arch/sh/drivers/heartbeat.c

   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
  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
  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
  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_nocache(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
 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);