1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * ImgTec IR Raw Decoder found in PowerDown Controller.
4  *
5  * Copyright 2010-2014 Imagination Technologies Ltd.
6  *
7  * This ties into the input subsystem using the RC-core in raw mode. Raw IR
8  * signal edges are reported and decoded by generic software decoders.
9  */
10 
11 #include <linux/spinlock.h>
12 #include <media/rc-core.h>
13 #include "img-ir.h"
14 
15 #define ECHO_TIMEOUT_MS 150	/* ms between echos */
16 
17 /* must be called with priv->lock held */
18 static void img_ir_refresh_raw(struct img_ir_priv *priv, u32 irq_status)
19 {
20 	struct img_ir_priv_raw *raw = &priv->raw;
21 	struct rc_dev *rc_dev = priv->raw.rdev;
22 	int multiple;
23 	u32 ir_status;
24 
25 	/* find whether both rise and fall was detected */
26 	multiple = ((irq_status & IMG_IR_IRQ_EDGE) == IMG_IR_IRQ_EDGE);
27 	/*
28 	 * If so, we need to see if the level has actually changed.
29 	 * If it's just noise that we didn't have time to process,
30 	 * there's no point reporting it.
31 	 */
32 	ir_status = img_ir_read(priv, IMG_IR_STATUS) & IMG_IR_IRRXD;
33 	if (multiple && ir_status == raw->last_status)
34 		return;
35 	raw->last_status = ir_status;
36 
37 	/* report the edge to the IR raw decoders */
38 	if (ir_status) /* low */
39 		ir_raw_event_store_edge(rc_dev, false);
40 	else /* high */
41 		ir_raw_event_store_edge(rc_dev, true);
42 	ir_raw_event_handle(rc_dev);
43 }
44 
45 /* called with priv->lock held */
46 void img_ir_isr_raw(struct img_ir_priv *priv, u32 irq_status)
47 {
48 	struct img_ir_priv_raw *raw = &priv->raw;
49 
50 	/* check not removing */
51 	if (!raw->rdev)
52 		return;
53 
54 	img_ir_refresh_raw(priv, irq_status);
55 
56 	/* start / push back the echo timer */
57 	mod_timer(&raw->timer, jiffies + msecs_to_jiffies(ECHO_TIMEOUT_MS));
58 }
59 
60 /*
61  * Echo timer callback function.
62  * The raw decoders expect to get a final sample even if there are no edges, in
63  * order to be assured of the final space. If there are no edges for a certain
64  * time we use this timer to emit a final sample to satisfy them.
65  */
66 static void img_ir_echo_timer(struct timer_list *t)
67 {
68 	struct img_ir_priv *priv = from_timer(priv, t, raw.timer);
69 
70 	spin_lock_irq(&priv->lock);
71 
72 	/* check not removing */
73 	if (priv->raw.rdev)
74 		/*
75 		 * It's safe to pass irq_status=0 since it's only used to check
76 		 * for double edges.
77 		 */
78 		img_ir_refresh_raw(priv, 0);
79 
80 	spin_unlock_irq(&priv->lock);
81 }
82 
83 void img_ir_setup_raw(struct img_ir_priv *priv)
84 {
85 	u32 irq_en;
86 
87 	if (!priv->raw.rdev)
88 		return;
89 
90 	/* clear and enable edge interrupts */
91 	spin_lock_irq(&priv->lock);
92 	irq_en = img_ir_read(priv, IMG_IR_IRQ_ENABLE);
93 	irq_en |= IMG_IR_IRQ_EDGE;
94 	img_ir_write(priv, IMG_IR_IRQ_CLEAR, IMG_IR_IRQ_EDGE);
95 	img_ir_write(priv, IMG_IR_IRQ_ENABLE, irq_en);
96 	spin_unlock_irq(&priv->lock);
97 }
98 
99 int img_ir_probe_raw(struct img_ir_priv *priv)
100 {
101 	struct img_ir_priv_raw *raw = &priv->raw;
102 	struct rc_dev *rdev;
103 	int error;
104 
105 	/* Set up the echo timer */
106 	timer_setup(&raw->timer, img_ir_echo_timer, 0);
107 
108 	/* Allocate raw decoder */
109 	raw->rdev = rdev = rc_allocate_device(RC_DRIVER_IR_RAW);
110 	if (!rdev) {
111 		dev_err(priv->dev, "cannot allocate raw input device\n");
112 		return -ENOMEM;
113 	}
114 	rdev->priv = priv;
115 	rdev->map_name = RC_MAP_EMPTY;
116 	rdev->device_name = "IMG Infrared Decoder Raw";
117 
118 	/* Register raw decoder */
119 	error = rc_register_device(rdev);
120 	if (error) {
121 		dev_err(priv->dev, "failed to register raw IR input device\n");
122 		rc_free_device(rdev);
123 		raw->rdev = NULL;
124 		return error;
125 	}
126 
127 	return 0;
128 }
129 
130 void img_ir_remove_raw(struct img_ir_priv *priv)
131 {
132 	struct img_ir_priv_raw *raw = &priv->raw;
133 	struct rc_dev *rdev = raw->rdev;
134 	u32 irq_en;
135 
136 	if (!rdev)
137 		return;
138 
139 	/* switch off and disable raw (edge) interrupts */
140 	spin_lock_irq(&priv->lock);
141 	raw->rdev = NULL;
142 	irq_en = img_ir_read(priv, IMG_IR_IRQ_ENABLE);
143 	irq_en &= ~IMG_IR_IRQ_EDGE;
144 	img_ir_write(priv, IMG_IR_IRQ_ENABLE, irq_en);
145 	img_ir_write(priv, IMG_IR_IRQ_CLEAR, IMG_IR_IRQ_EDGE);
146 	spin_unlock_irq(&priv->lock);
147 
148 	rc_unregister_device(rdev);
149 
150 	del_timer_sync(&raw->timer);
151 }
152