From: Hans-Joachim Picht <hpicht@redhat.com>
Date: Thu, 12 Mar 2009 15:23:11 +0100
Subject: [s390] kernel: processor degredation support
Message-id: 20090312142311.GF5103@redhat.com
O-Subject: [RHEL5 U4 PATCH 5/20] FEAT: s390 - kernel: Processor degredation support
Bugzilla: 475820

Description
============

Generate uevents for all cpus if cpu capability changes. This can
happen e.g. because the cpus are overheating. The cpu capability can
be read via /sys/devices/system/cpu/cpuN/capability.

Bugzilla
=========

BZ 475820
https://bugzilla.redhat.com/show_bug.cgi?id=475820

Upstream status of the patch:
=============================

The patch is upstream as of git commit
2fc2d1e9ffcde78af7ab63ed640d9a4901797de2

Test status:
============

The patch has been tested by the IBM test department.

Please ACK.

With best regards,

	--Hans

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index e07b571..29148ec 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -820,16 +820,56 @@ int setup_profiling_timer(unsigned int multiplier)
 
 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 
+static ssize_t show_capability(struct sys_device *dev, char *buf)
+{
+	unsigned int capability;
+	int rc;
+
+	rc = get_cpu_capability(&capability);
+	if (rc)
+		return rc;
+	return sprintf(buf, "%u\n", capability);
+}
+static SYSDEV_ATTR(capability, 0444, show_capability, NULL);
+
+static int __cpuinit smp_cpu_notify(struct notifier_block *self,
+				    unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned int)(long)hcpu;
+	struct cpu *c = &per_cpu(cpu_devices, cpu);
+	struct sys_device *s = &c->sysdev;
+
+	switch (action) {
+	case CPU_ONLINE:
+		if (sysdev_create_file(s, &attr_capability))
+			return NOTIFY_BAD;
+		break;
+	case CPU_DEAD:
+		sysdev_remove_file(s, &attr_capability);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata smp_cpu_nb = {
+	.notifier_call	= smp_cpu_notify,
+};
+
 static int __init topology_init(void)
 {
 	int cpu;
-	int ret;
+
+	register_cpu_notifier(&smp_cpu_nb);
 
 	for_each_possible_cpu(cpu) {
-		ret = register_cpu(&per_cpu(cpu_devices, cpu), cpu);
-		if (ret)
-			printk(KERN_WARNING "topology_init: register_cpu %d "
-			       "failed (%d)\n", cpu, ret);
+		struct cpu *c = &per_cpu(cpu_devices, cpu);
+		struct sys_device *s = &c->sysdev;
+
+		register_cpu(c, cpu);
+		if (!cpu_online(cpu))
+			continue;
+		s = &c->sysdev;
+		sysdev_create_file(s, &attr_capability);
 	}
 	return 0;
 }
diff --git a/drivers/s390/Kconfig b/drivers/s390/Kconfig
index 2fceefc..69c34c5 100644
--- a/drivers/s390/Kconfig
+++ b/drivers/s390/Kconfig
@@ -103,13 +103,8 @@ config CCW_CONSOLE
  	depends on TN3215_CONSOLE || TN3270_CONSOLE
  	default y
  
-config SCLP
-	bool
-	default y
-
 config SCLP_TTY
 	bool "Support for SCLP line mode terminal"
-	depends on SCLP
 	help
 	  Include support for IBM SCLP line-mode terminals.
 
@@ -122,7 +117,6 @@ config SCLP_CONSOLE
 
 config SCLP_VT220_TTY
 	bool "Support for SCLP VT220-compatible terminal"
-	depends on SCLP
 	help
 	  Include support for an IBM SCLP VT220-compatible terminal.
 
@@ -135,7 +129,6 @@ config SCLP_VT220_CONSOLE
 
 config SCLP_CPI
 	tristate "Control-Program Identification"
-	depends on SCLP
 	help
 	  This option enables the hardware console interface for system
 	  identification. This is commonly used for workload management and
diff --git a/drivers/s390/char/Makefile b/drivers/s390/char/Makefile
index bf90ae9..e3f5f9a 100644
--- a/drivers/s390/char/Makefile
+++ b/drivers/s390/char/Makefile
@@ -2,7 +2,8 @@
 # S/390 character devices
 #
 
-obj-y += ctrlchar.o keyboard.o defkeymap.o
+obj-y += ctrlchar.o keyboard.o defkeymap.o sclp.o sclp_rw.o sclp_quiesce.o \
+	 sclp_chp.o sclp_config.o
 
 obj-$(CONFIG_TN3270) += raw3270.o
 obj-$(CONFIG_TN3270_CONSOLE) += con3270.o
@@ -11,7 +12,6 @@ obj-$(CONFIG_TN3270_FS) += fs3270.o
 
 obj-$(CONFIG_TN3215) += con3215.o
 
-obj-$(CONFIG_SCLP) += sclp.o sclp_rw.o sclp_quiesce.o sclp_chp.o
 obj-$(CONFIG_SCLP_TTY) += sclp_tty.o
 obj-$(CONFIG_SCLP_CONSOLE) += sclp_con.o
 obj-$(CONFIG_SCLP_VT220_TTY) += sclp_vt220.o
diff --git a/drivers/s390/char/sclp.h b/drivers/s390/char/sclp.h
index 57bd20d..be612c1 100644
--- a/drivers/s390/char/sclp.h
+++ b/drivers/s390/char/sclp.h
@@ -28,6 +28,7 @@
 #define EvTyp_CntlProgIdent	0x0B
 #define EvTyp_SigQuiesce	0x1D
 #define EvTyp_VT220Msg		0x1A
+#define EVTYP_CONFMGMDATA	0x04
 #define EVTYP_SDIAS		0x1C
 
 #define EvTyp_OpCmd_Mask	0x80000000
@@ -38,6 +39,7 @@
 #define EvTyp_CtlProgIdent_Mask	0x00200000
 #define EvTyp_SigQuiesce_Mask	0x00000008
 #define EvTyp_VT220Msg_Mask	0x00000040
+#define EVTYP_CONFMGMDATA_MASK	0x10000000
 #define EVTYP_SDIAS_MASK	0x00000010
 
 #define GnrlMsgFlgs_DOM		0x8000
diff --git a/drivers/s390/char/sclp_config.c b/drivers/s390/char/sclp_config.c
new file mode 100644
index 0000000..94aec6d
--- /dev/null
+++ b/drivers/s390/char/sclp_config.c
@@ -0,0 +1,75 @@
+/*
+ *  drivers/s390/char/sclp_config.c
+ *
+ *    Copyright IBM Corp. 2007
+ *    Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/cpu.h>
+#include <linux/sysdev.h>
+#include <linux/workqueue.h>
+#include "sclp.h"
+
+#define TAG	"sclp_config: "
+
+struct conf_mgm_data {
+	u8 reserved;
+	u8 ev_qualifier;
+} __attribute__((packed));
+
+#define EV_QUAL_CAP_CHANGE	3
+
+static struct work_struct sclp_cpu_capability_work;
+
+static void sclp_cpu_capability_notify(void *data)
+{
+	int cpu;
+	struct sys_device *sysdev;
+
+	printk(KERN_WARNING TAG "cpu capability changed.\n");
+	lock_cpu_hotplug();
+	for_each_online_cpu(cpu) {
+		sysdev = get_cpu_sysdev(cpu);
+		kobject_uevent(&sysdev->kobj, KOBJ_CHANGE);
+	}
+	unlock_cpu_hotplug();
+}
+
+static void sclp_conf_receiver_fn(struct evbuf_header *evbuf)
+{
+	struct conf_mgm_data *cdata;
+
+	cdata = (struct conf_mgm_data *)(evbuf + 1);
+	if (cdata->ev_qualifier == EV_QUAL_CAP_CHANGE)
+		schedule_work(&sclp_cpu_capability_work);
+}
+
+static struct sclp_register sclp_conf_register =
+{
+	.receive_mask = EVTYP_CONFMGMDATA_MASK,
+	.receiver_fn  = sclp_conf_receiver_fn,
+};
+
+static int __init sclp_conf_init(void)
+{
+	int rc;
+
+	INIT_WORK(&sclp_cpu_capability_work, sclp_cpu_capability_notify, NULL);
+
+	rc = sclp_register(&sclp_conf_register);
+	if (rc) {
+		printk(KERN_ERR TAG "failed to register (%d).\n", rc);
+		return rc;
+	}
+
+	if (!(sclp_conf_register.sclp_receive_mask & EVTYP_CONFMGMDATA_MASK)) {
+		printk(KERN_WARNING TAG "no configuration management.\n");
+		sclp_unregister(&sclp_conf_register);
+		rc = -ENOSYS;
+	}
+	return rc;
+}
+
+__initcall(sclp_conf_init);
diff --git a/drivers/s390/sysinfo.c b/drivers/s390/sysinfo.c
index 0b05503..cfef136 100644
--- a/drivers/s390/sysinfo.c
+++ b/drivers/s390/sysinfo.c
@@ -269,6 +269,24 @@ static __init int create_proc_sysinfo(void)
 
 __initcall(create_proc_sysinfo);
 
+int get_cpu_capability(unsigned int *capability)
+{
+	struct sysinfo_1_2_2 *info;
+	int rc;
+
+	info = (void *) get_zeroed_page(GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+	rc = stsi(info, 1, 2, 2);
+	if (rc == -ENOSYS)
+		goto out;
+	rc = 0;
+	*capability = info->capability;
+out:
+	free_page((unsigned long) info);
+	return rc;
+}
+
 /*
  * Service levels interface.
  */
diff --git a/include/asm-s390/processor.h b/include/asm-s390/processor.h
index 671f104..81a5383 100644
--- a/include/asm-s390/processor.h
+++ b/include/asm-s390/processor.h
@@ -57,6 +57,7 @@ struct cpuinfo_S390
 };
 
 extern void print_cpu_info(struct cpuinfo_S390 *);
+extern int get_cpu_capability(unsigned int *);
 
 /* Lazy FPU handling on uni-processor */
 extern struct task_struct *last_task_used_math;