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