| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * c 2001 PPC 64 Team, IBM Corp |
| * |
| * 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/powerpc/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 <linux/delay.h> |
| #include <linux/slab.h> |
| #include <linux/uaccess.h> |
| #include <asm/rtas.h> |
| #include <asm/prom.h> |
| |
| #define MODULE_VERS "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 |
| |
| |
| static unsigned int ibm_scan_log_dump; /* RTAS token */ |
| static unsigned int *scanlog_buffer; /* The data buffer */ |
| |
| static ssize_t scanlog_read(struct file *file, char __user *buf, |
| size_t count, loff_t *ppos) |
| { |
| unsigned int *data = scanlog_buffer; |
| int status; |
| unsigned long len, off; |
| unsigned int wait_time; |
| |
| 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 (!access_ok(buf, count)) |
| return -EFAULT; |
| |
| for (;;) { |
| wait_time = 500; /* 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, |
| (u32) __pa(rtas_data_buf), (u32) count); |
| memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE); |
| spin_unlock(&rtas_data_buf_lock); |
| |
| pr_debug("scanlog: status=%d, data[0]=%x, data[1]=%x, " \ |
| "data[2]=%x\n", status, data[0], data[1], data[2]); |
| switch (status) { |
| case SCANLOG_COMPLETE: |
| pr_debug("scanlog: hit eof\n"); |
| return 0; |
| case SCANLOG_HWERROR: |
| pr_debug("scanlog: hardware error reading 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: |
| /* Assume extended busy */ |
| wait_time = rtas_busy_delay_time(status); |
| if (!wait_time) { |
| printk(KERN_ERR "scanlog: unknown error " \ |
| "from rtas: %d\n", status); |
| return -EIO; |
| } |
| } |
| /* Apparently no data yet. Wait and try again. */ |
| msleep_interruptible(wait_time); |
| } |
| /*NOTREACHED*/ |
| } |
| |
| static ssize_t scanlog_write(struct file * file, const char __user * buf, |
| size_t count, loff_t *ppos) |
| { |
| char stkbuf[20]; |
| int status; |
| |
| if (count > 19) count = 19; |
| if (copy_from_user (stkbuf, buf, count)) { |
| return -EFAULT; |
| } |
| stkbuf[count] = 0; |
| |
| if (buf) { |
| if (strncmp(stkbuf, "reset", 5) == 0) { |
| pr_debug("scanlog: reset scanlog\n"); |
| status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0); |
| pr_debug("scanlog: rtas returns %d\n", status); |
| } |
| } |
| return count; |
| } |
| |
| static int scanlog_open(struct inode * inode, struct file * file) |
| { |
| unsigned int *data = scanlog_buffer; |
| |
| 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) |
| { |
| unsigned int *data = scanlog_buffer; |
| |
| data[0] = 0; |
| return 0; |
| } |
| |
| static const struct file_operations scanlog_fops = { |
| .owner = THIS_MODULE, |
| .read = scanlog_read, |
| .write = scanlog_write, |
| .open = scanlog_open, |
| .release = scanlog_release, |
| .llseek = noop_llseek, |
| }; |
| |
| static int __init scanlog_init(void) |
| { |
| struct proc_dir_entry *ent; |
| int err = -ENOMEM; |
| |
| ibm_scan_log_dump = rtas_token("ibm,scan-log-dump"); |
| if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE) |
| return -ENODEV; |
| |
| /* Ideally we could allocate a buffer < 4G */ |
| scanlog_buffer = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL); |
| if (!scanlog_buffer) |
| goto err; |
| |
| ent = proc_create("powerpc/rtas/scan-log-dump", 0400, NULL, |
| &scanlog_fops); |
| if (!ent) |
| goto err; |
| return 0; |
| err: |
| kfree(scanlog_buffer); |
| return err; |
| } |
| |
| static void __exit scanlog_cleanup(void) |
| { |
| remove_proc_entry("powerpc/rtas/scan-log-dump", NULL); |
| kfree(scanlog_buffer); |
| } |
| |
| module_init(scanlog_init); |
| module_exit(scanlog_cleanup); |
| MODULE_LICENSE("GPL"); |