1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Generic heartbeat driver for regular LED banks
4  *
5  * Copyright (C) 2007 - 2010  Paul Mundt
6  *
7  * Most SH reference boards include a number of individual LEDs that can
8  * be independently controlled (either via a pre-defined hardware
9  * function or via the LED class, if desired -- the hardware tends to
10  * encapsulate some of the same "triggers" that the LED class supports,
11  * so there's not too much value in it).
12  *
13  * Additionally, most of these boards also have a LED bank that we've
14  * traditionally used for strobing the load average. This use case is
15  * handled by this driver, rather than giving each LED bit position its
16  * own struct device.
17  */
18 #include <linux/init.h>
19 #include <linux/platform_device.h>
20 #include <linux/sched.h>
21 #include <linux/sched/loadavg.h>
22 #include <linux/timer.h>
23 #include <linux/io.h>
24 #include <linux/slab.h>
25 #include <asm/heartbeat.h>
26 
27 #define DRV_NAME "heartbeat"
28 #define DRV_VERSION "0.1.2"
29 
30 static unsigned char default_bit_pos[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
31 
heartbeat_toggle_bit(struct heartbeat_data * hd,unsigned bit,unsigned int inverted)32 static inline void heartbeat_toggle_bit(struct heartbeat_data *hd,
33 					unsigned bit, unsigned int inverted)
34 {
35 	unsigned int new;
36 
37 	new = (1 << hd->bit_pos[bit]);
38 	if (inverted)
39 		new = ~new;
40 
41 	new &= hd->mask;
42 
43 	switch (hd->regsize) {
44 	case 32:
45 		new |= ioread32(hd->base) & ~hd->mask;
46 		iowrite32(new, hd->base);
47 		break;
48 	case 16:
49 		new |= ioread16(hd->base) & ~hd->mask;
50 		iowrite16(new, hd->base);
51 		break;
52 	default:
53 		new |= ioread8(hd->base) & ~hd->mask;
54 		iowrite8(new, hd->base);
55 		break;
56 	}
57 }
58 
heartbeat_timer(struct timer_list * t)59 static void heartbeat_timer(struct timer_list *t)
60 {
61 	struct heartbeat_data *hd = from_timer(hd, t, timer);
62 	static unsigned bit = 0, up = 1;
63 
64 	heartbeat_toggle_bit(hd, bit, hd->flags & HEARTBEAT_INVERTED);
65 
66 	bit += up;
67 	if ((bit == 0) || (bit == (hd->nr_bits)-1))
68 		up = -up;
69 
70 	mod_timer(&hd->timer, jiffies + (110 - ((300 << FSHIFT) /
71 			((avenrun[0] / 5) + (3 << FSHIFT)))));
72 }
73 
heartbeat_drv_probe(struct platform_device * pdev)74 static int heartbeat_drv_probe(struct platform_device *pdev)
75 {
76 	struct resource *res;
77 	struct heartbeat_data *hd;
78 	int i;
79 
80 	if (unlikely(pdev->num_resources != 1)) {
81 		dev_err(&pdev->dev, "invalid number of resources\n");
82 		return -EINVAL;
83 	}
84 
85 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
86 	if (unlikely(res == NULL)) {
87 		dev_err(&pdev->dev, "invalid resource\n");
88 		return -EINVAL;
89 	}
90 
91 	if (pdev->dev.platform_data) {
92 		hd = pdev->dev.platform_data;
93 	} else {
94 		hd = kzalloc(sizeof(struct heartbeat_data), GFP_KERNEL);
95 		if (unlikely(!hd))
96 			return -ENOMEM;
97 	}
98 
99 	hd->base = ioremap(res->start, resource_size(res));
100 	if (unlikely(!hd->base)) {
101 		dev_err(&pdev->dev, "ioremap failed\n");
102 
103 		if (!pdev->dev.platform_data)
104 			kfree(hd);
105 
106 		return -ENXIO;
107 	}
108 
109 	if (!hd->nr_bits) {
110 		hd->bit_pos = default_bit_pos;
111 		hd->nr_bits = ARRAY_SIZE(default_bit_pos);
112 	}
113 
114 	hd->mask = 0;
115 	for (i = 0; i < hd->nr_bits; i++)
116 		hd->mask |= (1 << hd->bit_pos[i]);
117 
118 	if (!hd->regsize) {
119 		switch (res->flags & IORESOURCE_MEM_TYPE_MASK) {
120 		case IORESOURCE_MEM_32BIT:
121 			hd->regsize = 32;
122 			break;
123 		case IORESOURCE_MEM_16BIT:
124 			hd->regsize = 16;
125 			break;
126 		case IORESOURCE_MEM_8BIT:
127 		default:
128 			hd->regsize = 8;
129 			break;
130 		}
131 	}
132 
133 	timer_setup(&hd->timer, heartbeat_timer, 0);
134 	platform_set_drvdata(pdev, hd);
135 
136 	return mod_timer(&hd->timer, jiffies + 1);
137 }
138 
139 static struct platform_driver heartbeat_driver = {
140 	.probe		= heartbeat_drv_probe,
141 	.driver		= {
142 		.name			= DRV_NAME,
143 		.suppress_bind_attrs	= true,
144 	},
145 };
146 
heartbeat_init(void)147 static int __init heartbeat_init(void)
148 {
149 	printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
150 	return platform_driver_register(&heartbeat_driver);
151 }
152 device_initcall(heartbeat_init);
153