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 #include <linux/of.h>
  22
  23 /* Serialize access to ssc_list and user count */
  24 static DEFINE_SPINLOCK(user_lock);
  25 static LIST_HEAD(ssc_list);
  26
  27 struct ssc_device *ssc_request(unsigned int ssc_num)
  28 {
  29         int ssc_valid = 0;
  30         struct ssc_device *ssc;
  31
  32         spin_lock(&user_lock);
  33         list_for_each_entry(ssc, &ssc_list, list) {
  34                 if (ssc->pdev->dev.of_node) {
  35                         if (of_alias_get_id(ssc->pdev->dev.of_node, "ssc")
  36                                 == ssc_num) {
  37                                 ssc_valid = 1;
  38                                 break;
  39                         }
  40                 } else if (ssc->pdev->id == ssc_num) {
  41                         ssc_valid = 1;
  42                         break;
  43                 }
  44         }
  45
  46         if (!ssc_valid) {
  47                 spin_unlock(&user_lock);
  48                 pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
  49                 return ERR_PTR(-ENODEV);
  50         }
  51
  52         if (ssc->user) {
  53                 spin_unlock(&user_lock);
  54                 dev_dbg(&ssc->pdev->dev, "module busy\n");
  55                 return ERR_PTR(-EBUSY);
  56         }
  57         ssc->user++;
  58         spin_unlock(&user_lock);
  59
  60         clk_prepare_enable(ssc->clk);
  61
  62         return ssc;
  63 }
  64 EXPORT_SYMBOL(ssc_request);
  65
  66 void ssc_free(struct ssc_device *ssc)
  67 {
  68         bool disable_clk = true;
  69
  70         spin_lock(&user_lock);
  71         if (ssc->user)
  72                 ssc->user--;
  73         else {
  74                 disable_clk = false;
  75                 dev_dbg(&ssc->pdev->dev, "device already free\n");
  76         }
  77         spin_unlock(&user_lock);
  78
  79         if (disable_clk)
  80                 clk_disable_unprepare(ssc->clk);
  81 }
  82 EXPORT_SYMBOL(ssc_free);
  83
  84 static struct atmel_ssc_platform_data at91rm9200_config = {
  85         .use_dma = 0,
  86 };
  87
  88 static struct atmel_ssc_platform_data at91sam9g45_config = {
  89         .use_dma = 1,
  90 };
  91
  92 static const struct platform_device_id atmel_ssc_devtypes[] = {
  93         {
  94                 .name = "at91rm9200_ssc",
  95                 .driver_data = (unsigned long) &at91rm9200_config,
  96         }, {
  97                 .name = "at91sam9g45_ssc",
  98                 .driver_data = (unsigned long) &at91sam9g45_config,
  99         }, {
 100                 /* sentinel */
 101         }
 102 };
 103
 104 #ifdef CONFIG_OF
 105 static const struct of_device_id atmel_ssc_dt_ids[] = {
 106         {
 107                 .compatible = "atmel,at91rm9200-ssc",
 108                 .data = &at91rm9200_config,
 109         }, {
 110                 .compatible = "atmel,at91sam9g45-ssc",
 111                 .data = &at91sam9g45_config,
 112         }, {
 113                 /* sentinel */
 114         }
 115 };
 116 MODULE_DEVICE_TABLE(of, atmel_ssc_dt_ids);
 117 #endif
 118
 119 static inline const struct atmel_ssc_platform_data * __init
 120         atmel_ssc_get_driver_data(struct platform_device *pdev)
 121 {
 122         if (pdev->dev.of_node) {
 123                 const struct of_device_id *match;
 124                 match = of_match_node(atmel_ssc_dt_ids, pdev->dev.of_node);
 125                 if (match == NULL)
 126                         return NULL;
 127                 return match->data;
 128         }
 129
 130         return (struct atmel_ssc_platform_data *)
 131                 platform_get_device_id(pdev)->driver_data;
 132 }
 133
 134 static int ssc_probe(struct platform_device *pdev)
 135 {
 136         struct resource *regs;
 137         struct ssc_device *ssc;
 138         const struct atmel_ssc_platform_data *plat_dat;
 139
 140         ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
 141         if (!ssc) {
 142                 dev_dbg(&pdev->dev, "out of memory\n");
 143                 return -ENOMEM;
 144         }
 145
 146         ssc->pdev = pdev;
 147
 148         plat_dat = atmel_ssc_get_driver_data(pdev);
 149         if (!plat_dat)
 150                 return -ENODEV;
 151         ssc->pdata = (struct atmel_ssc_platform_data *)plat_dat;
 152
 153         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 154         ssc->regs = devm_ioremap_resource(&pdev->dev, regs);
 155         if (IS_ERR(ssc->regs))
 156                 return PTR_ERR(ssc->regs);
 157
 158         ssc->phybase = regs->start;
 159
 160         ssc->clk = devm_clk_get(&pdev->dev, "pclk");
 161         if (IS_ERR(ssc->clk)) {
 162                 dev_dbg(&pdev->dev, "no pclk clock defined\n");
 163                 return -ENXIO;
 164         }
 165
 166         /* disable all interrupts */
 167         clk_prepare_enable(ssc->clk);
 168         ssc_writel(ssc->regs, IDR, -1);
 169         ssc_readl(ssc->regs, SR);
 170         clk_disable_unprepare(ssc->clk);
 171
 172         ssc->irq = platform_get_irq(pdev, 0);
 173         if (!ssc->irq) {
 174                 dev_dbg(&pdev->dev, "could not get irq\n");
 175                 return -ENXIO;
 176         }
 177
 178         spin_lock(&user_lock);
 179         list_add_tail(&ssc->list, &ssc_list);
 180         spin_unlock(&user_lock);
 181
 182         platform_set_drvdata(pdev, ssc);
 183
 184         dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
 185                         ssc->regs, ssc->irq);
 186
 187         return 0;
 188 }
 189
 190 static int ssc_remove(struct platform_device *pdev)
 191 {
 192         struct ssc_device *ssc = platform_get_drvdata(pdev);
 193
 194         spin_lock(&user_lock);
 195         list_del(&ssc->list);
 196         spin_unlock(&user_lock);
 197
 198         return 0;
 199 }
 200
 201 static struct platform_driver ssc_driver = {
 202         .driver         = {
 203                 .name           = "ssc",
 204                 .owner          = THIS_MODULE,
 205                 .of_match_table = of_match_ptr(atmel_ssc_dt_ids),
 206         },
 207         .id_table       = atmel_ssc_devtypes,
 208         .probe          = ssc_probe,
 209         .remove         = ssc_remove,
 210 };
 211 module_platform_driver(ssc_driver);
 212
 213 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 214 MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
 215 MODULE_LICENSE("GPL");
 216 MODULE_ALIAS("platform:ssc");