/*
   * Atmel SSC driver
   *
   * Copyright (C) 2007 Atmel Corporation
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/platform_device.h>
  #include <linux/list.h>
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/spinlock.h>
  #include <linux/atmel-ssc.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  
  #include <linux/of.h>
  
  /* Serialize access to ssc_list and user count */
  static DEFINE_SPINLOCK(user_lock);
  static LIST_HEAD(ssc_list);
  
  struct ssc_device *ssc_request(unsigned int ssc_num)
  {
  	int ssc_valid = 0;
  	struct ssc_device *ssc;
  
  	spin_lock(&user_lock);
  	list_for_each_entry(ssc, &ssc_list, list) {
  		if (ssc->pdev->dev.of_node) {
  			if (of_alias_get_id(ssc->pdev->dev.of_node, "ssc")
  				== ssc_num) {
  				ssc_valid = 1;
  				break;
  			}
  		} else if (ssc->pdev->id == ssc_num) {
  			ssc_valid = 1;
  			break;
  		}
  	}
  
  	if (!ssc_valid) {
  		spin_unlock(&user_lock);
  		pr_err("ssc: ssc%d platform device is missing
  ", ssc_num);
  		return ERR_PTR(-ENODEV);
  	}
  
  	if (ssc->user) {
  		spin_unlock(&user_lock);
  		dev_dbg(&ssc->pdev->dev, "module busy
  ");
  		return ERR_PTR(-EBUSY);
  	}
  	ssc->user++;
  	spin_unlock(&user_lock);
  
  	clk_prepare_enable(ssc->clk);
  
  	return ssc;
  }
  EXPORT_SYMBOL(ssc_request);
  
  void ssc_free(struct ssc_device *ssc)
  {
  	bool disable_clk = true;
  
  	spin_lock(&user_lock);
  	if (ssc->user)
  		ssc->user--;
  	else {
  		disable_clk = false;
  		dev_dbg(&ssc->pdev->dev, "device already free
  ");
  	}
  	spin_unlock(&user_lock);
  
  	if (disable_clk)
  		clk_disable_unprepare(ssc->clk);
  }
  EXPORT_SYMBOL(ssc_free);
  
  static struct atmel_ssc_platform_data at91rm9200_config = {
  	.use_dma = 0,
  };
  
  static struct atmel_ssc_platform_data at91sam9g45_config = {
  	.use_dma = 1,
  };
  
  static const struct platform_device_id atmel_ssc_devtypes[] = {
  	{
  		.name = "at91rm9200_ssc",
  		.driver_data = (unsigned long) &at91rm9200_config,
  	}, {
  		.name = "at91sam9g45_ssc",
  		.driver_data = (unsigned long) &at91sam9g45_config,
  	}, {
  		/* sentinel */
  	}
  };
  
  #ifdef CONFIG_OF
  static const struct of_device_id atmel_ssc_dt_ids[] = {
  	{
  		.compatible = "atmel,at91rm9200-ssc",
  		.data = &at91rm9200_config,
  	}, {
  		.compatible = "atmel,at91sam9g45-ssc",
  		.data = &at91sam9g45_config,
  	}, {
  		/* sentinel */
  	}
  };
  MODULE_DEVICE_TABLE(of, atmel_ssc_dt_ids);
  #endif
  
  static inline const struct atmel_ssc_platform_data * __init
  	atmel_ssc_get_driver_data(struct platform_device *pdev)
  {
  	if (pdev->dev.of_node) {
  		const struct of_device_id *match;
  		match = of_match_node(atmel_ssc_dt_ids, pdev->dev.of_node);
  		if (match == NULL)
  			return NULL;
  		return match->data;
  	}
  
  	return (struct atmel_ssc_platform_data *)
  		platform_get_device_id(pdev)->driver_data;
  }
  
  static int ssc_probe(struct platform_device *pdev)
  {
  	struct resource *regs;
  	struct ssc_device *ssc;
  	const struct atmel_ssc_platform_data *plat_dat;
  
  	ssc = devm_kzalloc(&pdev->dev, sizeof(struct ssc_device), GFP_KERNEL);
  	if (!ssc) {
  		dev_dbg(&pdev->dev, "out of memory
  ");
  		return -ENOMEM;
  	}
  
  	ssc->pdev = pdev;
  
  	plat_dat = atmel_ssc_get_driver_data(pdev);
  	if (!plat_dat)
  		return -ENODEV;
  	ssc->pdata = (struct atmel_ssc_platform_data *)plat_dat;
  
  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	ssc->regs = devm_ioremap_resource(&pdev->dev, regs);
  	if (IS_ERR(ssc->regs))
  		return PTR_ERR(ssc->regs);
  
  	ssc->phybase = regs->start;
  
  	ssc->clk = devm_clk_get(&pdev->dev, "pclk");
  	if (IS_ERR(ssc->clk)) {
  		dev_dbg(&pdev->dev, "no pclk clock defined
  ");
  		return -ENXIO;
  	}
  
  	/* disable all interrupts */
  	clk_prepare_enable(ssc->clk);
  	ssc_writel(ssc->regs, IDR, -1);
  	ssc_readl(ssc->regs, SR);
  	clk_disable_unprepare(ssc->clk);
  
  	ssc->irq = platform_get_irq(pdev, 0);
  	if (!ssc->irq) {
  		dev_dbg(&pdev->dev, "could not get irq
  ");
  		return -ENXIO;
  	}
  
  	spin_lock(&user_lock);
  	list_add_tail(&ssc->list, &ssc_list);
  	spin_unlock(&user_lock);
  
  	platform_set_drvdata(pdev, ssc);
  
  	dev_info(&pdev->dev, "Atmel SSC device at 0x%p (irq %d)
  ",
  			ssc->regs, ssc->irq);
  
  	return 0;
  }
  
  static int ssc_remove(struct platform_device *pdev)
  {
  	struct ssc_device *ssc = platform_get_drvdata(pdev);
  
  	spin_lock(&user_lock);
  	list_del(&ssc->list);
  	spin_unlock(&user_lock);
  
  	return 0;
  }
  
  static struct platform_driver ssc_driver = {
  	.driver		= {
  		.name		= "ssc",
  		.owner		= THIS_MODULE,
  		.of_match_table	= of_match_ptr(atmel_ssc_dt_ids),
  	},
  	.id_table	= atmel_ssc_devtypes,
  	.probe		= ssc_probe,
  	.remove		= ssc_remove,
  };
  module_platform_driver(ssc_driver);
  
  MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
  MODULE_DESCRIPTION("SSC driver for Atmel AVR32 and AT91");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:ssc");