125 lines
2.9 KiB
C
125 lines
2.9 KiB
C
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/*
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* PowerNV OPAL in-memory console interface
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*
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* Copyright 2014 IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/io.h>
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#include <asm/opal.h>
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#include <linux/debugfs.h>
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#include <linux/of.h>
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#include <linux/types.h>
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#include <asm/barrier.h>
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/* OPAL in-memory console. Defined in OPAL source at core/console.c */
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struct memcons {
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__be64 magic;
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#define MEMCONS_MAGIC 0x6630696567726173L
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__be64 obuf_phys;
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__be64 ibuf_phys;
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__be32 obuf_size;
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__be32 ibuf_size;
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__be32 out_pos;
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#define MEMCONS_OUT_POS_WRAP 0x80000000u
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#define MEMCONS_OUT_POS_MASK 0x00ffffffu
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__be32 in_prod;
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__be32 in_cons;
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};
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static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *to,
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loff_t pos, size_t count)
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{
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struct memcons *mc = bin_attr->private;
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const char *conbuf;
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ssize_t ret;
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size_t first_read = 0;
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uint32_t out_pos, avail;
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if (!mc)
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return -ENODEV;
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out_pos = be32_to_cpu(ACCESS_ONCE(mc->out_pos));
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/* Now we've read out_pos, put a barrier in before reading the new
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* data it points to in conbuf. */
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smp_rmb();
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conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys));
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/* When the buffer has wrapped, read from the out_pos marker to the end
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* of the buffer, and then read the remaining data as in the un-wrapped
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* case. */
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if (out_pos & MEMCONS_OUT_POS_WRAP) {
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out_pos &= MEMCONS_OUT_POS_MASK;
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avail = be32_to_cpu(mc->obuf_size) - out_pos;
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ret = memory_read_from_buffer(to, count, &pos,
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conbuf + out_pos, avail);
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if (ret < 0)
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goto out;
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first_read = ret;
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to += first_read;
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count -= first_read;
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pos -= avail;
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if (count <= 0)
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goto out;
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}
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/* Sanity check. The firmware should not do this to us. */
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if (out_pos > be32_to_cpu(mc->obuf_size)) {
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pr_err("OPAL: memory console corruption. Aborting read.\n");
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return -EINVAL;
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}
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ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos);
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if (ret < 0)
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goto out;
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ret += first_read;
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out:
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return ret;
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}
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static struct bin_attribute opal_msglog_attr = {
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.attr = {.name = "msglog", .mode = 0444},
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.read = opal_msglog_read
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};
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void __init opal_msglog_init(void)
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{
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u64 mcaddr;
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struct memcons *mc;
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if (of_property_read_u64(opal_node, "ibm,opal-memcons", &mcaddr)) {
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pr_warn("OPAL: Property ibm,opal-memcons not found, no message log\n");
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return;
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}
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mc = phys_to_virt(mcaddr);
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if (!mc) {
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pr_warn("OPAL: memory console address is invalid\n");
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return;
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}
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if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) {
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pr_warn("OPAL: memory console version is invalid\n");
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return;
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}
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opal_msglog_attr.private = mc;
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if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0)
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pr_warn("OPAL: sysfs file creation failed\n");
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}
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