drivers/misc/atmel-ssc.c

   1 /*
   2  * Atmel SSC driver
   3  *
   4  * Copyright (C) 2007 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/platform_device.h>
  12 #include <linux/list.h>
  13 #include <linux/clk.h>
  14 #include <linux/err.h>
  15 #include <linux/io.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/atmel-ssc.h>
  18
  19 /* Serialize access to ssc_list and user count */
  20 static DEFINE_SPINLOCK(user_lock);
  21 static LIST_HEAD(ssc_list);
  22
  23 struct ssc_device *ssc_request(unsigned int ssc_num)
  24 {
  25         int ssc_valid = 0;
  26         struct ssc_device *ssc;
  27
  28         spin_lock(&user_lock);
  29         list_for_each_entry(ssc, &ssc_list, list) {
  30                 if (ssc->pdev->id == ssc_num) {
  31                         ssc_valid = 1;
  32                         break;
  33                 }
  34         }
  35
  36         if (!ssc_valid) {
  37                 spin_unlock(&user_lock);
  38                 pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
  39                 return ERR_PTR(-ENODEV);
  40         }
  41
  42         if (ssc->user) {
  43                 spin_unlock(&user_lock);
  44                 dev_dbg(&ssc->pdev->dev, "module busy\n");
  45                 return ERR_PTR(-EBUSY);
  46         }
  47         ssc->user++;
  48         spin_unlock(&user_lock);
  49
  50         clk_enable(ssc->clk);
  51
  52         return ssc;
  53 }
  54 EXPORT_SYMBOL(ssc_request);
  55
  56 void ssc_free(struct ssc_device *ssc)
  57 {
  58         spin_lock(&user_lock);
  59         if (ssc->user) {
  60                 ssc->user--;
  61                 clk_disable(ssc->clk);
  62         } else {
  63                 dev_dbg(&ssc->pdev->dev, "device already free\n");
  64         }
  65         spin_unlock(&user_lock);
  66 }
  67 EXPORT_SYMBOL(ssc_free);
  68
  69 static int __init ssc_probe(struct platform_device *pdev)
  70 {
  71         int retval = 0;
  72         struct resource *regs;
  73         struct ssc_device *ssc;
  74
  75         ssc = kzalloc(sizeof(struct ssc_device), GFP_KERNEL);
  76         if (!ssc) {
  77                 dev_dbg(&pdev->dev, "out of memory\n");
  78                 retval = -ENOMEM;
  79                 goto out;
  80         }
  81
  82         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  83         if (!regs) {
  84                 dev_dbg(&pdev->dev, "no mmio resource defined\n");
  85                 retval = -ENXIO;
  86                 goto out_free;
  87         }
  88
  89         ssc->clk = clk_get(&pdev->dev, "pclk");
  90         if (IS_ERR(ssc->clk)) {
  91                 dev_dbg(&pdev->dev, "no pclk clock defined\n");
  92                 retval = -ENXIO;
  93                 goto out_free;
  94         }
  95
  96         ssc->pdev = pdev;
  97         ssc->regs = ioremap(regs->start, regs->end - regs->start + 1);
  98         if (!ssc->regs) {
  99                 dev_dbg(&pdev->dev, "ioremap failed\n");
 100                 retval = -EINVAL;
 101                 goto out_clk;
 102         }
 103
 104         /* disable all interrupts */
 105         clk_enable(ssc->clk);
 106         ssc_writel(ssc->regs, IDR, ~0UL);
 107         ssc_readl(ssc->regs, SR);
 108         clk_disable(ssc->clk);
 109
 110         ssc->irq = platform_get_irq(pdev, 0);
 111         if (!ssc->irq) {
 112                 dev_dbg(&pdev->dev, "could not get irq\n");
 113                 retval = -ENXIO;
 114                 goto out_unmap;
 115         }
 116
 117         spin_lock(&user_lock);
 118         list_add_tail(&ssc->list, &ssc_list);
 119         spin_unlock(&user_lock);
 120
 121         platform_set_drvdata(pdev, ssc);
 122
 123         dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
 124                         ssc->regs, ssc->irq);
 125
 126         goto out;
 127
 128 out_unmap:
 129         iounmap(ssc->regs);
 130 out_clk:
 131         clk_put(ssc->clk);
 132 out_free:
 133         kfree(ssc);
 134 out:
 135         return retval;
 136 }
 137
 138 static int __devexit ssc_remove(struct platform_device *pdev)
 139 {
 140         struct ssc_device *ssc = platform_get_drvdata(pdev);
 141
 142         spin_lock(&user_lock);
 143         iounmap(ssc->regs);
 144         clk_put(ssc->clk);
 145         list_del(&ssc->list);
 146         kfree(ssc);
 147         spin_unlock(&user_lock);
 148
 149         return 0;
 150 }
 151
 152 static struct platform_driver ssc_driver = {
 153         .remove         = __devexit_p(ssc_remove),
 154         .driver         = {
 155                 .name           = "ssc",
 156                 .owner          = THIS_MODULE,
 157         },
 158 };
 159
 160 static int __init ssc_init(void)
 161 {
 162         return platform_driver_probe(&ssc_driver, ssc_probe);
 163 }
 164 module_init(ssc_init);
 165
 166 static void __exit ssc_exit(void)
 167 {
 168         platform_driver_unregister(&ssc_driver);
 169 }
 170 module_exit(ssc_exit);
 171
 172 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 173 MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
 174 MODULE_LICENSE("GPL");
 175 MODULE_ALIAS("platform:ssc");