Fixed MTP to work with TWRP

drivers/s390/cio/crw.c

@@ -0,0 +1,161 @@
+/*
+ *   Channel report handling code
+ *
+ *    Copyright IBM Corp. 2000, 2009
+ *    Author(s): Ingo Adlung <adlung@de.ibm.com>,
+ *		 Martin Schwidefsky <schwidefsky@de.ibm.com>,
+ *		 Cornelia Huck <cornelia.huck@de.ibm.com>,
+ *		 Heiko Carstens <heiko.carstens@de.ibm.com>,
+ */
+
+#include <linux/mutex.h>
+#include <linux/kthread.h>
+#include <linux/init.h>
+#include <linux/wait.h>
+#include <asm/crw.h>
+#include <asm/ctl_reg.h>
+
+static DEFINE_MUTEX(crw_handler_mutex);
+static crw_handler_t crw_handlers[NR_RSCS];
+static atomic_t crw_nr_req = ATOMIC_INIT(0);
+static DECLARE_WAIT_QUEUE_HEAD(crw_handler_wait_q);
+
+/**
+ * crw_register_handler() - register a channel report word handler
+ * @rsc: reporting source code to handle
+ * @handler: handler to be registered
+ *
+ * Returns %0 on success and a negative error value otherwise.
+ */
+int crw_register_handler(int rsc, crw_handler_t handler)
+{
+	int rc = 0;
+
+	if ((rsc < 0) || (rsc >= NR_RSCS))
+		return -EINVAL;
+	mutex_lock(&crw_handler_mutex);
+	if (crw_handlers[rsc])
+		rc = -EBUSY;
+	else
+		crw_handlers[rsc] = handler;
+	mutex_unlock(&crw_handler_mutex);
+	return rc;
+}
+
+/**
+ * crw_unregister_handler() - unregister a channel report word handler
+ * @rsc: reporting source code to handle
+ */
+void crw_unregister_handler(int rsc)
+{
+	if ((rsc < 0) || (rsc >= NR_RSCS))
+		return;
+	mutex_lock(&crw_handler_mutex);
+	crw_handlers[rsc] = NULL;
+	mutex_unlock(&crw_handler_mutex);
+}
+
+/*
+ * Retrieve CRWs and call function to handle event.
+ */
+static int crw_collect_info(void *unused)
+{
+	struct crw crw[2];
+	int ccode, signal;
+	unsigned int chain;
+
+repeat:
+	signal = wait_event_interruptible(crw_handler_wait_q,
+					  atomic_read(&crw_nr_req) > 0);
+	if (unlikely(signal))
+		atomic_inc(&crw_nr_req);
+	chain = 0;
+	while (1) {
+		crw_handler_t handler;
+
+		if (unlikely(chain > 1)) {
+			struct crw tmp_crw;
+
+			printk(KERN_WARNING"%s: Code does not support more "
+			       "than two chained crws; please report to "
+			       "linux390@de.ibm.com!\n", __func__);
+			ccode = stcrw(&tmp_crw);
+			printk(KERN_WARNING"%s: crw reports slct=%d, oflw=%d, "
+			       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
+			       __func__, tmp_crw.slct, tmp_crw.oflw,
+			       tmp_crw.chn, tmp_crw.rsc, tmp_crw.anc,
+			       tmp_crw.erc, tmp_crw.rsid);
+			printk(KERN_WARNING"%s: This was crw number %x in the "
+			       "chain\n", __func__, chain);
+			if (ccode != 0)
+				break;
+			chain = tmp_crw.chn ? chain + 1 : 0;
+			continue;
+		}
+		ccode = stcrw(&crw[chain]);
+		if (ccode != 0)
+			break;
+		printk(KERN_DEBUG "crw_info : CRW reports slct=%d, oflw=%d, "
+		       "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
+		       crw[chain].slct, crw[chain].oflw, crw[chain].chn,
+		       crw[chain].rsc, crw[chain].anc, crw[chain].erc,
+		       crw[chain].rsid);
+		/* Check for overflows. */
+		if (crw[chain].oflw) {
+			int i;
+
+			pr_debug("%s: crw overflow detected!\n", __func__);
+			mutex_lock(&crw_handler_mutex);
+			for (i = 0; i < NR_RSCS; i++) {
+				if (crw_handlers[i])
+					crw_handlers[i](NULL, NULL, 1);
+			}
+			mutex_unlock(&crw_handler_mutex);
+			chain = 0;
+			continue;
+		}
+		if (crw[0].chn && !chain) {
+			chain++;
+			continue;
+		}
+		mutex_lock(&crw_handler_mutex);
+		handler = crw_handlers[crw[chain].rsc];
+		if (handler)
+			handler(&crw[0], chain ? &crw[1] : NULL, 0);
+		mutex_unlock(&crw_handler_mutex);
+		/* chain is always 0 or 1 here. */
+		chain = crw[chain].chn ? chain + 1 : 0;
+	}
+	if (atomic_dec_and_test(&crw_nr_req))
+		wake_up(&crw_handler_wait_q);
+	goto repeat;
+	return 0;
+}
+
+void crw_handle_channel_report(void)
+{
+	atomic_inc(&crw_nr_req);
+	wake_up(&crw_handler_wait_q);
+}
+
+void crw_wait_for_channel_report(void)
+{
+	crw_handle_channel_report();
+	wait_event(crw_handler_wait_q, atomic_read(&crw_nr_req) == 0);
+}
+
+/*
+ * Machine checks for the channel subsystem must be enabled
+ * after the channel subsystem is initialized
+ */
+static int __init crw_machine_check_init(void)
+{
+	struct task_struct *task;
+
+	task = kthread_run(crw_collect_info, NULL, "kmcheck");
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+	ctl_set_bit(14, 28);	/* enable channel report MCH */
+	return 0;
+}
+device_initcall(crw_machine_check_init);