drivers/power/reset/qnap-poweroff.c

   1 /*
   2  * QNAP Turbo NAS Board power off
   3  *
   4  * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
   5  *
   6  * Based on the code from:
   7  *
   8  * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
   9  * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; either version
  14  * 2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/serial_reg.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/of.h>
  23 #include <linux/io.h>
  24 #include <linux/clk.h>
  25
  26 #define UART1_REG(x)    (base + ((UART_##x) << 2))
  27
  28 static void __iomem *base;
  29 static unsigned long tclk;
  30
  31 static void qnap_power_off(void)
  32 {
  33         /* 19200 baud divisor */
  34         const unsigned divisor = ((tclk + (8 * 19200)) / (16 * 19200));
  35
  36         pr_err("%s: triggering power-off...\n", __func__);
  37
  38         /* hijack UART1 and reset into sane state (19200,8n1) */
  39         writel(0x83, UART1_REG(LCR));
  40         writel(divisor & 0xff, UART1_REG(DLL));
  41         writel((divisor >> 8) & 0xff, UART1_REG(DLM));
  42         writel(0x03, UART1_REG(LCR));
  43         writel(0x00, UART1_REG(IER));
  44         writel(0x00, UART1_REG(FCR));
  45         writel(0x00, UART1_REG(MCR));
  46
  47         /* send the power-off command 'A' to PIC */
  48         writel('A', UART1_REG(TX));
  49 }
  50
  51 static int qnap_power_off_probe(struct platform_device *pdev)
  52 {
  53         struct resource *res;
  54         struct clk *clk;
  55         char symname[KSYM_NAME_LEN];
  56
  57         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  58         if (!res) {
  59                 dev_err(&pdev->dev, "Missing resource");
  60                 return -EINVAL;
  61         }
  62
  63         base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
  64         if (!base) {
  65                 dev_err(&pdev->dev, "Unable to map resource");
  66                 return -EINVAL;
  67         }
  68
  69         /* We need to know tclk in order to calculate the UART divisor */
  70         clk = devm_clk_get(&pdev->dev, NULL);
  71         if (IS_ERR(clk)) {
  72                 dev_err(&pdev->dev, "Clk missing");
  73                 return PTR_ERR(clk);
  74         }
  75
  76         tclk = clk_get_rate(clk);
  77
  78         /* Check that nothing else has already setup a handler */
  79         if (pm_power_off) {
  80                 lookup_symbol_name((ulong)pm_power_off, symname);
  81                 dev_err(&pdev->dev,
  82                         "pm_power_off already claimed %p %s",
  83                         pm_power_off, symname);
  84                 return -EBUSY;
  85         }
  86         pm_power_off = qnap_power_off;
  87
  88         return 0;
  89 }
  90
  91 static int qnap_power_off_remove(struct platform_device *pdev)
  92 {
  93         pm_power_off = NULL;
  94         return 0;
  95 }
  96
  97 static const struct of_device_id qnap_power_off_of_match_table[] = {
  98         { .compatible = "qnap,power-off", },
  99         {}
 100 };
 101 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
 102
 103 static struct platform_driver qnap_power_off_driver = {
 104         .probe  = qnap_power_off_probe,
 105         .remove = qnap_power_off_remove,
 106         .driver = {
 107                 .owner  = THIS_MODULE,
 108                 .name   = "qnap_power_off",
 109                 .of_match_table = of_match_ptr(qnap_power_off_of_match_table),
 110         },
 111 };
 112 module_platform_driver(qnap_power_off_driver);
 113
 114 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
 115 MODULE_DESCRIPTION("QNAP Power off driver");
 116 MODULE_LICENSE("GPL v2");