powerpc/nvram: Move the log partition stuff to pseries

The nvram log partition stuff currently in nvram_64.c is really
pseries specific. It isn't actually used on anything else (despite
the fact that we ran the code to setup the partition on anything
except powermac) and the log format is specific to pseries RTAS
implementation. So move it where it belongs

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 200 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/nvram.c b/arch/powerpc/platforms/pseries/nvram.c
index 2a1ef5c25344..55a7141131f1 100644
--- a/arch/powerpc/platforms/pseries/nvram.c
+++ b/arch/powerpc/platforms/pseries/nvram.c
@@ -30,6 +30,16 @@ static int nvram_fetch, nvram_store;
 static char nvram_buf[NVRW_CNT];        /* assume this is in the first 4GB */
 static DEFINE_SPINLOCK(nvram_lock);
 
+static long nvram_error_log_index = -1;
+static long nvram_error_log_size = 0;
+
+struct err_log_info {
+        int error_type;
+        unsigned int seq_num;
+};
+#define NVRAM_MAX_REQ           2079
+#define NVRAM_MIN_REQ           1055
+
 static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
 {
         unsigned int i;
@@ -121,6 +131,196 @@ static ssize_t pSeries_nvram_get_size(void)
         return nvram_size ? nvram_size : -ENODEV;
 }
 
+
+/* nvram_write_error_log
+ *
+ * We need to buffer the error logs into nvram to ensure that we have
+ * the failure information to decode.  If we have a severe error there
+ * is no way to guarantee that the OS or the machine is in a state to
+ * get back to user land and write the error to disk.  For example if
+ * the SCSI device driver causes a Machine Check by writing to a bad
+ * IO address, there is no way of guaranteeing that the device driver
+ * is in any state that is would also be able to write the error data
+ * captured to disk, thus we buffer it in NVRAM for analysis on the
+ * next boot.
+ *
+ * In NVRAM the partition containing the error log buffer will looks like:
+ * Header (in bytes):
+ * +-----------+----------+--------+------------+------------------+
+ * | signature | checksum | length | name       | data             |
+ * |0          |1         |2      3|4         15|16        length-1|
+ * +-----------+----------+--------+------------+------------------+
+ *
+ * The 'data' section would look like (in bytes):
+ * +--------------+------------+-----------------------------------+
+ * | event_logged | sequence # | error log                         |
+ * |0            3|4          7|8            nvram_error_log_size-1|
+ * +--------------+------------+-----------------------------------+
+ *
+ * event_logged: 0 if event has not been logged to syslog, 1 if it has
+ * sequence #: The unique sequence # for each event. (until it wraps)
+ * error log: The error log from event_scan
+ */
+int nvram_write_error_log(char * buff, int length,
+                          unsigned int err_type, unsigned int error_log_cnt)
+{
+        int rc;
+        loff_t tmp_index;
+        struct err_log_info info;
+        
+        if (nvram_error_log_index == -1) {
+                return -ESPIPE;
+        }
+
+        if (length > nvram_error_log_size) {
+                length = nvram_error_log_size;
+        }
+
+        info.error_type = err_type;
+        info.seq_num = error_log_cnt;
+
+        tmp_index = nvram_error_log_index;
+
+        rc = ppc_md.nvram_write((char *)&info, sizeof(struct err_log_info), &tmp_index);
+        if (rc <= 0) {
+                printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
+                return rc;
+        }
+
+        rc = ppc_md.nvram_write(buff, length, &tmp_index);
+        if (rc <= 0) {
+                printk(KERN_ERR "nvram_write_error_log: Failed nvram_write (%d)\n", rc);
+                return rc;
+        }
+        
+        return 0;
+}
+
+/* nvram_read_error_log
+ *
+ * Reads nvram for error log for at most 'length'
+ */
+int nvram_read_error_log(char * buff, int length,
+                         unsigned int * err_type, unsigned int * error_log_cnt)
+{
+        int rc;
+        loff_t tmp_index;
+        struct err_log_info info;
+        
+        if (nvram_error_log_index == -1)
+                return -1;
+
+        if (length > nvram_error_log_size)
+                length = nvram_error_log_size;
+
+        tmp_index = nvram_error_log_index;
+
+        rc = ppc_md.nvram_read((char *)&info, sizeof(struct err_log_info), &tmp_index);
+        if (rc <= 0) {
+                printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
+                return rc;
+        }
+
+        rc = ppc_md.nvram_read(buff, length, &tmp_index);
+        if (rc <= 0) {
+                printk(KERN_ERR "nvram_read_error_log: Failed nvram_read (%d)\n", rc);
+                return rc;
+        }
+
+        *error_log_cnt = info.seq_num;
+        *err_type = info.error_type;
+
+        return 0;
+}
+
+/* This doesn't actually zero anything, but it sets the event_logged
+ * word to tell that this event is safely in syslog.
+ */
+int nvram_clear_error_log(void)
+{
+        loff_t tmp_index;
+        int clear_word = ERR_FLAG_ALREADY_LOGGED;
+        int rc;
+
+        if (nvram_error_log_index == -1)
+                return -1;
+
+        tmp_index = nvram_error_log_index;
+        
+        rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
+        if (rc <= 0) {
+                printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)\n", rc);
+                return rc;
+        }
+
+        return 0;
+}
+
+/* pseries_nvram_init_log_partition
+ *
+ * This will setup the partition we need for buffering the
+ * error logs and cleanup partitions if needed.
+ *
+ * The general strategy is the following:
+ * 1.) If there is ppc64,linux partition large enough then use it.
+ * 2.) If there is not a ppc64,linux partition large enough, search
+ * for a free partition that is large enough.
+ * 3.) If there is not a free partition large enough remove 
+ * _all_ OS partitions and consolidate the space.
+ * 4.) Will first try getting a chunk that will satisfy the maximum
+ * error log size (NVRAM_MAX_REQ).
+ * 5.) If the max chunk cannot be allocated then try finding a chunk
+ * that will satisfy the minum needed (NVRAM_MIN_REQ).
+ */
+static int __init pseries_nvram_init_log_partition(void)
+{
+        loff_t p;
+        int size;
+
+        /* Scan nvram for partitions */
+        nvram_scan_partitions();
+
+        /* Lookg for ours */
+        p = nvram_find_partition("ppc64,linux", NVRAM_SIG_OS, &size);
+
+        /* Found one but too small, remove it */
+        if (p && size < NVRAM_MIN_REQ) {
+                pr_info("nvram: Found too small ppc64,linux partition"
+                        ",removing it...");
+                nvram_remove_partition("ppc64,linux", NVRAM_SIG_OS);
+                p = 0;
+        }
+
+        /* Create one if we didn't find */
+        if (!p) {
+                p = nvram_create_partition("ppc64,linux", NVRAM_SIG_OS,
+                                           NVRAM_MAX_REQ, NVRAM_MIN_REQ);
+                /* No room for it, try to get rid of any OS partition
+                 * and try again
+                 */
+                if (p == -ENOSPC) {
+                        pr_info("nvram: No room to create ppc64,linux"
+                                " partition, deleting all OS partitions...");
+                        nvram_remove_partition(NULL, NVRAM_SIG_OS);
+                        p = nvram_create_partition("ppc64,linux", NVRAM_SIG_OS,
+                                                   NVRAM_MAX_REQ, NVRAM_MIN_REQ);
+                }
+        }
+
+        if (p <= 0) {
+                pr_err("nvram: Failed to find or create ppc64,linux"
+                       " partition, err %d\n", (int)p);
+                return 0;
+        }
+
+        nvram_error_log_index = p;
+        nvram_error_log_size = nvram_get_partition_size(p) -
+                sizeof(struct err_log_info);
+        
+        return 0;
+}
+machine_arch_initcall(pseries, pseries_nvram_init_log_partition);
+
 int __init pSeries_nvram_init(void)
 {
         struct device_node *nvram;