drivers: Import lastkmsg drivers from Xiaomi

The Patch based on QualComm release TAG:LA.UM.8.15.r1-06600-KAMORTA.0

Change-Id: I8331b7e35c3d5a3de88a701474ae4041e618cfcb
Signed-off-by: starlight5234 <starlight5234@protonmail.ch>

drivers/Kconfig

@@ -227,6 +227,8 @@ source "drivers/slimbus/Kconfig"
 
 source "drivers/esoc/Kconfig"
 
+source "drivers/lastkmsg/Kconfig"
+
 source "drivers/switch/Kconfig"
 
 source "drivers/sensors/Kconfig"

drivers/Makefile

@@ -188,6 +188,7 @@ obj-$(CONFIG_FSI)		+= fsi/
 obj-$(CONFIG_TEE)		+= tee/
 obj-$(CONFIG_MULTIPLEXER)	+= mux/
 obj-$(CONFIG_ESOC)              += esoc/
+obj-$(CONFIG_LAST_KMSG)         += lastkmsg/
 obj-$(CONFIG_SWITCH)            += switch/
 obj-$(CONFIG_UNISYS_VISORBUS)	+= visorbus/
 obj-$(CONFIG_SIOX)		+= siox/

drivers/lastkmsg/Kconfig

@@ -0,0 +1,5 @@
+menuconfig LAST_KMSG
+	tristate "Last Kmsg support"
+	default y
+	help
+	  Exports last_kmsg

drivers/lastkmsg/Makefile

@@ -0,0 +1 @@
+obj-y	+= last_kmsg.o

drivers/lastkmsg/last_kmsg.c

@@ -0,0 +1,132 @@
+/*
+ * Copyright (C) 2015 MediaTek Inc.
+ * Copyright (C) 2020 XiaoMi, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/slab.h>
+
+#include <linux/atomic.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/proc_fs.h>
+#include <linux/string.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/kthread.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_reserved_mem.h>
+#include <linux/pstore.h>
+#include <linux/io.h>
+extern struct pstore_info *psinfo;
+extern void pstore_record_init(struct pstore_record *record, struct pstore_info *psinfo);
+extern struct super_block *pstore_sb;
+
+#ifdef CONFIG_PSTORE
+void pstore_console_show(enum pstore_type_id type_id, struct seq_file *m, void *v)
+{
+	struct pstore_info *psi = psinfo;
+	unsigned int stop_loop = 65536;
+	struct dentry *root;
+
+	if (!psi || !pstore_sb)
+		return;
+
+	root = pstore_sb->s_root;
+
+	mutex_lock(&psi->read_mutex);
+	if (psi->open && psi->open(psi))
+		goto out;
+
+	for (; stop_loop; stop_loop--) {
+		struct pstore_record *record;
+		record = kzalloc(sizeof(*record), GFP_KERNEL);
+		if (!record) {
+			pr_err("out of memory creating record\n");
+			break;
+		}
+
+		pstore_record_init(record, psi);
+		record->size = psi->read(record);
+		if (record->size <= 0) {
+			kfree(record);
+			break;
+		}
+
+		if (record->type == type_id)
+			seq_write(m, record->buf, record->size);
+	}
+
+	if (psi->close)
+	  psi->close(psi);
+out:
+	mutex_unlock(&psi->read_mutex);
+
+	if (!stop_loop)
+		pr_err("looping? Too many records seen from '%s'\n",
+				  psi->name);
+}
+#endif
+
+static int ram_console_lastk_show(struct seq_file *m, void *v)
+{
+	pr_err("ram_console_lastk_show\n");
+
+#ifdef CONFIG_PSTORE_CONSOLE
+	/*pr_err("ram_console: pstore show start\n");*/
+	pstore_console_show(PSTORE_TYPE_CONSOLE, m, v);
+	/*pr_err("ram_console: pstore show end\n");*/
+#endif
+	return 0;
+}
+
+
+static int ram_console_show(struct seq_file *m, void *v)
+{
+	ram_console_lastk_show(m, v);
+	return 0;
+}
+
+static int ram_console_file_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, ram_console_show, inode->i_private);
+}
+
+static const struct file_operations ram_console_file_ops = {
+	.owner = THIS_MODULE,
+	.open = ram_console_file_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int __init ram_console_late_init(void)
+{
+	struct proc_dir_entry *entry;
+
+	entry = proc_create("last_kmsg", 0444, NULL, &ram_console_file_ops);
+	if (!entry) {
+		pr_err("ram_console: failed to create proc entry\n");
+
+		return 0;
+	}
+	return 0;
+}
+
+late_initcall(ram_console_late_init);