drivers/power/reset/qnap-poweroff.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * QNAP Turbo NAS Board power off. Can also be used on Synology devices.
   4  *
   5  * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
   6  *
   7  * Based on the code from:
   8  *
   9  * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
  10  * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/serial_reg.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/of.h>
  19 #include <linux/io.h>
  20 #include <linux/clk.h>
  21
  22 #define UART1_REG(x)    (base + ((UART_##x) << 2))
  23
  24 struct power_off_cfg {
  25         u32 baud;
  26         char cmd;
  27 };
  28
  29 static const struct power_off_cfg qnap_power_off_cfg = {
  30         .baud = 19200,
  31         .cmd = 'A',
  32 };
  33
  34 static const struct power_off_cfg synology_power_off_cfg = {
  35         .baud = 9600,
  36         .cmd = '1',
  37 };
  38
  39 static const struct of_device_id qnap_power_off_of_match_table[] = {
  40         { .compatible = "qnap,power-off",
  41           .data = &qnap_power_off_cfg,
  42         },
  43         { .compatible = "synology,power-off",
  44           .data = &synology_power_off_cfg,
  45         },
  46         {}
  47 };
  48 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
  49
  50 static void __iomem *base;
  51 static unsigned long tclk;
  52 static const struct power_off_cfg *cfg;
  53
  54 static void qnap_power_off(void)
  55 {
  56         const unsigned divisor = ((tclk + (8 * cfg->baud)) / (16 * cfg->baud));
  57
  58         pr_err("%s: triggering power-off...\n", __func__);
  59
  60         /* hijack UART1 and reset into sane state */
  61         writel(0x83, UART1_REG(LCR));
  62         writel(divisor & 0xff, UART1_REG(DLL));
  63         writel((divisor >> 8) & 0xff, UART1_REG(DLM));
  64         writel(0x03, UART1_REG(LCR));
  65         writel(0x00, UART1_REG(IER));
  66         writel(0x00, UART1_REG(FCR));
  67         writel(0x00, UART1_REG(MCR));
  68
  69         /* send the power-off command to PIC */
  70         writel(cfg->cmd, UART1_REG(TX));
  71 }
  72
  73 static int qnap_power_off_probe(struct platform_device *pdev)
  74 {
  75         struct device_node *np = pdev->dev.of_node;
  76         struct resource *res;
  77         struct clk *clk;
  78         char symname[KSYM_NAME_LEN];
  79
  80         const struct of_device_id *match =
  81                 of_match_node(qnap_power_off_of_match_table, np);
  82         cfg = match->data;
  83
  84         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  85         if (!res) {
  86                 dev_err(&pdev->dev, "Missing resource");
  87                 return -EINVAL;
  88         }
  89
  90         base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
  91         if (!base) {
  92                 dev_err(&pdev->dev, "Unable to map resource");
  93                 return -EINVAL;
  94         }
  95
  96         /* We need to know tclk in order to calculate the UART divisor */
  97         clk = devm_clk_get(&pdev->dev, NULL);
  98         if (IS_ERR(clk)) {
  99                 dev_err(&pdev->dev, "Clk missing");
 100                 return PTR_ERR(clk);
 101         }
 102
 103         tclk = clk_get_rate(clk);
 104
 105         /* Check that nothing else has already setup a handler */
 106         if (pm_power_off) {
 107                 lookup_symbol_name((ulong)pm_power_off, symname);
 108                 dev_err(&pdev->dev,
 109                         "pm_power_off already claimed %p %s",
 110                         pm_power_off, symname);
 111                 return -EBUSY;
 112         }
 113         pm_power_off = qnap_power_off;
 114
 115         return 0;
 116 }
 117
 118 static int qnap_power_off_remove(struct platform_device *pdev)
 119 {
 120         pm_power_off = NULL;
 121         return 0;
 122 }
 123
 124 static struct platform_driver qnap_power_off_driver = {
 125         .probe  = qnap_power_off_probe,
 126         .remove = qnap_power_off_remove,
 127         .driver = {
 128                 .name   = "qnap_power_off",
 129                 .of_match_table = of_match_ptr(qnap_power_off_of_match_table),
 130         },
 131 };
 132 module_platform_driver(qnap_power_off_driver);
 133
 134 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
 135 MODULE_DESCRIPTION("QNAP Power off driver");
 136 MODULE_LICENSE("GPL v2");