Move P8 timer code to separate file

Lets move P8 timer support code from slw.c to sbe-p8.c (as suggested
by BenH). There is a difference between timer support in P8 and P9.
Hence I think it makes sense to name it as sbe-p8.c.

Note that this is pure code movement and renaming functions/variables.
No functionality changes.

Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

1 files changed, 203 insertions, 0 deletions

diff --git a/hw/sbe-p8.c b/hw/sbe-p8.c
new file mode 100644
index 0000000..58049c7
--- /dev/null
+++ b/hw/sbe-p8.c
@@ -0,0 +1,203 @@
+/* Copyright 2013-2018 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <device.h>
+#include <sbe-p8.h>
+#include <skiboot.h>
+#include <timebase.h>
+#include <xscom.h>
+
+/* SLW timer related stuff */
+static bool sbe_has_timer;
+static uint64_t sbe_timer_inc;
+static uint64_t sbe_timer_target;
+static uint32_t sbe_timer_chip;
+static uint64_t sbe_last_gen;
+static uint64_t sbe_last_gen_stamp;
+
+static void p8_sbe_dump_timer_ffdc(void)
+{
+	uint64_t i, val;
+	int64_t rc;
+
+	static const uint32_t dump_regs[] = {
+		0xe0000, 0xe0001, 0xe0002, 0xe0003,
+		0xe0004, 0xe0005, 0xe0006, 0xe0007,
+		0xe0008, 0xe0009, 0xe000a, 0xe000b,
+		0xe000c, 0xe000d, 0xe000e, 0xe000f,
+		0xe0010, 0xe0011, 0xe0012, 0xe0013,
+		0xe0014, 0xe0015, 0xe0016, 0xe0017,
+		0xe0018, 0xe0019,
+		0x5001c,
+		0x50038, 0x50039, 0x5003a, 0x5003b
+	};
+
+	/**
+	 * @fwts-label SLWRegisterDump
+	 * @fwts-advice An error condition occurred in sleep/winkle
+	 * engines timer state machine. Dumping debug information to
+	 * root-cause. OPAL/skiboot may be stuck on some operation that
+	 * requires SLW timer state machine (e.g. core powersaving)
+	 */
+	prlog(PR_DEBUG, "SLW: Register state:\n");
+
+	for (i = 0; i < ARRAY_SIZE(dump_regs); i++) {
+		uint32_t reg = dump_regs[i];
+		rc = xscom_read(sbe_timer_chip, reg, &val);
+		if (rc) {
+			prlog(PR_DEBUG, "SLW: XSCOM error %lld reading"
+			      " reg 0x%x\n", rc, reg);
+			break;
+		}
+		prlog(PR_DEBUG, "SLW:  %5x = %016llx\n", reg, val);
+	}
+}
+
+/* This is called with the timer lock held, so there is no
+ * issue with re-entrancy or concurrence
+ */
+void p8_sbe_update_timer_expiry(uint64_t new_target)
+{
+	uint64_t count, gen, gen2, req, now = mftb();
+	int64_t rc;
+
+	if (!sbe_has_timer || new_target == sbe_timer_target)
+		return;
+
+	sbe_timer_target = new_target;
+
+	/* Calculate how many increments from now, rounded up */
+	if (now < new_target)
+		count = (new_target - now + sbe_timer_inc - 1) / sbe_timer_inc;
+	else
+		count = 1;
+
+	/* Max counter is 24-bit */
+	if (count > 0xffffff)
+		count = 0xffffff;
+	/* Fabricate update request */
+	req = (1ull << 63) | (count << 32);
+
+	prlog(PR_TRACE, "SLW: TMR expiry: 0x%llx, req: %016llx\n", count, req);
+
+	do {
+		/* Grab generation and spin if odd */
+		_xscom_lock();
+		for (;;) {
+			rc = _xscom_read(sbe_timer_chip, 0xE0006, &gen, false);
+			if (rc) {
+				prerror("SLW: Error %lld reading tmr gen "
+					" count\n", rc);
+				_xscom_unlock();
+				return;
+			}
+			if (!(gen & 1))
+				break;
+			if (tb_compare(now + msecs_to_tb(1), mftb()) == TB_ABEFOREB) {
+				/**
+				 * @fwts-label SLWTimerStuck
+				 * @fwts-advice The SLeep/Winkle Engine (SLW)
+				 * failed to increment the generation number
+				 * within our timeout period (it *should* have
+				 * done so within ~10us, not >1ms. OPAL uses
+				 * the SLW timer to schedule some operations,
+				 * but can fall back to the (much less frequent
+				 * OPAL poller, which although does not affect
+				 * functionality, runs *much* less frequently.
+				 * This could have the effect of slow I2C
+				 * operations (for example). It may also mean
+				 * that you *had* an increase in jitter, due
+				 * to slow interactions with SLW.
+				 * This error may also occur if the machine
+				 * is connected to via soft FSI.
+				 */
+				prerror("SLW: timer stuck, falling back to OPAL pollers. You will likely have slower I2C and may have experienced increased jitter.\n");
+				prlog(PR_DEBUG, "SLW: Stuck with odd generation !\n");
+				_xscom_unlock();
+				sbe_has_timer = false;
+				p8_sbe_dump_timer_ffdc();
+				return;
+			}
+		}
+
+		rc = _xscom_write(sbe_timer_chip, 0x5003A, req, false);
+		if (rc) {
+			prerror("SLW: Error %lld writing tmr request\n", rc);
+			_xscom_unlock();
+			return;
+		}
+
+		/* Re-check gen count */
+		rc = _xscom_read(sbe_timer_chip, 0xE0006, &gen2, false);
+		if (rc) {
+			prerror("SLW: Error %lld re-reading tmr gen "
+				" count\n", rc);
+			_xscom_unlock();
+			return;
+		}
+		_xscom_unlock();
+	} while(gen != gen2);
+
+	/* Check if the timer is working. If at least 1ms has elapsed
+	 * since the last call to this function, check that the gen
+	 * count has changed
+	 */
+	if (tb_compare(sbe_last_gen_stamp + msecs_to_tb(1), now)
+	    == TB_ABEFOREB) {
+		if (sbe_last_gen == gen) {
+			prlog(PR_ERR,
+			      "SLW: Timer appears to not be running !\n");
+			sbe_has_timer = false;
+			p8_sbe_dump_timer_ffdc();
+		}
+		sbe_last_gen = gen;
+		sbe_last_gen_stamp = mftb();
+	}
+
+	prlog(PR_TRACE, "SLW: gen: %llx\n", gen);
+}
+
+bool p8_sbe_timer_ok(void)
+{
+	return sbe_has_timer;
+}
+
+void p8_sbe_init_timer(void)
+{
+	struct dt_node *np;
+	int64_t rc;
+	uint32_t tick_us;
+
+	np = dt_find_compatible_node(dt_root, NULL, "ibm,power8-sbe-timer");
+	if (!np)
+		return;
+
+	sbe_timer_chip = dt_get_chip_id(np);
+	tick_us = dt_prop_get_u32(np, "tick-time-us");
+	sbe_timer_inc = usecs_to_tb(tick_us);
+	sbe_timer_target = ~0ull;
+
+	rc = xscom_read(sbe_timer_chip, 0xE0006, &sbe_last_gen);
+	if (rc) {
+		prerror("SLW: Error %lld reading tmr gen count\n", rc);
+		return;
+	}
+	sbe_last_gen_stamp = mftb();
+
+	prlog(PR_INFO, "SLW: Timer facility on chip %d, resolution %dus\n",
+	      sbe_timer_chip, tick_us);
+	sbe_has_timer = true;
+}