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2023-12-09 b22da3d8526a935aa31e086e63f60ff3246cb61c 
 kernel/drivers/platform/chrome/cros_ec_spi.c
....@@ -1,28 +1,20 @@
1
-/*
2
- * ChromeOS EC multi-function device (SPI)
3
- *
4
- * Copyright (C) 2012 Google, Inc
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- *
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- * This software is licensed under the terms of the GNU General Public
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- * License version 2, as published by the Free Software Foundation, and
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- * may be copied, distributed, and modified under those terms.
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- *
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- * This program is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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- * GNU General Public License for more details.
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- */
1
+// SPDX-License-Identifier: GPL-2.0
2
+// SPI interface for ChromeOS Embedded Controller
3
+//
4
+// Copyright (C) 2012 Google, Inc
155 
166 #include <linux/delay.h>
177 #include <linux/kernel.h>
188 #include <linux/module.h>
19
-#include <linux/mfd/cros_ec.h>
20
-#include <linux/mfd/cros_ec_commands.h>
219 #include <linux/of.h>
10
+#include <linux/platform_data/cros_ec_commands.h>
11
+#include <linux/platform_data/cros_ec_proto.h>
2212 #include <linux/platform_device.h>
2313 #include <linux/slab.h>
2414 #include <linux/spi/spi.h>
15
+#include <uapi/linux/sched/types.h>
2516 
17
+#include "cros_ec.h"
2618 
2719 /* The header byte, which follows the preamble */
2820 #define EC_MSG_HEADER			0xec
....@@ -77,12 +69,35 @@
7769  *      is sent when we want to turn on CS at the start of a transaction.
7870  * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that
7971  *      is sent when we want to turn off CS at the end of a transaction.
72
+ * @high_pri_worker: Used to schedule high priority work.
8073  */
8174 struct cros_ec_spi {
8275 	struct spi_device *spi;
8376 	s64 last_transfer_ns;
8477 	unsigned int start_of_msg_delay;
8578 	unsigned int end_of_msg_delay;
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+	struct kthread_worker *high_pri_worker;
80
+};
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+
82
+typedef int (*cros_ec_xfer_fn_t) (struct cros_ec_device *ec_dev,
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+				  struct cros_ec_command *ec_msg);
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+
85
+/**
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+ * struct cros_ec_xfer_work_params - params for our high priority workers
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+ *
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+ * @work: The work_struct needed to queue work
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+ * @fn: The function to use to transfer
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+ * @ec_dev: ChromeOS EC device
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+ * @ec_msg: Message to transfer
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+ * @ret: The return value of the function
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+ */
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+
95
+struct cros_ec_xfer_work_params {
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+	struct kthread_work work;
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+	cros_ec_xfer_fn_t fn;
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+	struct cros_ec_device *ec_dev;
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+	struct cros_ec_command *ec_msg;
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+	int ret;
86101 };
87102 
88103 static void debug_packet(struct device *dev, const char *name, u8 *ptr,
....@@ -112,7 +127,8 @@
112127 	 */
113128 	spi_message_init(&msg);
114129 	memset(&trans, 0, sizeof(trans));
115
-	trans.delay_usecs = ec_spi->end_of_msg_delay;
130
+	trans.delay.value = ec_spi->end_of_msg_delay;
131
+	trans.delay.unit = SPI_DELAY_UNIT_USECS;
116132 	spi_message_add_tail(&trans, &msg);
117133 
118134 	ret = spi_sync_locked(ec_spi->spi, &msg);
....@@ -132,6 +148,10 @@
132148  * receive_n_bytes - receive n bytes from the EC.
133149  *
134150  * Assumes buf is a pointer into the ec_dev->din buffer
151
+ *
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+ * @ec_dev: ChromeOS EC device.
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+ * @buf: Pointer to the buffer receiving the data.
154
+ * @n: Number of bytes received.
135155  */
136156 static int receive_n_bytes(struct cros_ec_device *ec_dev, u8 *buf, int n)
137157 {
....@@ -360,13 +380,13 @@
360380 }
361381 
362382 /**
363
- * cros_ec_pkt_xfer_spi - Transfer a packet over SPI and receive the reply
383
+ * do_cros_ec_pkt_xfer_spi - Transfer a packet over SPI and receive the reply
364384  *
365385  * @ec_dev: ChromeOS EC device
366386  * @ec_msg: Message to transfer
367387  */
368
-static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
369
-				struct cros_ec_command *ec_msg)
388
+static int do_cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
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+				   struct cros_ec_command *ec_msg)
370390 {
371391 	struct ec_host_response *response;
372392 	struct cros_ec_spi *ec_spi = ec_dev->priv;
....@@ -401,7 +421,8 @@
401421 	spi_message_init(&msg);
402422 	if (ec_spi->start_of_msg_delay) {
403423 		memset(&trans_delay, 0, sizeof(trans_delay));
404
-		trans_delay.delay_usecs = ec_spi->start_of_msg_delay;
424
+		trans_delay.delay.value = ec_spi->start_of_msg_delay;
425
+		trans_delay.delay.unit = SPI_DELAY_UNIT_USECS;
405426 		spi_message_add_tail(&trans_delay, &msg);
406427 	}
407428 
....@@ -503,13 +524,13 @@
503524 }
504525 
505526 /**
506
- * cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
527
+ * do_cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
507528  *
508529  * @ec_dev: ChromeOS EC device
509530  * @ec_msg: Message to transfer
510531  */
511
-static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
512
-				struct cros_ec_command *ec_msg)
532
+static int do_cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
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+				   struct cros_ec_command *ec_msg)
513534 {
514535 	struct cros_ec_spi *ec_spi = ec_dev->priv;
515536 	struct spi_transfer trans;
....@@ -621,6 +642,54 @@
621642 	return ret;
622643 }
623644 
645
+static void cros_ec_xfer_high_pri_work(struct kthread_work *work)
646
+{
647
+	struct cros_ec_xfer_work_params *params;
648
+
649
+	params = container_of(work, struct cros_ec_xfer_work_params, work);
650
+	params->ret = params->fn(params->ec_dev, params->ec_msg);
651
+}
652
+
653
+static int cros_ec_xfer_high_pri(struct cros_ec_device *ec_dev,
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+				 struct cros_ec_command *ec_msg,
655
+				 cros_ec_xfer_fn_t fn)
656
+{
657
+	struct cros_ec_spi *ec_spi = ec_dev->priv;
658
+	struct cros_ec_xfer_work_params params = {
659
+		.work = KTHREAD_WORK_INIT(params.work,
660
+					  cros_ec_xfer_high_pri_work),
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+		.ec_dev = ec_dev,
662
+		.ec_msg = ec_msg,
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+		.fn = fn,
664
+	};
665
+
666
+	/*
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+	 * This looks a bit ridiculous.  Why do the work on a
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+	 * different thread if we're just going to block waiting for
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+	 * the thread to finish?  The key here is that the thread is
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+	 * running at high priority but the calling context might not
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+	 * be.  We need to be at high priority to avoid getting
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+	 * context switched out for too long and the EC giving up on
673
+	 * the transfer.
674
+	 */
675
+	kthread_queue_work(ec_spi->high_pri_worker, &params.work);
676
+	kthread_flush_work(&params.work);
677
+
678
+	return params.ret;
679
+}
680
+
681
+static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
682
+				struct cros_ec_command *ec_msg)
683
+{
684
+	return cros_ec_xfer_high_pri(ec_dev, ec_msg, do_cros_ec_pkt_xfer_spi);
685
+}
686
+
687
+static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
688
+				struct cros_ec_command *ec_msg)
689
+{
690
+	return cros_ec_xfer_high_pri(ec_dev, ec_msg, do_cros_ec_cmd_xfer_spi);
691
+}
692
+
624693 static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
625694 {
626695 	struct device_node *np = dev->of_node;
....@@ -636,6 +705,35 @@
636705 		ec_spi->end_of_msg_delay = val;
637706 }
638707 
708
+static void cros_ec_spi_high_pri_release(void *worker)
709
+{
710
+	kthread_destroy_worker(worker);
711
+}
712
+
713
+static int cros_ec_spi_devm_high_pri_alloc(struct device *dev,
714
+					   struct cros_ec_spi *ec_spi)
715
+{
716
+	int err;
717
+
718
+	ec_spi->high_pri_worker =
719
+		kthread_create_worker(0, "cros_ec_spi_high_pri");
720
+
721
+	if (IS_ERR(ec_spi->high_pri_worker)) {
722
+		err = PTR_ERR(ec_spi->high_pri_worker);
723
+		dev_err(dev, "Can't create cros_ec high pri worker: %d\n", err);
724
+		return err;
725
+	}
726
+
727
+	err = devm_add_action_or_reset(dev, cros_ec_spi_high_pri_release,
728
+				       ec_spi->high_pri_worker);
729
+	if (err)
730
+		return err;
731
+
732
+	sched_set_fifo(ec_spi->high_pri_worker->task);
733
+
734
+	return 0;
735
+}
736
+
639737 static int cros_ec_spi_probe(struct spi_device *spi)
640738 {
641739 	struct device *dev = &spi->dev;
....@@ -644,7 +742,7 @@
644742 	int err;
645743 
646744 	spi->bits_per_word = 8;
647
-	spi->mode = SPI_MODE_0;
745
+	spi->rt = true;
648746 	err = spi_setup(spi);
649747 	if (err < 0)
650748 		return err;
....@@ -674,6 +772,10 @@
674772 
675773 	ec_spi->last_transfer_ns = ktime_get_ns();
676774 
775
+	err = cros_ec_spi_devm_high_pri_alloc(dev, ec_spi);
776
+	if (err)
777
+		return err;
778
+
677779 	err = cros_ec_register(ec_dev);
678780 	if (err) {
679781 		dev_err(dev, "cannot register EC\n");
....@@ -687,12 +789,9 @@
687789 
688790 static int cros_ec_spi_remove(struct spi_device *spi)
689791 {
690
-	struct cros_ec_device *ec_dev;
792
+	struct cros_ec_device *ec_dev = spi_get_drvdata(spi);
691793 
692
-	ec_dev = spi_get_drvdata(spi);
693
-	cros_ec_remove(ec_dev);
694
-
695
-	return 0;
794
+	return cros_ec_unregister(ec_dev);
696795 }
697796 
698797 #ifdef CONFIG_PM_SLEEP
....@@ -729,7 +828,7 @@
729828 static struct spi_driver cros_ec_driver_spi = {
730829 	.driver	= {
731830 		.name	= "cros-ec-spi",
732
-		.of_match_table = of_match_ptr(cros_ec_spi_of_match),
831
+		.of_match_table = cros_ec_spi_of_match,
733832 		.pm	= &cros_ec_spi_pm_ops,
734833 	},
735834 	.probe		= cros_ec_spi_probe,
....@@ -740,4 +839,4 @@
740839 module_spi_driver(cros_ec_driver_spi);
741840 
742841 MODULE_LICENSE("GPL v2");
743
-MODULE_DESCRIPTION("ChromeOS EC multi function device (SPI)");
842
+MODULE_DESCRIPTION("SPI interface for ChromeOS Embedded Controller");