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_enable(ssc->clk);
  61
  62         return ssc;
  63 }
  64 EXPORT_SYMBOL(ssc_request);
  65
  66 void ssc_free(struct ssc_device *ssc)
  67 {
  68         spin_lock(&user_lock);
  69         if (ssc->user) {
  70                 ssc->user--;
  71                 clk_disable(ssc->clk);
  72         } else {
  73                 dev_dbg(&ssc->pdev->dev, "device already free\n");
  74         }
  75         spin_unlock(&user_lock);
  76 }
  77 EXPORT_SYMBOL(ssc_free);
  78
  79 static struct atmel_ssc_platform_data at91rm9200_config = {
  80         .use_dma = 0,
  81 };
  82
  83 static struct atmel_ssc_platform_data at91sam9g45_config = {
  84         .use_dma = 1,
  85 };
  86
  87 static const struct platform_device_id atmel_ssc_devtypes[] = {
  88         {
  89                 .name = "at91rm9200_ssc",
  90                 .driver_data = (unsigned long) &at91rm9200_config,
  91         }, {
  92                 .name = "at91sam9g45_ssc",
  93                 .driver_data = (unsigned long) &at91sam9g45_config,
  94         }, {
  95                 /* sentinel */
  96         }
  97 };
  98
  99 #ifdef CONFIG_OF
 100 static const struct of_device_id atmel_ssc_dt_ids[] = {
 101         {
 102                 .compatible = "atmel,at91rm9200-ssc",
 103                 .data = &at91rm9200_config,
 104         }, {
 105                 .compatible = "atmel,at91sam9g45-ssc",
 106                 .data = &at91sam9g45_config,
 107         }, {
 108                 /* sentinel */
 109         }
 110 };
 111 MODULE_DEVICE_TABLE(of, atmel_ssc_dt_ids);
 112 #endif
 113
 114 static inline const struct atmel_ssc_platform_data * __init
 115         atmel_ssc_get_driver_data(struct platform_device *pdev)
 116 {
 117         if (pdev->dev.of_node) {
 118                 const struct of_device_id *match;
 119                 match = of_match_node(atmel_ssc_dt_ids, pdev->dev.of_node);
 120                 if (match == NULL)
 121                         return NULL;
 122                 return match->data;
 123         }
 124
 125         return (struct atmel_ssc_platform_data *)
 126                 platform_get_device_id(pdev)->driver_data;
 127 }
 128
 129 static int ssc_probe(struct platform_device *pdev)
 130 {
 131         struct resource *regs;
 132         struct ssc_device *ssc;
 133         const struct atmel_ssc_platform_data *plat_dat;
 134
 135         ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
 136         if (!ssc) {
 137                 dev_dbg(&pdev->dev, "out of memory\n");
 138                 return -ENOMEM;
 139         }
 140
 141         ssc->pdev = pdev;
 142
 143         plat_dat = atmel_ssc_get_driver_data(pdev);
 144         if (!plat_dat)
 145                 return -ENODEV;
 146         ssc->pdata = (struct atmel_ssc_platform_data *)plat_dat;
 147
 148         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 149         if (!regs) {
 150                 dev_dbg(&pdev->dev, "no mmio resource defined\n");
 151                 return -ENXIO;
 152         }
 153
 154         ssc->regs = devm_request_and_ioremap(&pdev->dev, regs);
 155         if (!ssc->regs) {
 156                 dev_dbg(&pdev->dev, "ioremap failed\n");
 157                 return -EINVAL;
 158         }
 159
 160         ssc->phybase = regs->start;
 161
 162         ssc->clk = devm_clk_get(&pdev->dev, "pclk");
 163         if (IS_ERR(ssc->clk)) {
 164                 dev_dbg(&pdev->dev, "no pclk clock defined\n");
 165                 return -ENXIO;
 166         }
 167
 168         /* disable all interrupts */
 169         clk_enable(ssc->clk);
 170         ssc_writel(ssc->regs, IDR, ~0UL);
 171         ssc_readl(ssc->regs, SR);
 172         clk_disable(ssc->clk);
 173
 174         ssc->irq = platform_get_irq(pdev, 0);
 175         if (!ssc->irq) {
 176                 dev_dbg(&pdev->dev, "could not get irq\n");
 177                 return -ENXIO;
 178         }
 179
 180         spin_lock(&user_lock);
 181         list_add_tail(&ssc->list, &ssc_list);
 182         spin_unlock(&user_lock);
 183
 184         platform_set_drvdata(pdev, ssc);
 185
 186         dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
 187                         ssc->regs, ssc->irq);
 188
 189         return 0;
 190 }
 191
 192 static int ssc_remove(struct platform_device *pdev)
 193 {
 194         struct ssc_device *ssc = platform_get_drvdata(pdev);
 195
 196         spin_lock(&user_lock);
 197         list_del(&ssc->list);
 198         spin_unlock(&user_lock);
 199
 200         return 0;
 201 }
 202
 203 static struct platform_driver ssc_driver = {
 204         .driver         = {
 205                 .name           = "ssc",
 206                 .owner          = THIS_MODULE,
 207                 .of_match_table = of_match_ptr(atmel_ssc_dt_ids),
 208         },
 209         .id_table       = atmel_ssc_devtypes,
 210         .probe          = ssc_probe,
 211         .remove         = ssc_remove,
 212 };
 213 module_platform_driver(ssc_driver);
 214
 215 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 216 MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
 217 MODULE_LICENSE("GPL");
 218 MODULE_ALIAS("platform:ssc");