drivers/power/reset/qnap-poweroff.c

   1 /*
   2  * QNAP Turbo NAS Board power off. Can also be used on Synology devices.
   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 struct power_off_cfg {
  29         u32 baud;
  30         char cmd;
  31 };
  32
  33 static const struct power_off_cfg qnap_power_off_cfg = {
  34         .baud = 19200,
  35         .cmd = 'A',
  36 };
  37
  38 static const struct power_off_cfg synology_power_off_cfg = {
  39         .baud = 9600,
  40         .cmd = '1',
  41 };
  42
  43 static const struct of_device_id qnap_power_off_of_match_table[] = {
  44         { .compatible = "qnap,power-off",
  45           .data = &qnap_power_off_cfg,
  46         },
  47         { .compatible = "synology,power-off",
  48           .data = &synology_power_off_cfg,
  49         },
  50         {}
  51 };
  52 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
  53
  54 static void __iomem *base;
  55 static unsigned long tclk;
  56 static const struct power_off_cfg *cfg;
  57
  58 static void qnap_power_off(void)
  59 {
  60         const unsigned divisor = ((tclk + (8 * cfg->baud)) / (16 * cfg->baud));
  61
  62         pr_err("%s: triggering power-off...\n", __func__);
  63
  64         /* hijack UART1 and reset into sane state */
  65         writel(0x83, UART1_REG(LCR));
  66         writel(divisor & 0xff, UART1_REG(DLL));
  67         writel((divisor >> 8) & 0xff, UART1_REG(DLM));
  68         writel(0x03, UART1_REG(LCR));
  69         writel(0x00, UART1_REG(IER));
  70         writel(0x00, UART1_REG(FCR));
  71         writel(0x00, UART1_REG(MCR));
  72
  73         /* send the power-off command to PIC */
  74         writel(cfg->cmd, UART1_REG(TX));
  75 }
  76
  77 static int qnap_power_off_probe(struct platform_device *pdev)
  78 {
  79         struct device_node *np = pdev->dev.of_node;
  80         struct resource *res;
  81         struct clk *clk;
  82         char symname[KSYM_NAME_LEN];
  83
  84         const struct of_device_id *match =
  85                 of_match_node(qnap_power_off_of_match_table, np);
  86         cfg = match->data;
  87
  88         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  89         if (!res) {
  90                 dev_err(&pdev->dev, "Missing resource");
  91                 return -EINVAL;
  92         }
  93
  94         base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
  95         if (!base) {
  96                 dev_err(&pdev->dev, "Unable to map resource");
  97                 return -EINVAL;
  98         }
  99
 100         /* We need to know tclk in order to calculate the UART divisor */
 101         clk = devm_clk_get(&pdev->dev, NULL);
 102         if (IS_ERR(clk)) {
 103                 dev_err(&pdev->dev, "Clk missing");
 104                 return PTR_ERR(clk);
 105         }
 106
 107         tclk = clk_get_rate(clk);
 108
 109         /* Check that nothing else has already setup a handler */
 110         if (pm_power_off) {
 111                 lookup_symbol_name((ulong)pm_power_off, symname);
 112                 dev_err(&pdev->dev,
 113                         "pm_power_off already claimed %p %s",
 114                         pm_power_off, symname);
 115                 return -EBUSY;
 116         }
 117         pm_power_off = qnap_power_off;
 118
 119         return 0;
 120 }
 121
 122 static int qnap_power_off_remove(struct platform_device *pdev)
 123 {
 124         pm_power_off = NULL;
 125         return 0;
 126 }
 127
 128 static struct platform_driver qnap_power_off_driver = {
 129         .probe  = qnap_power_off_probe,
 130         .remove = qnap_power_off_remove,
 131         .driver = {
 132                 .name   = "qnap_power_off",
 133                 .of_match_table = of_match_ptr(qnap_power_off_of_match_table),
 134         },
 135 };
 136 module_platform_driver(qnap_power_off_driver);
 137
 138 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
 139 MODULE_DESCRIPTION("QNAP Power off driver");
 140 MODULE_LICENSE("GPL v2");