LXR linux/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
  28struct power_off_cfg {
  29        u32 baud;
  30        char cmd;
  31};
  32
  33static const struct power_off_cfg qnap_power_off_cfg = {
  34        .baud = 19200,
  35        .cmd = 'A',
  36};
  37
  38static const struct power_off_cfg synology_power_off_cfg = {
  39        .baud = 9600,
  40        .cmd = '1',
  41};
  42
  43static 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};
  52MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
  53
  54static void __iomem *base;
  55static unsigned long tclk;
  56static const struct power_off_cfg *cfg;
  57
  58static 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
  77static 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
 122static int qnap_power_off_remove(struct platform_device *pdev)
 123{
 124        pm_power_off = NULL;
 125        return 0;
 126}
 127
 128static 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};
 136module_platform_driver(qnap_power_off_driver);
 137
 138MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
 139MODULE_DESCRIPTION("QNAP Power off driver");
 140MODULE_LICENSE("GPL v2");
 141