powerpc/powernv: Add support to set power-shifting-ratio

This patch adds support to set power-shifting-ratio which hints the
firmware how to distribute/throttle power between different entities
in a system (e.g CPU v/s GPU). This ratio is used by OCC for power
capping algorithm.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Documentation/ABI/testing/sysfs-firmware-opal-psr

@@ -0,0 +1,18 @@
+What:		/sys/firmware/opal/psr
+Date:		August 2017
+Contact:	Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description:	Power-Shift-Ratio directory for Powernv P9 servers
+
+		Power-Shift-Ratio allows to provide hints the firmware
+		to shift/throttle power between different entities in
+		the system. Each attribute in this directory indicates
+		a settable PSR.
+
+What:		/sys/firmware/opal/psr/cpu_to_gpu_X
+Date:		August 2017
+Contact:	Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
+Description:	PSR sysfs attributes for Powernv P9 servers
+
+		Power-Shift-Ratio between CPU and GPU for a given chip
+		with chip-id X. This file gives the ratio (0-100)
+		which is used by OCC for power-capping.

arch/powerpc/include/asm/opal-api.h

@@ -196,6 +196,8 @@
 #define OPAL_IMC_COUNTERS_STOP			151
 #define OPAL_GET_POWERCAP			152
 #define OPAL_SET_POWERCAP			153
+#define OPAL_GET_POWER_SHIFT_RATIO		154
+#define OPAL_SET_POWER_SHIFT_RATIO		155
 #define OPAL_PCI_SET_P2P			157
 #define OPAL_LAST				157
 

arch/powerpc/include/asm/opal.h

@@ -277,6 +277,8 @@ int64_t opal_imc_counters_stop(uint32_t type, uint64_t cpu_pir);
 
 int opal_get_powercap(u32 handle, int token, u32 *pcap);
 int opal_set_powercap(u32 handle, int token, u32 pcap);
+int opal_get_power_shift_ratio(u32 handle, int token, u32 *psr);
+int opal_set_power_shift_ratio(u32 handle, int token, u32 psr);
 
 /* Internal functions */
 extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
@@ -356,6 +358,7 @@ static inline int opal_get_async_rc(struct opal_msg msg)
 void opal_wake_poller(void);
 
 void opal_powercap_init(void);
+void opal_psr_init(void);
 
 #endif /* __ASSEMBLY__ */
 

arch/powerpc/platforms/powernv/Makefile

@@ -2,7 +2,7 @@ obj-y			+= setup.o opal-wrappers.o opal.o opal-async.o idle.o
 obj-y			+= opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
 obj-y			+= rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o
 obj-y			+= opal-msglog.o opal-hmi.o opal-power.o opal-irqchip.o
-obj-y			+= opal-kmsg.o opal-powercap.o
+obj-y			+= opal-kmsg.o opal-powercap.o opal-psr.o
 
 obj-$(CONFIG_SMP)	+= smp.o subcore.o subcore-asm.o
 obj-$(CONFIG_PCI)	+= pci.o pci-ioda.o npu-dma.o

arch/powerpc/platforms/powernv/opal-psr.c

@@ -0,0 +1,175 @@
+/*
+ * PowerNV OPAL Power-Shift-Ratio interface
+ *
+ * Copyright 2017 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt)     "opal-psr: " fmt
+
+#include <linux/of.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+
+#include <asm/opal.h>
+
+DEFINE_MUTEX(psr_mutex);
+
+static struct kobject *psr_kobj;
+
+struct psr_attr {
+	u32 handle;
+	struct kobj_attribute attr;
+} *psr_attrs;
+
+static ssize_t psr_show(struct kobject *kobj, struct kobj_attribute *attr,
+			char *buf)
+{
+	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
+	struct opal_msg msg;
+	int psr, ret, token;
+
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		pr_devel("Failed to get token\n");
+		return token;
+	}
+
+	ret = mutex_lock_interruptible(&psr_mutex);
+	if (ret)
+		goto out_token;
+
+	ret = opal_get_power_shift_ratio(psr_attr->handle, token,
+					    (u32 *)__pa(&psr));
+	switch (ret) {
+	case OPAL_ASYNC_COMPLETION:
+		ret = opal_async_wait_response(token, &msg);
+		if (ret) {
+			pr_devel("Failed to wait for the async response\n");
+			ret = -EIO;
+			goto out;
+		}
+		ret = opal_error_code(opal_get_async_rc(msg));
+		if (!ret) {
+			ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
+			if (ret < 0)
+				ret = -EIO;
+		}
+		break;
+	case OPAL_SUCCESS:
+		ret = sprintf(buf, "%u\n", be32_to_cpu(psr));
+		if (ret < 0)
+			ret = -EIO;
+		break;
+	default:
+		ret = opal_error_code(ret);
+	}
+
+out:
+	mutex_unlock(&psr_mutex);
+out_token:
+	opal_async_release_token(token);
+	return ret;
+}
+
+static ssize_t psr_store(struct kobject *kobj, struct kobj_attribute *attr,
+			 const char *buf, size_t count)
+{
+	struct psr_attr *psr_attr = container_of(attr, struct psr_attr, attr);
+	struct opal_msg msg;
+	int psr, ret, token;
+
+	ret = kstrtoint(buf, 0, &psr);
+	if (ret)
+		return ret;
+
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		pr_devel("Failed to get token\n");
+		return token;
+	}
+
+	ret = mutex_lock_interruptible(&psr_mutex);
+	if (ret)
+		goto out_token;
+
+	ret = opal_set_power_shift_ratio(psr_attr->handle, token, psr);
+	switch (ret) {
+	case OPAL_ASYNC_COMPLETION:
+		ret = opal_async_wait_response(token, &msg);
+		if (ret) {
+			pr_devel("Failed to wait for the async response\n");
+			ret = -EIO;
+			goto out;
+		}
+		ret = opal_error_code(opal_get_async_rc(msg));
+		if (!ret)
+			ret = count;
+		break;
+	case OPAL_SUCCESS:
+		ret = count;
+		break;
+	default:
+		ret = opal_error_code(ret);
+	}
+
+out:
+	mutex_unlock(&psr_mutex);
+out_token:
+	opal_async_release_token(token);
+	return ret;
+}
+
+void __init opal_psr_init(void)
+{
+	struct device_node *psr, *node;
+	int i = 0;
+
+	psr = of_find_compatible_node(NULL, NULL,
+				      "ibm,opal-power-shift-ratio");
+	if (!psr) {
+		pr_devel("Power-shift-ratio node not found\n");
+		return;
+	}
+
+	psr_attrs = kcalloc(of_get_child_count(psr), sizeof(struct psr_attr),
+			    GFP_KERNEL);
+	if (!psr_attrs)
+		return;
+
+	psr_kobj = kobject_create_and_add("psr", opal_kobj);
+	if (!psr_kobj) {
+		pr_warn("Failed to create psr kobject\n");
+		goto out;
+	}
+
+	for_each_child_of_node(psr, node) {
+		if (of_property_read_u32(node, "handle",
+					 &psr_attrs[i].handle))
+			goto out_kobj;
+
+		sysfs_attr_init(&psr_attrs[i].attr.attr);
+		if (of_property_read_string(node, "label",
+					    &psr_attrs[i].attr.attr.name))
+			goto out_kobj;
+		psr_attrs[i].attr.attr.mode = 0664;
+		psr_attrs[i].attr.show = psr_show;
+		psr_attrs[i].attr.store = psr_store;
+		if (sysfs_create_file(psr_kobj, &psr_attrs[i].attr.attr)) {
+			pr_devel("Failed to create psr sysfs file %s\n",
+				 psr_attrs[i].attr.attr.name);
+			goto out_kobj;
+		}
+		i++;
+	}
+
+	return;
+out_kobj:
+	kobject_put(psr_kobj);
+out:
+	kfree(psr_attrs);
+}

arch/powerpc/platforms/powernv/opal-wrappers.S

@@ -316,3 +316,5 @@ OPAL_CALL(opal_imc_counters_stop,		OPAL_IMC_COUNTERS_STOP);
 OPAL_CALL(opal_pci_set_p2p,			OPAL_PCI_SET_P2P);
 OPAL_CALL(opal_get_powercap,			OPAL_GET_POWERCAP);
 OPAL_CALL(opal_set_powercap,			OPAL_SET_POWERCAP);
+OPAL_CALL(opal_get_power_shift_ratio,		OPAL_GET_POWER_SHIFT_RATIO);
+OPAL_CALL(opal_set_power_shift_ratio,		OPAL_SET_POWER_SHIFT_RATIO);

arch/powerpc/platforms/powernv/opal.c

@@ -853,6 +853,9 @@ static int __init opal_init(void)
 	/* Initialise OPAL powercap interface */
 	opal_powercap_init();
 
+	/* Initialise OPAL Power-Shifting-Ratio interface */
+	opal_psr_init();
+
 	return 0;
 }
 machine_subsys_initcall(powernv, opal_init);