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/*
 * PowerNV OPAL high level interfaces
 *
 * Copyright 2011 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.
 */

#undef DEBUG

#include <linux/types.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_platform.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/kobject.h>
#include <asm/opal.h>
#include <asm/firmware.h>
#include <asm/mce.h>

#include "powernv.h"

/* /sys/firmware/opal */
struct kobject *opal_kobj;

struct opal {
	u64 base;
	u64 entry;
} opal;

static struct device_node *opal_node;
static DEFINE_SPINLOCK(opal_write_lock);
extern u64 opal_mc_secondary_handler[];
static unsigned int *opal_irqs;
static unsigned int opal_irq_count;
static ATOMIC_NOTIFIER_HEAD(opal_notifier_head);
static struct atomic_notifier_head opal_msg_notifier_head[OPAL_MSG_TYPE_MAX];
static DEFINE_SPINLOCK(opal_notifier_lock);
static uint64_t last_notified_mask = 0x0ul;
static atomic_t opal_notifier_hold = ATOMIC_INIT(0);

int __init early_init_dt_scan_opal(unsigned long node,
				   const char *uname, int depth, void *data)
{
	const void *basep, *entryp;
	unsigned long basesz, entrysz;

	if (depth != 1 || strcmp(uname, "ibm,opal") != 0)
		return 0;

	basep  = of_get_flat_dt_prop(node, "opal-base-address", &basesz);
	entryp = of_get_flat_dt_prop(node, "opal-entry-address", &entrysz);

	if (!basep || !entryp)
		return 1;

	opal.base = of_read_number(basep, basesz/4);
	opal.entry = of_read_number(entryp, entrysz/4);

	pr_debug("OPAL Base  = 0x%llx (basep=%p basesz=%ld)\n",
		 opal.base, basep, basesz);
	pr_debug("OPAL Entry = 0x%llx (entryp=%p basesz=%ld)\n",
		 opal.entry, entryp, entrysz);

	powerpc_firmware_features |= FW_FEATURE_OPAL;
	if (of_flat_dt_is_compatible(node, "ibm,opal-v3")) {
		powerpc_firmware_features |= FW_FEATURE_OPALv2;
		powerpc_firmware_features |= FW_FEATURE_OPALv3;
		printk("OPAL V3 detected !\n");
	} else if (of_flat_dt_is_compatible(node, "ibm,opal-v2")) {
		powerpc_firmware_features |= FW_FEATURE_OPALv2;
		printk("OPAL V2 detected !\n");
	} else {
		printk("OPAL V1 detected !\n");
	}

	return 1;
}

static int __init opal_register_exception_handlers(void)
{
#ifdef __BIG_ENDIAN__
	u64 glue;

	if (!(powerpc_firmware_features & FW_FEATURE_OPAL))
		return -ENODEV;

	/* Hookup some exception handlers except machine check. We use the
	 * fwnmi area at 0x7000 to provide the glue space to OPAL
	 */
	glue = 0x7000;
	opal_register_exception_handler(OPAL_HYPERVISOR_MAINTENANCE_HANDLER,
					0, glue);
	glue += 128;
	opal_register_exception_handler(OPAL_SOFTPATCH_HANDLER, 0, glue);
#endif

	return 0;
}

early_initcall(opal_register_exception_handlers);

int opal_notifier_register(struct notifier_block *nb)
{
	if (!nb) {
		pr_warning("%s: Invalid argument (%p)\n",
			   __func__, nb);
		return -EINVAL;
	}

	atomic_notifier_chain_register(&opal_notifier_head, nb);
	return 0;
}

static void opal_do_notifier(uint64_t events)
{
	unsigned long flags;
	uint64_t changed_mask;

	if (atomic_read(&opal_notifier_hold))
		return;

	spin_lock_irqsave(&opal_notifier_lock, flags);
	changed_mask = last_notified_mask ^ events;
	last_notified_mask = events;
	spin_unlock_irqrestore(&opal_notifier_lock, flags);

	/*
	 * We feed with the event bits and changed bits for
	 * enough information to the callback.
	 */
	atomic_notifier_call_chain(&opal_notifier_head,
				   events, (void *)changed_mask);
}

void opal_notifier_update_evt(uint64_t evt_mask,
			      uint64_t evt_val)
{
	unsigned long flags;

	spin_lock_irqsave(&opal_notifier_lock, flags);
	last_notified_mask &= ~evt_mask;
	last_notified_mask |= evt_val;
	spin_unlock_irqrestore(&opal_notifier_lock, flags);
}

void opal_notifier_enable(void)
{
	int64_t rc;
	uint64_t evt = 0;

	atomic_set(&opal_notifier_hold, 0);

	/* Process pending events */
	rc = opal_poll_events(&evt);
	if (rc == OPAL_SUCCESS && evt)
		opal_do_notifier(evt);
}

void opal_notifier_disable(void)
{
	atomic_set(&opal_notifier_hold, 1);
}

/*
 * Opal message notifier based on message type. Allow subscribers to get
 * notified for specific messgae type.
 */
int opal_message_notifier_register(enum OpalMessageType msg_type,
					struct notifier_block *nb)
{
	if (!nb) {
		pr_warning("%s: Invalid argument (%p)\n",
			   __func__, nb);
		return -EINVAL;
	}
	if (msg_type > OPAL_MSG_TYPE_MAX) {
		pr_warning("%s: Invalid message type argument (%d)\n",
			   __func__, msg_type);
		return -EINVAL;
	}
	return atomic_notifier_chain_register(
				&opal_msg_notifier_head[msg_type], nb);
}

static void opal_message_do_notify(uint32_t msg_type, void *msg)
{
	/* notify subscribers */
	atomic_notifier_call_chain(&opal_msg_notifier_head[msg_type],
					msg_type, msg);
}

static void opal_handle_message(void)
{
	s64 ret;
	/*
	 * TODO: pre-allocate a message buffer depending on opal-msg-size
	 * value in /proc/device-tree.
	 */
	static struct opal_msg msg;

	ret = opal_get_msg(__pa(&msg), sizeof(msg));
	/* No opal message pending. */
	if (ret == OPAL_RESOURCE)
		return;

	/* check for errors. */
	if (ret) {
		pr_warning("%s: Failed to retrive opal message, err=%lld\n",
				__func__, ret);
		return;
	}

	/* Sanity check */
	if (msg.msg_type > OPAL_MSG_TYPE_MAX) {
		pr_warning("%s: Unknown message type: %u\n",
				__func__, msg.msg_type);
		return;
	}
	opal_message_do_notify(msg.msg_type, (void *)&msg);
}

static int opal_message_notify(struct notifier_block *nb,
			  unsigned long events, void *change)
{
	if (events & OPAL_EVENT_MSG_PENDING)
		opal_handle_message();
	return 0;
}

static struct notifier_block opal_message_nb = {
	.notifier_call	= opal_message_notify,
	.next		= NULL,
	.priority	= 0,
};

static int __init opal_message_init(void)
{
	int ret, i;

	for (i = 0; i < OPAL_MSG_TYPE_MAX; i++)
		ATOMIC_INIT_NOTIFIER_HEAD(&opal_msg_notifier_head[i]);

	ret = opal_notifier_register(&opal_message_nb);
	if (ret) {
		pr_err("%s: Can't register OPAL event notifier (%d)\n",
		       __func__, ret);
		return ret;
	}
	return 0;
}
early_initcall(opal_message_init);

int opal_get_chars(uint32_t vtermno, char *buf, int count)
{
	s64 rc;
	__be64 evt, len;

	if (!opal.entry)
		return -ENODEV;
	opal_poll_events(&evt);
	if ((be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_INPUT) == 0)
		return 0;
	len = cpu_to_be64(count);
	rc = opal_console_read(vtermno, &len, buf);	
	if (rc == OPAL_SUCCESS)
		return be64_to_cpu(len);
	return 0;
}

int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
{
	int written = 0;
	__be64 olen;
	s64 len, rc;
	unsigned long flags;
	__be64 evt;

	if (!opal.entry)
		return -ENODEV;

	/* We want put_chars to be atomic to avoid mangling of hvsi
	 * packets. To do that, we first test for room and return
	 * -EAGAIN if there isn't enough.
	 *
	 * Unfortunately, opal_console_write_buffer_space() doesn't
	 * appear to work on opal v1, so we just assume there is
	 * enough room and be done with it
	 */
	spin_lock_irqsave(&opal_write_lock, flags);
	if (firmware_has_feature(FW_FEATURE_OPALv2)) {
		rc = opal_console_write_buffer_space(vtermno, &olen);
		len = be64_to_cpu(olen);
		if (rc || len < total_len) {
			spin_unlock_irqrestore(&opal_write_lock, flags);
			/* Closed -> drop characters */
			if (rc)
				return total_len;
			opal_poll_events(NULL);
			return -EAGAIN;
		}
	}

	/* We still try to handle partial completions, though they
	 * should no longer happen.
	 */
	rc = OPAL_BUSY;
	while(total_len > 0 && (rc == OPAL_BUSY ||
				rc == OPAL_BUSY_EVENT || rc == OPAL_SUCCESS)) {
		olen = cpu_to_be64(total_len);
		rc = opal_console_write(vtermno, &olen, data);
		len = be64_to_cpu(olen);

		/* Closed or other error drop */
		if (rc != OPAL_SUCCESS && rc != OPAL_BUSY &&
		    rc != OPAL_BUSY_EVENT) {
			written = total_len;
			break;
		}
		if (rc == OPAL_SUCCESS) {
			total_len -= len;
			data += len;
			written += len;
		}
		/* This is a bit nasty but we need that for the console to
		 * flush when there aren't any interrupts. We will clean
		 * things a bit later to limit that to synchronous path
		 * such as the kernel console and xmon/udbg
		 */
		do
			opal_poll_events(&evt);
		while(rc == OPAL_SUCCESS &&
			(be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT));
	}
	spin_unlock_irqrestore(&opal_write_lock, flags);
	return written;
}

static int opal_recover_mce(struct pt_regs *regs,
					struct machine_check_event *evt)
{
	int recovered = 0;
	uint64_t ea = get_mce_fault_addr(evt);

	if (!(regs->msr & MSR_RI)) {
		/* If MSR_RI isn't set, we cannot recover */
		recovered = 0;
	} else if (evt->disposition == MCE_DISPOSITION_RECOVERED) {
		/* Platform corrected itself */
		recovered = 1;
	} else if (ea && !is_kernel_addr(ea)) {
		/*
		 * Faulting address is not in kernel text. We should be fine.
		 * We need to find which process uses this address.
		 * For now, kill the task if we have received exception when
		 * in userspace.
		 *
		 * TODO: Queue up this address for hwpoisioning later.
		 */
		if (user_mode(regs) && !is_global_init(current)) {
			_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
			recovered = 1;
		} else
			recovered = 0;
	} else if (user_mode(regs) && !is_global_init(current) &&
		evt->severity == MCE_SEV_ERROR_SYNC) {
		/*
		 * If we have received a synchronous error when in userspace
		 * kill the task.
		 */
		_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
		recovered = 1;
	}
	return recovered;
}

int opal_machine_check(struct pt_regs *regs)
{
	struct machine_check_event evt;

	if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
		return 0;

	/* Print things out */
	if (evt.version != MCE_V1) {
		pr_err("Machine Check Exception, Unknown event version %d !\n",
		       evt.version);
		return 0;
	}
	machine_check_print_event_info(&evt);

	if (opal_recover_mce(regs, &evt))
		return 1;
	return 0;
}

static irqreturn_t opal_interrupt(int irq, void *data)
{
	__be64 events;

	opal_handle_interrupt(virq_to_hw(irq), &events);

	opal_do_notifier(events);

	return IRQ_HANDLED;
}

static int opal_sysfs_init(void)
{
	opal_kobj = kobject_create_and_add("opal", firmware_kobj);
	if (!opal_kobj) {
		pr_warn("kobject_create_and_add opal failed\n");
		return -ENOMEM;
	}

	return 0;
}

static int __init opal_init(void)
{
	struct device_node *np, *consoles;
	const __be32 *irqs;
	int rc, i, irqlen;

	opal_node = of_find_node_by_path("/ibm,opal");
	if (!opal_node) {
		pr_warn("opal: Node not found\n");
		return -ENODEV;
	}

	/* Register OPAL consoles if any ports */
	if (firmware_has_feature(FW_FEATURE_OPALv2))
		consoles = of_find_node_by_path("/ibm,opal/consoles");
	else
		consoles = of_node_get(opal_node);
	if (consoles) {
		for_each_child_of_node(consoles, np) {
			if (strcmp(np->name, "serial"))
				continue;
			of_platform_device_create(np, NULL, NULL);
		}
		of_node_put(consoles);
	}

	/* Find all OPAL interrupts and request them */
	irqs = of_get_property(opal_node, "opal-interrupts", &irqlen);
	pr_debug("opal: Found %d interrupts reserved for OPAL\n",
		 irqs ? (irqlen / 4) : 0);
	opal_irq_count = irqlen / 4;
	opal_irqs = kzalloc(opal_irq_count * sizeof(unsigned int), GFP_KERNEL);
	for (i = 0; irqs && i < (irqlen / 4); i++, irqs++) {
		unsigned int hwirq = be32_to_cpup(irqs);
		unsigned int irq = irq_create_mapping(NULL, hwirq);
		if (irq == NO_IRQ) {
			pr_warning("opal: Failed to map irq 0x%x\n", hwirq);
			continue;
		}
		rc = request_irq(irq, opal_interrupt, 0, "opal", NULL);
		if (rc)
			pr_warning("opal: Error %d requesting irq %d"
				   " (0x%x)\n", rc, irq, hwirq);
		opal_irqs[i] = irq;
	}

	/* Create "opal" kobject under /sys/firmware */
	rc = opal_sysfs_init();
	if (rc == 0) {
		/* Setup code update interface */
		opal_flash_init();
	}

	return 0;
}
subsys_initcall(opal_init);

void opal_shutdown(void)
{
	unsigned int i;

	for (i = 0; i < opal_irq_count; i++) {
		if (opal_irqs[i])
			free_irq(opal_irqs[i], NULL);
		opal_irqs[i] = 0;
	}
}

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