linux/drivers/misc/atmel-ssc.c
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   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 */
  20static DEFINE_SPINLOCK(user_lock);
  21static LIST_HEAD(ssc_list);
  22
  23struct 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                dev_dbg(&ssc->pdev->dev, "could not find requested device\n");
  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}
  54EXPORT_SYMBOL(ssc_request);
  55
  56void 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}
  67EXPORT_SYMBOL(ssc_free);
  68
  69static 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
 128out_unmap:
 129        iounmap(ssc->regs);
 130out_clk:
 131        clk_put(ssc->clk);
 132out_free:
 133        kfree(ssc);
 134out:
 135        return retval;
 136}
 137
 138static 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
 152static struct platform_driver ssc_driver = {
 153        .remove         = __devexit_p(ssc_remove),
 154        .driver         = {
 155                .name           = "ssc",
 156                .owner          = THIS_MODULE,
 157        },
 158};
 159
 160static int __init ssc_init(void)
 161{
 162        return platform_driver_probe(&ssc_driver, ssc_probe);
 163}
 164module_init(ssc_init);
 165
 166static void __exit ssc_exit(void)
 167{
 168        platform_driver_unregister(&ssc_driver);
 169}
 170module_exit(ssc_exit);
 171
 172MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 173MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
 174MODULE_LICENSE("GPL");
 175MODULE_ALIAS("platform:ssc");
 176