ppc64: new scanlog interface

arch/ppc64/Kconfig

@@ -128,6 +128,10 @@ config RTAS_FLASH
 	tristate "Firmware flash interface"
 	depends on !PPC_ISERIES
 
+config SCANLOG
+	tristate "Scanlog dump interface"
+	depends on !PPC_ISERIES
+
 config PPC_RTAS
 	bool "Proc interface to RTAS"
 	depends on !PPC_ISERIES

arch/ppc64/kernel/Makefile

@@ -30,3 +30,4 @@ obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_PROFILING)		+= profile.o
 obj-$(CONFIG_MODULES)		+= module.o ppc_ksyms.o
 obj-$(CONFIG_PPC_RTAS)		+= rtas-proc.o
+obj-$(CONFIG_SCANLOG)		+= scanlog.o

arch/ppc64/kernel/rtas.c

@@ -56,6 +56,9 @@ struct rtas_t rtas = {
 
 extern unsigned long reloc_offset(void);
 
+spinlock_t rtas_data_buf_lock = SPIN_LOCK_UNLOCKED;
+char rtas_data_buf[RTAS_DATA_BUF_SIZE];
+
 void
 phys_call_rtas(int token, int nargs, int nret, ...)
 {
@@ -278,3 +281,10 @@ rtas_halt(void)
 		rtas_flash_bypass_warning();
         rtas_power_off();
 }
+
+EXPORT_SYMBOL(rtas_proc_dir);
+EXPORT_SYMBOL(rtas_firmware_flash_list);
+EXPORT_SYMBOL(rtas_token);
+EXPORT_SYMBOL(rtas_call);
+EXPORT_SYMBOL(rtas_data_buf);
+EXPORT_SYMBOL(rtas_data_buf_lock);

arch/ppc64/kernel/scanlog.c

+/*
+ *  c 2001 PPC 64 Team, 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.
+ *
+ * scan-log-data driver for PPC64  Todd Inglett <tinglett@vnet.ibm.com>
+ *
+ * When ppc64 hardware fails the service processor dumps internal state
+ * of the system.  After a reboot the operating system can access a dump
+ * of this data using this driver.  A dump exists if the device-tree
+ * /chosen/ibm,scan-log-data property exists.
+ *
+ * This driver exports /proc/ppc64/scan-log-dump which can be read.
+ * The driver supports only sequential reads.
+ *
+ * The driver looks at a write to the driver for the single word "reset".
+ * If given, the driver will reset the scanlog so the platform can free it.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/proc_fs.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+#include <asm/rtas.h>
+#include <asm/prom.h>
+
+#define MODULE_VERSION "1.0"
+#define MODULE_NAME "scanlog"
+
+/* Status returns from ibm,scan-log-dump */
+#define SCANLOG_COMPLETE 0
+#define SCANLOG_HWERROR -1
+#define SCANLOG_CONTINUE 1
+
+#define DEBUG(A...) do { if (scanlog_debug) printk(KERN_ERR "scanlog: " A); } while (0)
+
+static int scanlog_debug;
+static unsigned int ibm_scan_log_dump;			/* RTAS token */
+static struct proc_dir_entry *proc_ppc64_scan_log_dump;	/* The proc file */
+
+extern struct proc_dir_entry *proc_rtas;
+
+
+static ssize_t scanlog_read(struct file *file, char *buf,
+			    size_t count, loff_t *ppos)
+{
+        struct inode * inode = file->f_dentry->d_inode;
+	struct proc_dir_entry *dp;
+	unsigned int *data;
+	unsigned long status;
+	unsigned long len, off;
+	unsigned int wait_time;
+
+        dp = PDE(inode);
+ 	data = (unsigned int *)dp->data;
+
+	if (!data) {
+		printk(KERN_ERR "scanlog: read failed no data\n");
+		return -EIO;
+	}
+
+	if (count > RTAS_DATA_BUF_SIZE)
+		count = RTAS_DATA_BUF_SIZE;
+
+	if (count < 1024) {
+		/* This is the min supported by this RTAS call.  Rather
+		 * than do all the buffering we insist the user code handle
+		 * larger reads.  As long as cp works... :)
+		 */
+		printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
+		return -EINVAL;
+	}
+
+	if (verify_area(VERIFY_WRITE, buf, count))
+		return -EFAULT;
+
+	for (;;) {
+		wait_time = HZ/2;	/* default wait if no data */
+		spin_lock(&rtas_data_buf_lock);
+		memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
+		status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
+				   __pa(rtas_data_buf), count);
+		memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
+		spin_unlock(&rtas_data_buf_lock);
+
+		DEBUG("status=%ld, data[0]=%x, data[1]=%x, data[2]=%x\n",
+		      status, data[0], data[1], data[2]);
+		switch (status) {
+		    case SCANLOG_COMPLETE:
+			DEBUG("hit eof\n");
+			return 0;
+		    case SCANLOG_HWERROR:
+			DEBUG("hardware error reading scan log data\n");
+			return -EIO;
+		    case SCANLOG_CONTINUE:
+			/* We may or may not have data yet */
+			len = data[1];
+			off = data[2];
+			if (len > 0) {
+				if (copy_to_user(buf, ((char *)data)+off, len))
+					return -EFAULT;
+				return len;
+			}
+			/* Break to sleep default time */
+			break;
+		    default:
+			if (status > 9900 && status <= 9905) {
+				/* No data.  RTAS is hinting at a delay required
+				 * between 1-100000 milliseconds
+				 */
+				int ms = 1;
+				for (; status > 9900; status--)
+					ms = ms * 10;
+				/* Use microseconds for reasonable accuracy */
+				ms *= 1000;
+				wait_time = ms / (1000000/HZ); /* round down is fine */
+				/* Fall through to sleep */
+			} else {
+				printk(KERN_ERR "scanlog: unknown error from rtas: %ld\n", status);
+				return -EIO;
+			}
+		}
+		/* Apparently no data yet.  Wait and try again. */
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule_timeout(wait_time);
+	}
+	/*NOTREACHED*/
+}
+
+static ssize_t scanlog_write(struct file * file, const char * buf,
+			     size_t count, loff_t *ppos)
+{
+	unsigned long status;
+
+	if (buf) {
+		if (strncmp(buf, "reset", 5) == 0) {
+			DEBUG("reset scanlog\n");
+			status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, NULL, 0);
+			DEBUG("rtas returns %ld\n", status);
+		} else if (strncmp(buf, "debugon", 7) == 0) {
+			printk(KERN_ERR "scanlog: debug on\n");
+			scanlog_debug = 1;
+		} else if (strncmp(buf, "debugoff", 8) == 0) {
+			printk(KERN_ERR "scanlog: debug off\n");
+			scanlog_debug = 0;
+		}
+	}
+	return count;
+}
+
+static int scanlog_open(struct inode * inode, struct file * file)
+{
+	struct proc_dir_entry *dp = PDE(inode);
+	unsigned int *data = (unsigned int *)dp->data;
+
+	if (!data) {
+		printk(KERN_ERR "scanlog: open failed no data\n");
+		return -EIO;
+	}
+
+	if (data[0] != 0) {
+		/* This imperfect test stops a second copy of the
+		 * data (or a reset while data is being copied)
+		 */
+		return -EBUSY;
+	}
+
+	data[0] = 0;	/* re-init so we restart the scan */
+
+	return 0;
+}
+
+static int scanlog_release(struct inode * inode, struct file * file)
+{
+	struct proc_dir_entry *dp = PDE(inode);
+	unsigned int *data = (unsigned int *)dp->data;
+
+	if (!data) {
+		printk(KERN_ERR "scanlog: release failed no data\n");
+		return -EIO;
+	}
+	data[0] = 0;
+
+	return 0;
+}
+
+struct file_operations scanlog_fops = {
+	owner:		THIS_MODULE,
+	read:		scanlog_read,
+	write:		scanlog_write,
+	open:		scanlog_open,
+	release:	scanlog_release,
+};
+
+int __init scanlog_init(void)
+{
+	struct proc_dir_entry *ent;
+
+	ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
+	if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE) {
+		printk(KERN_ERR "scan-log-dump not implemented on this system\n");
+		return -EIO;
+	}
+
+	if (proc_rtas == NULL)
+                proc_rtas = proc_mkdir("rtas", 0);
+
+	if (proc_rtas == NULL) {
+		printk(KERN_ERR "Failed to create /proc/rtas in scanlog_init\n");
+		return -EIO;
+	}
+
+        ent = create_proc_entry("scan-log-dump",  S_IRUSR, proc_rtas);
+	if (ent) {
+		ent->proc_fops = &scanlog_fops;
+		/* Ideally we could allocate a buffer < 4G */
+		ent->data = kmalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
+		if (!ent->data) {
+			printk(KERN_ERR "Failed to allocate a buffer\n");
+			remove_proc_entry("scan-log-dump", ent->parent);
+			return -ENOMEM;
+		}
+		((unsigned int *)ent->data)[0] = 0;
+	} else {
+		printk(KERN_ERR "Failed to create ppc64/scan-log-dump proc entry\n");
+		return -EIO;
+	}
+	proc_ppc64_scan_log_dump = ent;
+
+	return 0;
+}
+
+void __exit scanlog_cleanup(void)
+{
+	if (proc_ppc64_scan_log_dump) {
+		if (proc_ppc64_scan_log_dump->data)
+			kfree(proc_ppc64_scan_log_dump->data);
+		remove_proc_entry("scan-log-dump", proc_ppc64_scan_log_dump->parent);
+	}
+}
+
+module_init(scanlog_init);
+module_exit(scanlog_cleanup);
+MODULE_LICENSE("GPL");

include/asm-ppc64/rtas.h

@@ -168,5 +168,13 @@ extern void rtas_halt(void);
 
 extern struct proc_dir_entry *rtas_proc_dir;
 
+/* Some RTAS ops require a data buffer and that buffer must be < 4G.
+ * Rather than having a memory allocator, just use this buffer
+ * (get the lock first), make the RTAS call.  Copy the data instead
+ * of holding the buffer for long.
+ */
+#define RTAS_DATA_BUF_SIZE 1024
+extern spinlock_t rtas_data_buf_lock;
+extern char rtas_data_buf[RTAS_DATA_BUF_SIZE];
 
 #endif /* _PPC64_RTAS_H */