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kernel/linux-imx6_3.14.28/drivers/power/reset/qnap-poweroff.c 2.94 KB
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  /*
   * QNAP Turbo NAS Board power off
   *
   * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
   *
   * Based on the code from:
   *
   * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
   * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/serial_reg.h>
  #include <linux/kallsyms.h>
  #include <linux/of.h>
  #include <linux/io.h>
  #include <linux/clk.h>
  
  #define UART1_REG(x)	(base + ((UART_##x) << 2))
  
  static void __iomem *base;
  static unsigned long tclk;
  
  static void qnap_power_off(void)
  {
  	/* 19200 baud divisor */
  	const unsigned divisor = ((tclk + (8 * 19200)) / (16 * 19200));
  
  	pr_err("%s: triggering power-off...
  ", __func__);
  
  	/* hijack UART1 and reset into sane state (19200,8n1) */
  	writel(0x83, UART1_REG(LCR));
  	writel(divisor & 0xff, UART1_REG(DLL));
  	writel((divisor >> 8) & 0xff, UART1_REG(DLM));
  	writel(0x03, UART1_REG(LCR));
  	writel(0x00, UART1_REG(IER));
  	writel(0x00, UART1_REG(FCR));
  	writel(0x00, UART1_REG(MCR));
  
  	/* send the power-off command 'A' to PIC */
  	writel('A', UART1_REG(TX));
  }
  
  static int qnap_power_off_probe(struct platform_device *pdev)
  {
  	struct resource *res;
  	struct clk *clk;
  	char symname[KSYM_NAME_LEN];
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res) {
  		dev_err(&pdev->dev, "Missing resource");
  		return -EINVAL;
  	}
  
  	base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
  	if (!base) {
  		dev_err(&pdev->dev, "Unable to map resource");
  		return -EINVAL;
  	}
  
  	/* We need to know tclk in order to calculate the UART divisor */
  	clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(clk)) {
  		dev_err(&pdev->dev, "Clk missing");
  		return PTR_ERR(clk);
  	}
  
  	tclk = clk_get_rate(clk);
  
  	/* Check that nothing else has already setup a handler */
  	if (pm_power_off) {
  		lookup_symbol_name((ulong)pm_power_off, symname);
  		dev_err(&pdev->dev,
  			"pm_power_off already claimed %p %s",
  			pm_power_off, symname);
  		return -EBUSY;
  	}
  	pm_power_off = qnap_power_off;
  
  	return 0;
  }
  
  static int qnap_power_off_remove(struct platform_device *pdev)
  {
  	pm_power_off = NULL;
  	return 0;
  }
  
  static const struct of_device_id qnap_power_off_of_match_table[] = {
  	{ .compatible = "qnap,power-off", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
  
  static struct platform_driver qnap_power_off_driver = {
  	.probe	= qnap_power_off_probe,
  	.remove	= qnap_power_off_remove,
  	.driver	= {
  		.owner	= THIS_MODULE,
  		.name	= "qnap_power_off",
  		.of_match_table = of_match_ptr(qnap_power_off_of_match_table),
  	},
  };
  module_platform_driver(qnap_power_off_driver);
  
  MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
  MODULE_DESCRIPTION("QNAP Power off driver");
  MODULE_LICENSE("GPL v2");