1 files changed, 161 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-msglog.c b/arch/powerpc/platforms/powernv/opal-msglog.c
new file mode 100644
index 000000000..d3b6e135c
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-msglog.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PowerNV OPAL in-memory console interface
+ *
+ * Copyright 2014 IBM Corp.
+ */
+
+#include <asm/io.h>
+#include <asm/opal.h>
+#include <linux/debugfs.h>
+#include <linux/of.h>
+#include <linux/types.h>
+#include <asm/barrier.h>
+
+#include "powernv.h"
+
+/* OPAL in-memory console. Defined in OPAL source at core/console.c */
+struct memcons {
+	__be64 magic;
+#define MEMCONS_MAGIC	0x6630696567726173L
+	__be64 obuf_phys;
+	__be64 ibuf_phys;
+	__be32 obuf_size;
+	__be32 ibuf_size;
+	__be32 out_pos;
+#define MEMCONS_OUT_POS_WRAP	0x80000000u
+#define MEMCONS_OUT_POS_MASK	0x00ffffffu
+	__be32 in_prod;
+	__be32 in_cons;
+};
+
+static struct memcons *opal_memcons = NULL;
+
+ssize_t memcons_copy(struct memcons *mc, char *to, loff_t pos, size_t count)
+{
+	const char *conbuf;
+	ssize_t ret;
+	size_t first_read = 0;
+	uint32_t out_pos, avail;
+
+	if (!mc)
+		return -ENODEV;
+
+	out_pos = be32_to_cpu(READ_ONCE(mc->out_pos));
+
+	/* Now we've read out_pos, put a barrier in before reading the new
+	 * data it points to in conbuf. */
+	smp_rmb();
+
+	conbuf = phys_to_virt(be64_to_cpu(mc->obuf_phys));
+
+	/* When the buffer has wrapped, read from the out_pos marker to the end
+	 * of the buffer, and then read the remaining data as in the un-wrapped
+	 * case. */
+	if (out_pos & MEMCONS_OUT_POS_WRAP) {
+
+		out_pos &= MEMCONS_OUT_POS_MASK;
+		avail = be32_to_cpu(mc->obuf_size) - out_pos;
+
+		ret = memory_read_from_buffer(to, count, &pos,
+				conbuf + out_pos, avail);
+
+		if (ret < 0)
+			goto out;
+
+		first_read = ret;
+		to += first_read;
+		count -= first_read;
+		pos -= avail;
+
+		if (count <= 0)
+			goto out;
+	}
+
+	/* Sanity check. The firmware should not do this to us. */
+	if (out_pos > be32_to_cpu(mc->obuf_size)) {
+		pr_err("OPAL: memory console corruption. Aborting read.\n");
+		return -EINVAL;
+	}
+
+	ret = memory_read_from_buffer(to, count, &pos, conbuf, out_pos);
+
+	if (ret < 0)
+		goto out;
+
+	ret += first_read;
+out:
+	return ret;
+}
+
+ssize_t opal_msglog_copy(char *to, loff_t pos, size_t count)
+{
+	return memcons_copy(opal_memcons, to, pos, count);
+}
+
+static ssize_t opal_msglog_read(struct file *file, struct kobject *kobj,
+				struct bin_attribute *bin_attr, char *to,
+				loff_t pos, size_t count)
+{
+	return opal_msglog_copy(to, pos, count);
+}
+
+static struct bin_attribute opal_msglog_attr = {
+	.attr = {.name = "msglog", .mode = 0400},
+	.read = opal_msglog_read
+};
+
+struct memcons *memcons_init(struct device_node *node, const char *mc_prop_name)
+{
+	u64 mcaddr;
+	struct memcons *mc;
+
+	if (of_property_read_u64(node, mc_prop_name, &mcaddr)) {
+		pr_warn("%s property not found, no message log\n",
+			mc_prop_name);
+		goto out_err;
+	}
+
+	mc = phys_to_virt(mcaddr);
+	if (!mc) {
+		pr_warn("memory console address is invalid\n");
+		goto out_err;
+	}
+
+	if (be64_to_cpu(mc->magic) != MEMCONS_MAGIC) {
+		pr_warn("memory console version is invalid\n");
+		goto out_err;
+	}
+
+	return mc;
+
+out_err:
+	return NULL;
+}
+
+u32 memcons_get_size(struct memcons *mc)
+{
+	return be32_to_cpu(mc->ibuf_size) + be32_to_cpu(mc->obuf_size);
+}
+
+void __init opal_msglog_init(void)
+{
+	opal_memcons = memcons_init(opal_node, "ibm,opal-memcons");
+	if (!opal_memcons) {
+		pr_warn("OPAL: memcons failed to load from ibm,opal-memcons\n");
+		return;
+	}
+
+	opal_msglog_attr.size = memcons_get_size(opal_memcons);
+}
+
+void __init opal_msglog_sysfs_init(void)
+{
+	if (!opal_memcons) {
+		pr_warn("OPAL: message log initialisation failed, not creating sysfs entry\n");
+		return;
+	}
+
+	if (sysfs_create_bin_file(opal_kobj, &opal_msglog_attr) != 0)
+		pr_warn("OPAL: sysfs file creation failed\n");
+}