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