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 #include <linux/pinctrl/consumer.h>
  23
  24 /* Serialize access to ssc_list and user count */
  25 static DEFINE_SPINLOCK(user_lock);
  26 static LIST_HEAD(ssc_list);
  27
  28 struct ssc_device *ssc_request(unsigned int ssc_num)
  29 {
  30         int ssc_valid = 0;
  31         struct ssc_device *ssc;
  32
  33         spin_lock(&user_lock);
  34         list_for_each_entry(ssc, &ssc_list, list) {
  35                 if (ssc->pdev->dev.of_node) {
  36                         if (of_alias_get_id(ssc->pdev->dev.of_node, "ssc")
  37                                 == 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                 spin_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                 spin_unlock(&user_lock);
  55                 dev_dbg(&ssc->pdev->dev, "module busy\n");
  56                 return ERR_PTR(-EBUSY);
  57         }
  58         ssc->user++;
  59         spin_unlock(&user_lock);
  60
  61         clk_prepare_enable(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         spin_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         spin_unlock(&user_lock);
  79
  80         if (disable_clk)
  81                 clk_disable_unprepare(ssc->clk);
  82 }
  83 EXPORT_SYMBOL(ssc_free);
  84
  85 static struct atmel_ssc_platform_data at91rm9200_config = {
  86         .use_dma = 0,
  87 };
  88
  89 static struct atmel_ssc_platform_data at91sam9g45_config = {
  90         .use_dma = 1,
  91 };
  92
  93 static const struct platform_device_id atmel_ssc_devtypes[] = {
  94         {
  95                 .name = "at91rm9200_ssc",
  96                 .driver_data = (unsigned long) &at91rm9200_config,
  97         }, {
  98                 .name = "at91sam9g45_ssc",
  99                 .driver_data = (unsigned long) &at91sam9g45_config,
 100         }, {
 101                 /* sentinel */
 102         }
 103 };
 104
 105 #ifdef CONFIG_OF
 106 static const struct of_device_id atmel_ssc_dt_ids[] = {
 107         {
 108                 .compatible = "atmel,at91rm9200-ssc",
 109                 .data = &at91rm9200_config,
 110         }, {
 111                 .compatible = "atmel,at91sam9g45-ssc",
 112                 .data = &at91sam9g45_config,
 113         }, {
 114                 /* sentinel */
 115         }
 116 };
 117 MODULE_DEVICE_TABLE(of, atmel_ssc_dt_ids);
 118 #endif
 119
 120 static inline const struct atmel_ssc_platform_data * __init
 121         atmel_ssc_get_driver_data(struct platform_device *pdev)
 122 {
 123         if (pdev->dev.of_node) {
 124                 const struct of_device_id *match;
 125                 match = of_match_node(atmel_ssc_dt_ids, pdev->dev.of_node);
 126                 if (match == NULL)
 127                         return NULL;
 128                 return match->data;
 129         }
 130
 131         return (struct atmel_ssc_platform_data *)
 132                 platform_get_device_id(pdev)->driver_data;
 133 }
 134
 135 static int ssc_probe(struct platform_device *pdev)
 136 {
 137         struct resource *regs;
 138         struct ssc_device *ssc;
 139         const struct atmel_ssc_platform_data *plat_dat;
 140         struct pinctrl *pinctrl;
 141
 142         pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
 143         if (IS_ERR(pinctrl)) {
 144                 dev_err(&pdev->dev, "Failed to request pinctrl\n");
 145                 return PTR_ERR(pinctrl);
 146         }
 147
 148         ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
 149         if (!ssc) {
 150                 dev_dbg(&pdev->dev, "out of memory\n");
 151                 return -ENOMEM;
 152         }
 153
 154         ssc->pdev = pdev;
 155
 156         plat_dat = atmel_ssc_get_driver_data(pdev);
 157         if (!plat_dat)
 158                 return -ENODEV;
 159         ssc->pdata = (struct atmel_ssc_platform_data *)plat_dat;
 160
 161         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 162         ssc->regs = devm_ioremap_resource(&pdev->dev, regs);
 163         if (IS_ERR(ssc->regs))
 164                 return PTR_ERR(ssc->regs);
 165
 166         ssc->phybase = regs->start;
 167
 168         ssc->clk = devm_clk_get(&pdev->dev, "pclk");
 169         if (IS_ERR(ssc->clk)) {
 170                 dev_dbg(&pdev->dev, "no pclk clock defined\n");
 171                 return -ENXIO;
 172         }
 173
 174         /* disable all interrupts */
 175         clk_prepare_enable(ssc->clk);
 176         ssc_writel(ssc->regs, IDR, -1);
 177         ssc_readl(ssc->regs, SR);
 178         clk_disable_unprepare(ssc->clk);
 179
 180         ssc->irq = platform_get_irq(pdev, 0);
 181         if (!ssc->irq) {
 182                 dev_dbg(&pdev->dev, "could not get irq\n");
 183                 return -ENXIO;
 184         }
 185
 186         spin_lock(&user_lock);
 187         list_add_tail(&ssc->list, &ssc_list);
 188         spin_unlock(&user_lock);
 189
 190         platform_set_drvdata(pdev, ssc);
 191
 192         dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)\n",
 193                         ssc->regs, ssc->irq);
 194
 195         return 0;
 196 }
 197
 198 static int ssc_remove(struct platform_device *pdev)
 199 {
 200         struct ssc_device *ssc = platform_get_drvdata(pdev);
 201
 202         spin_lock(&user_lock);
 203         list_del(&ssc->list);
 204         spin_unlock(&user_lock);
 205
 206         return 0;
 207 }
 208
 209 static struct platform_driver ssc_driver = {
 210         .driver         = {
 211                 .name           = "ssc",
 212                 .owner          = THIS_MODULE,
 213                 .of_match_table = of_match_ptr(atmel_ssc_dt_ids),
 214         },
 215         .id_table       = atmel_ssc_devtypes,
 216         .probe          = ssc_probe,
 217         .remove         = ssc_remove,
 218 };
 219 module_platform_driver(ssc_driver);
 220
 221 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
 222 MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
 223 MODULE_LICENSE("GPL");
 224 MODULE_ALIAS("platform:ssc");