drivers/hwmon/jz4740-hwmon.c

   1 /*
   2  * Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
   3  * JZ4740 SoC HWMON driver
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under  the terms of the GNU General  Public License as published by the
   7  * Free Software Foundation;  either version 2 of the License, or (at your
   8  * option) any later version.
   9  *
  10  * You should have received a copy of the GNU General Public License along
  11  * with this program; if not, write to the Free Software Foundation, Inc.,
  12  * 675 Mass Ave, Cambridge, MA 02139, USA.
  13  *
  14  */
  15
  16 #include <linux/err.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/slab.h>
  23 #include <linux/io.h>
  24
  25 #include <linux/completion.h>
  26 #include <linux/mfd/core.h>
  27
  28 #include <linux/hwmon.h>
  29
  30 struct jz4740_hwmon {
  31         void __iomem *base;
  32         int irq;
  33         const struct mfd_cell *cell;
  34         struct platform_device *pdev;
  35         struct completion read_completion;
  36         struct mutex lock;
  37 };
  38
  39 static irqreturn_t jz4740_hwmon_irq(int irq, void *data)
  40 {
  41         struct jz4740_hwmon *hwmon = data;
  42
  43         complete(&hwmon->read_completion);
  44         return IRQ_HANDLED;
  45 }
  46
  47 static ssize_t in0_input_show(struct device *dev,
  48                               struct device_attribute *dev_attr, char *buf)
  49 {
  50         struct jz4740_hwmon *hwmon = dev_get_drvdata(dev);
  51         struct platform_device *pdev = hwmon->pdev;
  52         struct completion *completion = &hwmon->read_completion;
  53         long t;
  54         unsigned long val;
  55         int ret;
  56
  57         mutex_lock(&hwmon->lock);
  58
  59         reinit_completion(completion);
  60
  61         enable_irq(hwmon->irq);
  62         hwmon->cell->enable(pdev);
  63
  64         t = wait_for_completion_interruptible_timeout(completion, HZ);
  65
  66         if (t > 0) {
  67                 val = readw(hwmon->base) & 0xfff;
  68                 val = (val * 3300) >> 12;
  69                 ret = sprintf(buf, "%lu\n", val);
  70         } else {
  71                 ret = t ? t : -ETIMEDOUT;
  72         }
  73
  74         hwmon->cell->disable(pdev);
  75         disable_irq(hwmon->irq);
  76
  77         mutex_unlock(&hwmon->lock);
  78
  79         return ret;
  80 }
  81
  82 static DEVICE_ATTR_RO(in0_input);
  83
  84 static struct attribute *jz4740_attrs[] = {
  85         &dev_attr_in0_input.attr,
  86         NULL
  87 };
  88
  89 ATTRIBUTE_GROUPS(jz4740);
  90
  91 static int jz4740_hwmon_probe(struct platform_device *pdev)
  92 {
  93         int ret;
  94         struct device *dev = &pdev->dev;
  95         struct jz4740_hwmon *hwmon;
  96         struct device *hwmon_dev;
  97         struct resource *mem;
  98
  99         hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
 100         if (!hwmon)
 101                 return -ENOMEM;
 102
 103         hwmon->cell = mfd_get_cell(pdev);
 104
 105         hwmon->irq = platform_get_irq(pdev, 0);
 106         if (hwmon->irq < 0) {
 107                 dev_err(&pdev->dev, "Failed to get platform irq: %d\n",
 108                         hwmon->irq);
 109                 return hwmon->irq;
 110         }
 111
 112         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 113         hwmon->base = devm_ioremap_resource(&pdev->dev, mem);
 114         if (IS_ERR(hwmon->base))
 115                 return PTR_ERR(hwmon->base);
 116
 117         hwmon->pdev = pdev;
 118         init_completion(&hwmon->read_completion);
 119         mutex_init(&hwmon->lock);
 120
 121         ret = devm_request_irq(dev, hwmon->irq, jz4740_hwmon_irq, 0,
 122                                pdev->name, hwmon);
 123         if (ret) {
 124                 dev_err(&pdev->dev, "Failed to request irq: %d\n", ret);
 125                 return ret;
 126         }
 127         disable_irq(hwmon->irq);
 128
 129         hwmon_dev = devm_hwmon_device_register_with_groups(dev, "jz4740", hwmon,
 130                                                            jz4740_groups);
 131         return PTR_ERR_OR_ZERO(hwmon_dev);
 132 }
 133
 134 static struct platform_driver jz4740_hwmon_driver = {
 135         .probe  = jz4740_hwmon_probe,
 136         .driver = {
 137                 .name = "jz4740-hwmon",
 138         },
 139 };
 140
 141 module_platform_driver(jz4740_hwmon_driver);
 142
 143 MODULE_DESCRIPTION("JZ4740 SoC HWMON driver");
 144 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 145 MODULE_LICENSE("GPL");
 146 MODULE_ALIAS("platform:jz4740-hwmon");