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/mutex.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_MUTEX(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         mutex_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->pdev->id = ssc_num;
  38                                 ssc_valid = 1;
  39                                 break;
  40                         }
  41                 } else if (ssc->pdev->id == ssc_num) {
  42                         ssc_valid = 1;
  43                         break;
  44                 }
  45         }
  46
  47         if (!ssc_valid) {
  48                 mutex_unlock(&user_lock);
  49                 pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
  50                 return ERR_PTR(-ENODEV);
  51         }
  52
  53         if (ssc->user) {
  54                 mutex_unlock(&user_lock);
  55                 dev_dbg(&ssc->pdev->dev, "module busy\n");
  56                 return ERR_PTR(-EBUSY);
  57         }
  58         ssc->user++;
  59         mutex_unlock(&user_lock);
  60
  61         clk_prepare(ssc->clk);
  62
  63         return ssc;
  64 }
  65 EXPORT_SYMBOL(ssc_request);
  66
  67 void ssc_free(struct ssc_device *ssc)
  68 {
  69         bool disable_clk = true;
  70
  71         mutex_lock(&user_lock);
  72         if (ssc->user)
  73                 ssc->user--;
  74         else {
  75                 disable_clk = false;
  76                 dev_dbg(&ssc->pdev->dev, "device already free\n");
  77         }
  78         mutex_unlock(&user_lock);
  79
  80         if (disable_clk)
  81                 clk_unprepare(ssc->clk);
  82 }
  83 EXPORT_SYMBOL(ssc_free);
  84
  85 static struct atmel_ssc_platform_data at91rm9200_config = {
  86         .use_dma = 0,
  87         .has_fslen_ext = 0,
  88 };
  89
  90 static struct atmel_ssc_platform_data at91sam9rl_config = {
  91         .use_dma = 0,
  92         .has_fslen_ext = 1,
  93 };
  94
  95 static struct atmel_ssc_platform_data at91sam9g45_config = {
  96         .use_dma = 1,
  97         .has_fslen_ext = 1,
  98 };
  99
 100 static const struct platform_device_id atmel_ssc_devtypes[] = {
 101         {
 102                 .name = "at91rm9200_ssc",
 103                 .driver_data = (unsigned long) &at91rm9200_config,
 104         }, {
 105                 .name = "at91sam9rl_ssc",
 106                 .driver_data = (unsigned long) &at91sam9rl_config,
 107         }, {
 108                 .name = "at91sam9g45_ssc",
 109                 .driver_data = (unsigned long) &at91sam9g45_config,
 110         }, {
 111                 /* sentinel */
 112         }
 113 };
 114
 115 #ifdef CONFIG_OF
 116 static const struct of_device_id atmel_ssc_dt_ids[] = {
 117         {
 118                 .compatible = "atmel,at91rm9200-ssc",
 119                 .data = &at91rm9200_config,
 120         }, {
 121                 .compatible = "atmel,at91sam9rl-ssc",
 122                 .data = &at91sam9rl_config,
 123         }, {
 124                 .compatible = "atmel,at91sam9g45-ssc",
 125                 .data = &at91sam9g45_config,
 126         }, {
 127                 /* sentinel */
 128         }
 129 };
 130 MODULE_DEVICE_TABLE(of, atmel_ssc_dt_ids);
 131 #endif
 132
 133 static inline const struct atmel_ssc_platform_data *
 134         atmel_ssc_get_driver_data(struct platform_device *pdev)
 135 {
 136         if (pdev->dev.of_node) {
 137                 const struct of_device_id *match;
 138                 match = of_match_node(atmel_ssc_dt_ids, pdev->dev.of_node);
 139                 if (match == NULL)
 140                         return NULL;
 141                 return match->data;
 142         }
 143
 144         return (struct atmel_ssc_platform_data *)
 145                 platform_get_device_id(pdev)->driver_data;
 146 }
 147
 148 static int ssc_probe(struct platform_device *pdev)
 149 {
 150         struct resource *regs;
 151         struct ssc_device *ssc;
 152         const struct atmel_ssc_platform_data *plat_dat;
 153
 154         ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
 155         if (!ssc) {
 156                 dev_dbg(&pdev->dev, "out of memory\n");
 157                 return -ENOMEM;
 158         }
 159
 160         ssc->pdev = pdev;
 161
 162         plat_dat = atmel_ssc_get_driver_data(pdev);
 163         if (!plat_dat)
 164                 return -ENODEV;
 165         ssc->pdata = (struct atmel_ssc_platform_data *)plat_dat;
 166
 167         if (pdev->dev.of_node) {
 168                 struct device_node *np = pdev->dev.of_node;
 169                 ssc->clk_from_rk_pin =
 170                         of_property_read_bool(np, "atmel,clk-from-rk-pin");
 171         }
 172
 173         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 174         ssc->regs = devm_ioremap_resource(&pdev->dev, regs);
 175         if (IS_ERR(ssc->regs))
 176                 return PTR_ERR(ssc->regs);
 177
 178         ssc->phybase = regs->start;
 179
 180         ssc->clk = devm_clk_get(&pdev->dev, "pclk");
 181         if (IS_ERR(ssc->clk)) {
 182                 dev_dbg(&pdev->dev, "no pclk clock defined\n");
 183                 return -ENXIO;
 184         }
 185
 186         /* disable all interrupts */
 187         clk_prepare_enable(ssc->clk);
 188         ssc_writel(ssc->regs, IDR, -1);
 189         ssc_readl(ssc->regs, SR);
 190         clk_disable_unprepare(ssc->clk);
 191
 192         ssc->irq = platform_get_irq(pdev, 0);
 193         if (!ssc->irq) {
 194                 dev_dbg(&pdev->dev, "could not get irq\n");
 195                 return -ENXIO;
 196         }
 197
 198         mutex_lock(&user_lock);
 199         list_add_tail(&ssc->list, &ssc_list);
 200         mutex_unlock(&user_lock);
 201
 202         platform_set_drvdata(pdev, ssc);
 203
 204         dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
 205                         ssc->regs, ssc->irq);
 206
 207         return 0;
 208 }
 209
 210 static int ssc_remove(struct platform_device *pdev)
 211 {
 212         struct ssc_device *ssc = platform_get_drvdata(pdev);
 213
 214         mutex_lock(&user_lock);
 215         list_del(&ssc->list);
 216         mutex_unlock(&user_lock);
 217
 218         return 0;
 219 }
 220
 221 static struct platform_driver ssc_driver = {
 222         .driver         = {
 223                 .name           = "ssc",
 224                 .of_match_table = of_match_ptr(atmel_ssc_dt_ids),
 225         },
 226         .id_table       = atmel_ssc_devtypes,
 227         .probe          = ssc_probe,
 228         .remove         = ssc_remove,
 229 };
 230 module_platform_driver(ssc_driver);
 231
 232 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 233 MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
 234 MODULE_LICENSE("GPL");
 235 MODULE_ALIAS("platform:ssc");