr)
+#define S5P_ARM_CORE_STATUS(_cpunr)		\
+		(S5P_ARM_CORE0_STATUS + 0x80 * _cpunr)

Please wrap _cpunr in parentheses to make sure that passed value doesn't affect the order of computations.

Best regards,
Tomasz
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