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Linux/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");
117 

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